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//===-- ChangeNamespace.cpp - Change namespace implementation -------------===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#include "ChangeNamespace.h"
#include "clang/AST/ASTContext.h"
#include "clang/Format/Format.h"
#include "clang/Lex/Lexer.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/ErrorHandling.h"
using namespace clang::ast_matchers;
namespace clang {
namespace change_namespace {
namespace {
inline std::string joinNamespaces(ArrayRef<StringRef> Namespaces) {
return llvm::join(Namespaces, "::");
// Given "a::b::c", returns {"a", "b", "c"}.
llvm::SmallVector<llvm::StringRef, 4> splitSymbolName(llvm::StringRef Name) {
llvm::SmallVector<llvm::StringRef, 4> Splitted;
Name.split(Splitted, "::", /*MaxSplit=*/-1,
return Splitted;
SourceLocation startLocationForType(TypeLoc TLoc) {
// For elaborated types (e.g. `struct a::A`) we want the portion after the
// `struct` but including the namespace qualifier, `a::`.
if (TLoc.getTypeLocClass() == TypeLoc::Elaborated) {
NestedNameSpecifierLoc NestedNameSpecifier =
if (NestedNameSpecifier.getNestedNameSpecifier())
return NestedNameSpecifier.getBeginLoc();
TLoc = TLoc.getNextTypeLoc();
return TLoc.getBeginLoc();
SourceLocation endLocationForType(TypeLoc TLoc) {
// Dig past any namespace or keyword qualifications.
while (TLoc.getTypeLocClass() == TypeLoc::Elaborated ||
TLoc.getTypeLocClass() == TypeLoc::Qualified)
TLoc = TLoc.getNextTypeLoc();
// The location for template specializations (e.g. Foo<int>) includes the
// templated types in its location range. We want to restrict this to just
// before the `<` character.
if (TLoc.getTypeLocClass() == TypeLoc::TemplateSpecialization)
return TLoc.castAs<TemplateSpecializationTypeLoc>()
return TLoc.getEndLoc();
// Returns the containing namespace of `InnerNs` by skipping `PartialNsName`.
// If the `InnerNs` does not have `PartialNsName` as suffix, or `PartialNsName`
// is empty, nullptr is returned.
// For example, if `InnerNs` is "a::b::c" and `PartialNsName` is "b::c", then
// the NamespaceDecl of namespace "a" will be returned.
const NamespaceDecl *getOuterNamespace(const NamespaceDecl *InnerNs,
llvm::StringRef PartialNsName) {
if (!InnerNs || PartialNsName.empty())
return nullptr;
const auto *CurrentContext = llvm::cast<DeclContext>(InnerNs);
const auto *CurrentNs = InnerNs;
auto PartialNsNameSplitted = splitSymbolName(PartialNsName);
while (!PartialNsNameSplitted.empty()) {
// Get the inner-most namespace in CurrentContext.
while (CurrentContext && !llvm::isa<NamespaceDecl>(CurrentContext))
CurrentContext = CurrentContext->getParent();
if (!CurrentContext)
return nullptr;
CurrentNs = llvm::cast<NamespaceDecl>(CurrentContext);
if (PartialNsNameSplitted.back() != CurrentNs->getNameAsString())
return nullptr;
CurrentContext = CurrentContext->getParent();
return CurrentNs;
static std::unique_ptr<Lexer>
getLexerStartingFromLoc(SourceLocation Loc, const SourceManager &SM,
const LangOptions &LangOpts) {
if (Loc.isMacroID() &&
!Lexer::isAtEndOfMacroExpansion(Loc, SM, LangOpts, &Loc))
return nullptr;
// Break down the source location.
std::pair<FileID, unsigned> LocInfo = SM.getDecomposedLoc(Loc);
// Try to load the file buffer.
bool InvalidTemp = false;
llvm::StringRef File = SM.getBufferData(LocInfo.first, &InvalidTemp);
if (InvalidTemp)
return nullptr;
const char *TokBegin = + LocInfo.second;
// Lex from the start of the given location.
