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fuchsia / third_party / swift / 34960788aa9e62e4c36d2cf5da08bd56a6635af5 / . / lib / Sema / TypeChecker.h
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//===--- TypeChecker.h - Type Checking Class --------------------*- C++ -*-===//
//
// 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 defines the TypeChecking class.
//
//===----------------------------------------------------------------------===//
#ifndef TYPECHECKING_H
#define TYPECHECKING_H
#include "swift/AST/ASTContext.h"
#include "swift/AST/AccessScope.h"
#include "swift/AST/AnyFunctionRef.h"
#include "swift/AST/Availability.h"
#include "swift/AST/DiagnosticsSema.h"
#include "swift/AST/KnownProtocols.h"
#include "swift/AST/LazyResolver.h"
#include "swift/AST/NameLookup.h"
#include "swift/AST/TypeRefinementContext.h"
#include "swift/Parse/Lexer.h"
#include "swift/Basic/OptionSet.h"
#include "swift/Config.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/TinyPtrVector.h"
#include <functional>
namespace swift {
class GenericSignatureBuilder;
class NominalTypeDecl;
class NormalProtocolConformance;
class TopLevelContext;
class TypeChecker;
class TypeResolution;
class TypeResolutionOptions;
class TypoCorrectionResults;
class ExprPattern;
enum class TypeResolutionStage : uint8_t;
namespace constraints {
enum class ConstraintKind : char;
enum class SolutionKind : char;
class ConstraintSystem;
class Solution;
}
/// A mapping from substitutable types to the protocol-conformance
/// mappings for those types.
using ConformanceMap =
llvm::DenseMap<SubstitutableType *, SmallVector<ProtocolConformance *, 2>>;
/// Special-case type checking semantics for certain declarations.
enum class DeclTypeCheckingSemantics {
/// A normal declaration.
Normal,
/// The type(of:) declaration, which performs a "dynamic type" operation,
/// with different behavior for existential and non-existential arguments.
TypeOf,
/// The withoutActuallyEscaping(_:do:) declaration, which makes a nonescaping
/// closure temporarily escapable.
WithoutActuallyEscaping,
/// The _openExistential(_:do:) declaration, which extracts the value inside
/// an existential and passes it as a value of its own dynamic type.
OpenExistential,
};
/// The result of name lookup.
class LookupResult {
private:
/// The set of results found.
SmallVector<LookupResultEntry, 4> Results;
size_t IndexOfFirstOuterResult = 0;
public:
LookupResult() {}
explicit LookupResult(const SmallVectorImpl<LookupResultEntry> &Results,
size_t indexOfFirstOuterResult)
: Results(Results.begin(), Results.end()),
IndexOfFirstOuterResult(indexOfFirstOuterResult) {}
using iterator = SmallVectorImpl<LookupResultEntry>::iterator;
iterator begin() { return Results.begin(); }
iterator end() {
return Results.begin() + IndexOfFirstOuterResult;
}
unsigned size() const { return innerResults().size(); }
bool empty() const { return innerResults().empty(); }
ArrayRef<LookupResultEntry> innerResults() const {
return llvm::makeArrayRef(Results).take_front(IndexOfFirstOuterResult);
}
ArrayRef<LookupResultEntry> outerResults() const {
return llvm::makeArrayRef(Results).drop_front(IndexOfFirstOuterResult);
}
const LookupResultEntry& operator[](unsigned index) const {
return Results[index];
}
LookupResultEntry front() const { return innerResults().front(); }
LookupResultEntry back() const { return innerResults().back(); }
/// Add a result to the set of results.
void add(LookupResultEntry result, bool isOuter) {
Results.push_back(result);
if (!isOuter) {
IndexOfFirstOuterResult++;
assert(IndexOfFirstOuterResult == Results.size() &&
"found an outer result before an inner one");
} else {
assert(IndexOfFirstOuterResult > 0 &&
"found outer results without an inner one");
}
}
void clear() { Results.clear(); }
/// Determine whether the result set is nonempty.
explicit operator bool() const {
return !empty();
}
TypeDecl *getSingleTypeResult() const {
if (size() != 1)
return nullptr;
return dyn_cast<TypeDecl>(front().getValueDecl());
}
/// Filter out any results that aren't accepted by the given predicate.
void
filter(llvm::function_ref<bool(LookupResultEntry, /*isOuter*/ bool)> pred);
/// Shift down results by dropping inner results while keeping outer
/// results (if any), the innermost of which are recogized as inner
/// results afterwards.
void shiftDownResults();
};
/// An individual result of a name lookup for a type.
struct LookupTypeResultEntry {
TypeDecl *Member;
Type MemberType;
/// The associated type that the Member/MemberType were inferred for, but only
/// if inference happened when creating this entry.
AssociatedTypeDecl *InferredAssociatedType;
};
/// The result of name lookup for types.
class LookupTypeResult {
/// The set of results found.
SmallVector<LookupTypeResultEntry, 4> Results;
friend class TypeChecker;
public:
using iterator = SmallVectorImpl<LookupTypeResultEntry>::iterator;
iterator begin() { return Results.begin(); }
iterator end() { return Results.end(); }
unsigned size() const { return Results.size(); }
LookupTypeResultEntry operator[](unsigned index) const {
return Results[index];
}
LookupTypeResultEntry front() const { return Results.front(); }
LookupTypeResultEntry back() const { return Results.back(); }
/// Add a result to the set of results.
void addResult(LookupTypeResultEntry result) { Results.push_back(result); }
/// Determine whether this result set is ambiguous.
bool isAmbiguous() const {
return Results.size() > 1;
}
/// Determine whether the result set is nonempty.
explicit operator bool() const {
return !Results.empty();
}
};
/// This specifies the purpose of the contextual type, when specified to
/// typeCheckExpression. This is used for diagnostic generation to produce more
/// specified error messages when the conversion fails.
///
enum ContextualTypePurpose {
CTP_Unused, ///< No contextual type is specified.
CTP_Initialization, ///< Pattern binding initialization.
CTP_ReturnStmt, ///< Value specified to a 'return' statement.
CTP_YieldByValue, ///< By-value yield operand.
CTP_YieldByReference, ///< By-reference yield operand.
CTP_ThrowStmt, ///< Value specified to a 'throw' statement.
CTP_EnumCaseRawValue, ///< Raw value specified for "case X = 42" in enum.
CTP_DefaultParameter, ///< Default value in parameter 'foo(a : Int = 42)'.
CTP_CalleeResult, ///< Constraint is placed on the result of a callee.
CTP_CallArgument, ///< Call to function or operator requires type.
CTP_ClosureResult, ///< Closure result expects a specific type.
CTP_ArrayElement, ///< ArrayExpr wants elements to have a specific type.
CTP_DictionaryKey, ///< DictionaryExpr keys should have a specific type.
CTP_DictionaryValue, ///< DictionaryExpr values should have a specific type.
CTP_CoerceOperand, ///< CoerceExpr operand coerced to specific type.
CTP_AssignSource, ///< AssignExpr source operand coerced to result type.
CTP_CannotFail, ///< Conversion can never fail. abort() if it does.
};
/// Flags that can be used to control name lookup.
enum class TypeCheckExprFlags {
/// Whether we know that the result of the expression is discarded. This
/// disables constraints forcing an lvalue result to be loadable.
IsDiscarded = 0x01,
/// Whether the client wants to disable the structural syntactic restrictions
/// that we force for style or other reasons.
DisableStructuralChecks = 0x02,
/// Set if the client wants diagnostics suppressed.
SuppressDiagnostics = 0x04,
/// If set, the client wants a best-effort solution to the constraint system,
/// but can tolerate a solution where all of the constraints are solved, but
/// not all type variables have been determined. In this case, the constraint
/// system is not applied to the expression AST, but the ConstraintSystem is
/// left in-tact.
AllowUnresolvedTypeVariables = 0x08,
/// If set, the 'convertType' specified to typeCheckExpression should not
/// produce a conversion constraint, but it should be used to guide the
/// solution in terms of performance optimizations of the solver, and in terms
/// of guiding diagnostics.
ConvertTypeIsOnlyAHint = 0x10,
/// If set, this expression isn't embedded in a larger expression or
/// statement. This should only be used for syntactic restrictions, and should
/// not affect type checking itself.
IsExprStmt = 0x20,
/// If set, this expression is being re-type checked as part of diagnostics,
/// and so we should not visit bodies of non-single expression closures.
SkipMultiStmtClosures = 0x40,
/// This is an inout yield.
IsInOutYield = 0x100,
/// If set, a conversion constraint should be specified so that the result of
/// the expression is an optional type.
ExpressionTypeMustBeOptional = 0x200,
/// FIXME(diagnostics): Once diagnostics are completely switched to new
/// framework, this flag could be removed as obsolete.
///
/// If set, this is a sub-expression, and it is being re-typechecked
/// as part of the expression diagnostics, which is attempting to narrow
/// down failure location.
SubExpressionDiagnostics = 0x400,
};
using TypeCheckExprOptions = OptionSet<TypeCheckExprFlags>;
inline TypeCheckExprOptions operator|(TypeCheckExprFlags flag1,
TypeCheckExprFlags flag2) {
return TypeCheckExprOptions(flag1) | flag2;
}
/// Flags that can be used to control name lookup.
enum class NameLookupFlags {
/// Whether we know that this lookup is always a private dependency.
KnownPrivate = 0x01,
/// Whether name lookup should be able to find protocol members.
ProtocolMembers = 0x02,
/// Whether we should map the requirement to the witness if we
/// find a protocol member and the base type is a concrete type.
