Google Git
Sign in
fuchsia / third_party / swift / da71432af404b88f758a5be58c9b4ed919f74a6d / . / lib / Sema / TypeCheckConstraints.cpp
blob: 30e18531661bd783e99487a1d99dc538c78288c1 [file] [log] [blame]
//===--- TypeCheckConstraints.cpp - Constraint-based Type Checking --------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
//
// This file provides high-level entry points that use constraint
// systems for type checking, as well as a few miscellaneous helper
// functions that support the constraint system.
//
//===----------------------------------------------------------------------===//
#include "ConstraintSystem.h"
#include "GenericTypeResolver.h"
#include "TypeChecker.h"
#include "MiscDiagnostics.h"
#include "swift/AST/ASTVisitor.h"
#include "swift/AST/ASTWalker.h"
#include "swift/AST/DiagnosticsParse.h"
#include "swift/AST/Initializer.h"
#include "swift/AST/NameLookup.h"
#include "swift/AST/PrettyStackTrace.h"
#include "swift/AST/SubstitutionMap.h"
#include "swift/AST/TypeCheckerDebugConsumer.h"
#include "swift/Parse/Lexer.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/FoldingSet.h"
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/Allocator.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/SaveAndRestore.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/Timer.h"
#include <iterator>
#include <map>
#include <memory>
#include <utility>
#include <tuple>
using namespace swift;
using namespace constraints;
//===----------------------------------------------------------------------===//
// Type variable implementation.
//===----------------------------------------------------------------------===//
#pragma mark Type variable implementation
void TypeVariableType::Implementation::print(llvm::raw_ostream &OS) {
getTypeVariable()->print(OS, PrintOptions());
}
SavedTypeVariableBinding::SavedTypeVariableBinding(TypeVariableType *typeVar)
: TypeVarAndOptions(typeVar, typeVar->getImpl().Options),
ParentOrFixed(typeVar->getImpl().ParentOrFixed) { }
void SavedTypeVariableBinding::restore() {
auto *typeVar = getTypeVariable();
typeVar->getImpl().Options = getOptions();
typeVar->getImpl().ParentOrFixed = ParentOrFixed;
}
ArchetypeType *TypeVariableType::Implementation::getArchetype() const {
// Check whether we have a path that terminates at an archetype locator.
if (!locator || locator->getPath().empty() ||
locator->getPath().back().getKind() != ConstraintLocator::Archetype)
return nullptr;
// Retrieve the archetype.
return locator->getPath().back().getArchetype();
}
// Only allow allocation of resolved overload set list items using the
// allocator in ASTContext.
void *ResolvedOverloadSetListItem::operator new(size_t bytes,
ConstraintSystem &cs,
unsigned alignment) {
return cs.getAllocator().Allocate(bytes, alignment);
}
void *operator new(size_t bytes, ConstraintSystem& cs,
size_t alignment) {
return cs.getAllocator().Allocate(bytes, alignment);
}
bool constraints::computeTupleShuffle(ArrayRef<TupleTypeElt> fromTuple,
ArrayRef<TupleTypeElt> toTuple,
SmallVectorImpl<int> &sources,
SmallVectorImpl<unsigned> &variadicArgs) {
const int unassigned = -3;
SmallVector<bool, 4> consumed(fromTuple.size(), false);
sources.clear();
variadicArgs.clear();
sources.assign(toTuple.size(), unassigned);
// Match up any named elements.
for (unsigned i = 0, n = toTuple.size(); i != n; ++i) {
const auto &toElt = toTuple[i];
// Skip unnamed elements.
if (!toElt.hasName())
continue;
// Find the corresponding named element.
int matched = -1;
{
int index = 0;
for (auto field : fromTuple) {
if (field.getName() == toElt.getName() && !consumed[index]) {
matched = index;
break;
}
++index;
}
}
if (matched == -1)
continue;
// Record this match.
sources[i] = matched;
consumed[matched] = true;
}
// Resolve any unmatched elements.
unsigned fromNext = 0, fromLast = fromTuple.size();
auto skipToNextAvailableInput = [&] {
while (fromNext != fromLast && consumed[fromNext])
++fromNext;
};
skipToNextAvailableInput();
for (unsigned i = 0, n = toTuple.size(); i != n; ++i) {
// Check whether we already found a value for this element.
if (sources[i] != unassigned)
continue;
const auto &elt2 = toTuple[i];
// Variadic tuple elements match the rest of the input elements.
if (elt2.isVararg()) {
// Collect the remaining (unnamed) inputs.
while (fromNext != fromLast) {
// Labeled elements can't be adopted into varargs even if
// they're non-mandatory. There isn't a really strong reason
// for this, though.
if (fromTuple[fromNext].hasName())
return true;
variadicArgs.push_back(fromNext);
consumed[fromNext] = true;
skipToNextAvailableInput();
}
sources[i] = TupleShuffleExpr::Variadic;
// Keep looking at subsequent arguments. Non-variadic arguments may
// follow the variadic one.
continue;
}
// If there aren't any more inputs, we are done.
if (fromNext == fromLast) {
return true;
}
// Otherwise, assign this input to the next output element.
// Fail if the input element is named and we're trying to match it with
// something with a different label.
if (fromTuple[fromNext].hasName() && elt2.hasName())
return true;
sources[i] = fromNext;
consumed[fromNext] = true;
skipToNextAvailableInput();
}
// Complain if we didn't reach the end of the inputs.
if (fromNext != fromLast) {
return true;
}
// If we got here, we should have claimed all the arguments.
assert(std::find(consumed.begin(), consumed.end(), false) == consumed.end());
return false;
}
Expr *ConstraintLocatorBuilder::trySimplifyToExpr() const {
SmallVector<LocatorPathElt, 4> pathBuffer;
Expr *anchor = getLocatorParts(pathBuffer);
ArrayRef<LocatorPathElt> path = pathBuffer;
Expr *targetAnchor;
SmallVector<LocatorPathElt, 4> targetPathBuffer;
SourceRange range;
simplifyLocator(anchor, path, targetAnchor, targetPathBuffer, range);
return (path.empty() ? anchor : nullptr);
}
//===----------------------------------------------------------------------===//
// High-level entry points.
//===----------------------------------------------------------------------===//
static unsigned getNumArgs(ValueDecl *value) {
if (!isa<FuncDecl>(value)) return ~0U;
AnyFunctionType *fnTy = value->getInterfaceType()->castTo<AnyFunctionType>();
if (value->getDeclContext()->isTypeContext())
fnTy = fnTy->getResult()->castTo<AnyFunctionType>();
Type argTy = fnTy->getInput();
if (auto tuple = argTy->getAs<TupleType>()) {
return tuple->getNumElements();
} else {
return 1;
}
}
static bool matchesDeclRefKind(ValueDecl *value, DeclRefKind refKind) {
if (value->getInterfaceType()->hasError())
return true;
switch (refKind) {
// An ordinary reference doesn't ignore anything.
case DeclRefKind::Ordinary:
return true;
// A binary-operator reference only honors FuncDecls with a certain type.
case DeclRefKind::BinaryOperator:
return (getNumArgs(value) == 2);
case DeclRefKind::PrefixOperator:
return (!value->getAttrs().hasAttribute<PostfixAttr>() &&
getNumArgs(value) == 1);
case DeclRefKind::PostfixOperator:
return (value->getAttrs().hasAttribute<PostfixAttr>() &&
getNumArgs(value) == 1);
}
llvm_unreachable("bad declaration reference kind");
}
static bool containsDeclRefKind(LookupResult &lookupResult,
DeclRefKind refKind) {
for (auto candidate : lookupResult) {
ValueDecl *D = candidate.Decl;
if (!D || !D->hasInterfaceType())
continue;
if (matchesDeclRefKind(D, refKind))
return true;
}
return false;
}
/// Emit a diagnostic with a fixit hint for an invalid binary operator, showing
/// how to split it according to splitCandidate.
static void diagnoseBinOpSplit(UnresolvedDeclRefExpr *UDRE,
std::pair<unsigned, bool> splitCandidate,
Diag<Identifier, Identifier, bool> diagID,
TypeChecker &TC) {
unsigned splitLoc = splitCandidate.first;
bool isBinOpFirst = splitCandidate.second;
StringRef nameStr = UDRE->getName().getBaseName().str();
auto startStr = nameStr.substr(0, splitLoc);
auto endStr = nameStr.drop_front(splitLoc);
// One valid split found, it is almost certainly the right answer.
auto diag = TC.diagnose(UDRE->getLoc(), diagID,
TC.Context.getIdentifier(startStr),
TC.Context.getIdentifier(endStr), isBinOpFirst);
// Highlight the whole operator.
diag.highlight(UDRE->getLoc());
// Insert whitespace on the left if the binop is at the start, or to the
// right if it is end.
if (isBinOpFirst)
diag.fixItInsert(UDRE->getLoc(), " ");
else
diag.fixItInsertAfter(UDRE->getLoc(), " ");
// Insert a space between the operators.
diag.fixItInsert(UDRE->getLoc().getAdvancedLoc(splitLoc), " ");
}
/// If we failed lookup of a binary operator, check to see it to see if
/// it is a binary operator juxtaposed with a unary operator (x*-4) that
/// needs whitespace. If so, emit specific diagnostics for it and return true,
/// otherwise return false.
static bool diagnoseOperatorJuxtaposition(UnresolvedDeclRefExpr *UDRE,
DeclContext *DC,
TypeChecker &TC) {
Identifier name = UDRE->getName().getBaseName();
StringRef nameStr = name.str();
if (!name.isOperator() || nameStr.size() < 2)
return false;
bool isBinOp = UDRE->getRefKind() == DeclRefKind::BinaryOperator;
// If this is a binary operator, relex the token, to decide whether it has
// whitespace around it or not. If it does "x +++ y", then it isn't likely to
// be a case where a space was forgotten.
if (isBinOp) {
auto tok = Lexer::getTokenAtLocation(TC.Context.SourceMgr, UDRE->getLoc());
if (tok.getKind() != tok::oper_binary_unspaced)
return false;
}
// Okay, we have a failed lookup of a multicharacter operator. Check to see if
// lookup succeeds if part is split off, and record the matches found.
//
// In the case of a binary operator, the bool indicated is false if the
// first half of the split is the unary operator (x!*4) or true if it is the
// binary operator (x*+4).
std::vector<std::pair<unsigned, bool>> WorkableSplits;
// Check all the potential splits.
for (unsigned splitLoc = 1, e = nameStr.size(); splitLoc != e; ++splitLoc) {
// For it to be a valid split, the start and end section must be valid
// operators, splitting a unicode code point isn't kosher.
auto startStr = nameStr.substr(0, splitLoc);
auto endStr = nameStr.drop_front(splitLoc);
if (!Lexer::isOperator(startStr) || !Lexer::isOperator(endStr))
continue;
auto startName = TC.Context.getIdentifier(startStr);
auto endName = TC.Context.getIdentifier(endStr);
// Perform name lookup for the first and second pieces. If either fail to
// be found, then it isn't a valid split.
NameLookupOptions LookupOptions = defaultUnqualifiedLookupOptions;
// This is only used for diagnostics, so always use KnownPrivate.
LookupOptions |= NameLookupFlags::KnownPrivate;
auto startLookup = TC.lookupUnqualified(DC, startName, UDRE->getLoc(),
LookupOptions);
if (!startLookup) continue;
auto endLookup = TC.lookupUnqualified(DC, endName, UDRE->getLoc(),
LookupOptions);
if (!endLookup) continue;
// If the overall operator is a binary one, then we're looking at
// juxtaposed binary and unary operators.
if (isBinOp) {
// Look to see if the candidates found could possibly match.
if (containsDeclRefKind(startLookup, DeclRefKind::PostfixOperator) &&
containsDeclRefKind(endLookup, DeclRefKind::BinaryOperator))
WorkableSplits.push_back({ splitLoc, false });
if (containsDeclRefKind(startLookup, DeclRefKind::BinaryOperator) &&
containsDeclRefKind(endLookup, DeclRefKind::PrefixOperator))
WorkableSplits.push_back({ splitLoc, true });
} else {
// Otherwise, it is two of the same kind, e.g. "!!x" or "!~x".
if (containsDeclRefKind(startLookup, UDRE->getRefKind()) &&
containsDeclRefKind(endLookup, UDRE->getRefKind()))
WorkableSplits.push_back({ splitLoc, false });
}
}
switch (WorkableSplits.size()) {
case 0:
// No splits found, can't produce this diagnostic.
return false;
case 1:
// One candidate: produce an error with a fixit on it.
if (isBinOp)
diagnoseBinOpSplit(UDRE, WorkableSplits[0],
diag::unspaced_binary_operator_fixit, TC);
else
TC.diagnose(UDRE->getLoc().getAdvancedLoc(WorkableSplits[0].first),
diag::unspaced_unary_operator);
return true;
default:
// Otherwise, we have to produce a series of notes listing the various
// options.
TC.diagnose(UDRE->getLoc(), isBinOp ? diag::unspaced_binary_operator :
diag::unspaced_unary_operator)
.highlight(UDRE->getLoc());
if (isBinOp) {
for (auto candidateSplit : WorkableSplits)
diagnoseBinOpSplit(UDRE, candidateSplit,
diag::unspaced_binary_operators_candidate, TC);
}
return true;
}
}
/// Bind an UnresolvedDeclRefExpr by performing name lookup and
/// returning the resultant expression. Context is the DeclContext used
/// for the lookup.
Expr *TypeChecker::
resolveDeclRefExpr(UnresolvedDeclRefExpr *UDRE, DeclContext *DC) {
// Process UnresolvedDeclRefExpr by doing an unqualified lookup.
DeclName Name = UDRE->getName();
SourceLoc Loc = UDRE->getLoc();
// Perform standard value name lookup.
NameLookupOptions lookupOptions = defaultUnqualifiedLookupOptions;
if (isa<AbstractFunctionDecl>(DC))
lookupOptions |= NameLookupFlags::KnownPrivate;
auto Lookup = lookupUnqualified(DC, Name, Loc, lookupOptions);
if (!Lookup) {
// If we failed lookup of an operator, check to see it to see if it is
// because two operators are juxtaposed e.g. (x*-4) that needs whitespace.
// If so, emit specific diagnostics for it.
if (diagnoseOperatorJuxtaposition(UDRE, DC, *this)) {
return new (Context) ErrorExpr(UDRE->getSourceRange());
}
// Try ignoring access control.