return std::make_unique<Lexer>(SM.getLocForStartOfFile(LocInfo.first),
LangOpts, File.begin(), TokBegin, File.end());
// FIXME: get rid of this helper function if this is supported in clang-refactor
// library.
static SourceLocation getStartOfNextLine(SourceLocation Loc,
const SourceManager &SM,
const LangOptions &LangOpts) {
std::unique_ptr<Lexer> Lex = getLexerStartingFromLoc(Loc, SM, LangOpts);
if (!Lex.get())
return SourceLocation();
llvm::SmallVector<char, 16> Line;
// FIXME: this is a bit hacky to get ReadToEndOfLine work.
auto End = Loc.getLocWithOffset(Line.size());
return SM.getLocForEndOfFile(SM.getDecomposedLoc(Loc).first) == End
? End
: End.getLocWithOffset(1);
// Returns `R` with new range that refers to code after `Replaces` being
// applied.
getReplacementInChangedCode(const tooling::Replacements &Replaces,
const tooling::Replacement &R) {
unsigned NewStart = Replaces.getShiftedCodePosition(R.getOffset());
unsigned NewEnd =
Replaces.getShiftedCodePosition(R.getOffset() + R.getLength());
return tooling::Replacement(R.getFilePath(), NewStart, NewEnd - NewStart,
// Adds a replacement `R` into `Replaces` or merges it into `Replaces` by
// applying all existing Replaces first if there is conflict.
void addOrMergeReplacement(const tooling::Replacement &R,
tooling::Replacements *Replaces) {
auto Err = Replaces->add(R);
if (Err) {
auto Replace = getReplacementInChangedCode(*Replaces, R);
*Replaces = Replaces->merge(tooling::Replacements(Replace));
tooling::Replacement createReplacement(SourceLocation Start, SourceLocation End,
llvm::StringRef ReplacementText,
const SourceManager &SM) {
if (!Start.isValid() || !End.isValid()) {
llvm::errs() << "start or end location were invalid\n";
return tooling::Replacement();
if (SM.getDecomposedLoc(Start).first != SM.getDecomposedLoc(End).first) {
<< "start or end location were in different macro expansions\n";
return tooling::Replacement();
Start = SM.getSpellingLoc(Start);
End = SM.getSpellingLoc(End);
if (SM.getFileID(Start) != SM.getFileID(End)) {
llvm::errs() << "start or end location were in different files\n";
return tooling::Replacement();
return tooling::Replacement(
SM, CharSourceRange::getTokenRange(SM.getSpellingLoc(Start),
void addReplacementOrDie(
SourceLocation Start, SourceLocation End, llvm::StringRef ReplacementText,
const SourceManager &SM,
std::map<std::string, tooling::Replacements> *FileToReplacements) {
const auto R = createReplacement(Start, End, ReplacementText, SM);
auto Err = (*FileToReplacements)[std::string(R.getFilePath())].add(R);
if (Err)
tooling::Replacement createInsertion(SourceLocation Loc,
llvm::StringRef InsertText,
const SourceManager &SM) {
if (Loc.isInvalid()) {
llvm::errs() << "insert Location is invalid.\n";
return tooling::Replacement();
Loc = SM.getSpellingLoc(Loc);
return tooling::Replacement(SM, Loc, 0, InsertText);
// Returns the shortest qualified name for declaration `DeclName` in the
// namespace `NsName`. For example, if `DeclName` is "a::b::X" and `NsName`
// is "a::c::d", then "b::X" will be returned.
// Note that if `DeclName` is `::b::X` and `NsName` is `::a::b`, this returns
// "::b::X" instead of "b::X" since there will be a name conflict otherwise.
// \param DeclName A fully qualified name, "::a::b::X" or "a::b::X".