///
/// If this is not set but ProtocolMembers is set, we will
/// find protocol extension members, but not protocol requirements
/// that do not yet have a witness (such as inferred associated
/// types, or witnesses for derived conformances).
PerformConformanceCheck = 0x04,
/// Whether to perform 'dynamic' name lookup that finds @objc
/// members of any class or protocol.
DynamicLookup = 0x08,
/// Whether to ignore access control for this lookup, allowing inaccessible
/// results to be returned.
IgnoreAccessControl = 0x10,
/// Whether to include results from outside the innermost scope that has a
/// result.
IncludeOuterResults = 0x20,
/// Whether to consider synonyms declared through @_implements().
IncludeAttributeImplements = 0x40,
};
/// A set of options that control name lookup.
using NameLookupOptions = OptionSet<NameLookupFlags>;
inline NameLookupOptions operator|(NameLookupFlags flag1,
NameLookupFlags flag2) {
return NameLookupOptions(flag1) | flag2;
}
/// Default options for member name lookup.
const NameLookupOptions defaultMemberLookupOptions
= NameLookupFlags::ProtocolMembers |
NameLookupFlags::PerformConformanceCheck;
/// Default options for constructor lookup.
const NameLookupOptions defaultConstructorLookupOptions
= NameLookupFlags::ProtocolMembers |
NameLookupFlags::PerformConformanceCheck;
/// Default options for member type lookup.
const NameLookupOptions defaultMemberTypeLookupOptions
= NameLookupFlags::ProtocolMembers |
NameLookupFlags::PerformConformanceCheck;
/// Default options for unqualified name lookup.
const NameLookupOptions defaultUnqualifiedLookupOptions
= NameLookupFlags::ProtocolMembers |
NameLookupFlags::PerformConformanceCheck;
/// Describes the result of comparing two entities, of which one may be better
/// or worse than the other, or they are unordered.
enum class Comparison {
/// Neither entity is better than the other.
Unordered,
/// The first entity is better than the second.
Better,
/// The first entity is worse than the second.
Worse
};
/// Specify how we handle the binding of underconstrained (free) type variables
/// within a solution to a constraint system.
enum class FreeTypeVariableBinding {
/// Disallow any binding of such free type variables.
Disallow,
/// Allow the free type variables to persist in the solution.
Allow,
/// Bind the type variables to UnresolvedType to represent the ambiguity.
UnresolvedType
};
/// An abstract interface that can interact with the type checker during
/// the type checking of a particular expression.
class ExprTypeCheckListener {
public:
virtual ~ExprTypeCheckListener();
/// Callback invoked once the constraint system has been constructed.
///
/// \param cs The constraint system that has been constructed.
///
/// \param expr The pre-checked expression from which the constraint system
/// was generated.
///
/// \returns true if an error occurred that is not itself part of the
/// constraint system, or false otherwise.
virtual bool builtConstraints(constraints::ConstraintSystem &cs, Expr *expr);
/// Callback invoked once a solution has been found.
///
/// The callback may further alter the expression, returning either a
/// new expression (to replace the result) or a null pointer to indicate
/// failure.
virtual Expr *foundSolution(constraints::Solution &solution, Expr *expr);
/// Callback invokes once the chosen solution has been applied to the
/// expression.
///
/// The callback may further alter the expression, returning either a
/// new expression (to replace the result) or a null pointer to indicate
/// failure.
virtual Expr *appliedSolution(constraints::Solution &solution,
Expr *expr);
/// Callback invoked if expression is structurally unsound and can't
/// be correctly processed by the constraint solver.
virtual void preCheckFailed(Expr *expr);
/// Callback invoked if constraint system failed to generate
/// constraints for a given expression.
virtual void constraintGenerationFailed(Expr *expr);
/// Callback invoked if application of chosen solution to
/// expression has failed.
virtual void applySolutionFailed(constraints::Solution &solution, Expr *expr);
};
/// A conditional conformance that implied some other requirements. That is, \c
/// ConformingType conforming to \c Protocol may have required additional
/// requirements to be satisfied.
///
/// This is designed to be used in a stack of such requirements, which can be
/// formatted with \c diagnoseConformanceStack.
struct ParentConditionalConformance {
Type ConformingType;
ProtocolType *Protocol;
/// Format the stack \c conformances as a series of notes that trace a path of
/// conditional conformances that lead to some other failing requirement (that
/// is not in \c conformances).
///
/// The end of \c conformances is the active end of the stack, i.e. \c
/// conformances[0] is a conditional conformance that requires \c
/// conformances[1], etc.
static void
diagnoseConformanceStack(DiagnosticEngine &diags, SourceLoc location,
ArrayRef<ParentConditionalConformance> conformances);
};
/// An abstract interface that is used by `checkGenericArguments`.
class GenericRequirementsCheckListener {
public:
virtual ~GenericRequirementsCheckListener();
/// Callback invoked before trying to check generic requirement placed
/// between given types. Note: if either of the types assigned to the
/// requirement is generic parameter or dependent member, this callback
/// method is going to get their substitutions.
///
/// \param kind The kind of generic requirement to check.
///
/// \param first The left-hand side type assigned to the requirement,
/// possibly represented by its generic substitute.
///
/// \param second The right-hand side type assigned to the requirement,
/// possibly represented by its generic substitute.
///
///
/// \returns true if it's ok to validate requirement, false otherwise.
virtual bool shouldCheck(RequirementKind kind, Type first, Type second);
/// Callback to report the result of a satisfied conformance requirement.
///
/// \param depTy The dependent type, from the signature.
/// \param replacementTy The type \c depTy was replaced with.
/// \param conformance The conformance itself.
virtual void satisfiedConformance(Type depTy, Type replacementTy,
ProtocolConformanceRef conformance);
/// Callback to diagnose problem with unsatisfied generic requirement.
///
/// \param req The unsatisfied generic requirement.
///
/// \param first The left-hand side type assigned to the requirement,
/// possibly represented by its generic substitute.
///
/// \param second The right-hand side type assigned to the requirement,
/// possibly represented by its generic substitute.
///
/// \returns true if problem has been diagnosed, false otherwise.
virtual bool diagnoseUnsatisfiedRequirement(
const Requirement &req, Type first, Type second,
ArrayRef<ParentConditionalConformance> parents);
};
/// The result of `checkGenericRequirement`.
enum class RequirementCheckResult {
Success, Failure, SubstitutionFailure
};
/// Flags that control protocol conformance checking.
enum class ConformanceCheckFlags {
/// Whether we're performing the check from within an expression.
InExpression = 0x01,
/// Whether we will be using the conformance in the AST.
///
/// This implies that the conformance will have to be complete.
Used = 0x02,
/// Whether to suppress dependency tracking entirely.
///
/// FIXME: This deals with some oddities with the
/// _ObjectiveCBridgeable conformances.
SuppressDependencyTracking = 0x04,
/// Whether to skip the check for any conditional conformances.
///
/// When set, the caller takes responsibility for any
/// conditional requirements required for the conformance to be
/// correctly used. Otherwise (the default), all of the conditional
/// requirements will be checked.
SkipConditionalRequirements = 0x08,
/// Whether to require that the conditional requirements have been computed.
///
/// When set, if the conditional requirements aren't available, they are just
/// skipped, and the caller is responsible for detecting and handling this
/// case (likely via another call to getConditionalRequirementsIfAvailable).
AllowUnavailableConditionalRequirements = 0x10,
};
/// Options that control protocol conformance checking.
using ConformanceCheckOptions = OptionSet<ConformanceCheckFlags>;
inline ConformanceCheckOptions operator|(ConformanceCheckFlags lhs,
ConformanceCheckFlags rhs) {
return ConformanceCheckOptions(lhs) | rhs;
}
/// Describes the kind of checked cast operation being performed.
enum class CheckedCastContextKind {
/// None: we're just establishing how to perform the checked cast. This
/// is useful when we don't care to produce any diagnostics.
None,
/// A forced cast, with "as!".
ForcedCast,
/// A conditional cast, with "as?".
ConditionalCast,
/// An "is" expression.
IsExpr,
/// An "is" pattern.
IsPattern,
/// An enum-element pattern.
EnumElementPattern,
};
/// The Swift type checker, which takes a parsed AST and performs name binding,
/// type checking, and semantic analysis to produce a type-annotated AST.
class TypeChecker final : public LazyResolver {
public:
ASTContext &Context;
DiagnosticEngine &Diags;
/// The list of function definitions we've encountered.
std::vector<AbstractFunctionDecl *> definedFunctions;
/// Declarations that need their conformances checked.
llvm::SmallVector<Decl *, 8> ConformanceContexts;
/// The list of protocol conformances that were "used" and will need to be
/// completed before type checking is considered complete.
llvm::SetVector<NormalProtocolConformance *> UsedConformances;
/// The list of protocol conformances whose requirements could not be
/// fully checked and, therefore, should be checked again at the top
/// level.
llvm::SetVector<NormalProtocolConformance *> PartiallyCheckedConformances;
/// The list of declarations that we've done at least partial validation
/// of during type-checking, but which will need to be finalized before
/// we can hand them off to SILGen etc.
llvm::SetVector<ValueDecl *> DeclsToFinalize;
/// Track the index of the next declaration that needs to be finalized,
/// from the \c DeclsToFinalize set.
unsigned NextDeclToFinalize = 0;
/// The list of protocols that need their requirement signatures computed,
/// because they were first validated by validateDeclForNameLookup(),
/// which skips this step.
llvm::SetVector<ProtocolDecl *> DelayedRequirementSignatures;
/// The list of types whose circularity checks were delayed.