NameLookupOptions relookupOptions = lookupOptions;
relookupOptions |= NameLookupFlags::KnownPrivate;
relookupOptions |= NameLookupFlags::IgnoreAccessibility;
LookupResult inaccessibleResults = lookupUnqualified(DC, Name, Loc,
relookupOptions);
if (inaccessibleResults) {
// FIXME: What if the unviable candidates have different levels of access?
const ValueDecl *first = inaccessibleResults.front().Decl;
diagnose(Loc, diag::candidate_inaccessible,
Name, first->getFormalAccess());
// FIXME: If any of the candidates (usually just one) are in the same
// module we could offer a fix-it.
for (auto lookupResult : inaccessibleResults) {
diagnose(lookupResult.Decl, diag::decl_declared_here,
lookupResult.Decl->getFullName());
}
// Don't try to recover here; we'll get more access-related diagnostics
// downstream if the type of the inaccessible decl is also inaccessible.
return new (Context) ErrorExpr(UDRE->getSourceRange());
}
// TODO: Name will be a compound name if it was written explicitly as
// one, but we should also try to propagate labels into this.
DeclNameLoc nameLoc = UDRE->getNameLoc();
performTypoCorrection(DC, UDRE->getRefKind(), Type(), Name, Loc,
lookupOptions, Lookup);
diagnose(Loc, diag::use_unresolved_identifier, Name, Name.isOperator())
.highlight(UDRE->getSourceRange());
// Note all the correction candidates.
for (auto &result : Lookup) {
noteTypoCorrection(Name, nameLoc, result);
}
// TODO: consider recovering from here. We may want some way to suppress
// downstream diagnostics, though.
return new (Context) ErrorExpr(UDRE->getSourceRange());
}
// FIXME: Need to refactor the way we build an AST node from a lookup result!
bool AllDeclRefs = true;
SmallVector<ValueDecl*, 4> ResultValues;
for (auto Result : Lookup) {
// If we find a member, then all of the results aren't non-members.
bool IsMember = Result.Base && !isa<ModuleDecl>(Result.Base);
if (IsMember && !isa<TypeDecl>(Result.Decl)) {
AllDeclRefs = false;
break;
}
ValueDecl *D = Result.Decl;
if (!D->hasInterfaceType()) validateDecl(D);
// FIXME: Circularity hack.
if (!D->hasInterfaceType()) {
AllDeclRefs = false;
continue;
}
// FIXME: The source-location checks won't make sense once
// EnableASTScopeLookup is the default.
if (Loc.isValid() && D->getLoc().isValid() &&
D->getDeclContext()->isLocalContext() &&
D->getDeclContext() == DC &&
Context.SourceMgr.isBeforeInBuffer(Loc, D->getLoc())) {
if (!D->isInvalid()) {
diagnose(Loc, diag::use_local_before_declaration, Name);
diagnose(D, diag::decl_declared_here, Name);
}
return new (Context) ErrorExpr(UDRE->getSourceRange());
}
if (matchesDeclRefKind(D, UDRE->getRefKind()))
ResultValues.push_back(D);
}
// If we have an unambiguous reference to a type decl, form a TypeExpr. This
// doesn't handle specialized decls since they are processed when the
// UnresolvedSpecializeExpr is seen.
if (!UDRE->isSpecialized() &&
ResultValues.size() == 1 && UDRE->getRefKind() == DeclRefKind::Ordinary &&
isa<TypeDecl>(ResultValues[0])) {
// FIXME: This is odd.
if (isa<ModuleDecl>(ResultValues[0])) {
return new (Context) DeclRefExpr(ResultValues[0], UDRE->getNameLoc(),
/*Implicit=*/false,
AccessSemantics::Ordinary,
ResultValues[0]->getInterfaceType());
}
return TypeExpr::createForDecl(Loc, cast<TypeDecl>(ResultValues[0]),
UDRE->isImplicit());
}
if (AllDeclRefs) {
// Diagnose uses of operators that found no matching candidates.
if (ResultValues.empty()) {
assert(UDRE->getRefKind() != DeclRefKind::Ordinary);
diagnose(Loc, diag::use_nonmatching_operator, Name.getBaseName(),
UDRE->getRefKind() == DeclRefKind::BinaryOperator ? 0 :
UDRE->getRefKind() == DeclRefKind::PrefixOperator ? 1 : 2);
return new (Context) ErrorExpr(UDRE->getSourceRange());
}
// For operators, sort the results so that non-generic operations come
// first.
// Note: this is part of a performance hack to prefer non-generic operators
// to generic operators, because the former is far more efficient to check.
if (UDRE->getRefKind() != DeclRefKind::Ordinary) {
std::stable_sort(ResultValues.begin(), ResultValues.end(),
[&](ValueDecl *x, ValueDecl *y) -> bool {
auto xGeneric = x->getInterfaceType()->getAs<GenericFunctionType>();
auto yGeneric = y->getInterfaceType()->getAs<GenericFunctionType>();
if (static_cast<bool>(xGeneric) != static_cast<bool>(yGeneric)) {
return xGeneric? false : true;
}
if (!xGeneric)
return false;
unsigned xDepth = xGeneric->getGenericParams().back()->getDepth();
unsigned yDepth = yGeneric->getGenericParams().back()->getDepth();
return xDepth < yDepth;
});
}
return buildRefExpr(ResultValues, DC, UDRE->getNameLoc(),
UDRE->isImplicit(), UDRE->isSpecialized(),
UDRE->getFunctionRefKind());
}
ResultValues.clear();
bool AllMemberRefs = true;
ValueDecl *Base = nullptr;
for (auto Result : Lookup) {
// Track the base for member declarations.
if (Result.Base && !isa<ModuleDecl>(Result.Base)) {
ResultValues.push_back(Result.Decl);
if (Base && Result.Base != Base) {
AllMemberRefs = false;
break;
}
Base = Result.Base;
continue;
}
AllMemberRefs = false;
break;
}
if (AllMemberRefs) {
Expr *BaseExpr;
if (auto NTD = dyn_cast<NominalTypeDecl>(Base)) {
BaseExpr = TypeExpr::createForDecl(Loc, NTD, /*isImplicit=*/true);
} else {
BaseExpr = new (Context) DeclRefExpr(Base, UDRE->getNameLoc(),
/*Implicit=*/true);
}
// Otherwise, form an UnresolvedDotExpr and sema will resolve it based on
// type information.
return new (Context) UnresolvedDotExpr(BaseExpr, SourceLoc(), Name,
UDRE->getNameLoc(),
UDRE->isImplicit());
}
// FIXME: If we reach this point, the program we're being handed is likely
// very broken, but it's still conceivable that this may happen due to
// invalid shadowed declarations.
// llvm_unreachable("Can't represent lookup result");
return new (Context) ErrorExpr(UDRE->getSourceRange());
}
/// If an expression references 'self.init' or 'super.init' in an
/// initializer context, returns the implicit 'self' decl of the constructor.
/// Otherwise, return nil.
VarDecl *
TypeChecker::getSelfForInitDelegationInConstructor(DeclContext *DC,
UnresolvedDotExpr *ctorRef) {
// If the reference isn't to a constructor, we're done.
if (ctorRef->getName().getBaseName() != Context.Id_init)
return nullptr;
if (auto ctorContext
= dyn_cast_or_null<ConstructorDecl>(DC->getInnermostMethodContext())) {
auto nestedArg = ctorRef->getBase();
if (auto inout = dyn_cast<InOutExpr>(nestedArg))
nestedArg = inout->getSubExpr();
if (nestedArg->isSuperExpr())
return ctorContext->getImplicitSelfDecl();
if (auto declRef = dyn_cast<DeclRefExpr>(nestedArg))
if (declRef->getDecl()->getName() == Context.Id_self)
return ctorContext->getImplicitSelfDecl();
}
return nullptr;
}
namespace {
/// Update the function reference kind based on adding a direct call to a
/// callee with this kind.
FunctionRefKind addingDirectCall(FunctionRefKind kind) {
switch (kind) {
case FunctionRefKind::Unapplied:
return FunctionRefKind::SingleApply;
case FunctionRefKind::SingleApply:
case FunctionRefKind::DoubleApply:
return FunctionRefKind::DoubleApply;
case FunctionRefKind::Compound:
return FunctionRefKind::Compound;
}
llvm_unreachable("Unhandled FunctionRefKind in switch.");
}
/// Update a direct callee expression node that has a function reference kind
/// based on seeing a call to this callee.
template<typename E,
typename = decltype(((E*)nullptr)->getFunctionRefKind())>
void tryUpdateDirectCalleeImpl(E *callee, int) {
callee->setFunctionRefKind(addingDirectCall(callee->getFunctionRefKind()));
}
/// Version of tryUpdateDirectCalleeImpl for when the callee
/// expression type doesn't carry a reference.
template<typename E>
void tryUpdateDirectCalleeImpl(E *callee, ...) { }
/// The given expression is the direct callee of a call expression; mark it to
/// indicate that it has been called.
void markDirectCallee(Expr *callee) {
while (true) {
// Look through identity expressions.
if (auto identity = dyn_cast<IdentityExpr>(callee)) {
callee = identity->getSubExpr();
continue;
}
// Look through unresolved 'specialize' expressions.
if (auto specialize = dyn_cast<UnresolvedSpecializeExpr>(callee)) {
callee = specialize->getSubExpr();
continue;
}
// Look through optional binding.
if (auto bindOptional = dyn_cast<BindOptionalExpr>(callee)) {
callee = bindOptional->getSubExpr();
continue;
}
// Look through forced binding.
if (auto force = dyn_cast<ForceValueExpr>(callee)) {
callee = force->getSubExpr();
continue;
}
// Calls compose.
if (auto call = dyn_cast<CallExpr>(callee)) {
callee = call->getFn();
continue;
}
// Coercions can be used for disambiguation.
if (auto coerce = dyn_cast<CoerceExpr>(callee)) {
callee = coerce->getSubExpr();
continue;
}
// We're done.
break;
}
// Cast the callee to its most-specific class, then try to perform an
// update. If the expression node has a declaration reference in it, the
// update will succeed. Otherwise, we're done propagating.
switch (callee->getKind()) {
#define EXPR(Id, Parent) \
case ExprKind::Id: \
tryUpdateDirectCalleeImpl(cast<Id##Expr>(callee), 0); \
break;
#include "swift/AST/ExprNodes.def"
}
}
class PreCheckExpression : public ASTWalker {
TypeChecker &TC;
DeclContext *DC;
/// A stack of expressions being walked, used to determine where to
/// insert RebindSelfInConstructorExpr nodes.
llvm::SmallVector<Expr *, 8> ExprStack;
/// The 'self' variable to use when rebinding 'self' in a constructor.
VarDecl *UnresolvedCtorSelf = nullptr;
/// The expression that will be wrapped by a RebindSelfInConstructorExpr
/// node when visited.
Expr *UnresolvedCtorRebindTarget = nullptr;
/// The expressions that are direct arguments of call expressions.
llvm::SmallPtrSet<Expr *, 4> CallArgs;
public:
PreCheckExpression(TypeChecker &tc, DeclContext *dc) : TC(tc), DC(dc) { }
bool walkToClosureExprPre(ClosureExpr *expr);
std::pair<bool, Expr *> walkToExprPre(Expr *expr) override {
// If this is a call, record the argument expression.
if (auto call = dyn_cast<CallExpr>(expr)) {
CallArgs.insert(call->getArg());
}
// If this is an unresolved member with a call argument (e.g.,
// .some(x)), record the argument expression.
if (auto unresolvedMember = dyn_cast<UnresolvedMemberExpr>(expr)) {
if (auto arg = unresolvedMember->getArgument())
CallArgs.insert(arg);
}
// Local function used to finish up processing before returning. Every
// return site should call through here.
auto finish = [&](bool recursive, Expr *expr) {
// If we're going to recurse, record this expression on the stack.
if (recursive)
ExprStack.push_back(expr);
return std::make_pair(recursive, expr);
};
// For capture lists, we typecheck the decls they contain.
if (auto captureList = dyn_cast<CaptureListExpr>(expr)) {
// Validate the capture list.
for (auto capture : captureList->getCaptureList()) {
TC.typeCheckDecl(capture.Init, true);
TC.typeCheckDecl(capture.Init, false);
TC.typeCheckDecl(capture.Var, true);
TC.typeCheckDecl(capture.Var, false);
}
return finish(true, expr);
}
// For closures, type-check the patterns and result type as written,
// but do not walk into the body. That will be type-checked after
// we've determine the complete function type.
if (auto closure = dyn_cast<ClosureExpr>(expr))
return finish(walkToClosureExprPre(closure), expr);
if (auto unresolved = dyn_cast<UnresolvedDeclRefExpr>(expr)) {
TC.checkForForbiddenPrefix(unresolved);
return finish(true, TC.resolveDeclRefExpr(unresolved, DC));
}
if (auto PlaceholderE = dyn_cast<EditorPlaceholderExpr>(expr)) {
if (!PlaceholderE->getTypeLoc().isNull()) {
if (!TC.validateType(PlaceholderE->getTypeLoc(), DC))
expr->setType(PlaceholderE->getTypeLoc().getType());
}
return finish(true, expr);
}
return finish(true, expr);
}
Expr *walkToExprPost(Expr *expr) override {
// Remove this expression from the stack.
assert(ExprStack.back() == expr);
ExprStack.pop_back();
// Mark the direct callee as being a callee.
if (auto call = dyn_cast<CallExpr>(expr))
markDirectCallee(call->getFn());
// Fold sequence expressions.
if (auto seqExpr = dyn_cast<SequenceExpr>(expr)) {
auto result = TC.foldSequence(seqExpr, DC);
return result->walk(*this);
}
// Type check the type parameters in an UnresolvedSpecializeExpr.
if (auto us = dyn_cast<UnresolvedSpecializeExpr>(expr)) {
for (TypeLoc &type : us->getUnresolvedParams()) {
if (TC.validateType(type, DC))
return nullptr;
}
// If this is a reference type a specialized type, form a TypeExpr.
if (auto *dre = dyn_cast<DeclRefExpr>(us->getSubExpr())) {
if (auto *TD = dyn_cast<TypeDecl>(dre->getDecl())) {
SmallVector<TypeRepr*, 4> TypeReprs;
for (auto elt : us->getUnresolvedParams())
TypeReprs.push_back(elt.getTypeRepr());
auto angles = SourceRange(us->getLAngleLoc(), us->getRAngleLoc());
return TypeExpr::createForSpecializedDecl(dre->getLoc(),
TD,
TC.Context.AllocateCopy(TypeReprs),
angles);
}
}
return expr;
}
// If we're about to step out of a ClosureExpr, restore the DeclContext.
if (auto *ce = dyn_cast<ClosureExpr>(expr)) {
assert(DC == ce && "DeclContext imbalance");
DC = ce->getParent();
}
// Strip off any AutoClosures that were produced by a previous type check
// so that we don't choke in CSGen.
// FIXME: we shouldn't double typecheck, but it looks like code completion
// may do so in some circumstances. rdar://21466394
if (auto autoClosure = dyn_cast<AutoClosureExpr>(expr))
return autoClosure->getSingleExpressionBody();
// A 'self.init' or 'super.init' application inside a constructor will
// evaluate to void, with the initializer's result implicitly rebound
// to 'self'. Recognize the unresolved constructor expression and
// determine where to place the RebindSelfInConstructorExpr node.