// \param NsName A fully qualified name, "::a::b" or "a::b". Global namespace
// will have empty name.
std::string getShortestQualifiedNameInNamespace(llvm::StringRef DeclName,
llvm::StringRef NsName) {
DeclName = DeclName.ltrim(':');
NsName = NsName.ltrim(':');
if (!DeclName.contains(':'))
return std::string(DeclName);
auto NsNameSplitted = splitSymbolName(NsName);
auto DeclNsSplitted = splitSymbolName(DeclName);
llvm::StringRef UnqualifiedDeclName = DeclNsSplitted.pop_back_val();
// If the Decl is in global namespace, there is no need to shorten it.
if (DeclNsSplitted.empty())
return std::string(UnqualifiedDeclName);
// If NsName is the global namespace, we can simply use the DeclName sans
// leading "::".
if (NsNameSplitted.empty())
return std::string(DeclName);
if (NsNameSplitted.front() != DeclNsSplitted.front()) {
// The DeclName must be fully-qualified, but we still need to decide if a
// leading "::" is necessary. For example, if `NsName` is "a::b::c" and the
// `DeclName` is "b::X", then the reference must be qualified as "::b::X"
// to avoid conflict.
if (llvm::is_contained(NsNameSplitted, DeclNsSplitted.front()))
return ("::" + DeclName).str();
return std::string(DeclName);
// Since there is already an overlap namespace, we know that `DeclName` can be
// shortened, so we reduce the longest common prefix.
auto DeclI = DeclNsSplitted.begin();
auto DeclE = DeclNsSplitted.end();
auto NsI = NsNameSplitted.begin();
auto NsE = NsNameSplitted.end();
for (; DeclI != DeclE && NsI != NsE && *DeclI == *NsI; ++DeclI, ++NsI) {
return (DeclI == DeclE)
? UnqualifiedDeclName.str()
: (llvm::join(DeclI, DeclE, "::") + "::" + UnqualifiedDeclName)
std::string wrapCodeInNamespace(StringRef NestedNs, std::string Code) {
if (Code.back() != '\n')
Code += "\n";
auto NsSplitted = splitSymbolName(NestedNs);
while (!NsSplitted.empty()) {
// FIXME: consider code style for comments.
Code = ("namespace " + NsSplitted.back() + " {\n" + Code +
"} // namespace " + NsSplitted.back() + "\n")
return Code;
// Returns true if \p D is a nested DeclContext in \p Context
bool isNestedDeclContext(const DeclContext *D, const DeclContext *Context) {
while (D) {
if (D == Context)
return true;
D = D->getParent();
return false;
// Returns true if \p D is visible at \p Loc with DeclContext \p DeclCtx.
bool isDeclVisibleAtLocation(const SourceManager &SM, const Decl *D,
const DeclContext *DeclCtx, SourceLocation Loc) {
SourceLocation DeclLoc = SM.getSpellingLoc(D->getBeginLoc());
Loc = SM.getSpellingLoc(Loc);
return SM.isBeforeInTranslationUnit(DeclLoc, Loc) &&
(SM.getFileID(DeclLoc) == SM.getFileID(Loc) &&
isNestedDeclContext(DeclCtx, D->getDeclContext()));
// Given a qualified symbol name, returns true if the symbol will be
// incorrectly qualified without leading "::". For example, a symbol
// "nx::ny::Foo" in namespace "na::nx::ny" without leading "::"; a symbol
// "util::X" in namespace "na" can potentially conflict with "na::util" (if this
// exists).
bool conflictInNamespace(const ASTContext &AST, llvm::StringRef QualifiedSymbol,
llvm::StringRef Namespace) {
auto SymbolSplitted = splitSymbolName(QualifiedSymbol.trim(":"));
SymbolSplitted.pop_back(); // We are only interested in namespaces.
if (SymbolSplitted.size() >= 1 && !Namespace.empty()) {
auto SymbolTopNs = SymbolSplitted.front();
auto NsSplitted = splitSymbolName(Namespace.trim(":"));
auto LookupDecl = [&AST](const Decl &Scope,
llvm::StringRef Name) -> const NamedDecl * {
const auto *DC = llvm::dyn_cast<DeclContext>(&Scope);
if (!DC)
return nullptr;
auto LookupRes = DC->lookup(DeclarationName(&AST.Idents.get(Name)));
if (LookupRes.empty())
return nullptr;
return LookupRes.front();
// We do not check the outermost namespace since it would not be a
// conflict if it equals to the symbol's outermost namespace and the
// symbol name would have been shortened.