SmallVector<NominalTypeDecl*, 8> DelayedCircularityChecks;
// Caches whether a given declaration is "as specialized" as another.
llvm::DenseMap<std::tuple<ValueDecl *, ValueDecl *,
/*isDynamicOverloadComparison*/ unsigned>,
bool>
specializedOverloadComparisonCache;
/// A list of closures for the most recently type-checked function, which we
/// will need to compute captures for.
std::vector<AbstractClosureExpr *> ClosuresWithUncomputedCaptures;
/// Local functions that have been captured before their definitions.
///
/// We need this to guard against functions that would transitively capture
/// variables before their definition, e.g.:
///
/// func outer() {
/// func first() {
/// second()
/// }
/// second()
/// var x
/// func second() {
/// use(x)
/// }
/// }
llvm::SmallDenseMap<AnyFunctionRef, SmallVector<AnyFunctionRef, 4>, 4>
ForwardCapturedFuncs;
/// A set of local functions from which C function pointers are derived.
///
/// This is used to diagnose the use of local functions with captured context
/// as C function pointers when the function's captures have not yet been
/// computed.
llvm::DenseMap<AnyFunctionRef, std::vector<Expr*>> LocalCFunctionPointers;
private:
/// The # of times we have performed typo correction.
unsigned NumTypoCorrections = 0;
private:
Type MaxIntegerType;
Type NSObjectType;
Type NSNumberType;
Type NSValueType;
Type ObjCSelectorType;
/// The set of expressions currently being analyzed for failures.
llvm::DenseMap<Expr*, Expr*> DiagnosedExprs;
ModuleDecl *StdlibModule = nullptr;
/// The index of the next response metavariable to bind to a REPL result.
unsigned NextResponseVariableIndex = 0;
/// If non-zero, warn when a function body takes longer than this many
/// milliseconds to type-check.
///
/// Intended for debugging purposes only.
unsigned WarnLongFunctionBodies = 0;
/// If non-zero, warn when type-checking an expression takes longer
/// than this many milliseconds.
///
/// Intended for debugging purposes only.
unsigned WarnLongExpressionTypeChecking = 0;
/// If non-zero, abort the expression type checker if it takes more
/// than this many seconds.
unsigned ExpressionTimeoutThreshold = 600;
/// If non-zero, abort the switch statement exhaustiveness checker if
/// the Space::minus function is called more than this many times.
///
/// Why this number? Times out in about a second on a 2017 iMac, Retina 5K,
// 4.2 GHz Intel Core i7.
// (It's arbitrary, but will keep the compiler from taking too much time.)
unsigned SwitchCheckingInvocationThreshold = 200000;
/// If true, the time it takes to type-check each function will be dumped
/// to llvm::errs().
bool DebugTimeFunctionBodies = false;
/// If true, the time it takes to type-check each expression will be
/// dumped to llvm::errs().
bool DebugTimeExpressions = false;
/// Indicate that the type checker is checking code that will be
/// immediately executed. This will suppress certain warnings
/// when executing scripts.
bool InImmediateMode = false;
/// A helper to construct and typecheck call to super.init().
///
/// \returns NULL if the constructed expression does not typecheck.
Expr* constructCallToSuperInit(ConstructorDecl *ctor, ClassDecl *ClDecl);
TypeChecker(ASTContext &Ctx);
friend class ASTContext;
public:
/// Create a new type checker instance for the given ASTContext, if it
/// doesn't already have one.
///
/// \returns a reference to the type vchecker.
static TypeChecker &createForContext(ASTContext &ctx);
TypeChecker(const TypeChecker&) = delete;
TypeChecker& operator=(const TypeChecker&) = delete;
~TypeChecker();
LangOptions &getLangOpts() const { return Context.LangOpts; }
/// Dump the time it takes to type-check each function to llvm::errs().
void enableDebugTimeFunctionBodies() {
DebugTimeFunctionBodies = true;
}
/// Dump the time it takes to type-check each function to llvm::errs().
void enableDebugTimeExpressions() {
DebugTimeExpressions = true;
}
bool getDebugTimeExpressions() {
return DebugTimeExpressions;
}
/// If \p timeInMS is non-zero, warn when a function body takes longer than
/// this many milliseconds to type-check.
///
/// Intended for debugging purposes only.
void setWarnLongFunctionBodies(unsigned timeInMS) {
WarnLongFunctionBodies = timeInMS;
}
/// If \p timeInMS is non-zero, warn when type-checking an expression
/// takes longer than this many milliseconds.
///
/// Intended for debugging purposes only.
void setWarnLongExpressionTypeChecking(unsigned timeInMS) {
WarnLongExpressionTypeChecking = timeInMS;
}
/// Return the current setting for the number of milliseconds
/// threshold we use to determine whether to warn about an
/// expression taking a long time.
unsigned getWarnLongExpressionTypeChecking() {
return WarnLongExpressionTypeChecking;
}
/// Set the threshold that determines the upper bound for the number
/// of seconds we'll let the expression type checker run before
/// considering an expression "too complex".
void setExpressionTimeoutThreshold(unsigned timeInSeconds) {
ExpressionTimeoutThreshold = timeInSeconds;
}
/// Return the current setting for the threshold that determines
/// the upper bound for the number of seconds we'll let the
/// expression type checker run before considering an expression
/// "too complex".
/// If zero, do not limit the checking.
unsigned getExpressionTimeoutThresholdInSeconds() {
return ExpressionTimeoutThreshold;
}
/// Get the threshold that determines the upper bound for the number
/// of times we'll let the Space::minus routine run before
/// considering a switch statement "too complex".
/// If zero, do not limit the checking.
unsigned getSwitchCheckingInvocationThreshold() const {
return SwitchCheckingInvocationThreshold;
}
/// Set the threshold that determines the upper bound for the number
/// of times we'll let the Space::minus routine run before
/// considering a switch statement "too complex".
void setSwitchCheckingInvocationThreshold(unsigned invocationCount) {
SwitchCheckingInvocationThreshold = invocationCount;
}
bool getInImmediateMode() {
return InImmediateMode;
}
void setInImmediateMode(bool InImmediateMode) {
this->InImmediateMode = InImmediateMode;
}
template<typename ...ArgTypes>
InFlightDiagnostic diagnose(ArgTypes &&...Args) {
return Diags.diagnose(std::forward<ArgTypes>(Args)...);
}
static Type getArraySliceType(SourceLoc loc, Type elementType);
static Type getDictionaryType(SourceLoc loc, Type keyType, Type valueType);
static Type getOptionalType(SourceLoc loc, Type elementType);
Type getUnsafePointerType(SourceLoc loc, Type pointeeType);
Type getUnsafeMutablePointerType(SourceLoc loc, Type pointeeType);
Type getStringType(DeclContext *dc);
Type getSubstringType(DeclContext *dc);
Type getIntType(DeclContext *dc);
Type getInt8Type(DeclContext *dc);
Type getUInt8Type(DeclContext *dc);
Type getNSObjectType(DeclContext *dc);
Type getObjCSelectorType(DeclContext *dc);
Type getExceptionType(DeclContext *dc, SourceLoc loc);
/// Try to resolve an IdentTypeRepr, returning either the referenced
/// Type or an ErrorType in case of error.
static Type resolveIdentifierType(TypeResolution resolution,
IdentTypeRepr *IdType,
TypeResolutionOptions options);
/// Bind an UnresolvedDeclRefExpr by performing name lookup and
/// returning the resultant expression. Context is the DeclContext used
/// for the lookup.
Expr *resolveDeclRefExpr(UnresolvedDeclRefExpr *UDRE, DeclContext *Context);
/// Validate the given type.
///
/// Type validation performs name binding, checking of generic arguments,
/// and so on to determine whether the given type is well-formed and can
/// be used as a type.
///
/// \param Loc The type (with source location information) to validate.
/// If the type has already been validated, returns immediately.
///
/// \param resolution The type resolution being performed.
///
/// \param options Options that alter type resolution.
///
/// \returns true if type validation failed, or false otherwise.
bool validateType(TypeLoc &Loc, TypeResolution resolution,
TypeResolutionOptions options);
/// Check for unsupported protocol types in the given declaration.
void checkUnsupportedProtocolType(Decl *decl);
/// Check for unsupported protocol types in the given statement.
void checkUnsupportedProtocolType(Stmt *stmt);
/// Check for unsupported protocol types in the given generic requirement
/// list.
void checkUnsupportedProtocolType(TrailingWhereClause *whereClause);
/// Check for unsupported protocol types in the given generic requirement
/// list.
void checkUnsupportedProtocolType(GenericParamList *genericParams);
/// Expose TypeChecker's handling of GenericParamList to SIL parsing.
GenericEnvironment *handleSILGenericParams(GenericParamList *genericParams,
DeclContext *DC);
void validateDecl(ValueDecl *D);
void validateDecl(OperatorDecl *decl);
void validateDecl(PrecedenceGroupDecl *decl);
/// Perform just enough validation for looking up names using the Decl.
void validateDeclForNameLookup(ValueDecl *D);
/// Validate the given extension declaration, ensuring that it
/// properly extends the nominal type it names.
void validateExtension(ExtensionDecl *ext);
/// Request that type containing the given member needs to have all
/// members validated after everythign in the translation unit has
/// been processed.
void requestMemberLayout(ValueDecl *member);
/// Request that the given class needs to have all members validated
/// after everything in the translation unit has been processed.
void requestNominalLayout(NominalTypeDecl *nominalDecl);
/// Request that the superclass of the given class, if any, needs to have
/// all members validated after everything in the translation unit has
/// been processed.
void requestSuperclassLayout(ClassDecl *classDecl);
/// Perform final validation of a declaration after everything in the
/// translation unit has been processed.
void finalizeDecl(ValueDecl *D);
/// Resolve a reference to the given type declaration within a particular
/// context.