// When updating this logic, also update
// RebindSelfInConstructorExpr::getCalledConstructor.
if (auto unresolvedDot = dyn_cast<UnresolvedDotExpr>(expr)) {
if (auto self
= TC.getSelfForInitDelegationInConstructor(DC, unresolvedDot)) {
// Walk our ancestor expressions looking for the appropriate place
// to insert the RebindSelfInConstructorExpr.
Expr *target = nullptr;
bool foundApply = false;
bool foundRebind = false;
for (auto ancestor : reversed(ExprStack)) {
if (isa<RebindSelfInConstructorExpr>(ancestor)) {
// If we already have a rebind, then we're re-typechecking an
// expression and are done.
foundRebind = true;
break;
}
// Recognize applications.
if (auto apply = dyn_cast<ApplyExpr>(ancestor)) {
// If we already saw an application, we're done.
if (foundApply)
break;
// If the function being called is not our unresolved initializer
// reference, we're done.
if (apply->getSemanticFn() != unresolvedDot)
break;
foundApply = true;
target = ancestor;
continue;
}
// Look through identity, force-value, and 'try' expressions.
if (isa<IdentityExpr>(ancestor) ||
isa<ForceValueExpr>(ancestor) ||
isa<AnyTryExpr>(ancestor)) {
if (target)
target = ancestor;
continue;
}
// No other expression kinds are permitted.
break;
}
// If we found a rebind target, note the insertion point.
if (target && !foundRebind) {
UnresolvedCtorRebindTarget = target;
UnresolvedCtorSelf = self;
}
}
}
// If the expression we've found is the intended target of an
// RebindSelfInConstructorExpr, wrap it in the
// RebindSelfInConstructorExpr.
if (expr == UnresolvedCtorRebindTarget) {
expr = new (TC.Context) RebindSelfInConstructorExpr(expr,
UnresolvedCtorSelf);
UnresolvedCtorRebindTarget = nullptr;
return expr;
}
// Double check if there are any BindOptionalExpr remaining in the
// tree (see comment below for more details), if there are no BOE
// expressions remaining remove OptionalEvaluationExpr from the tree.
if (auto OEE = dyn_cast<OptionalEvaluationExpr>(expr)) {
bool hasBindOptional = false;
OEE->forEachChildExpr([&](Expr *expr) -> Expr * {
if (isa<BindOptionalExpr>(expr))
hasBindOptional = true;
// If at least a single BOE was found, no reason
// to walk any further in the tree.
return hasBindOptional ? nullptr : expr;
});
return hasBindOptional ? OEE : OEE->getSubExpr();
}
// Check if there are any BindOptionalExpr in the tree which
// wrap DiscardAssignmentExpr, such situation corresponds to syntax
// like - `_? = <value>`, since it doesn't really make
// sense to have optional assignment to discarded LValue which can
// never be optional, we can remove BOE from the tree and avoid
// generating any of the unnecessary constraints.
if (auto BOE = dyn_cast<BindOptionalExpr>(expr)) {
if (auto DAE = dyn_cast<DiscardAssignmentExpr>(BOE->getSubExpr()))
return DAE;
}
// If this is a sugared type that needs to be folded into a single
// TypeExpr, do it.
if (auto *simplified = simplifyTypeExpr(expr))
return simplified;
return expr;
}
std::pair<bool, Stmt *> walkToStmtPre(Stmt *stmt) override {
// Never walk into statements.
return { false, stmt };
}
/// Simplify expressions which are type sugar productions that got parsed
/// as expressions due to the parser not knowing which identifiers are
/// type names.
TypeExpr *simplifyTypeExpr(Expr *E);
};
} // end anonymous namespace
/// Perform prechecking of a ClosureExpr before we dive into it. This returns
/// true for single-expression closures, where we want the body to be considered
/// part of this larger expression.
bool PreCheckExpression::walkToClosureExprPre(ClosureExpr *closure) {
auto *PL = closure->getParameters();
// Validate the parameters.
TypeResolutionOptions options;
options |= TR_AllowUnspecifiedTypes;
options |= TR_AllowUnboundGenerics;
options |= TR_InExpression;
bool hadParameterError = false;
GenericTypeToArchetypeResolver resolver(closure);
if (TC.typeCheckParameterList(PL, DC, options, resolver)) {
closure->setType(ErrorType::get(TC.Context));
// If we encounter an error validating the parameter list, don't bail.
// Instead, go on to validate any potential result type, and bail
// afterwards. This allows for better diagnostics, and keeps the
// closure expression type well-formed.
hadParameterError = true;
}
// Validate the result type, if present.
if (closure->hasExplicitResultType() &&
TC.validateType(closure->getExplicitResultTypeLoc(), DC,
TR_InExpression, &resolver)) {
closure->setType(ErrorType::get(TC.Context));
return false;
}
if (hadParameterError)
return false;
// If the closure has a multi-statement body, we don't walk into it
// here.
if (!closure->hasSingleExpressionBody())
return false;
// Update the current DeclContext to be the closure we're about to
// recurse into.
assert(DC == closure->getParent() && "Decl context isn't correct");
DC = closure;
return true;
}
/// Simplify expressions which are type sugar productions that got parsed
/// as expressions due to the parser not knowing which identifiers are
/// type names.
TypeExpr *PreCheckExpression::simplifyTypeExpr(Expr *E) {
// Don't try simplifying a call argument, because we don't want to
// simplify away the required ParenExpr/TupleExpr.
if (CallArgs.count(E) > 0) return nullptr;
// Fold 'T.Type' or 'T.Protocol' into a metatype when T is a TypeExpr.
if (auto *MRE = dyn_cast<UnresolvedDotExpr>(E)) {
auto *TyExpr = dyn_cast<TypeExpr>(MRE->getBase());
if (!TyExpr) return nullptr;
auto *InnerTypeRepr = TyExpr->getTypeRepr();
if (MRE->getName() == TC.Context.Id_Protocol) {
assert(!TyExpr->isImplicit() && InnerTypeRepr &&
"This doesn't work on implicit TypeExpr's, "
"TypeExpr should have been built correctly in the first place");
auto *NewTypeRepr =
new (TC.Context) ProtocolTypeRepr(InnerTypeRepr,
MRE->getNameLoc().getBaseNameLoc());
return new (TC.Context) TypeExpr(TypeLoc(NewTypeRepr, Type()));
}
if (MRE->getName() == TC.Context.Id_Type) {
assert(!TyExpr->isImplicit() && InnerTypeRepr &&
"This doesn't work on implicit TypeExpr's, "
"TypeExpr should have been built correctly in the first place");
auto *NewTypeRepr =
new (TC.Context) MetatypeTypeRepr(InnerTypeRepr,
MRE->getNameLoc().getBaseNameLoc());
return new (TC.Context) TypeExpr(TypeLoc(NewTypeRepr, Type()));
}
}
// Fold T? into an optional type when T is a TypeExpr.
if (isa<OptionalEvaluationExpr>(E) || isa<BindOptionalExpr>(E)) {
TypeExpr *TyExpr;
SourceLoc QuestionLoc;
if (auto *OOE = dyn_cast<OptionalEvaluationExpr>(E)) {
TyExpr = dyn_cast<TypeExpr>(OOE->getSubExpr());
QuestionLoc = OOE->getLoc();
} else {
TyExpr = dyn_cast<TypeExpr>(cast<BindOptionalExpr>(E)->getSubExpr());
QuestionLoc = cast<BindOptionalExpr>(E)->getQuestionLoc();
}
if (!TyExpr) return nullptr;
auto *InnerTypeRepr = TyExpr->getTypeRepr();
assert(!TyExpr->isImplicit() && InnerTypeRepr &&
"This doesn't work on implicit TypeExpr's, "
"the TypeExpr should have been built correctly in the first place");
// The optional evaluation is passed through.
if (isa<OptionalEvaluationExpr>(E))
return TyExpr;
auto *NewTypeRepr =
new (TC.Context) OptionalTypeRepr(InnerTypeRepr, QuestionLoc);
return new (TC.Context) TypeExpr(TypeLoc(NewTypeRepr, Type()));
}
// Fold T! into an IUO type when T is a TypeExpr.
if (auto *FVE = dyn_cast<ForceValueExpr>(E)) {
auto *TyExpr = dyn_cast<TypeExpr>(FVE->getSubExpr());
if (!TyExpr) return nullptr;
auto *InnerTypeRepr = TyExpr->getTypeRepr();
assert(!TyExpr->isImplicit() && InnerTypeRepr &&
"This doesn't work on implicit TypeExpr's, "
"the TypeExpr should have been built correctly in the first place");
auto *NewTypeRepr =
new (TC.Context) ImplicitlyUnwrappedOptionalTypeRepr(InnerTypeRepr,
FVE->getExclaimLoc());
return new (TC.Context) TypeExpr(TypeLoc(NewTypeRepr, Type()));
}
// Fold (T) into a type T with parens around it.
if (auto *PE = dyn_cast<ParenExpr>(E)) {
auto *TyExpr = dyn_cast<TypeExpr>(PE->getSubExpr());
if (!TyExpr) return nullptr;
TypeRepr *InnerTypeRepr[] = { TyExpr->getTypeRepr() };
assert(!TyExpr->isImplicit() && InnerTypeRepr[0] &&
"SubscriptExpr doesn't work on implicit TypeExpr's, "
"the TypeExpr should have been built correctly in the first place");
auto *NewTypeRepr = TupleTypeRepr::create(TC.Context, InnerTypeRepr,
PE->getSourceRange());
return new (TC.Context) TypeExpr(TypeLoc(NewTypeRepr, Type()));
}
// Fold a tuple expr like (T1,T2) into a tuple type (T1,T2).
if (auto *TE = dyn_cast<TupleExpr>(E)) {
if (TE->hasTrailingClosure() ||
// FIXME: Decide what to do about (). It could be a type or an expr.
TE->getNumElements() == 0)
return nullptr;
SmallVector<TypeRepr *, 4> Elts;
SmallVector<Identifier, 4> EltNames;
SmallVector<SourceLoc, 4> EltNameLocs;
unsigned EltNo = 0;
for (auto Elt : TE->getElements()) {
auto *eltTE = dyn_cast<TypeExpr>(Elt);
if (!eltTE) return nullptr;
assert(eltTE->getTypeRepr() && !eltTE->isImplicit() &&
"This doesn't work on implicit TypeExpr's, the "
"TypeExpr should have been built correctly in the first place");
// If the tuple element has a label, propagate it.
auto *eltTR = eltTE->getTypeRepr();
Identifier name = TE->getElementName(EltNo);
if (!name.empty()) {
if (EltNames.empty()) {
EltNames.resize(TE->getNumElements());
EltNameLocs.resize(TE->getNumElements());
}
EltNames[EltNo] = name;
EltNameLocs[EltNo] = TE->getElementNameLoc(EltNo);
}
Elts.push_back(eltTR);
++EltNo;
}
auto *NewTypeRepr = TupleTypeRepr::create(TC.Context, Elts,
TE->getSourceRange(),
EltNames, EltNameLocs, {},
SourceLoc(), Elts.size());
return new (TC.Context) TypeExpr(TypeLoc(NewTypeRepr, Type()));
}
// Fold [T] into an array type.
if (auto *AE = dyn_cast<ArrayExpr>(E)) {
if (AE->getElements().size() != 1)
return nullptr;
TypeExpr *TyExpr = dyn_cast<TypeExpr>(AE->getElement(0));
if (!TyExpr)
return nullptr;
auto *NewTypeRepr =
new (TC.Context) ArrayTypeRepr(TyExpr->getTypeRepr(),
SourceRange(AE->getLBracketLoc(),
AE->getRBracketLoc()));
return new (TC.Context) TypeExpr(TypeLoc(NewTypeRepr, Type()));
}
// Fold [K : V] into a dictionary type.
if (auto *DE = dyn_cast<DictionaryExpr>(E)) {
if (DE->getElements().size() != 1)
return nullptr;
TypeRepr *keyTypeRepr, *valueTypeRepr;
if (auto EltTuple = dyn_cast<TupleExpr>(DE->getElement(0))) {
TypeExpr *KeyTyExpr = dyn_cast<TypeExpr>(EltTuple->getElement(0));
if (!KeyTyExpr)
return nullptr;
TypeExpr *ValueTyExpr = dyn_cast<TypeExpr>(EltTuple->getElement(1));
if (!ValueTyExpr)
return nullptr;
keyTypeRepr = KeyTyExpr->getTypeRepr();
valueTypeRepr = ValueTyExpr->getTypeRepr();
} else {
auto *TE = dyn_cast<TypeExpr>(DE->getElement(0));
if (!TE) return nullptr;
auto *TRE = dyn_cast_or_null<TupleTypeRepr>(TE->getTypeRepr());
if (!TRE || TRE->getEllipsisLoc().isValid()) return nullptr;
while (TRE->isParenType()) {
TRE = dyn_cast_or_null<TupleTypeRepr>(TRE->getElement(0));
if (!TRE || TRE->getEllipsisLoc().isValid()) return nullptr;
}
assert(TRE->getElements().size() == 2);
keyTypeRepr = TRE->getElement(0);
valueTypeRepr = TRE->getElement(1);
}
auto *NewTypeRepr =
new (TC.Context) DictionaryTypeRepr(keyTypeRepr, valueTypeRepr,
/*FIXME:colonLoc=*/SourceLoc(),
SourceRange(DE->getLBracketLoc(),
DE->getRBracketLoc()));
return new (TC.Context) TypeExpr(TypeLoc(NewTypeRepr, Type()));
}
// Reinterpret arrow expr T1 -> T2 as function type.