const NamedDecl *Scope =
LookupDecl(*AST.getTranslationUnitDecl(), NsSplitted.front());
for (const auto &I : llvm::drop_begin(NsSplitted)) {
if (I == SymbolTopNs) // Handles "::ny" in "::nx::ny" case.
return true;
// Handles "::util" and "::nx::util" conflicts.
if (Scope) {
if (LookupDecl(*Scope, SymbolTopNs))
return true;
Scope = LookupDecl(*Scope, I);
if (Scope && LookupDecl(*Scope, SymbolTopNs))
return true;
return false;
bool isTemplateParameter(TypeLoc Type) {
while (!Type.isNull()) {
if (Type.getTypeLocClass() == TypeLoc::SubstTemplateTypeParm)
return true;
Type = Type.getNextTypeLoc();
return false;
} // anonymous namespace
llvm::StringRef OldNs, llvm::StringRef NewNs, llvm::StringRef FilePattern,
llvm::ArrayRef<std::string> AllowedSymbolPatterns,
std::map<std::string, tooling::Replacements> *FileToReplacements,
llvm::StringRef FallbackStyle)
: FallbackStyle(FallbackStyle), FileToReplacements(*FileToReplacements),
OldNamespace(OldNs.ltrim(':')), NewNamespace(NewNs.ltrim(':')),
FilePattern(FilePattern), FilePatternRE(FilePattern) {
auto OldNsSplitted = splitSymbolName(OldNamespace);
auto NewNsSplitted = splitSymbolName(NewNamespace);
// Calculates `DiffOldNamespace` and `DiffNewNamespace`.
while (!OldNsSplitted.empty() && !NewNsSplitted.empty() &&
OldNsSplitted.front() == NewNsSplitted.front()) {
DiffOldNamespace = joinNamespaces(OldNsSplitted);
DiffNewNamespace = joinNamespaces(NewNsSplitted);
for (const auto &Pattern : AllowedSymbolPatterns)
void ChangeNamespaceTool::registerMatchers(ast_matchers::MatchFinder *Finder) {
std::string FullOldNs = "::" + OldNamespace;
// Prefix is the outer-most namespace in DiffOldNamespace. For example, if the
// OldNamespace is "a::b::c" and DiffOldNamespace is "b::c", then Prefix will
// be "a::b". Declarations in this namespace will not be visible in the new
// namespace. If DiffOldNamespace is empty, Prefix will be a invalid name "-".
llvm::SmallVector<llvm::StringRef, 4> DiffOldNsSplitted;
.split(DiffOldNsSplitted, "::", /*MaxSplit=*/-1,
std::string Prefix = "-";
if (!DiffOldNsSplitted.empty())
Prefix = (StringRef(FullOldNs).drop_back(DiffOldNamespace.size()) +
auto IsInMovedNs =
auto IsVisibleInNewNs = anyOf(
IsInMovedNs, unless(hasAncestor(namespaceDecl(hasName(Prefix)))));
// Match using declarations.
usingDecl(isExpansionInFileMatching(FilePattern), IsVisibleInNewNs)
// Match using namespace declarations.
// Match namespace alias declarations.
// Match old namespace blocks.
namespaceDecl(hasName(FullOldNs), isExpansionInFileMatching(FilePattern))
// Match class forward-declarations in the old namespace.
// Note that forward-declarations in classes are not matched.
Finder->addMatcher(cxxRecordDecl(unless(anyOf(isImplicit(), isDefinition())),
IsInMovedNs, hasParent(namespaceDecl()))
// Match template class forward-declarations in the old namespace.
IsInMovedNs, hasParent(namespaceDecl()))
// Match references to types that are not defined in the old namespace.
// Forward-declarations in the old namespace are also matched since they will
// be moved back to the old namespace.
auto DeclMatcher = namedDecl(
isImplicit(), hasAncestor(namespaceDecl(isAnonymous())),
allOf(IsInMovedNs, unless(cxxRecordDecl(unless(isDefinition())))))));
// Using shadow declarations in classes always refers to base class, which
// does not need to be qualified since it can be inferred from inheritance.