///
/// This routine aids unqualified name lookup for types by performing the
/// resolution necessary to rectify the declaration found by name lookup with
/// the declaration context from which name lookup started.
///
/// \param typeDecl The type declaration found by name lookup.
/// \param isSpecialized Whether the type will have generic arguments applied.
/// \param resolution The resolution to perform.
///
/// \returns the resolved type.
static Type resolveTypeInContext(TypeDecl *typeDecl,
DeclContext *foundDC,
TypeResolution resolution,
TypeResolutionOptions options,
bool isSpecialized);
/// Apply generic arguments to the given type.
///
/// This function emits diagnostics about an invalid type or the wrong number
/// of generic arguments, whereas applyUnboundGenericArguments requires this
/// to be in a correct and valid form.
///
/// \param type The generic type to which to apply arguments.
/// \param loc The source location for diagnostic reporting.
/// \param resolution The type resolution to perform.
/// \param generic The arguments to apply with the angle bracket range for
/// diagnostics.
/// \param options The type resolution context.
///
/// \returns A BoundGenericType bound to the given arguments, or null on
/// error.
///
/// \see applyUnboundGenericArguments
static Type applyGenericArguments(Type type, SourceLoc loc,
TypeResolution resolution,
GenericIdentTypeRepr *generic,
TypeResolutionOptions options);
/// Apply generic arguments to the given type.
///
/// This function requires a valid unbound generic type with the correct
/// number of generic arguments given, whereas applyGenericArguments emits
/// diagnostics in those cases.
///
/// \param unboundType The unbound generic type to which to apply arguments.
/// \param decl The declaration of the type.
/// \param loc The source location for diagnostic reporting.
/// \param resolution The type resolution.
/// \param genericArgs The list of generic arguments to apply to the type.
///
/// \returns A BoundGenericType bound to the given arguments, or null on
/// error.
///
/// \see applyGenericArguments
static Type applyUnboundGenericArguments(UnboundGenericType *unboundType,
GenericTypeDecl *decl,
SourceLoc loc,
TypeResolution resolution,
ArrayRef<Type> genericArgs);
/// Substitute the given base type into the type of the given nested type,
/// producing the effective type that the nested type will have.
///
/// \param module The module in which the substitution will be performed.
/// \param member The member whose type projection is being computed.
/// \param baseTy The base type that will be substituted for the 'Self' of the
/// member.
/// \param useArchetypes Whether to use context archetypes for outer generic
/// parameters if the class is nested inside a generic function.
static Type substMemberTypeWithBase(ModuleDecl *module, TypeDecl *member,
Type baseTy, bool useArchetypes = true);
/// Determine whether one type is a subtype of another.
///
/// \param t1 The potential subtype.
/// \param t2 The potential supertype.
/// \param dc The context of the check.
///
/// \returns true if \c t1 is a subtype of \c t2.
bool isSubtypeOf(Type t1, Type t2, DeclContext *dc);
/// Determine whether one type is implicitly convertible to another.
///
/// \param t1 The potential source type of the conversion.
///
/// \param t2 The potential destination type of the conversion.
///
/// \param dc The context of the conversion.
///
/// \param unwrappedIUO If non-null, will be set to indicate whether the
/// conversion force-unwrapped an implicitly-unwrapped optional.
///
/// \returns true if \c t1 can be implicitly converted to \c t2.
bool isConvertibleTo(Type t1, Type t2, DeclContext *dc,
bool *unwrappedIUO = nullptr);
/// Determine whether one type is explicitly convertible to another,
/// i.e. using an 'as' expression.
///
/// \param t1 The potential source type of the conversion.
///
/// \param t2 The potential destination type of the conversion.
///
/// \param dc The context of the conversion.
///
/// \returns true if \c t1 can be explicitly converted to \c t2.
bool isExplicitlyConvertibleTo(Type t1, Type t2, DeclContext *dc);
/// Determine whether one type is bridged to another type.
///
/// \param t1 The potential source type of the conversion.
///
/// \param t2 The potential destination type of the conversion.
///
/// \param dc The context of the conversion.
///
/// \param unwrappedIUO If non-null, will be set to indicate whether the
/// conversion force-unwrapped an implicitly-unwrapped optional.
///
/// \returns true if \c t1 can be explicitly converted to \c t2.
bool isObjCBridgedTo(Type t1, Type t2, DeclContext *dc,
bool *unwrappedIUO = nullptr);
/// Return true if performing a checked cast from one type to another
/// with the "as!" operator could possibly succeed.
///
/// \param t1 The potential source type of the cast.
///
/// \param t2 The potential destination type of the cast.
///
/// \param dc The context of the cast.
///
/// \returns true if a checked cast from \c t1 to \c t2 may succeed, and
/// false if it will certainly fail, e.g. because the types are unrelated.
bool checkedCastMaySucceed(Type t1, Type t2, DeclContext *dc);
/// Determine whether a constraint of the given kind can be satisfied
/// by the two types.
///
/// \param t1 The first type of the constraint.
///
/// \param t2 The second type of the constraint.
///
/// \param openArchetypes If true, archetypes are replaced with type
/// variables, and the result can be interpreted as whether or not the
/// two types can possibly equal at runtime.
///
/// \param dc The context of the conversion.
///
/// \param unwrappedIUO If non-null, will be set to \c true if the coercion
/// or bridge operation force-unwraps an implicitly-unwrapped optional.
///
/// \returns true if \c t1 and \c t2 satisfy the constraint.
bool typesSatisfyConstraint(Type t1, Type t2,
bool openArchetypes,
constraints::ConstraintKind kind,
DeclContext *dc,
bool *unwrappedIUO = nullptr);
/// If the inputs to an apply expression use a consistent "sugar" type
/// (that is, a typealias or shorthand syntax) equivalent to the result type
/// of the function, set the result type of the expression to that sugar type.
Expr *substituteInputSugarTypeForResult(ApplyExpr *E);
bool typeCheckAbstractFunctionBodyUntil(AbstractFunctionDecl *AFD,
SourceLoc EndTypeCheckLoc);
bool typeCheckAbstractFunctionBody(AbstractFunctionDecl *AFD);
bool typeCheckFunctionBodyUntil(FuncDecl *FD, SourceLoc EndTypeCheckLoc);
bool typeCheckConstructorBodyUntil(ConstructorDecl *CD,
SourceLoc EndTypeCheckLoc);
bool typeCheckDestructorBodyUntil(DestructorDecl *DD,
SourceLoc EndTypeCheckLoc);
bool typeCheckClosureBody(ClosureExpr *closure);
bool typeCheckTapBody(TapExpr *expr, DeclContext *DC);
Type typeCheckParameterDefault(Expr *&defaultValue, DeclContext *DC,
Type paramType, bool isAutoClosure = false,
bool canFail = true);
void typeCheckTopLevelCodeDecl(TopLevelCodeDecl *TLCD);
void processREPLTopLevel(SourceFile &SF, TopLevelContext &TLC,
unsigned StartElem);
Identifier getNextResponseVariableName(DeclContext *DC);
void typeCheckDecl(Decl *D);
void checkDeclAttributesEarly(Decl *D);
static void addImplicitDynamicAttribute(Decl *D);
void checkDeclAttributes(Decl *D);
void checkDynamicReplacementAttribute(ValueDecl *D);
static ValueDecl *findReplacedDynamicFunction(const ValueDecl *d);
void checkTypeModifyingDeclAttributes(VarDecl *var);
void checkReferenceOwnershipAttr(VarDecl *D, ReferenceOwnershipAttr *attr);
/// Check the default arguments that occur within this value decl.
void checkDefaultArguments(ParameterList *params, ValueDecl *VD);
virtual void resolveDeclSignature(ValueDecl *VD) override {
validateDeclForNameLookup(VD);
}
virtual void resolveProtocolEnvironment(ProtocolDecl *proto) override {
validateDecl(proto);
}
virtual void resolveExtension(ExtensionDecl *ext) override {
validateExtension(ext);
}
virtual void resolveImplicitConstructors(NominalTypeDecl *nominal) override {
addImplicitConstructors(nominal);
}
virtual void resolveImplicitMember(NominalTypeDecl *nominal, DeclName member) override {
synthesizeMemberForLookup(nominal, member);
}
/// Infer default value witnesses for all requirements in the given protocol.
void inferDefaultWitnesses(ProtocolDecl *proto);
/// Compute the generic signature, generic environment and interface type
/// of a generic function.
void validateGenericFuncSignature(AbstractFunctionDecl *func);
/// Compute the generic signature, generic environment and interface type
/// of a generic subscript.
void validateGenericSubscriptSignature(SubscriptDecl *subscript);
/// For a generic requirement in a protocol, make sure that the requirement
/// set didn't add any requirements to Self or its associated types.
void checkProtocolSelfRequirements(ValueDecl *decl);
/// All generic parameters of a generic function must be referenced in the
/// declaration's type, otherwise we have no way to infer them.
void checkReferencedGenericParams(GenericContext *dc);
/// Construct a new generic environment for the given declaration context.
///
/// \param genericParams The generic parameters to validate.
///
/// \param dc The declaration context in which to perform the validation.
///
/// \param outerSignature The generic signature of the outer
/// context, if not available as part of the \c dc argument (used
/// for SIL parsing).
///
/// \param ext The extension for which we're checking the generic
/// environment, or null if we're not checking an extension.
///
/// \param inferRequirements When non-empty, callback that will be invoked
/// to perform any additional requirement inference that contributes to the
/// generic environment..