// FIXME: support 'inout', etc.
if (auto *AE = dyn_cast<ArrowExpr>(E)) {
if (!AE->isFolded()) return nullptr;
auto extractTypeRepr = [&](Expr *E) -> TypeRepr * {
if (!E)
return nullptr;
if (auto *TyE = dyn_cast<TypeExpr>(E))
return TyE->getTypeRepr();
if (auto *TE = dyn_cast<TupleExpr>(E))
if (TE->getNumElements() == 0)
return TupleTypeRepr::createEmpty(TC.Context, TE->getSourceRange());
// When simplifying a type expr like "P1 & P2 -> P3 & P4 -> Int",
// it may have been folded at the same time; recursively simplify it.
if (auto ArgsTypeExpr = simplifyTypeExpr(E))
return ArgsTypeExpr->getTypeRepr();
return nullptr;
};
TypeRepr *ArgsTypeRepr = extractTypeRepr(AE->getArgsExpr());
if (!ArgsTypeRepr) {
TC.diagnose(AE->getArgsExpr()->getLoc(),
diag::expected_type_before_arrow);
ArgsTypeRepr =
new (TC.Context) ErrorTypeRepr(AE->getArgsExpr()->getSourceRange());
}
TypeRepr *ResultTypeRepr = extractTypeRepr(AE->getResultExpr());
if (!ResultTypeRepr) {
TC.diagnose(AE->getResultExpr()->getLoc(),
diag::expected_type_after_arrow);
ResultTypeRepr =
new (TC.Context) ErrorTypeRepr(AE->getResultExpr()->getSourceRange());
}
auto NewTypeRepr =
new (TC.Context) FunctionTypeRepr(nullptr, ArgsTypeRepr,
AE->getThrowsLoc(), AE->getArrowLoc(),
ResultTypeRepr);
return new (TC.Context) TypeExpr(TypeLoc(NewTypeRepr, Type()));
}
// Fold 'P & Q' into a composition type
if (auto *binaryExpr = dyn_cast<BinaryExpr>(E)) {
bool isComposition = false;
// look at the name of the operator, if it is a '&' we can create the
// composition TypeExpr
auto fn = binaryExpr->getFn();
if (auto Overload = dyn_cast<OverloadedDeclRefExpr>(fn)) {
for (auto Decl : Overload->getDecls())
if (Decl->getName().str() == "&") {
isComposition = true;
break;
}
} else if (auto *Decl = dyn_cast<UnresolvedDeclRefExpr>(fn)) {
if (Decl->getName().isSimpleName() &&
Decl->getName().getBaseName().str() == "&")
isComposition = true;
}
if (isComposition) {
// The protocols we are composing
SmallVector<TypeRepr *, 4> Types;
auto lhsExpr = binaryExpr->getArg()->getElement(0);
if (auto *lhs = dyn_cast<TypeExpr>(lhsExpr)) {
Types.push_back(lhs->getTypeRepr());
} else if (isa<BinaryExpr>(lhsExpr)) {
// If the lhs is another binary expression, we have a multi element
// composition: 'A & B & C' is parsed as ((A & B) & C); we get
// the protocols from the lhs here
if (auto expr = simplifyTypeExpr(lhsExpr))
if (auto *repr = dyn_cast<CompositionTypeRepr>(expr->getTypeRepr()))
// add the protocols to our list
for (auto proto : repr->getTypes())
Types.push_back(proto);
else
return nullptr;
else
return nullptr;
}
// Add the rhs which is just a TypeExpr
auto *rhs = dyn_cast<TypeExpr>(binaryExpr->getArg()->getElement(1));
if (!rhs) return nullptr;
Types.push_back(rhs->getTypeRepr());
auto CompRepr = new (TC.Context) CompositionTypeRepr(
TC.Context.AllocateCopy(Types),
lhsExpr->getStartLoc(), binaryExpr->getSourceRange());
return new (TC.Context) TypeExpr(TypeLoc(CompRepr, Type()));
}
}
return nullptr;
}
/// \brief Clean up the given ill-formed expression, removing any references
/// to type variables and setting error types on erroneous expression nodes.
void CleanupIllFormedExpressionRAII::doIt(Expr *expr, ASTContext &Context) {
class CleanupIllFormedExpression : public ASTWalker {
ASTContext &context;
public:
CleanupIllFormedExpression(ASTContext &context) : context(context) { }
std::pair<bool, Expr *> walkToExprPre(Expr *expr) override {
// If the type of this expression has a type variable or is invalid,
// overwrite it with ErrorType.
Type type = expr->getType();
if (!type || type->hasTypeVariable())
expr->setType(ErrorType::get(context));
return { true, expr };
}
// If we find a TypeLoc (e.g. in an as? expr) with a type variable, rewrite
// it.
bool walkToTypeLocPre(TypeLoc &TL) override {
if (TL.getType() && TL.getType()->hasTypeVariable())
TL.setType(Type(), /*was validated*/false);
return true;
}
bool walkToDeclPre(Decl *D) override {
// This handles parameter decls in ClosureExprs.
if (auto VD = dyn_cast<VarDecl>(D)) {
if (VD->hasType() && VD->getType()->hasTypeVariable()) {
VD->markInvalid();
}
}
return true;
}
// Don't walk into statements. This handles the BraceStmt in
// non-single-expr closures, so we don't walk into their body.
std::pair<bool, Stmt *> walkToStmtPre(Stmt *S) override {
return { false, S };
}
};
if (expr)
expr->walk(CleanupIllFormedExpression(Context));
}
CleanupIllFormedExpressionRAII::~CleanupIllFormedExpressionRAII() {
if (expr)
CleanupIllFormedExpressionRAII::doIt(*expr, Context);
}
/// Pre-check the expression, validating any types that occur in the
/// expression and folding sequence expressions.
static bool preCheckExpression(TypeChecker &tc, Expr *&expr, DeclContext *dc) {
PreCheckExpression preCheck(tc, dc);
// Perform the pre-check.
if (auto result = expr->walk(preCheck)) {
expr = result;
return false;
}
// Pre-check failed. Clean up and return.
CleanupIllFormedExpressionRAII::doIt(expr, tc.Context);
return true;
}
ExprTypeCheckListener::~ExprTypeCheckListener() { }
bool ExprTypeCheckListener::builtConstraints(ConstraintSystem &cs, Expr *expr) {
return false;
}
Expr *ExprTypeCheckListener::appliedSolution(Solution &solution, Expr *expr) {
return expr;
}
GenericRequirementsCheckListener::~GenericRequirementsCheckListener() {}
bool GenericRequirementsCheckListener::shouldCheck(RequirementKind kind,
Type first, Type second) {
return true;
}
void GenericRequirementsCheckListener::satisfiedConformance(
Type depTy, Type replacementTy,
ProtocolConformanceRef conformance) {
}
bool TypeChecker::
solveForExpression(Expr *&expr, DeclContext *dc, Type convertType,
FreeTypeVariableBinding allowFreeTypeVariables,
ExprTypeCheckListener *listener, ConstraintSystem &cs,
SmallVectorImpl<Solution> &viable,
TypeCheckExprOptions options) {
// First, pre-check the expression, validating any types that occur in the
// expression and folding sequence expressions.
if (preCheckExpression(*this, expr, dc))
return true;
// Attempt to solve the constraint system.
auto solution = cs.solve(expr,
convertType,
listener,
viable,
allowFreeTypeVariables);
// The constraint system has failed
if (solution == ConstraintSystem::SolutionKind::Error)
return true;
// If the system is unsolved or there are multiple solutions present but
// type checker options do not allow unresolved types, let's try to salvage
if (solution == ConstraintSystem::SolutionKind::Unsolved
|| (viable.size() != 1 &&
!options.contains(TypeCheckExprFlags::AllowUnresolvedTypeVariables))) {
if (options.contains(TypeCheckExprFlags::SuppressDiagnostics))
return true;
// Try to provide a decent diagnostic.
if (cs.salvage(viable, expr)) {
// If salvage produced an error message, then it failed to salvage the
// expression, just bail out having reported the error.
return true;
}
// The system was salvaged; continue on as if nothing happened.
}
if (getLangOpts().DebugConstraintSolver) {
auto &log = Context.TypeCheckerDebug->getStream();
if (viable.size() == 1) {
log << "---Solution---\n";
viable[0].dump(log);
} else {
for (unsigned i = 0, e = viable.size(); i != e; ++i) {
log << "--- Solution #" << i << " ---\n";
viable[i].dump(log);
}
}
}
return false;
}
namespace {
/// ExprCleanser - This class is used by typeCheckExpression to ensure that in
/// no situation will an expr node be left with a dangling type variable stuck
/// to it. Often type checking will create new AST nodes and replace old ones
/// (e.g. by turning an UnresolvedDotExpr into a MemberRefExpr). These nodes
/// might be left with pointers into the temporary constraint system through
/// their type variables, and we don't want pointers into the original AST to
/// dereference these now-dangling types.
class ExprCleanser {
llvm::SmallVector<Expr*,4> Exprs;
llvm::SmallVector<TypeLoc*, 4> TypeLocs;
llvm::SmallVector<Pattern*, 4> Patterns;
public:
ExprCleanser(Expr *E) {
struct ExprCleanserImpl : public ASTWalker {
ExprCleanser *TS;
ExprCleanserImpl(ExprCleanser *TS) : TS(TS) {}
std::pair<bool, Expr *> walkToExprPre(Expr *expr) override {
TS->Exprs.push_back(expr);
return { true, expr };
}
bool walkToTypeLocPre(TypeLoc &TL) override {
TS->TypeLocs.push_back(&TL);
return true;
}
std::pair<bool, Pattern*> walkToPatternPre(Pattern *P) override {
TS->Patterns.push_back(P);
return { true, P };
}
// Don't walk into statements. This handles the BraceStmt in
// non-single-expr closures, so we don't walk into their body.
std::pair<bool, Stmt *> walkToStmtPre(Stmt *S) override {
return { false, S };
}
};
E->walk(ExprCleanserImpl(this));
}
~ExprCleanser() {
// Check each of the expression nodes to verify that there are no type
// variables hanging out. If so, just nuke the type.
for (auto E : Exprs) {
if (E->getType() && E->getType()->hasTypeVariable())
E->setType(Type());
}
for (auto TL : TypeLocs) {
if (TL->getTypeRepr() && TL->getType() &&
TL->getType()->hasTypeVariable())
TL->setType(Type(), false);
}
for (auto P : Patterns) {
if (P->hasType() && P->getType()->hasTypeVariable())
P->setType(Type());
}
}
};
class ExpressionTimer {
Expr* E;
ASTContext &Context;
llvm::TimeRecord StartTime = llvm::TimeRecord::getCurrentTime();
public:
ExpressionTimer(Expr *E, ASTContext &Context) : E(E), Context(Context) {}
~ExpressionTimer() {
llvm::TimeRecord endTime = llvm::TimeRecord::getCurrentTime(false);
auto elapsed = endTime.getProcessTime() - StartTime.getProcessTime();
// Round up to the nearest 100th of a millisecond.
llvm::errs() << llvm::format("%0.2f", ceil(elapsed * 100000) / 100)
<< "ms\t";
E->getLoc().print(llvm::errs(), Context.SourceMgr);
llvm::errs() << "\n";
}
};
} // end anonymous namespace
#pragma mark High-level entry points
bool TypeChecker::typeCheckExpression(Expr *&expr, DeclContext *dc,
TypeLoc convertType,
ContextualTypePurpose convertTypePurpose,
TypeCheckExprOptions options,
ExprTypeCheckListener *listener,
ConstraintSystem *baseCS) {
Optional<ExpressionTimer> timer;
if (DebugTimeExpressions)
timer.emplace(expr, Context);
PrettyStackTraceExpr stackTrace(Context, "type-checking", expr);
// Construct a constraint system from this expression.
ConstraintSystemOptions csOptions = ConstraintSystemFlags::AllowFixes;
if (options.contains(TypeCheckExprFlags::PreferForceUnwrapToOptional))
csOptions |= ConstraintSystemFlags::PreferForceUnwrapToOptional;
ConstraintSystem cs(*this, dc, csOptions);
cs.baseCS = baseCS;
CleanupIllFormedExpressionRAII cleanup(Context, expr);
ExprCleanser cleanup2(expr);
// Verify that a purpose was specified if a convertType was. Note that it is
// ok to have a purpose without a convertType (which is used for call
// return types).
assert((!convertType.getType() || convertTypePurpose != CTP_Unused) &&
"Purpose for conversion type was not specified");
// Take a look at the conversion type to check to make sure it is sensible.
if (convertType.getType()) {
// If we're asked to convert to an UnresolvedType, then ignore the request.
// This happens when CSDiags nukes a type.
if (convertType.getType()->is<UnresolvedType>() ||
(convertType.getType()->is<MetatypeType>() &&
convertType.getType()->hasUnresolvedType())) {
convertType = TypeLoc();
convertTypePurpose = CTP_Unused;
}
}
// Tell the constraint system what the contextual type is. This informs
// diagnostics and is a hint for various performance optimizations.
cs.setContextualType(expr, convertType, convertTypePurpose);
// If the convertType is *only* provided for that hint, then null it out so
// that we don't later treat it as an actual conversion constraint.
if (options.contains(TypeCheckExprFlags::ConvertTypeIsOnlyAHint))
convertType = TypeLoc();
bool suppressDiagnostics =
options.contains(TypeCheckExprFlags::SuppressDiagnostics);
// If the client can handle unresolved type variables, leave them in the
// system.
auto allowFreeTypeVariables = FreeTypeVariableBinding::Disallow;
if (options.contains(TypeCheckExprFlags::AllowUnresolvedTypeVariables))
allowFreeTypeVariables = FreeTypeVariableBinding::UnresolvedType;
// Attempt to solve the constraint system.
SmallVector<Solution, 4> viable;
if (solveForExpression(expr, dc, convertType.getType(),
allowFreeTypeVariables, listener, cs, viable, options))
return true;
// If the client allows the solution to have unresolved type expressions,
// check for them now. We cannot apply the solution with unresolved TypeVars,
// because they will leak out into arbitrary places in the resultant AST.
if (options.contains(TypeCheckExprFlags::AllowUnresolvedTypeVariables) &&
(viable.size() != 1 ||
(convertType.getType() && convertType.getType()->hasUnresolvedType()))) {
expr->setType(ErrorType::get(Context));
return false;
}
// Apply the solution to the expression.
auto &solution = viable[0];
bool isDiscarded = options.contains(TypeCheckExprFlags::IsDiscarded);
bool skipClosures = options.contains(TypeCheckExprFlags::SkipMultiStmtClosures);
auto result = cs.applySolution(solution, expr, convertType.getType(),
isDiscarded, suppressDiagnostics,
skipClosures);
if (!result) {
// Failure already diagnosed, above, as part of applying the solution.
return true;
}
if (getLangOpts().DebugConstraintSolver) {
auto &log = Context.TypeCheckerDebug->getStream();
log << "---Type-checked expression---\n";
result->dump(log);
}
// If there's a listener, notify it that we've applied the solution.
if (listener) {
result = listener->appliedSolution(solution, result);
if (!result) {
return true;
}
}
// Unless the client has disabled them, perform syntactic checks on the
// expression now.
if (!suppressDiagnostics &&
!options.contains(TypeCheckExprFlags::DisableStructuralChecks)) {
bool isExprStmt = options.contains(TypeCheckExprFlags::IsExprStmt);
performSyntacticExprDiagnostics(*this, result, dc, isExprStmt);
}
expr = result;
cleanup.disable();
return false;
}
Optional<Type> TypeChecker::
getTypeOfExpressionWithoutApplying(Expr *&expr, DeclContext *dc,
ConcreteDeclRef &referencedDecl,
FreeTypeVariableBinding allowFreeTypeVariables,
ExprTypeCheckListener *listener) {
PrettyStackTraceExpr stackTrace(Context, "type-checking", expr);
referencedDecl = nullptr;
// Construct a constraint system from this expression.