// Note that this does not match using alias declarations.
auto UsingShadowDeclInClass =
usingDecl(hasAnyUsingShadowDecl(decl()), hasParent(cxxRecordDecl()));
// Match TypeLocs on the declaration. Carefully match only the outermost
// TypeLoc and template specialization arguments (which are not outermost)
// that are directly linked to types matching `DeclMatcher`. Nested name
// specifier locs are handled separately below.
// Types in `UsingShadowDecl` is not matched by `typeLoc` above, so we need to
// special case it.
// Since using declarations inside classes must have the base class in the
// nested name specifier, we leave it to the nested name specifier matcher.
Finder->addMatcher(usingDecl(IsInMovedNs, hasAnyUsingShadowDecl(decl()),
// Handle types in nested name specifier. Specifiers that are in a TypeLoc
// matched above are not matched, e.g. "A::" in "A::A" is not matched since
// "A::A" would have already been fixed.
// Matches base class initializers in constructors. TypeLocs of base class
// initializers do not need to be fixed. For example,
// class X : public a::b::Y {
// public:
// X() : Y::Y() {} // Y::Y do not need namespace specifier.
// };
cxxCtorInitializer(isBaseInitializer()).bind("base_initializer"), this);
// Handle function.
// Only handle functions that are defined in a namespace excluding member
// function, static methods (qualified by nested specifier), and functions
// defined in the global namespace.
// Note that the matcher does not exclude calls to out-of-line static method
// definitions, so we need to exclude them in the callback handler.
auto FuncMatcher =
functionDecl(unless(anyOf(cxxMethodDecl(), IsInMovedNs,
Finder->addMatcher(expr(hasAncestor(decl().bind("dc")), IsInMovedNs,
auto GlobalVarMatcher = varDecl(
hasGlobalStorage(), hasParent(namespaceDecl()),
unless(anyOf(IsInMovedNs, hasAncestor(namespaceDecl(isAnonymous())))));
Finder->addMatcher(declRefExpr(IsInMovedNs, hasAncestor(decl().bind("dc")),
// Handle unscoped enum constant.
auto UnscopedEnumMatcher = enumConstantDecl(hasParent(enumDecl(
unless(anyOf(isScoped(), IsInMovedNs, hasAncestor(cxxRecordDecl()),
declRefExpr(IsInMovedNs, hasAncestor(decl().bind("dc")),
void ChangeNamespaceTool::run(
const ast_matchers::MatchFinder::MatchResult &Result) {
if (const auto *Using = Result.Nodes.getNodeAs<UsingDecl>("using")) {
} else if (const auto *UsingNamespace =
"using_namespace")) {
} else if (const auto *NamespaceAlias =
"namespace_alias")) {
} else if (const auto *NsDecl =
Result.Nodes.getNodeAs<NamespaceDecl>("old_ns")) {
moveOldNamespace(Result, NsDecl);
} else if (const auto *FwdDecl =
Result.Nodes.getNodeAs<CXXRecordDecl>("class_fwd_decl")) {
moveClassForwardDeclaration(Result, cast<NamedDecl>(FwdDecl));
} else if (const auto *TemplateFwdDecl =
"template_class_fwd_decl")) {
moveClassForwardDeclaration(Result, cast<NamedDecl>(TemplateFwdDecl));
} else if (const auto *UsingWithShadow =
Result.Nodes.getNodeAs<UsingDecl>("using_with_shadow")) {
fixUsingShadowDecl(Result, UsingWithShadow);
} else if (const auto *Specifier =
"nested_specifier_loc")) {
SourceLocation Start = Specifier->getBeginLoc();
SourceLocation End = endLocationForType(Specifier->getTypeLoc());
fixTypeLoc(Result, Start, End, Specifier->getTypeLoc());
} else if (const auto *BaseInitializer =
"base_initializer")) {
} else if (const auto *TLoc = Result.Nodes.getNodeAs<TypeLoc>("type")) {
// This avoids fixing types with record types as qualifier, which is not
// filtered by matchers in some cases, e.g. the type is templated. We should
// handle the record type qualifier instead.