///
/// \returns the resulting generic environment.
GenericEnvironment *checkGenericEnvironment(
GenericParamList *genericParams,
DeclContext *dc,
GenericSignature *outerSignature,
bool allowConcreteGenericParams,
ExtensionDecl *ext,
llvm::function_ref<void(GenericSignatureBuilder &)>
inferRequirements,
bool mustInferRequirements);
/// Construct a new generic environment for the given declaration context.
///
/// \param genericParams The generic parameters to validate.
///
/// \param dc The declaration context in which to perform the validation.
///
/// \param outerSignature The generic signature of the outer
/// context, if not available as part of the \c dc argument (used
/// for SIL parsing).
/// \returns the resulting generic environment.
GenericEnvironment *checkGenericEnvironment(
GenericParamList *genericParams,
DeclContext *dc,
GenericSignature *outerSignature,
bool allowConcreteGenericParams,
ExtensionDecl *ext) {
return checkGenericEnvironment(genericParams, dc, outerSignature,
allowConcreteGenericParams, ext,
[&](GenericSignatureBuilder &) { },
/*mustInferRequirements=*/false);
}
/// Validate the signature of a generic type.
///
/// \param nominal The generic type.
void validateGenericTypeSignature(GenericTypeDecl *nominal);
/// Create a text string that describes the bindings of generic parameters
/// that are relevant to the given set of types, e.g.,
/// "[with T = Bar, U = Wibble]".
///
/// \param types The types that will be scanned for generic type parameters,
/// which will be used in the resulting type.
///
/// \param genericParams The generic parameters to use to resugar any
/// generic parameters that occur within the types.
///
/// \param substitutions The generic parameter -> generic argument
/// substitutions that will have been applied to these types.
/// These are used to produce the "parameter = argument" bindings in the test.
static std::string
gatherGenericParamBindingsText(ArrayRef<Type> types,
TypeArrayView<GenericTypeParamType> genericParams,
TypeSubstitutionFn substitutions);
/// Check the given set of generic arguments against the requirements in a
/// generic signature.
///
/// \param dc The context in which the generic arguments should be checked.
/// \param loc The location at which any diagnostics should be emitted.
/// \param noteLoc The location at which any notes will be printed.
/// \param owner The type that owns the generic signature.
/// \param genericParams The generic parameters being substituted.
/// \param requirements The requirements against which the generic arguments
/// should be checked.
/// \param substitutions Substitutions from interface types of the signature.
/// \param conformanceOptions The flags to use when checking conformance
/// requirement.
/// \param listener The generic check listener used to pick requirements and
/// notify callers about diagnosed errors.
static RequirementCheckResult checkGenericArguments(
DeclContext *dc, SourceLoc loc, SourceLoc noteLoc, Type owner,
TypeArrayView<GenericTypeParamType> genericParams,
ArrayRef<Requirement> requirements,
TypeSubstitutionFn substitutions,
LookupConformanceFn conformances,
ConformanceCheckOptions conformanceOptions = ConformanceCheckFlags::Used,
GenericRequirementsCheckListener *listener = nullptr,
SubstOptions options = None);
/// Diagnose if the class has no designated initializers.
void maybeDiagnoseClassWithoutInitializers(ClassDecl *classDecl);
///
/// Add any implicitly-defined constructors required for the given
/// struct or class.
void addImplicitConstructors(NominalTypeDecl *typeDecl);
/// Synthesize the member with the given name on the target if applicable,
/// i.e. if the member is synthesizable and has not yet been added to the
/// target.
void synthesizeMemberForLookup(NominalTypeDecl *target, DeclName member);
/// The specified AbstractStorageDecl \c storage was just found to satisfy
/// the protocol property \c requirement. Ensure that it has the full
/// complement of accessors.
void synthesizeWitnessAccessorsForStorage(AbstractStorageDecl *requirement,
AbstractStorageDecl *storage);
/// Pre-check the expression, validating any types that occur in the
/// expression and folding sequence expressions.
bool preCheckExpression(Expr *&expr, DeclContext *dc);
/// \name Name lookup
///
/// Routines that perform name lookup.
///
/// During type checking, these routines should be used instead of
/// \c MemberLookup and \c UnqualifiedLookup, because these routines will
/// lazily introduce declarations and (FIXME: eventually) perform recursive
/// type-checking that the AST-level lookup routines don't.
///
/// @{
private:
Optional<Type> boolType;
public:
/// Define the default constructor for the given struct or class.
void defineDefaultConstructor(NominalTypeDecl *decl);
/// Fold the given sequence expression into an (unchecked) expression
/// tree.
Expr *foldSequence(SequenceExpr *expr, DeclContext *dc);
/// Type check the given expression.
///
/// \param expr The expression to type-check, which will be modified in
/// place.
///
/// \param convertTypePurpose When convertType is specified, this indicates
/// what the conversion is doing. This allows diagnostics generation to
/// produce more specific and helpful error messages when the conversion fails
/// to be possible.
///
/// \param convertType The type that the expression is being converted to,
/// or null if the expression is standalone. If the 'ConvertTypeIsOnlyAHint'
/// option is specified, then this is only a hint, it doesn't produce a full
/// conversion constraint. The location information is only used for
/// diagnostics should the conversion fail; it is safe to pass a TypeLoc
/// without location information.
///
/// \param options Options that control how type checking is performed.
///
/// \param listener If non-null, a listener that will be notified of important
/// events in the type checking of this expression, and which can introduce
/// additional constraints.
///
/// \param baseCS If this type checking process is the simplification of
/// another constraint system, set the original constraint system. \c null
/// otherwise
///
/// \returns The type of the top-level expression, or Type() if an
/// error occurred.
Type
typeCheckExpression(Expr *&expr, DeclContext *dc,
TypeLoc convertType = TypeLoc(),
ContextualTypePurpose convertTypePurpose = CTP_Unused,
TypeCheckExprOptions options = TypeCheckExprOptions(),
ExprTypeCheckListener *listener = nullptr,
constraints::ConstraintSystem *baseCS = nullptr);
Type typeCheckExpression(Expr *&expr, DeclContext *dc,
ExprTypeCheckListener *listener) {
return typeCheckExpression(expr, dc, TypeLoc(), CTP_Unused,
TypeCheckExprOptions(), listener);
}
private:
Type typeCheckExpressionImpl(Expr *&expr, DeclContext *dc,
TypeLoc convertType,
ContextualTypePurpose convertTypePurpose,
TypeCheckExprOptions options,
ExprTypeCheckListener &listener,
constraints::ConstraintSystem *baseCS);
public:
/// Type check the given expression and return its type without
/// applying the solution.
///
/// \param expr The expression to type-check.
///
/// \param referencedDecl Will be set to the declaration that is referenced by
/// the expression.
///
/// \param allowFreeTypeVariables Whether free type variables are allowed in
/// the solution, and what to do with them.
///
/// \param listener If non-null, a listener that will be notified of important
/// events in the type checking of this expression, and which can introduce
/// additional constraints.
///
/// \returns the type of \p expr on success, Type() otherwise.
/// FIXME: expr may still be modified...
Type getTypeOfExpressionWithoutApplying(
Expr *&expr, DeclContext *dc,
ConcreteDeclRef &referencedDecl,
FreeTypeVariableBinding allowFreeTypeVariables =
FreeTypeVariableBinding::Disallow,
ExprTypeCheckListener *listener = nullptr);
void getPossibleTypesOfExpressionWithoutApplying(
Expr *&expr, DeclContext *dc, SmallPtrSetImpl<TypeBase *> &types,
FreeTypeVariableBinding allowFreeTypeVariables =
FreeTypeVariableBinding::Disallow,
ExprTypeCheckListener *listener = nullptr);
/// Return the type of operator function for specified LHS, or a null
/// \c Type on error.
FunctionType *getTypeOfCompletionOperator(DeclContext *DC, Expr *LHS,
Identifier opName,
DeclRefKind refKind,
ConcreteDeclRef &referencedDecl);
/// Check the key-path expression.
///
/// Returns the type of the last component of the key-path.
Optional<Type> checkObjCKeyPathExpr(DeclContext *dc, KeyPathExpr *expr,
bool requireResultType = false);
/// Type check whether the given type declaration includes members of
/// unsupported recursive value types.
///
/// \param decl The declaration to be type-checked. This process will not
/// modify the declaration.
void checkDeclCircularity(NominalTypeDecl *decl);
/// Type check whether the given switch statement exhaustively covers
/// its domain.
///
/// \param stmt The switch statement to be type-checked. No modification of
/// the statement occurs.
/// \param DC The decl context containing \p stmt.
/// \param limitChecking The checking process relies on the switch statement
/// being well-formed. If it is not, pass true to this flag to run a limited
/// form of analysis.
void checkSwitchExhaustiveness(const SwitchStmt *stmt, const DeclContext *DC,
bool limitChecking);
/// Type check the given expression as a condition, which converts
/// it to a logic value.
///
/// \param expr The expression to type-check, which will be modified in place
/// to return a logic value (builtin i1).
///
/// \returns true if an error occurred, false otherwise.
bool typeCheckCondition(Expr *&expr, DeclContext *dc);
/// Type check the given 'if' or 'while' statement condition, which
/// either converts an expression to a logic value or bind variables to the
/// contents of an Optional.
///
/// \param cond The condition to type-check, which will be modified in place.
///
/// \returns true if an error occurred, false otherwise.
bool typeCheckStmtCondition(StmtCondition &cond, DeclContext *dc,
Diag<> diagnosticForAlwaysTrue);
/// Determine the semantics of a checked cast operation.
///
/// \param fromType The source type of the cast.