ConstraintSystem cs(*this, dc, ConstraintSystemFlags::AllowFixes);
CleanupIllFormedExpressionRAII cleanup(Context, expr);
// Attempt to solve the constraint system.
SmallVector<Solution, 4> viable;
const Type originalType = expr->getType();
const bool needClearType = originalType && originalType->hasError();
const auto recoverOriginalType = [&] () {
if (needClearType)
expr->setType(originalType);
};
// If the previous checking gives the expr error type, clear the result and
// re-check.
if (needClearType)
expr->setType(Type());
if (solveForExpression(expr, dc, /*convertType*/Type(),
allowFreeTypeVariables, listener, cs, viable,
TypeCheckExprFlags::SuppressDiagnostics)) {
recoverOriginalType();
return None;
}
// Get the expression's simplified type.
auto &solution = viable[0];
Type exprType = solution.simplifyType(expr->getType());
assert(exprType && !exprType->hasTypeVariable() &&
"free type variable with FreeTypeVariableBinding::GenericParameters?");
if (exprType->hasError()) {
recoverOriginalType();
return None;
}
// Dig the declaration out of the solution.
auto semanticExpr = expr->getSemanticsProvidingExpr();
auto topLocator = cs.getConstraintLocator(semanticExpr);
referencedDecl = solution.resolveLocatorToDecl(topLocator);
if (!referencedDecl.getDecl()) {
// Do another check in case we have a curried call from binding a function
// reference to a variable, for example:
//
// class C {
// func instanceFunc(p1: Int, p2: Int) {}
// }
// func t(c: C) {
// C.instanceFunc(c)#^COMPLETE^#
// }
//
// We need to get the referenced function so we can complete the argument
// labels. (Note that the requirement to have labels in the curried call
// seems inconsistent with the removal of labels from function types.
// If this changes the following code could be removed).
if (auto *CE = dyn_cast<CallExpr>(semanticExpr)) {
if (auto *UDE = dyn_cast<UnresolvedDotExpr>(CE->getFn())) {
if (isa<TypeExpr>(UDE->getBase())) {
auto udeLocator = cs.getConstraintLocator(UDE);
auto udeRefDecl = solution.resolveLocatorToDecl(udeLocator);
if (auto *FD = dyn_cast_or_null<FuncDecl>(udeRefDecl.getDecl())) {
if (FD->isInstanceMember())
referencedDecl = udeRefDecl;
}
}
}
}
}
// Recover the original type if needed.
recoverOriginalType();
return exprType;
}
bool TypeChecker::typeCheckCompletionSequence(Expr *&expr, DeclContext *DC) {
PrettyStackTraceExpr stackTrace(Context, "type-checking", expr);
// Construct a constraint system from this expression.
ConstraintSystem CS(*this, DC, ConstraintSystemFlags::AllowFixes);
CleanupIllFormedExpressionRAII cleanup(Context, expr);
auto *SE = cast<SequenceExpr>(expr);
assert(SE->getNumElements() >= 3);
auto *op = SE->getElement(SE->getNumElements() - 2);
auto *CCE = cast<CodeCompletionExpr>(SE->getElements().back());
// Resolve the op.
op = resolveDeclRefExpr(cast<UnresolvedDeclRefExpr>(op), DC);
SE->setElement(SE->getNumElements() - 2, op);
// Fold the sequence.
expr = foldSequence(SE, DC);
// Find the code-completion expression and operator again.
BinaryExpr *exprAsBinOp = nullptr;
while (auto *binExpr = dyn_cast<BinaryExpr>(expr)) {
auto *RHS = binExpr->getArg()->getElement(1);
if (RHS == CCE) {
exprAsBinOp = binExpr;
break;
}
expr = RHS;
}
if (!exprAsBinOp)
return true;
// Ensure the output expression is up to date.
assert(exprAsBinOp == expr && "found wrong expr?");
// Add type variable for the code-completion expression.
auto tvRHS =
CS.createTypeVariable(CS.getConstraintLocator(CCE), TVO_CanBindToLValue);
CCE->setType(tvRHS);
if (auto generated = CS.generateConstraints(expr)) {
expr = generated;
} else {
return true;
}
if (getLangOpts().DebugConstraintSolver) {
auto &log = Context.TypeCheckerDebug->getStream();
log << "---Initial constraints for the given expression---\n";
expr->print(log);
log << "\n";
CS.print(log);
}
// Attempt to solve the constraint system.
SmallVector<Solution, 4> viable;
if (CS.solve(viable, FreeTypeVariableBinding::GenericParameters))
return true;
auto &solution = viable[0];
if (getLangOpts().DebugConstraintSolver) {
auto &log = Context.TypeCheckerDebug->getStream();
log << "---Solution---\n";
solution.dump(log);
}
expr->setType(solution.simplifyType(expr->getType()));
CCE->setType(solution.simplifyType(CCE->getType()));
return false;
}
bool TypeChecker::typeCheckExpressionShallow(Expr *&expr, DeclContext *dc) {
PrettyStackTraceExpr stackTrace(Context, "shallow type-checking", expr);
// Construct a constraint system from this expression.
ConstraintSystem cs(*this, dc, ConstraintSystemFlags::AllowFixes);
CleanupIllFormedExpressionRAII cleanup(Context, expr);
if (auto generatedExpr = cs.generateConstraintsShallow(expr))
expr = generatedExpr;
else
return true;
if (getLangOpts().DebugConstraintSolver) {
auto &log = Context.TypeCheckerDebug->getStream();
log << "---Initial constraints for the given expression---\n";
expr->print(log);
log << "\n";
cs.print(log);
}
// Attempt to solve the constraint system.
SmallVector<Solution, 4> viable;
if ((cs.solve(viable) || viable.size() != 1) &&
cs.salvage(viable, expr)) {
return true;
}
auto &solution = viable[0];
if (getLangOpts().DebugConstraintSolver) {
auto &log = Context.TypeCheckerDebug->getStream();
log << "---Solution---\n";
solution.dump(log);
}
// Apply the solution to the expression.
auto result = cs.applySolutionShallow(solution, expr,
/*suppressDiagnostics=*/false);
if (!result) {
// Failure already diagnosed, above, as part of applying the solution.
return true;
}
if (getLangOpts().DebugConstraintSolver) {
auto &log = Context.TypeCheckerDebug->getStream();
log << "---Type-checked expression---\n";
result->dump(log);
}
expr = result;
cleanup.disable();
return false;
}
bool TypeChecker::typeCheckBinding(Pattern *&pattern, Expr *&initializer,
DeclContext *DC, bool skipClosures) {
/// Type checking listener for pattern binding initializers.
class BindingListener : public ExprTypeCheckListener {
Pattern *&pattern;
Expr *&initializer;
DeclContext *DC;
bool skipClosures;
/// The locator we're using.
ConstraintLocator *Locator;
/// The type of the initializer.
Type InitType;
public:
explicit BindingListener(Pattern *&pattern, Expr *&initializer,
DeclContext *DC, bool skipClosures)
: pattern(pattern), initializer(initializer), DC(DC),
skipClosures(skipClosures) { }
bool builtConstraints(ConstraintSystem &cs, Expr *expr) override {
// Save the locator we're using for the expression.
Locator = cs.getConstraintLocator(expr);
// Collect constraints from the pattern.
InitType = cs.generateConstraints(pattern, Locator);
if (!InitType)
return true;
// Add a conversion constraint between the types.
cs.addConstraint(ConstraintKind::Conversion, cs.getType(expr),
InitType, Locator, /*isFavored*/true);
// The expression has been pre-checked; save it in case we fail later.
initializer = expr;
return false;
}
Expr *appliedSolution(Solution &solution, Expr *expr) override {
// Figure out what type the constraints decided on.
auto &cs = solution.getConstraintSystem();
auto &tc = cs.getTypeChecker();
InitType = solution.simplifyType(InitType);
// Convert the initializer to the type of the pattern.
// ignoreTopLevelInjection = Binding->isConditional()
expr = solution.coerceToType(expr, InitType, Locator,
false /* ignoreTopLevelInjection */,
skipClosures);
if (!expr) {
return nullptr;
}
// Force the initializer to be materializable.
// FIXME: work this into the constraint system
expr = tc.coerceToMaterializable(expr);
// Apply the solution to the pattern as well.
Type patternType = expr->getType();
TypeResolutionOptions options;
options |= TR_OverrideType;
options |= TR_InExpression;
if (isa<EditorPlaceholderExpr>(expr->getSemanticsProvidingExpr())) {
options |= TR_EditorPlaceholder;
}
if (tc.coercePatternToType(pattern, DC, patternType, options)) {
return nullptr;
}
initializer = expr;
return expr;
}
};
assert(initializer && "type-checking an uninitialized binding?");
BindingListener listener(pattern, initializer, DC, skipClosures);
TypeLoc contextualType;
auto contextualPurpose = CTP_Unused;
if (pattern->hasType()) {
contextualType = TypeLoc::withoutLoc(pattern->getType());
contextualPurpose = CTP_Initialization;
// If we already had an error, don't repeat the problem.
if (contextualType.getType()->hasError())
return true;
// Only provide a TypeLoc if it makes sense to allow diagnostics.
if (auto *typedPattern = dyn_cast<TypedPattern>(pattern)) {
const Pattern *inner = typedPattern->getSemanticsProvidingPattern();
if (isa<NamedPattern>(inner) || isa<AnyPattern>(inner))
contextualType = typedPattern->getTypeLoc();
}
}
// Type-check the initializer.
TypeCheckExprOptions flags = TypeCheckExprFlags::ConvertTypeIsOnlyAHint;
if (skipClosures)
flags |= TypeCheckExprFlags::SkipMultiStmtClosures;
bool hadError = typeCheckExpression(initializer, DC, contextualType,
contextualPurpose,
flags,
&listener);
if (hadError && !pattern->hasType()) {
pattern->setType(ErrorType::get(Context));
pattern->forEachVariable([&](VarDecl *var) {
// Don't change the type of a variable that we've been able to
// compute a type for.
if (var->hasType() && !var->getType()->hasError())
return;
var->markInvalid();
});
}
return hadError;
}
bool TypeChecker::typeCheckPatternBinding(PatternBindingDecl *PBD,
unsigned patternNumber,
bool skipClosures) {
Pattern *pattern = PBD->getPattern(patternNumber);
Expr *init = PBD->getInit(patternNumber);
if (!init) {
PBD->setInvalid();
return true;
}
// Enter an initializer context if necessary.
PatternBindingInitializer *initContext = nullptr;
DeclContext *DC = PBD->getDeclContext();
if (!DC->isLocalContext()) {
initContext = cast_or_null<PatternBindingInitializer>(
PBD->getPatternList()[patternNumber].getInitContext());
if (initContext)
DC = initContext;
}
bool hadError = typeCheckBinding(pattern, init, DC, skipClosures);
PBD->setPattern(patternNumber, pattern, initContext);
PBD->setInit(patternNumber, init);
// If we entered an initializer context, contextualize any
// auto-closures we might have created.
if (initContext) {
// Check safety of error-handling in the declaration, too.
if (!hadError) {
checkInitializerErrorHandling(initContext, init);
}
if (!hadError)
(void)contextualizeInitializer(initContext, init);
}
if (hadError) {
PBD->setInvalid();
}
PBD->setInitializerChecked(patternNumber);
return hadError;
}
bool TypeChecker::typeCheckForEachBinding(DeclContext *dc, ForEachStmt *stmt) {
/// Type checking listener for for-each binding.
class BindingListener : public ExprTypeCheckListener {
/// The for-each statement.
ForEachStmt *Stmt;
/// The locator we're using.
ConstraintLocator *Locator;
/// The type of the initializer.
Type InitType;
/// The type of the sequence.
Type SequenceType;
public:
explicit BindingListener(ForEachStmt *stmt) : Stmt(stmt) { }
bool builtConstraints(ConstraintSystem &cs, Expr *expr) override {
// Save the locator we're using for the expression.
Locator = cs.getConstraintLocator(expr);
// The expression type must conform to the Sequence.
auto &tc = cs.getTypeChecker();
ProtocolDecl *sequenceProto
= tc.getProtocol(Stmt->getForLoc(), KnownProtocolKind::Sequence);
if (!sequenceProto) {
return true;
}
SequenceType =
cs.createTypeVariable(Locator, /*options=*/TVO_MustBeMaterializable);
cs.addConstraint(ConstraintKind::Conversion, cs.getType(expr),
SequenceType, Locator);
cs.addConstraint(ConstraintKind::ConformsTo, SequenceType,
sequenceProto->getDeclaredType(), Locator);
auto iteratorLocator =
cs.getConstraintLocator(Locator,
ConstraintLocator::SequenceIteratorProtocol);
auto elementLocator =
cs.getConstraintLocator(iteratorLocator,
ConstraintLocator::GeneratorElementType);
// Collect constraints from the element pattern.
auto pattern = Stmt->getPattern();
InitType = cs.generateConstraints(pattern, elementLocator);
if (!InitType)
return true;
// Manually search for the iterator witness. If no iterator/element pair
// exists, solve for them.
Type iteratorType;
Type elementType;
NameLookupOptions lookupOptions = defaultMemberTypeLookupOptions;
if (isa<AbstractFunctionDecl>(cs.DC))
lookupOptions |= NameLookupFlags::KnownPrivate;
auto sequenceType = cs.getType(expr)->getRValueType();
// Look through one level of optional; this improves recovery but doesn't
// change the result.
if (auto sequenceObjectType = sequenceType->getAnyOptionalObjectType())
sequenceType = sequenceObjectType;
// If the sequence type is an existential, we should not attempt to
// look up the member type at all, since we cannot represent associated
// types of existentials.
//
// We will diagnose it later.
if (!sequenceType->isExistentialType() &&
(sequenceType->mayHaveMembers() ||
sequenceType->isTypeVariableOrMember())) {
ASTContext &ctx = tc.Context;
auto iteratorAssocType =
cast<AssociatedTypeDecl>(
sequenceProto->lookupDirect(ctx.Id_Iterator).front());
auto subs = sequenceType->getContextSubstitutionMap(
cs.DC->getParentModule(),
sequenceProto);
iteratorType = iteratorAssocType->getDeclaredInterfaceType()
.subst(subs);
if (iteratorType) {
auto iteratorProto =
tc.getProtocol(Stmt->getForLoc(),
KnownProtocolKind::IteratorProtocol);
if (!iteratorProto)
return true;
auto elementAssocType =
cast<AssociatedTypeDecl>(
iteratorProto->lookupDirect(ctx.Id_Element).front());
elementType = iteratorType->getTypeOfMember(
cs.DC->getParentModule(),
elementAssocType,
elementAssocType->getDeclaredInterfaceType());
}
}
if (elementType.isNull()) {
elementType = cs.createTypeVariable(elementLocator,
TVO_MustBeMaterializable);
}
// Add a conversion constraint between the element type of the sequence
// and the type of the element pattern.
cs.addConstraint(ConstraintKind::Conversion, elementType, InitType,
elementLocator);
Stmt->setSequence(expr);
return false;
}
Expr *appliedSolution(Solution &solution, Expr *expr) override {
// Figure out what types the constraints decided on.
auto &cs = solution.getConstraintSystem();
auto &tc = cs.getTypeChecker();
InitType = solution.simplifyType(InitType);
SequenceType = solution.simplifyType(SequenceType);
// Perform any necessary conversions of the sequence (e.g. [T]! -> [T]).
if (tc.convertToType(expr, SequenceType, cs.DC)) {
return nullptr;
}
cs.cacheExprTypes(expr);
// Apply the solution to the iteration pattern as well.