/// \param toType The destination type of the cast.
/// \param dc The context of the cast.
/// \param diagLoc The location at which to report diagnostics.
/// \param fromExpr The expression describing the input operand.
/// \param diagToRange The source range of the destination type.
///
/// \returns a CheckedCastKind indicating the semantics of the cast. If the
/// cast is invalid, Unresolved is returned. If the cast represents an implicit
/// conversion, Coercion is returned.
CheckedCastKind typeCheckCheckedCast(Type fromType,
Type toType,
CheckedCastContextKind contextKind,
DeclContext *dc,
SourceLoc diagLoc,
Expr *fromExpr,
SourceRange diagToRange);
/// Find the Objective-C class that bridges between a value of the given
/// dynamic type and the given value type.
///
/// \param dc The declaration context from which we will look for
/// bridging.
///
/// \param dynamicType A dynamic type from which we are bridging. Class and
/// Objective-C protocol types can be used for bridging.
///
/// \param valueType The value type being queried, e.g., String.
///
/// \returns the Objective-C class type that represents the value
/// type as an Objective-C class, e.g., \c NSString represents \c
/// String, or a null type if there is no such type or if the
/// dynamic type isn't something we can start from.
Type getDynamicBridgedThroughObjCClass(DeclContext *dc,
Type dynamicType,
Type valueType);
/// Resolve ambiguous pattern/expr productions inside a pattern using
/// name lookup information. Must be done before type-checking the pattern.
Pattern *resolvePattern(Pattern *P, DeclContext *dc,
bool isStmtCondition);
/// Type check the given pattern.
///
/// \param P The pattern to type check.
/// \param dc The context in which type checking occurs.
/// \param options Options that control type resolution.
///
/// \returns true if any errors occurred during type checking.
bool typeCheckPattern(Pattern *P, DeclContext *dc,
TypeResolutionOptions options);
bool typeCheckCatchPattern(CatchStmt *S, DeclContext *dc);
/// Request nominal layout for any types that could be sources of typemetadata
/// or conformances.
void requestRequiredNominalTypeLayoutForParameters(ParameterList *PL);
/// Type check a parameter list.
bool typeCheckParameterList(ParameterList *PL, TypeResolution resolution,
TypeResolutionOptions options);
/// Coerce a pattern to the given type.
///
/// \param P The pattern, which may be modified by this coercion.
/// \param resolution The type resolution.
/// \param type the type to coerce the pattern to.
/// \param options Options describing how to perform this coercion.
///
/// \returns true if an error occurred, false otherwise.
bool coercePatternToType(Pattern *&P, TypeResolution resolution, Type type,
TypeResolutionOptions options,
TypeLoc tyLoc = TypeLoc());
bool typeCheckExprPattern(ExprPattern *EP, DeclContext *DC,
Type type);
/// Coerce the specified parameter list of a ClosureExpr to the specified
/// contextual type.
void coerceParameterListToType(ParameterList *P, ClosureExpr *CE, AnyFunctionType *FN);
/// Type-check an initialized variable pattern declaration.
bool typeCheckBinding(Pattern *&P, Expr *&Init, DeclContext *DC);
bool typeCheckPatternBinding(PatternBindingDecl *PBD, unsigned patternNumber);
/// Type-check a for-each loop's pattern binding and sequence together.
bool typeCheckForEachBinding(DeclContext *dc, ForEachStmt *stmt);
/// Lazily diagnose conversions to C function pointers of closures
/// with captures.
void maybeDiagnoseCaptures(Expr *E, AnyFunctionRef AFR);
/// Compute the set of captures for the given function or closure.
void computeCaptures(AnyFunctionRef AFR);
/// Change the context of closures in the given initializer
/// expression to the given context.
///
/// \returns true if any closures were found
static bool contextualizeInitializer(Initializer *DC, Expr *init);
static void contextualizeTopLevelCode(TopLevelContext &TLC,
ArrayRef<Decl*> topLevelDecls);
/// Return the type-of-reference of the given value.
///
/// \param baseType if non-null, return the type of a member reference to
/// this value when the base has the given type
///
/// \param UseDC The context of the access. Some variables have different
/// types depending on where they are used.
///
/// \param base The optional base expression of this value reference
///
/// \param wantInterfaceType Whether we want the interface type, if available.
///
/// \param getType Optional callback to extract a type for given declaration.
Type getUnopenedTypeOfReference(VarDecl *value, Type baseType,
DeclContext *UseDC,
llvm::function_ref<Type(VarDecl *)> getType,
const DeclRefExpr *base = nullptr,
bool wantInterfaceType = false);
/// Return the type-of-reference of the given value.
///
/// \param baseType if non-null, return the type of a member reference to
/// this value when the base has the given type
///
/// \param UseDC The context of the access. Some variables have different
/// types depending on where they are used.
///
/// \param base The optional base expression of this value reference
///
/// \param wantInterfaceType Whether we want the interface type, if available.
Type getUnopenedTypeOfReference(VarDecl *value, Type baseType,
DeclContext *UseDC,
const DeclRefExpr *base = nullptr,
bool wantInterfaceType = false) {
return getUnopenedTypeOfReference(
value, baseType, UseDC,
[&](VarDecl *var) -> Type {
validateDecl(var);
if (!var->hasValidSignature() || var->isInvalid())
return ErrorType::get(Context);
return wantInterfaceType ? value->getInterfaceType()
: value->getType();
},
base, wantInterfaceType);
}
/// Retrieve the default type for the given protocol.
///
/// Some protocols, particularly those that correspond to literals, have
/// default types associated with them. This routine retrieves that default
/// type.
///
/// \returns the default type, or null if there is no default type for
/// this protocol.
Type getDefaultType(ProtocolDecl *protocol, DeclContext *dc);
/// Convert the given expression to the given type.
///
/// \param expr The expression, which will be updated in place.
/// \param type The type to convert to.
/// \param typeFromPattern Optionally, the caller can specify the pattern
/// from where the toType is derived, so that we can deliver better fixit.
///
/// \returns true if an error occurred, false otherwise.
bool convertToType(Expr *&expr, Type type, DeclContext *dc,
Optional<Pattern*> typeFromPattern = None);
/// Coerce the given expression to materializable type, if it
/// isn't already.
Expr *coerceToRValue(Expr *expr,
llvm::function_ref<Type(Expr *)> getType
= [](Expr *expr) { return expr->getType(); },
llvm::function_ref<void(Expr *, Type)> setType
= [](Expr *expr, Type type) {
expr->setType(type);
});
/// Add implicit load expression to given AST, this is sometimes
/// more complicated than simplify wrapping given root in newly created
/// `LoadExpr`, because `ForceValueExpr` and `ParenExpr` supposed to appear
/// only at certain positions in AST.
Expr *addImplicitLoadExpr(Expr *expr,
std::function<Type(Expr *)> getType,
std::function<void(Expr *, Type)> setType);
/// Require that the library intrinsics for working with Optional<T>
/// exist.
bool requireOptionalIntrinsics(SourceLoc loc);
/// Require that the library intrinsics for working with
/// UnsafeMutablePointer<T> exist.
bool requirePointerArgumentIntrinsics(SourceLoc loc);
/// Require that the library intrinsics for creating
/// array literals exist.
bool requireArrayLiteralIntrinsics(SourceLoc loc);
/// Retrieve the witness type with the given name.
///
/// \param type The type that conforms to the given protocol.
///
/// \param protocol The protocol through which we're looking.
///
/// \param conformance The protocol conformance.
///
/// \param name The name of the associated type.
///
/// \param brokenProtocolDiag Diagnostic to emit if the type cannot be
/// accessed.
///
/// \return the witness type, or null if an error occurs or the type
/// returned would contain an ErrorType.
Type getWitnessType(Type type, ProtocolDecl *protocol,
ProtocolConformanceRef conformance,
Identifier name,
Diag<> brokenProtocolDiag);
/// Build a call to the witness with the given name and arguments.
///
/// \param base The base expression, whose witness will be invoked.
///
/// \param protocol The protocol to call through.
///
/// \param conformance The conformance of the base type to the given
/// protocol.
///
/// \param name The name of the method to call.
///
/// \param arguments The arguments to the witness.
///
/// \param brokenProtocolDiag Diagnostic to emit if the protocol is broken.
///
/// \returns a fully type-checked call, or null if the protocol was broken.
Expr *callWitness(Expr *base, DeclContext *dc,
ProtocolDecl *protocol,
ProtocolConformanceRef conformance,
DeclName name,
ArrayRef<Expr *> arguments,
Diag<> brokenProtocolDiag);
/// Determine whether the given type contains the given protocol.
///
/// \param DC The context in which to check conformance. This affects, for
/// example, extension visibility.
///
/// \param options Options that control the conformance check.
///
/// \returns the conformance, if \c T conforms to the protocol \c Proto, or
/// an empty optional.
static Optional<ProtocolConformanceRef> containsProtocol(
Type T, ProtocolDecl *Proto,
DeclContext *DC,
ConformanceCheckOptions options);
/// Determine whether the given type conforms to the given protocol.
///
/// Unlike subTypeOfProtocol(), this will return false for existentials of
/// non-self conforming protocols.
///
/// \param DC The context in which to check conformance. This affects, for
/// example, extension visibility.
///
/// \param options Options that control the conformance check.
///
/// \param ComplainLoc If valid, then this function will emit diagnostics if
/// T does not conform to the given protocol. The primary diagnostic will
/// be placed at this location, with notes for each of the protocol
/// requirements not satisfied.
///
/// \returns The protocol conformance, if \c T conforms to the
/// protocol \c Proto, or \c None.
static Optional<ProtocolConformanceRef> conformsToProtocol(
Type T,
ProtocolDecl *Proto,
DeclContext *DC,
ConformanceCheckOptions options,
SourceLoc ComplainLoc = SourceLoc());
/// Mark the given protocol conformance as "used" from the given declaration
/// context.
void markConformanceUsed(ProtocolConformanceRef conformance,
DeclContext *dc) override final;
/// Functor class suitable for use as a \c LookupConformanceFn to look up a
/// conformance through a particular declaration context using the given
/// type checker.
class LookUpConformance {
DeclContext *dc;
public:
explicit LookUpConformance(DeclContext *dc) : dc(dc) { }
Optional<ProtocolConformanceRef>
operator()(CanType dependentType,
Type conformingReplacementType,
ProtocolDecl *conformedProtocol) const;
};
/// Completely check the given conformance.
void checkConformance(NormalProtocolConformance *conformance);
/// Check the requirement signature of the given conformance.
void checkConformanceRequirements(NormalProtocolConformance *conformance)
override ;
/// Check all of the conformances in the given context.
void checkConformancesInContext(DeclContext *dc,
IterableDeclContext *idc);
/// Check that the type of the given property conforms to NSCopying.
///
/// Return true if there was an error.
bool checkConformanceToNSCopying(VarDecl *var);
/// Mark any _BridgedNSError/_BridgedStoredNSError/related
/// conformances in the given type as "used".
void useBridgedNSErrorConformances(DeclContext *dc, Type type);
/// Derive an implicit declaration to satisfy a requirement of a derived
/// protocol conformance.
///
/// \param DC The declaration context where the conformance was
/// defined, either the type itself or an extension
/// \param TypeDecl The type for which the requirement is being derived.
/// \param Requirement The protocol requirement.
///
/// \returns nullptr if the derivation failed, or the derived declaration
/// if it succeeded. If successful, the derived declaration is added
/// to TypeDecl's body.
ValueDecl *deriveProtocolRequirement(DeclContext *DC,
NominalTypeDecl *TypeDecl,
ValueDecl *Requirement);
/// Derive an implicit type witness for the given associated type in
/// the conformance of the given nominal type to some known
/// protocol.
Type deriveTypeWitness(DeclContext *DC,
NominalTypeDecl *nominal,
AssociatedTypeDecl *assocType);
/// Perform unqualified name lookup at the given source location
/// within a particular declaration context.
///
/// \param dc The declaration context in which to perform name lookup.
/// \param name The name of the entity to look for.
/// \param loc The source location at which name lookup occurs.
/// \param options Options that control name lookup.
static LookupResult lookupUnqualified(DeclContext *dc, DeclName name,
SourceLoc loc,
NameLookupOptions options
= defaultUnqualifiedLookupOptions);
/// Perform unqualified type lookup at the given source location
/// within a particular declaration context.
///
/// \param dc The declaration context in which to perform name lookup.
/// \param name The name of the entity to look for.
/// \param loc The source location at which name lookup occurs.
/// \param options Options that control name lookup.
LookupResult
static lookupUnqualifiedType(DeclContext *dc, DeclName name, SourceLoc loc,
NameLookupOptions options
= defaultUnqualifiedLookupOptions);
/// Lookup a member in the given type.
///
/// \param dc The context that needs the member.
/// \param type The type in which we will look for a member.
/// \param name The name of the member to look for.
/// \param options Options that control name lookup.
///
/// \returns The result of name lookup.
static LookupResult lookupMember(DeclContext *dc, Type type, DeclName name,
NameLookupOptions options
= defaultMemberLookupOptions);
/// Check whether the given declaration can be written as a
/// member of the given base type.
static bool isUnsupportedMemberTypeAccess(Type type, TypeDecl *typeDecl);
/// Look up a member type within the given type.
///
/// This routine looks for member types with the given name within the
/// given type.
///
/// \param dc The context that needs the member.
/// \param type The type in which we will look for a member type.
/// \param name The name of the member to look for.
/// \param options Options that control name lookup.
///
/// \returns The result of name lookup.
static LookupTypeResult lookupMemberType(DeclContext *dc, Type type,
Identifier name,
NameLookupOptions options
= defaultMemberTypeLookupOptions);
/// Look up the constructors of the given type.
///
/// \param dc The context that needs the constructor.
/// \param type The type for which we will look for constructors.
/// \param options Options that control name lookup.
///
/// \returns the constructors found for this type.
LookupResult lookupConstructors(DeclContext *dc, Type type,
NameLookupOptions options
= defaultConstructorLookupOptions);
/// Given an expression that's known to be an infix operator,
/// look up its precedence group.
PrecedenceGroupDecl *
lookupPrecedenceGroupForInfixOperator(DeclContext *dc, Expr *op);
PrecedenceGroupDecl *lookupPrecedenceGroup(DeclContext *dc, Identifier name,
SourceLoc nameLoc);
/// Given an pre-folded expression, find LHS from the expression if a binary
/// operator \c name appended to the expression.
Expr *findLHS(DeclContext *DC, Expr *E, Identifier name);
/// @}
/// \name Overload resolution
///
/// Routines that perform overload resolution or provide diagnostics related
/// to overload resolution.
/// @{
/// Compare two declarations to determine whether one is more specialized
/// than the other.
///
/// A declaration is more specialized than another declaration if its type
/// is a subtype of the other declaration's type (ignoring the 'self'
/// parameter of function declarations) and if
Comparison compareDeclarations(DeclContext *dc,
ValueDecl *decl1,
ValueDecl *decl2);
/// Build a type-checked reference to the given value.
Expr *buildCheckedRefExpr(VarDecl *D, DeclContext *UseDC,
DeclNameLoc nameLoc, bool Implicit);
/// Build a reference to a declaration, where name lookup returned
/// the given set of declarations.
Expr *buildRefExpr(ArrayRef<ValueDecl *> Decls, DeclContext *UseDC,
DeclNameLoc NameLoc, bool Implicit,
FunctionRefKind functionRefKind);
/// Build implicit autoclosure expression wrapping a given expression.
/// Given expression represents computed result of the closure.
Expr *buildAutoClosureExpr(DeclContext *DC, Expr *expr,
FunctionType *closureType);
/// @}
/// Retrieve a specific, known protocol.
///
/// \param loc The location at which we need to look for the protocol.
/// \param kind The known protocol we're looking for.
///
/// \returns null if the protocol is not available. This represents a
/// problem with the Standard Library.
ProtocolDecl *getProtocol(SourceLoc loc, KnownProtocolKind kind);
/// Retrieve the literal protocol for the given expression.
///
/// \returns the literal protocol, if known and available, or null if the
/// expression does not have an associated literal protocol.
ProtocolDecl *getLiteralProtocol(Expr *expr);
DeclName getObjectLiteralConstructorName(ObjectLiteralExpr *expr);
Type getObjectLiteralParameterType(ObjectLiteralExpr *expr,
ConstructorDecl *ctor);
/// Get the module appropriate for looking up standard library types.
///
/// This is "Swift", if that module is imported, or the current module if
/// we're parsing the standard library.
ModuleDecl *getStdlibModule(const DeclContext *dc);
/// \name Lazy resolution.
///
/// Routines that perform lazy resolution as required for AST operations.
/// @{
void resolveTypeWitness(const NormalProtocolConformance *conformance,
AssociatedTypeDecl *assocType) override;
void resolveWitness(const NormalProtocolConformance *conformance,
ValueDecl *requirement) override;
/// \name Resilience diagnostics
void diagnoseInlinableLocalType(const NominalTypeDecl *NTD);
/// Used in diagnostic %selects.
enum class FragileFunctionKind : unsigned {
Transparent,
Inlinable,
AlwaysEmitIntoClient,
DefaultArgument,
PropertyInitializer
};
bool diagnoseInlinableDeclRef(SourceLoc loc, const ValueDecl *D,
const DeclContext *DC,
FragileFunctionKind Kind,
bool TreatUsableFromInlineAsPublic);
private:
bool diagnoseInlinableDeclRefAccess(SourceLoc loc, const ValueDecl *D,
const DeclContext *DC,
FragileFunctionKind Kind,
bool TreatUsableFromInlineAsPublic);
public:
/// Given that a declaration is used from a particular context which
/// exposes it in the interface of the current module, diagnose if it cannot
/// reasonably be shared.
bool diagnoseDeclRefExportability(SourceLoc loc, const ValueDecl *D,
const DeclContext *DC);
/// Given that \p DC is within a fragile context for some reason, describe
/// why.
///
/// The second element of the pair is true if references to @usableFromInline
/// declarations are permitted.
///
/// \see FragileFunctionKind
std::pair<FragileFunctionKind, bool>
getFragileFunctionKind(const DeclContext *DC);
/// \name Availability checking
///
/// Routines that perform API availability checking and type checking of
/// potentially unavailable API elements
/// @{
/// Returns true if the availability of the witness
/// is sufficient to safely conform to the requirement in the context
/// the provided conformance. On return, requiredAvailability holds th
/// availability levels required for conformance.
bool
isAvailabilitySafeForConformance(ProtocolDecl *proto, ValueDecl *requirement,
ValueDecl *witness, DeclContext *dc,
AvailabilityContext &requiredAvailability);
/// Returns an over-approximation of the range of operating system versions
/// that could the passed-in location could be executing upon for
/// the target platform. If MostRefined != nullptr, set to the most-refined
/// TRC found while approximating.