Pattern *pattern = Stmt->getPattern();
TypeResolutionOptions options;
options |= TR_OverrideType;
options |= TR_EnumerationVariable;
options |= TR_InExpression;
if (tc.coercePatternToType(pattern, cs.DC, InitType, options)) {
return nullptr;
}
Stmt->setPattern(pattern);
Stmt->setSequence(expr);
cs.setExprTypes(expr);
return expr;
}
};
BindingListener listener(stmt);
Expr *seq = stmt->getSequence();
assert(seq && "type-checking an uninitialized for-each statement?");
// Type-check the for-each loop sequence and element pattern.
return typeCheckExpression(seq, dc, &listener);
}
/// \brief Compute the rvalue type of the given expression, which is the
/// destination of an assignment statement.
Type ConstraintSystem::computeAssignDestType(Expr *dest, SourceLoc equalLoc) {
if (TupleExpr *TE = dyn_cast<TupleExpr>(dest)) {
auto &ctx = getASTContext();
SmallVector<TupleTypeElt, 4> destTupleTypes;
for (unsigned i = 0; i != TE->getNumElements(); ++i) {
Expr *subExpr = TE->getElement(i);
Type elemTy = computeAssignDestType(subExpr, equalLoc);
if (!elemTy)
return Type();
destTupleTypes.push_back(TupleTypeElt(elemTy, TE->getElementName(i)));
}
return TupleType::get(destTupleTypes, ctx);
}
Type destTy = simplifyType(getType(dest));
if (destTy->hasError())
return Type();
// If we have already resolved a concrete lvalue destination type, return it.
if (LValueType *destLV = destTy->getAs<LValueType>())
return destLV->getObjectType();
// If the destination is a type variable, the type variable must be an
// lvalue type, which we enforce via an equality relationship with
// @lvalue T, where T is a fresh type variable that will be the object type of
// this particular expression type.
if (auto typeVar = dyn_cast<TypeVariableType>(destTy.getPointer())) {
// Newly allocated type should be explicitly materializable,
// it's invalid to use non-materializable types as assignment destination.
auto objectTv = createTypeVariable(getConstraintLocator(dest),
TVO_MustBeMaterializable);
auto refTv = LValueType::get(objectTv);
addConstraint(ConstraintKind::Bind, typeVar, refTv,
getConstraintLocator(dest));
return objectTv;
}
// Otherwise, the destination is erroneous. If there are FixIt hints
// introduced into the system, they may well be the reason that this isn't an
// lvalue. Emit them if present.
if (!Fixes.empty()) {
auto solution = finalize(FreeTypeVariableBinding::Allow);
if (applySolutionFixes(dest, solution))
return Type();
}
// Otherwise, it is a structural problem, diagnose that.
diagnoseAssignmentFailure(dest, destTy, equalLoc);
return Type();
}
bool TypeChecker::typeCheckCondition(Expr *&expr, DeclContext *dc) {
// If this expression is already typechecked and has an i1 type, then it has
// already got its conversion from Boolean back to i1. Just re-typecheck
// it.
if (expr->getType() && expr->getType()->isBuiltinIntegerType(1))
return typeCheckExpression(expr, dc);
/// Expression type checking listener for conditions.
class ConditionListener : public ExprTypeCheckListener {
Expr *OrigExpr = nullptr;
public:
// Add the appropriate Boolean constraint.
bool builtConstraints(ConstraintSystem &cs, Expr *expr) override {
// Save the original expression.
OrigExpr = expr;
// Otherwise, the result must be convertible to Bool.
auto boolDecl = cs.getASTContext().getBoolDecl();
if (!boolDecl)
return true;
// Condition must convert to Bool.
cs.addConstraint(ConstraintKind::Conversion, cs.getType(expr),
boolDecl->getDeclaredType(),
cs.getConstraintLocator(expr));
return false;
}
// Convert the result to a Builtin.i1.
Expr *appliedSolution(constraints::Solution &solution,
Expr *expr) override {
auto &cs = solution.getConstraintSystem();
auto converted =
solution.convertBooleanTypeToBuiltinI1(expr,
cs.getConstraintLocator(OrigExpr));
cs.setExprTypes(converted);
return converted;
}
};
ConditionListener listener;
return typeCheckExpression(expr, dc, &listener);
}
bool TypeChecker::typeCheckStmtCondition(StmtCondition &cond, DeclContext *dc,
Diag<> diagnosticForAlwaysTrue) {
bool hadError = false;
bool hadAnyFalsable = false;
for (auto &elt : cond) {
if (elt.getKind() == StmtConditionElement::CK_Availability) {
hadAnyFalsable = true;
continue;
}
if (auto E = elt.getBooleanOrNull()) {
hadError |= typeCheckCondition(E, dc);
elt.setBoolean(E);
hadAnyFalsable = true;
continue;
}
// This is cleanup goop run on the various paths where type checking of the
// pattern binding fails.
auto typeCheckPatternFailed = [&] {
hadError = true;
elt.getPattern()->setType(ErrorType::get(Context));
elt.getInitializer()->setType(ErrorType::get(Context));
elt.getPattern()->forEachVariable([&](VarDecl *var) {
// Don't change the type of a variable that we've been able to
// compute a type for.
if (var->hasType() && !var->getType()->hasError())
return;
var->markInvalid();
});
};
// Resolve the pattern.
auto *pattern = resolvePattern(elt.getPattern(), dc,
/*isStmtCondition*/true);
if (!pattern) {
typeCheckPatternFailed();
continue;
}
elt.setPattern(pattern);
// Check the pattern, it allows unspecified types because the pattern can
// provide type information.
TypeResolutionOptions options = TR_InExpression;
options |= TR_AllowUnspecifiedTypes;
options |= TR_AllowUnboundGenerics;
if (typeCheckPattern(pattern, dc, options)) {
typeCheckPatternFailed();
continue;
}
// If the pattern didn't get a type, it's because we ran into some
// unknown types along the way. We'll need to check the initializer.
auto init = elt.getInitializer();
hadError |= typeCheckBinding(pattern, init, dc, /*skipClosures*/false);
elt.setPattern(pattern);
elt.setInitializer(init);
hadAnyFalsable |= pattern->isRefutablePattern();
}
// If the binding is not refutable, and there *is* an else, reject it as
// unreachable.
if (!hadAnyFalsable && !hadError)
diagnose(cond[0].getStartLoc(), diagnosticForAlwaysTrue);
return false;
}
/// Find the '~=` operator that can compare an expression inside a pattern to a
/// value of a given type.
bool TypeChecker::typeCheckExprPattern(ExprPattern *EP, DeclContext *DC,
Type rhsType) {
PrettyStackTracePattern stackTrace(Context, "type-checking", EP);
// Create a 'let' binding to stand in for the RHS value.
auto *matchVar = new (Context) VarDecl(/*IsStatic*/false, /*IsLet*/true,
/*IsCaptureList*/false,
EP->getLoc(),
Context.getIdentifier("$match"),
rhsType,
DC);
matchVar->setInterfaceType(DC->mapTypeOutOfContext(rhsType));
matchVar->setImplicit();
EP->setMatchVar(matchVar);
matchVar->setHasNonPatternBindingInit();
// Find '~=' operators for the match.
auto lookupOptions = defaultUnqualifiedLookupOptions;
lookupOptions |= NameLookupFlags::KnownPrivate;
auto matchLookup = lookupUnqualified(DC, Context.Id_MatchOperator,
SourceLoc(), lookupOptions);
if (!matchLookup) {
diagnose(EP->getLoc(), diag::no_match_operator);
return true;
}
SmallVector<ValueDecl*, 4> choices;
for (auto &result : matchLookup) {
choices.push_back(result.Decl);
}
if (choices.empty()) {
diagnose(EP->getLoc(), diag::no_match_operator);
return true;
}
// Build the 'expr ~= var' expression.
// FIXME: Compound name locations.
auto *matchOp = buildRefExpr(choices, DC, DeclNameLoc(EP->getLoc()),
/*Implicit=*/true, /*isSpecialized=*/false,
FunctionRefKind::Compound);
auto *matchVarRef = new (Context) DeclRefExpr(matchVar,
DeclNameLoc(EP->getLoc()),
/*Implicit=*/true);
Expr *matchArgElts[] = {EP->getSubExpr(), matchVarRef};
auto *matchArgs
= TupleExpr::create(Context, EP->getSubExpr()->getSourceRange().Start,
matchArgElts, { }, { },
EP->getSubExpr()->getSourceRange().End,
/*HasTrailingClosure=*/false, /*Implicit=*/true);
Expr *matchCall = new (Context) BinaryExpr(matchOp, matchArgs,
/*Implicit=*/true);
// Check the expression as a condition.
bool hadError = typeCheckCondition(matchCall, DC);
// Save the type-checked expression in the pattern.
EP->setMatchExpr(matchCall);
// Set the type on the pattern.
EP->setType(rhsType);
return hadError;
}
bool TypeChecker::typesSatisfyConstraint(Type type1, Type type2,
ConstraintKind kind, DeclContext *dc,
bool *unwrappedIUO) {
ConstraintSystem cs(*this, dc, ConstraintSystemOptions());
cs.addConstraint(kind, type1, type2, cs.getConstraintLocator(nullptr));
if (auto solution = cs.solveSingle()) {
if (unwrappedIUO)
*unwrappedIUO = solution->getFixedScore().Data[SK_ForceUnchecked] > 0;
return true;
}
return false;
}
bool TypeChecker::isSubtypeOf(Type type1, Type type2, DeclContext *dc) {
return typesSatisfyConstraint(type1, type2, ConstraintKind::Subtype, dc);
}
bool TypeChecker::isConvertibleTo(Type type1, Type type2, DeclContext *dc,
bool *unwrappedIUO) {
return typesSatisfyConstraint(type1, type2, ConstraintKind::Conversion, dc,
unwrappedIUO);
}
bool TypeChecker::isExplicitlyConvertibleTo(Type type1, Type type2,
DeclContext *dc) {
return typesSatisfyConstraint(type1, type2, ConstraintKind::Conversion, dc) ||
isObjCBridgedTo(type1, type2, dc);
}
bool TypeChecker::isObjCBridgedTo(Type type1, Type type2, DeclContext *dc,
bool *unwrappedIUO) {
return (Context.LangOpts.EnableObjCInterop &&
typesSatisfyConstraint(type1, type2, ConstraintKind::BridgingConversion,
dc, unwrappedIUO));
}
bool TypeChecker::checkedCastMaySucceed(Type t1, Type t2, DeclContext *dc) {
auto kind = typeCheckCheckedCast(t1, t2, CheckedCastContextKind::None, dc,
SourceLoc(), nullptr, SourceRange());
return (kind != CheckedCastKind::Unresolved);
}
bool TypeChecker::isSubstitutableFor(Type type, ArchetypeType *archetype,
DeclContext *dc) {
ConstraintSystem cs(*this, dc, ConstraintSystemOptions());
auto locator = cs.getConstraintLocator(nullptr);
// Add all of the requirements of the archetype to the given type.
// FIXME: Short-circuit if any of the constraints fails.
if (archetype->requiresClass() && !type->mayHaveSuperclass())
return false;
if (auto superclass = archetype->getSuperclass()) {
cs.addConstraint(ConstraintKind::Subtype, type, superclass, locator);
}
for (auto proto : archetype->getConformsTo()) {
cs.addConstraint(ConstraintKind::ConformsTo, type,
proto->getDeclaredType(), locator);
}
// Solve the system.
return cs.solveSingle().hasValue();
}
Expr *TypeChecker::coerceToMaterializable(Expr *expr) {
// If the type is already materializable, then we're already done.
if (expr->getType()->isMaterializable())
return expr;
// Load lvalues.
if (auto lvalue = expr->getType()->getAs<LValueType>()) {
expr->propagateLValueAccessKind(AccessKind::Read);
return new (Context) LoadExpr(expr, lvalue->getObjectType());
}
// Walk into parenthesized expressions to update the subexpression.
if (auto paren = dyn_cast<IdentityExpr>(expr)) {
auto sub = coerceToMaterializable(paren->getSubExpr());
paren->setSubExpr(sub);
paren->setType(sub->getType());
return paren;
}
// Walk into 'try' and 'try!' expressions to update the subexpression.
if (auto tryExpr = dyn_cast<AnyTryExpr>(expr)) {
auto sub = coerceToMaterializable(tryExpr->getSubExpr());
tryExpr->setSubExpr(sub);
if (isa<OptionalTryExpr>(tryExpr) && !sub->getType()->hasError())
tryExpr->setType(OptionalType::get(sub->getType()));
else
tryExpr->setType(sub->getType());
return tryExpr;
}
// Walk into tuples to update the subexpressions.
if (auto tuple = dyn_cast<TupleExpr>(expr)) {
bool anyChanged = false;
for (auto &elt : tuple->getElements()) {
// Materialize the element.
auto oldType = elt->getType();
elt = coerceToMaterializable(elt);
// If the type changed at all, make a note of it.
if (elt->getType().getPointer() != oldType.getPointer()) {
anyChanged = true;
}
}
// If any of the types changed, rebuild the tuple type.
if (anyChanged) {
SmallVector<TupleTypeElt, 4> elements;
elements.reserve(tuple->getElements().size());
for (unsigned i = 0, n = tuple->getNumElements(); i != n; ++i) {
Type type = tuple->getElement(i)->getType();
Identifier name = tuple->getElementName(i);
elements.push_back(TupleTypeElt(type, name));
}
tuple->setType(TupleType::get(elements, Context));
}
return tuple;
}
// Nothing to do.
return expr;
}
bool TypeChecker::convertToType(Expr *&expr, Type type, DeclContext *dc,
Optional<Pattern*> typeFromPattern) {
// TODO: need to add kind arg?
// Construct a constraint system from this expression.
ConstraintSystem cs(*this, dc, ConstraintSystemFlags::AllowFixes);
CleanupIllFormedExpressionRAII cleanup(Context, expr);
// If there is a type that we're expected to convert to, add the conversion
// constraint.
cs.addConstraint(ConstraintKind::Conversion, expr->getType(), type,
cs.getConstraintLocator(expr));
if (getLangOpts().DebugConstraintSolver) {
auto &log = Context.TypeCheckerDebug->getStream();
log << "---Initial constraints for the given expression---\n";
expr->print(log);
log << "\n";
cs.print(log);
}
// Attempt to solve the constraint system.