AvailabilityContext
overApproximateAvailabilityAtLocation(SourceLoc loc, const DeclContext *DC,
const TypeRefinementContext **MostRefined=nullptr);
/// Walk the AST to build the hierarchy of TypeRefinementContexts
///
/// \param StartElem Where to start for incremental building of refinement
/// contexts
void buildTypeRefinementContextHierarchy(SourceFile &SF,
unsigned StartElem);
/// Build the hierarchy of TypeRefinementContexts for the entire
/// source file, if it has not already been built. Returns the root
/// TypeRefinementContext for the source file.
TypeRefinementContext *getOrBuildTypeRefinementContext(SourceFile *SF);
/// Returns a diagnostic indicating why the declaration cannot be annotated
/// with an @available() attribute indicating it is potentially unavailable
/// or None if this is allowed.
Optional<Diag<>>
diagnosticIfDeclCannotBePotentiallyUnavailable(const Decl *D);
/// Checks whether a declaration is available when referred to at the given
/// location (this reference location must be in the passed-in
/// reference DeclContext).
/// If the declaration is available, return true.
/// If the declaration is not available, return false and write the
/// declaration's availability info to the out parameter
/// \p OutAvailableRange.
bool isDeclAvailable(const Decl *D, SourceLoc referenceLoc,
const DeclContext *referenceDC,
AvailabilityContext &OutAvailableRange);
/// Checks whether a declaration should be considered unavailable when
/// referred to at the given location and, if so, returns the reason why the
/// declaration is unavailable. Returns None is the declaration is
/// definitely available.
Optional<UnavailabilityReason>
checkDeclarationAvailability(const Decl *D, SourceLoc referenceLoc,
const DeclContext *referenceDC);
/// Checks an "ignored" expression to see if it's okay for it to be ignored.
///
/// An ignored expression is one that is not nested within a larger
/// expression or statement.
void checkIgnoredExpr(Expr *E);
// Emits a diagnostic, if necessary, for a reference to a declaration
// that is potentially unavailable at the given source location.
void diagnosePotentialUnavailability(const ValueDecl *D,
SourceRange ReferenceRange,
const DeclContext *ReferenceDC,
const UnavailabilityReason &Reason);
// Emits a diagnostic, if necessary, for a reference to a declaration
// that is potentially unavailable at the given source location, using
// Name as the diagnostic name.
void diagnosePotentialUnavailability(const Decl *D, DeclName Name,
SourceRange ReferenceRange,
const DeclContext *ReferenceDC,
const UnavailabilityReason &Reason);
/// Emits a diagnostic for a reference to a storage accessor that is
/// potentially unavailable.
void diagnosePotentialAccessorUnavailability(
const AccessorDecl *Accessor, SourceRange ReferenceRange,
const DeclContext *ReferenceDC, const UnavailabilityReason &Reason,
bool ForInout);
/// Returns the availability attribute indicating deprecation if the
/// declaration is deprecated or null otherwise.
static const AvailableAttr *getDeprecated(const Decl *D);
/// Emits a diagnostic for a reference to a declaration that is deprecated.
/// Callers can provide a lambda that adds additional information (such as a
/// fixit hint) to the deprecation diagnostic, if it is emitted.
void diagnoseIfDeprecated(SourceRange SourceRange,
const DeclContext *ReferenceDC,
const ValueDecl *DeprecatedDecl,
const ApplyExpr *Call);
/// @}
/// If LangOptions::DebugForbidTypecheckPrefix is set and the given decl
/// has a name with that prefix, an llvm fatal_error is triggered.
/// This is for testing purposes.
void checkForForbiddenPrefix(const Decl *D);
void checkForForbiddenPrefix(const UnresolvedDeclRefExpr *E);
void checkForForbiddenPrefix(Identifier Ident);
void checkForForbiddenPrefix(StringRef Name);
bool hasEnabledForbiddenTypecheckPrefix() const {
return !Context.LangOpts.DebugForbidTypecheckPrefix.empty();
}
/// Check error handling in the given type-checked top-level code.
void checkTopLevelErrorHandling(TopLevelCodeDecl *D);
void checkFunctionErrorHandling(AbstractFunctionDecl *D);
void checkInitializerErrorHandling(Initializer *I, Expr *E);
void checkEnumElementErrorHandling(EnumElementDecl *D);
void addExprForDiagnosis(Expr *E1, Expr *Result) {
DiagnosedExprs[E1] = Result;
}
bool isExprBeingDiagnosed(Expr *E) {
return DiagnosedExprs.count(E);
}
Expr *getExprBeingDiagnosed(Expr *E) {
return DiagnosedExprs[E];
}
/// 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 *getSelfForInitDelegationInConstructor(DeclContext *DC,
UnresolvedDotExpr *ctorRef);
/// Diagnose assigning variable to itself.
bool diagnoseSelfAssignment(const Expr *E);
/// Builds a string representing a "default" generic argument list for
/// \p typeDecl. In general, this means taking the bound of each generic
/// parameter. The \p getPreferredType callback can be used to provide a
/// different type from the bound.
///
/// It may not always be possible to find a single appropriate type for a
/// particular parameter (say, if it has two bounds). In this case, an
/// Xcode-style placeholder will be used instead.
///
/// Returns true if the arguments list could be constructed, false if for
/// some reason it could not.
static bool getDefaultGenericArgumentsString(
SmallVectorImpl<char> &buf,
const GenericTypeDecl *typeDecl,
llvm::function_ref<Type(const GenericTypeParamDecl *)> getPreferredType =
[](const GenericTypeParamDecl *) { return Type(); });
/// Attempt to omit needless words from the name of the given declaration.
Optional<DeclName> omitNeedlessWords(AbstractFunctionDecl *afd);
/// Attempt to omit needless words from the name of the given declaration.
Optional<Identifier> omitNeedlessWords(VarDecl *var);
/// Calculate edit distance between declaration names.
static unsigned getCallEditDistance(DeclName writtenName,
DeclName correctedName,
unsigned maxEditDistance);
enum : unsigned {
/// Never consider a candidate that's this distance away or worse.
UnreasonableCallEditDistance = 8,
/// Don't consider candidates that score worse than the given distance
/// from the best candidate.
MaxCallEditDistanceFromBestCandidate = 1
};
/// Check for a typo correction.
void performTypoCorrection(DeclContext *DC,
DeclRefKind refKind,
Type baseTypeOrNull,
NameLookupOptions lookupOptions,
TypoCorrectionResults &corrections,
GenericSignatureBuilder *gsb = nullptr,
unsigned maxResults = 4);
/// Check if the given decl has a @_semantics attribute that gives it
/// special case type-checking behavior.
DeclTypeCheckingSemantics getDeclTypeCheckingSemantics(ValueDecl *decl);
};
/// Temporary on-stack storage and unescaping for encoded diagnostic
/// messages.
///
///
class EncodedDiagnosticMessage {
llvm::SmallString<128> Buf;
public:
/// \param S A string with an encoded message
EncodedDiagnosticMessage(StringRef S)
: Message(Lexer::getEncodedStringSegment(S, Buf, true, true, ~0U)) {}
/// The unescaped message to display to the user.
const StringRef Message;
};
/// Returns true if the given method is an valid implementation of a
/// @dynamicCallable attribute requirement. The method is given to be defined
/// as one of the following: `dynamicallyCall(withArguments:)` or
/// `dynamicallyCall(withKeywordArguments:)`.
bool isValidDynamicCallableMethod(FuncDecl *decl, DeclContext *DC,
TypeChecker &TC, bool hasKeywordArguments);
/// Returns true if the given subscript method is an valid implementation of
/// the `subscript(dynamicMember:)` requirement for @dynamicMemberLookup.
/// The method is given to be defined as `subscript(dynamicMember:)`.
bool isValidDynamicMemberLookupSubscript(SubscriptDecl *decl, DeclContext *DC,
TypeChecker &TC);
/// Returns true if the given subscript method is an valid implementation of
/// the `subscript(dynamicMember:)` requirement for @dynamicMemberLookup.
/// The method is given to be defined as `subscript(dynamicMember:)` which
/// takes a single non-variadic parameter that conforms to
/// `ExpressibleByStringLiteral` protocol.
bool isValidStringDynamicMemberLookup(SubscriptDecl *decl, DeclContext *DC,
TypeChecker &TC);
/// Returns true if the given subscript method is an valid implementation of
/// the `subscript(dynamicMember: {Writable}KeyPath<...>)` requirement for
/// @dynamicMemberLookup.
/// The method is given to be defined as `subscript(dynamicMember:)` which
/// takes a single non-variadic parameter of `{Writable}KeyPath<T, U>` type.
bool isValidKeyPathDynamicMemberLookup(SubscriptDecl *decl, TypeChecker &TC);
/// Whether an overriding declaration requires the 'override' keyword.
enum class OverrideRequiresKeyword {
/// The keyword is never required.
Never,
/// The keyword is always required.
Always,
/// The keyword can be implicit; it is not required.
Implicit,
};
/// Determine whether overriding the given declaration requires a keyword.
OverrideRequiresKeyword overrideRequiresKeyword(ValueDecl *overridden);
/// Compute the type of a member that will be used for comparison when
/// performing override checking.
Type getMemberTypeForComparison(ASTContext &ctx, ValueDecl *member,
ValueDecl *derivedDecl = nullptr);
/// Determine whether the given declaration is an override by comparing type
/// information.
bool isOverrideBasedOnType(ValueDecl *decl, Type declTy,
ValueDecl *parentDecl, Type parentDeclTy);
/// Determine whether the given declaration is an operator defined in a
/// protocol. If \p type is not null, check specifically whether \p decl
/// could fulfill a protocol requirement for it.
bool isMemberOperator(FuncDecl *decl, Type type);
} // end namespace swift
#endif