SmallVector<Solution, 4> viable;
if ((cs.solve(viable) || viable.size() != 1) &&
cs.salvage(viable, expr)) {
return true;
}
auto &solution = viable[0];
if (getLangOpts().DebugConstraintSolver) {
auto &log = Context.TypeCheckerDebug->getStream();
log << "---Solution---\n";
solution.dump(log);
}
cs.cacheExprTypes(expr);
// Perform the conversion.
Expr *result = solution.coerceToType(expr, type,
cs.getConstraintLocator(expr),
/*ignoreTopLevelInjection*/false,
/*skipClosures*/false,
typeFromPattern);
if (!result) {
return true;
}
cs.setExprTypes(expr);
if (getLangOpts().DebugConstraintSolver) {
auto &log = Context.TypeCheckerDebug->getStream();
log << "---Type-checked expression---\n";
result->dump(log);
}
expr = result;
cleanup.disable();
return false;
}
//===----------------------------------------------------------------------===//
// Debugging
//===----------------------------------------------------------------------===//
#pragma mark Debugging
void Solution::dump() const {
dump(llvm::errs());
}
void Solution::dump(raw_ostream &out) const {
ASTContext &ctx = getConstraintSystem().getASTContext();
llvm::SaveAndRestore<bool> debugSolver(ctx.LangOpts.DebugConstraintSolver,
true);
SourceManager *sm = &ctx.SourceMgr;
out << "Fixed score: " << FixedScore << "\n";
out << "Type variables:\n";
for (auto binding : typeBindings) {
out.indent(2);
binding.first->getImpl().print(out);
out << " as ";
binding.second.print(out);
out << "\n";
}
out << "\n";
out << "Overload choices:\n";
for (auto ovl : overloadChoices) {
out.indent(2);
if (ovl.first)
ovl.first->dump(sm, out);
out << " with ";
auto choice = ovl.second.choice;
switch (choice.getKind()) {
case OverloadChoiceKind::Decl:
case OverloadChoiceKind::DeclViaDynamic:
case OverloadChoiceKind::TypeDecl:
case OverloadChoiceKind::DeclViaBridge:
case OverloadChoiceKind::DeclViaUnwrappedOptional:
choice.getDecl()->dumpRef(out);
out << " as ";
if (choice.getBaseType())
out << choice.getBaseType()->getString() << ".";
out << choice.getDecl()->getName().str() << ": "
<< ovl.second.openedType->getString() << "\n";
break;
case OverloadChoiceKind::BaseType:
out << "base type " << choice.getBaseType()->getString() << "\n";
break;
case OverloadChoiceKind::TupleIndex:
out << "tuple " << choice.getBaseType()->getString() << " index "
<< choice.getTupleIndex() << "\n";
break;
}
out << "\n";
}
out << "\n";
out << "Constraint restrictions:\n";
for (auto &restriction : ConstraintRestrictions) {
out.indent(2) << restriction.first.first
<< " to " << restriction.first.second
<< " is " << getName(restriction.second) << "\n";
}
out << "\nDisjunction choices:\n";
for (auto &choice : DisjunctionChoices) {
out.indent(2);
choice.first->dump(sm, out);
out << " is #" << choice.second << "\n";
}
if (!OpenedTypes.empty()) {
out << "\nOpened types:\n";
for (const auto &opened : OpenedTypes) {
out.indent(2);
opened.first->dump(sm, out);
out << " opens ";
interleave(opened.second.begin(), opened.second.end(),
[&](OpenedType opened) {
opened.first.print(out);
out << " -> ";
opened.second->print(out);
},
[&]() {
out << ", ";
});
out << "\n";
}
}
if (!OpenedExistentialTypes.empty()) {
out << "\nOpened existential types:\n";
for (const auto &openedExistential : OpenedExistentialTypes) {
out.indent(2);
openedExistential.first->dump(sm, out);
out << " opens to " << openedExistential.second->getString();
out << "\n";
}
}
if (!DefaultedConstraints.empty()) {
out << "\nDefaulted constraints: ";
interleave(DefaultedConstraints, [&](ConstraintLocator *locator) {
locator->dump(sm, out);
}, [&] {
out << ", ";
});
}
if (!Fixes.empty()) {
out << "\nFixes:\n";
for (auto &fix : Fixes) {
out.indent(2);
fix.first.print(out, &getConstraintSystem());
out << " @ ";
fix.second->dump(sm, out);
out << "\n";
}
}
}
void ConstraintSystem::dump() {
print(llvm::errs());
}
void ConstraintSystem::print(raw_ostream &out) {
// Print all type variables as $T0 instead of _ here.
llvm::SaveAndRestore<bool> X(getASTContext().LangOpts.DebugConstraintSolver,
true);
out << "Score: " << CurrentScore << "\n";
if (contextualType.getType()) {
out << "Contextual Type: " << contextualType.getType();
if (TypeRepr *TR = contextualType.getTypeRepr()) {
out << " at ";
TR->getSourceRange().print(out, getASTContext().SourceMgr, /*text*/false);
}
out << "\n";
}
out << "Type Variables:\n";
for (auto tv : TypeVariables) {
out.indent(2);
out << '#' << tv->getID() << " = ";
tv->getImpl().print(out);
if (tv->getImpl().canBindToLValue())
out << " [lvalue allowed]";
if (tv->getImpl().mustBeMaterializable())
out << " [must be materializable]";
auto rep = getRepresentative(tv);
if (rep == tv) {
if (auto fixed = getFixedType(tv)) {
out << " as ";
fixed->print(out);
}
} else {
out << " equivalent to ";
rep->print(out);
}
out << "\n";
}
out << "\nActive Constraints:\n";
for (auto &constraint : ActiveConstraints) {
out.indent(2);
constraint.print(out, &getTypeChecker().Context.SourceMgr);
out << "\n";
}
out << "\nInactive Constraints:\n";
for (auto &constraint : InactiveConstraints) {
out.indent(2);
constraint.print(out, &getTypeChecker().Context.SourceMgr);
out << "\n";
}
if (solverState && !solverState->hasRetiredConstraints()) {
out << "\nRetired Constraints:\n";
solverState->forEachRetired([&](Constraint &constraint) {
out.indent(2);
constraint.print(out, &getTypeChecker().Context.SourceMgr);
out << "\n";
});
}
if (resolvedOverloadSets) {
out << "Resolved overloads:\n";
// Otherwise, report the resolved overloads.
for (auto resolved = resolvedOverloadSets;
resolved; resolved = resolved->Previous) {
auto &choice = resolved->Choice;
out << " selected overload set choice ";
switch (choice.getKind()) {
case OverloadChoiceKind::Decl:
case OverloadChoiceKind::DeclViaDynamic:
case OverloadChoiceKind::TypeDecl:
case OverloadChoiceKind::DeclViaBridge:
case OverloadChoiceKind::DeclViaUnwrappedOptional:
if (choice.getBaseType())
out << choice.getBaseType()->getString() << ".";
out << choice.getDecl()->getName() << ": "
<< resolved->BoundType->getString() << " == "
<< resolved->ImpliedType->getString() << "\n";
break;
case OverloadChoiceKind::BaseType:
out << "base type " << choice.getBaseType()->getString() << "\n";
break;
case OverloadChoiceKind::TupleIndex:
out << "tuple " << choice.getBaseType()->getString() << " index "
<< choice.getTupleIndex() << "\n";
break;
}
}
out << "\n";
}
if (!DisjunctionChoices.empty()) {
out << "\nDisjunction choices:\n";
for (auto &choice : DisjunctionChoices) {
out.indent(2);
choice.first->dump(&getTypeChecker().Context.SourceMgr, out);
out << " is #" << choice.second << "\n";
}
}
if (!OpenedTypes.empty()) {
out << "\nOpened types:\n";
for (const auto &opened : OpenedTypes) {
out.indent(2);
opened.first->dump(&getTypeChecker().Context.SourceMgr, out);
out << " opens ";
interleave(opened.second.begin(), opened.second.end(),
[&](OpenedType opened) {
opened.first.print(out);
out << " -> ";
opened.second->print(out);
},
[&]() {
out << ", ";
});
out << "\n";
}
}
if (!OpenedExistentialTypes.empty()) {
out << "\nOpened existential types:\n";
for (const auto &openedExistential : OpenedExistentialTypes) {
out.indent(2);
openedExistential.first->dump(&getTypeChecker().Context.SourceMgr, out);
out << " opens to " << openedExistential.second->getString();
out << "\n";
}
}
if (!DefaultedConstraints.empty()) {
out << "\nDefaulted constraints: ";
interleave(DefaultedConstraints, [&](ConstraintLocator *locator) {
locator->dump(&getTypeChecker().Context.SourceMgr, out);
}, [&] {
out << ", ";
});
}
if (failedConstraint) {
out << "\nFailed constraint:\n";
out.indent(2);
failedConstraint->print(out, &getTypeChecker().Context.SourceMgr);
out << "\n";
}
if (!Fixes.empty()) {
out << "\nFixes:\n";
for (auto &fix : Fixes) {
out.indent(2);
fix.first.print(out, this);
out << " @ ";
fix.second->dump(&getTypeChecker().Context.SourceMgr, out);
out << "\n";
}
}
}
/// Determine the semantics of a checked cast operation.
CheckedCastKind TypeChecker::typeCheckCheckedCast(Type fromType,
Type toType,
CheckedCastContextKind contextKind,
DeclContext *dc,
SourceLoc diagLoc,
Expr *fromExpr,
SourceRange diagToRange) {
SourceRange diagFromRange;
if (fromExpr)
diagFromRange = fromExpr->getSourceRange();
// If the from/to types are equivalent or convertible, this is a coercion.
bool unwrappedIUO = false;
if (fromType->isEqual(toType) ||
(isConvertibleTo(fromType, toType, dc, &unwrappedIUO) &&
!unwrappedIUO)) {
return CheckedCastKind::Coercion;
}
// Check for a bridging conversion.
// Anything bridges to AnyObject in ObjC interop mode.
if (Context.LangOpts.EnableObjCInterop
&& toType->isAnyObject())
return CheckedCastKind::BridgingCoercion;
// Do this check later in Swift 3 mode so that we check for NSNumber and
// NSValue casts (and container casts thereof) first.
if (!Context.LangOpts.isSwiftVersion3()
&& isObjCBridgedTo(fromType, toType, dc, &unwrappedIUO) && !unwrappedIUO){
return CheckedCastKind::BridgingCoercion;
}
Type origFromType = fromType;
Type origToType = toType;
// Determine whether we should suppress diagnostics.
bool suppressDiagnostics = (contextKind == CheckedCastContextKind::None);
// Local function to indicate failure.
auto failed = [&] {
if (suppressDiagnostics) {
return CheckedCastKind::Unresolved;
}
diagnose(diagLoc, diag::downcast_to_unrelated, origFromType, origToType)
.highlight(diagFromRange)
.highlight(diagToRange);
return CheckedCastKind::ValueCast;
};
// Strip optional wrappers off of the destination type in sync with
// stripping them off the origin type.
while (auto toValueType = toType->getAnyOptionalObjectType()) {
// Complain if we're trying to increase optionality, e.g.
// casting an NSObject? to an NSString??. That's not a subtype
// relationship.
auto fromValueType = fromType->getAnyOptionalObjectType();
if (!fromValueType) {
if (!suppressDiagnostics) {
diagnose(diagLoc, diag::downcast_to_more_optional,
origFromType, origToType)
.highlight(diagFromRange)
.highlight(diagToRange);
}
return CheckedCastKind::Unresolved;
}
toType = toValueType;
fromType = fromValueType;
}
// On the other hand, casts can decrease optionality monadically.
unsigned extraFromOptionals = 0;
while (auto fromValueType = fromType->getAnyOptionalObjectType()) {
fromType = fromValueType;
++extraFromOptionals;
}
// If the unwrapped from/to types are equivalent or bridged, this isn't a real
// downcast. Complain.
if (extraFromOptionals > 0) {
switch (typeCheckCheckedCast(fromType, toType,
CheckedCastContextKind::None, dc,
SourceLoc(), nullptr, SourceRange())) {
case CheckedCastKind::Coercion:
case CheckedCastKind::BridgingCoercion: {
// FIXME: Add a Fix-It, when the caller provides us with enough
// information.
if (!suppressDiagnostics) {
bool isBridged =
!fromType->isEqual(toType) && !isConvertibleTo(fromType, toType, dc);
switch (contextKind) {
case CheckedCastContextKind::None:
llvm_unreachable("suppressing diagnostics");
case CheckedCastContextKind::ForcedCast: {
std::string extraFromOptionalsStr(extraFromOptionals, '!');
auto diag = diagnose(diagLoc, diag::downcast_same_type,
origFromType, origToType,
extraFromOptionalsStr,
isBridged);
diag.highlight(diagFromRange);
diag.highlight(diagToRange);
/// Add the '!''s needed to adjust the type.
diag.fixItInsertAfter(diagFromRange.End,
std::string(extraFromOptionals, '!'));
if (isBridged) {
// If it's bridged, we still need the 'as' to perform the bridging.
diag.fixItReplaceChars(diagLoc, diagLoc.getAdvancedLocOrInvalid(3),
"as");
} else {
// Otherwise, implicit conversions will handle it in most cases.
SourceLoc afterExprLoc = Lexer::getLocForEndOfToken(Context.SourceMgr,
diagFromRange.End);
diag.fixItRemove(SourceRange(afterExprLoc, diagToRange.End));
}
break;
}
case CheckedCastContextKind::ConditionalCast:
// If we're only unwrapping a single optional, that optional value is
// effectively carried through to the underlying conversion, making this
// the moral equivalent of a map. Complain that one can do this with
// 'as' more effectively.
if (extraFromOptionals == 1) {
// A single optional is carried through. It's better to use 'as' to
// the appropriate optional type.
auto diag = diagnose(diagLoc, diag::conditional_downcast_same_type,
origFromType, origToType,
fromType->isEqual(toType) ? 0
: isBridged ? 2
: 1);
diag.highlight(diagFromRange);
diag.highlight(diagToRange);
if (isBridged) {
// For a bridged cast, replace the 'as?' with 'as'.
diag.fixItReplaceChars(diagLoc, diagLoc.getAdvancedLocOrInvalid(3),
"as");
// Make sure we'll cast to the appropriately-optional type by adding
// the '?'.
// FIXME: Parenthesize!
diag.fixItInsertAfter(diagToRange.End, "?");
} else {
// Just remove the cast; implicit conversions will handle it.
SourceLoc afterExprLoc =
Lexer::getLocForEndOfToken(Context.SourceMgr, diagFromRange.End);
if (afterExprLoc.isValid() && diagToRange.isValid())
diag.fixItRemove(SourceRange(afterExprLoc, diagToRange.End));
}
}
// If there is more than one extra optional, don't do anything: this
// conditional cast is trying to unwrap some levels of optional;
// let the runtime handle it.
break;
case CheckedCastContextKind::IsExpr:
// If we're only unwrapping a single optional, we could have just
// checked for 'nil'.
if (extraFromOptionals == 1) {
auto diag = diagnose(diagLoc, diag::is_expr_same_type,
origFromType, origToType);
diag.highlight(diagFromRange);
diag.highlight(diagToRange);
diag.fixItReplace(SourceRange(diagLoc, diagToRange.End), "!= nil");
// Add parentheses if needed.
if (!fromExpr->canAppendCallParentheses()) {
diag.fixItInsert(fromExpr->getStartLoc(), "(");
diag.fixItInsertAfter(fromExpr->getEndLoc(), ")");
}
}
// If there is more than one extra optional, don't do anything: this
// is performing a deeper check that the runtime will handle.
break;
case CheckedCastContextKind::IsPattern:
case CheckedCastContextKind::EnumElementPattern:
// Note: Don't diagnose these, because the code is testing whether
// the optionals can be unwrapped.
break;
}
}
// Treat this as a value cast so we preserve the semantics.
return CheckedCastKind::ValueCast;
}
case CheckedCastKind::Swift3BridgingDowncast:
case CheckedCastKind::ArrayDowncast:
case CheckedCastKind::DictionaryDowncast:
case CheckedCastKind::SetDowncast:
case CheckedCastKind::ValueCast:
break;
case CheckedCastKind::Unresolved:
return failed();
}
}
// Check for casts between specific concrete types that cannot succeed.
ConstraintSystem cs(*this, dc, ConstraintSystemOptions());
if (auto toElementType = cs.isArrayType(toType)) {
if (auto fromElementType = cs.isArrayType(fromType)) {
switch (typeCheckCheckedCast(*fromElementType, *toElementType,
CheckedCastContextKind::None, dc,
SourceLoc(), nullptr, SourceRange())) {
case CheckedCastKind::Coercion:
return CheckedCastKind::Coercion;
case CheckedCastKind::BridgingCoercion:
return CheckedCastKind::BridgingCoercion;
case CheckedCastKind::Swift3BridgingDowncast:
return CheckedCastKind::Swift3BridgingDowncast;
case CheckedCastKind::ArrayDowncast:
case CheckedCastKind::DictionaryDowncast:
case CheckedCastKind::SetDowncast:
case CheckedCastKind::ValueCast:
return CheckedCastKind::ArrayDowncast;
case CheckedCastKind::Unresolved:
return failed();
}
}
}
if (auto toKeyValue = cs.isDictionaryType(toType)) {
if (auto fromKeyValue = cs.isDictionaryType(fromType)) {
bool hasCoercion = false;
enum { NoBridging, BridgingCoercion, Swift3BridgingDowncast }
hasBridgingConversion = NoBridging;
bool hasCast = false;
switch (typeCheckCheckedCast(fromKeyValue->first, toKeyValue->first,
CheckedCastContextKind::None, dc,
SourceLoc(), nullptr, SourceRange())) {
case CheckedCastKind::Coercion:
hasCoercion = true;
break;
case CheckedCastKind::BridgingCoercion:
hasBridgingConversion = std::max(hasBridgingConversion,
BridgingCoercion);
break;
case CheckedCastKind::Swift3BridgingDowncast:
hasBridgingConversion = std::max(hasBridgingConversion,
Swift3BridgingDowncast);
break;
case CheckedCastKind::ArrayDowncast:
case CheckedCastKind::DictionaryDowncast:
case CheckedCastKind::SetDowncast:
case CheckedCastKind::ValueCast:
hasCast = true;
break;
case CheckedCastKind::Unresolved:
return failed();
}
switch (typeCheckCheckedCast(fromKeyValue->second, toKeyValue->second,
CheckedCastContextKind::None, dc,
SourceLoc(), nullptr, SourceRange())) {
case CheckedCastKind::Coercion:
hasCoercion = true;
break;
case CheckedCastKind::BridgingCoercion:
hasBridgingConversion = std::max(hasBridgingConversion,
BridgingCoercion);
break;
case CheckedCastKind::Swift3BridgingDowncast:
hasBridgingConversion = std::max(hasBridgingConversion,
Swift3BridgingDowncast);
break;
case CheckedCastKind::ArrayDowncast:
case CheckedCastKind::DictionaryDowncast:
case CheckedCastKind::SetDowncast:
case CheckedCastKind::ValueCast:
hasCast = true;
break;
case CheckedCastKind::Unresolved:
return failed();
}
if (hasCast) return CheckedCastKind::DictionaryDowncast;
switch (hasBridgingConversion) {
case NoBridging:
break;
case BridgingCoercion:
return CheckedCastKind::BridgingCoercion;
case Swift3BridgingDowncast:
return CheckedCastKind::Swift3BridgingDowncast;
}
assert(hasCoercion && "Not a coercion?");
return CheckedCastKind::Coercion;
}
}
if (auto toElementType = cs.isSetType(toType)) {
if (auto fromElementType = cs.isSetType(fromType)) {
switch (typeCheckCheckedCast(*fromElementType, *toElementType,
CheckedCastContextKind::None, dc,
SourceLoc(), nullptr, SourceRange())) {
case CheckedCastKind::Coercion:
return CheckedCastKind::Coercion;
case CheckedCastKind::BridgingCoercion:
return CheckedCastKind::BridgingCoercion;
case CheckedCastKind::Swift3BridgingDowncast:
return CheckedCastKind::Swift3BridgingDowncast;
case CheckedCastKind::ArrayDowncast:
case CheckedCastKind::DictionaryDowncast:
case CheckedCastKind::SetDowncast:
case CheckedCastKind::ValueCast:
return CheckedCastKind::SetDowncast;
case CheckedCastKind::Unresolved:
return failed();
}
}
}
// We accepted `NSNumber`-to-`*Int*` and `NSValue`-to-struct as bridging
// conversions in Swift 3. For compatibility, we need to distinguish these
// cases so we can accept them as coercions (with a warning).
if (Context.LangOpts.isSwiftVersion3() && extraFromOptionals == 0) {
// Do the check for a bridging conversion now that we deferred above.
if (isObjCBridgedTo(fromType, toType, dc, &unwrappedIUO) && !unwrappedIUO) {
if (isObjCClassWithMultipleSwiftBridgedTypes(fromType, dc)) {
return CheckedCastKind::Swift3BridgingDowncast;
}
return CheckedCastKind::BridgingCoercion;
}
}
// If we can bridge through an Objective-C class, do so.
if (Type bridgedToClass = getDynamicBridgedThroughObjCClass(dc, fromType,
toType)) {
switch (typeCheckCheckedCast(bridgedToClass, fromType,
CheckedCastContextKind::None, dc, SourceLoc(),
nullptr, SourceRange())) {
case CheckedCastKind::ArrayDowncast:
case CheckedCastKind::BridgingCoercion:
case CheckedCastKind::Swift3BridgingDowncast:
case CheckedCastKind::Coercion:
case CheckedCastKind::DictionaryDowncast:
case CheckedCastKind::SetDowncast:
case CheckedCastKind::ValueCast:
return CheckedCastKind::ValueCast;
case CheckedCastKind::Unresolved:
break;
}
}
// If we can bridge through an Objective-C class, do so.
if (Type bridgedFromClass = getDynamicBridgedThroughObjCClass(dc, toType,
fromType)) {
switch (typeCheckCheckedCast(toType, bridgedFromClass,
CheckedCastContextKind::None, dc, SourceLoc(),
nullptr, SourceRange())) {
case CheckedCastKind::ArrayDowncast:
case CheckedCastKind::BridgingCoercion:
case CheckedCastKind::Swift3BridgingDowncast:
case CheckedCastKind::Coercion:
case CheckedCastKind::DictionaryDowncast:
case CheckedCastKind::SetDowncast:
case CheckedCastKind::ValueCast:
return CheckedCastKind::ValueCast;
case CheckedCastKind::Unresolved:
break;
}
}
// Strip metatypes. If we can cast two types, we can cast their metatypes.
bool metatypeCast = false;
while (auto toMetatype = toType->getAs<MetatypeType>()) {
auto fromMetatype = fromType->getAs<MetatypeType>();
if (!fromMetatype)
break;
metatypeCast = true;
toType = toMetatype->getInstanceType();
fromType = fromMetatype->getInstanceType();
}
// Strip an inner layer of potentially existential metatype.
bool toExistentialMetatype = false;
bool fromExistentialMetatype = false;
if (auto toMetatype = toType->getAs<AnyMetatypeType>()) {
toExistentialMetatype = toMetatype->is<ExistentialMetatypeType>();
if (auto fromMetatype = fromType->getAs<AnyMetatypeType>()) {
fromExistentialMetatype = fromMetatype->is<ExistentialMetatypeType>();
toType = toMetatype->getInstanceType();
fromType = fromMetatype->getInstanceType();
}
}
bool toArchetype = toType->is<ArchetypeType>();
bool fromArchetype = fromType->is<ArchetypeType>();
SmallVector<ProtocolDecl*, 2> toProtocols;
bool toExistential = toType->isExistentialType(toProtocols);
SmallVector<ProtocolDecl*, 2> fromProtocols;
bool fromExistential = fromType->isExistentialType(fromProtocols);
// If we're doing a metatype cast, it can only be existential if we're
// casting to/from the existential metatype. 'T.self as P.Protocol'
// can only succeed if T is exactly the type P, so is a concrete cast,
// whereas 'T.self as P.Type' succeeds for types conforming to the protocol
// P, and is an existential cast.
if (metatypeCast) {
toExistential &= toExistentialMetatype;
fromExistential &= fromExistentialMetatype;
}
// Casts to or from generic types can't be statically constrained in most
// cases, because there may be protocol conformances we don't statically
// know about.
//
// TODO: There are cases we could statically warn about, such as casting
// from a non-class to a class-constrained archetype or existential.
if (toExistential || fromExistential || fromArchetype || toArchetype)
return CheckedCastKind::ValueCast;
if (cs.isAnyHashableType(toType) || cs.isAnyHashableType(fromType)) {
return CheckedCastKind::ValueCast;
}
// If the destination type is a subtype of the source type, we have
// a downcast.
if (isSubtypeOf(toType, fromType, dc)) {
return CheckedCastKind::ValueCast;
}
// Objective-C metaclasses are subclasses of NSObject in the ObjC runtime,
// so casts from NSObject to potentially-class metatypes may succeed.
if (auto nsObject = cs.TC.getNSObjectType(dc)) {
if (fromType->isEqual(nsObject)) {
if (auto toMeta = toType->getAs<MetatypeType>()) {
if (toMeta->getInstanceType()->mayHaveSuperclass()
|| toMeta->getInstanceType()->is<ArchetypeType>())
return CheckedCastKind::ValueCast;
}
if (toType->is<ExistentialMetatypeType>())
return CheckedCastKind::ValueCast;
}
}
// We can conditionally cast from NSError to an Error-conforming
// type. This is handled in the runtime, so it doesn't need a special cast
// kind.
if (Context.LangOpts.EnableObjCInterop) {
if (auto errorTypeProto = Context.getProtocol(KnownProtocolKind::Error)) {
if (conformsToProtocol(toType, errorTypeProto, dc,
(ConformanceCheckFlags::InExpression|
ConformanceCheckFlags::Used)))
if (auto NSErrorTy = getNSErrorType(dc))
if (isSubtypeOf(fromType, NSErrorTy, dc)
// Don't mask "always true" warnings if NSError is cast to
// Error itself.
&& !isSubtypeOf(fromType, toType, dc))
return CheckedCastKind::ValueCast;
}
}
// The runtime doesn't support casts to CF types and always lets them succeed.
// This "always fails" diagnosis makes no sense when paired with the CF
// one.
auto clas = toType->getClassOrBoundGenericClass();
if (clas && clas->getForeignClassKind() == ClassDecl::ForeignKind::CFType)
return CheckedCastKind::ValueCast;
// Don't warn on casts that change the generic parameters of ObjC generic
// classes. This may be necessary to force-fit ObjC APIs that depend on
// covariance, or for APIs where the generic parameter annotations in the
// ObjC headers are inaccurate.
if (clas && clas->usesObjCGenericsModel()) {
if (fromType->getClassOrBoundGenericClass() == clas)
return CheckedCastKind::ValueCast;
}
return failed();
}
/// If the expression is an implicit call to _forceBridgeFromObjectiveC or
/// _conditionallyBridgeFromObjectiveC, returns the argument of that call.
static Expr *lookThroughBridgeFromObjCCall(ASTContext &ctx, Expr *expr) {
auto call = dyn_cast<CallExpr>(expr);
if (!call || !call->isImplicit())
return nullptr;
auto callee = call->getCalledValue();
if (!callee)
return nullptr;
if (callee == ctx.getForceBridgeFromObjectiveC(nullptr) ||
callee == ctx.getConditionallyBridgeFromObjectiveC(nullptr))
return cast<TupleExpr>(call->getArg())->getElement(0);
return nullptr;
}
/// If the expression has the effect of a forced downcast, find the
/// underlying forced downcast expression.
ForcedCheckedCastExpr *swift::findForcedDowncast(ASTContext &ctx, Expr *expr) {
expr = expr->getSemanticsProvidingExpr();
// Simple case: forced checked cast.
if (auto forced = dyn_cast<ForcedCheckedCastExpr>(expr)) {
return forced;
}
// If we have an implicit force, look through it.
if (auto forced = dyn_cast<ForceValueExpr>(expr)) {
if (forced->isImplicit()) {
expr = forced->getSubExpr();
}
}
// Skip through optional evaluations and binds.
auto skipOptionalEvalAndBinds = [](Expr *expr) -> Expr* {
do {
if (!expr->isImplicit())
break;
if (auto optionalEval = dyn_cast<OptionalEvaluationExpr>(expr)) {
expr = optionalEval->getSubExpr();
continue;
}
if (auto bindOptional = dyn_cast<BindOptionalExpr>(expr)) {
expr = bindOptional->getSubExpr();
continue;
}
break;
} while (true);
return expr;
};
auto sub = skipOptionalEvalAndBinds(expr);
// If we have an explicit cast, we're done.
if (auto *FCE = dyn_cast<ForcedCheckedCastExpr>(sub))
return FCE;
// Otherwise, try to look through an implicit _forceBridgeFromObjectiveC() call.
if (auto arg = lookThroughBridgeFromObjCCall(ctx, sub)) {
sub = skipOptionalEvalAndBinds(arg);
if (auto *FCE = dyn_cast<ForcedCheckedCastExpr>(sub))
return FCE;
}
return nullptr;
}