TypeLoc Loc = *TLoc;
while (Loc.getTypeLocClass() == TypeLoc::Qualified)
Loc = Loc.getNextTypeLoc();
if (Loc.getTypeLocClass() == TypeLoc::Elaborated) {
NestedNameSpecifierLoc NestedNameSpecifier =
// FIXME: avoid changing injected class names.
if (auto *NNS = NestedNameSpecifier.getNestedNameSpecifier()) {
const Type *SpecifierType = NNS->getAsType();
if (SpecifierType && SpecifierType->isRecordType())
fixTypeLoc(Result, startLocationForType(Loc), endLocationForType(Loc), Loc);
} else if (const auto *VarRef =
Result.Nodes.getNodeAs<DeclRefExpr>("var_ref")) {
const auto *Var = Result.Nodes.getNodeAs<VarDecl>("var_decl");
if (Var->getCanonicalDecl()->isStaticDataMember())
const auto *Context = Result.Nodes.getNodeAs<Decl>("dc");
assert(Context && "Empty decl context.");
fixDeclRefExpr(Result, Context->getDeclContext(),
llvm::cast<NamedDecl>(Var), VarRef);
} else if (const auto *EnumConstRef =
Result.Nodes.getNodeAs<DeclRefExpr>("enum_const_ref")) {
// Do not rename the reference if it is already scoped by the EnumDecl name.
if (EnumConstRef->hasQualifier() &&
EnumConstRef->getQualifier()->getKind() ==
NestedNameSpecifier::SpecifierKind::TypeSpec &&
const auto *EnumConstDecl =
const auto *Context = Result.Nodes.getNodeAs<Decl>("dc");
assert(Context && "Empty decl context.");
// FIXME: this would qualify "ns::VALUE" as "ns::EnumValue::VALUE". Fix it
// if it turns out to be an issue.
fixDeclRefExpr(Result, Context->getDeclContext(),
llvm::cast<NamedDecl>(EnumConstDecl), EnumConstRef);
} else if (const auto *FuncRef =
Result.Nodes.getNodeAs<DeclRefExpr>("func_ref")) {
// If this reference has been processed as a function call, we do not
// process it again.
if (ProcessedFuncRefs.count(FuncRef))
const auto *Func = Result.Nodes.getNodeAs<FunctionDecl>("func_decl");
const auto *Context = Result.Nodes.getNodeAs<Decl>("dc");
assert(Context && "Empty decl context.");
fixDeclRefExpr(Result, Context->getDeclContext(),
llvm::cast<NamedDecl>(Func), FuncRef);
} else {
const auto *Call = Result.Nodes.getNodeAs<CallExpr>("call");
assert(Call != nullptr && "Expecting callback for CallExpr.");
const auto *CalleeFuncRef =
const FunctionDecl *Func = Call->getDirectCallee();
assert(Func != nullptr);
// FIXME: ignore overloaded operators. This would miss cases where operators
// are called by qualified names (i.e. "ns::operator <"). Ignore such
// cases for now.
if (Func->isOverloadedOperator())
// Ignore out-of-line static methods since they will be handled by nested
// name specifiers.
if (Func->getCanonicalDecl()->getStorageClass() ==
StorageClass::SC_Static &&
const auto *Context = Result.Nodes.getNodeAs<Decl>("dc");
assert(Context && "Empty decl context.");
SourceRange CalleeRange = Call->getCallee()->getSourceRange();
Result, Context->getDeclContext(), CalleeRange.getBegin(),
CalleeRange.getEnd(), llvm::cast<NamedDecl>(Func));
static SourceLocation getLocAfterNamespaceLBrace(const NamespaceDecl *NsDecl,
const SourceManager &SM,
const LangOptions &LangOpts) {
std::unique_ptr<Lexer> Lex =
getLexerStartingFromLoc(NsDecl->getBeginLoc(), SM, LangOpts);
assert(Lex.get() &&
"Failed to create lexer from the beginning of namespace.");
if (!Lex.get())
return SourceLocation();
Token Tok;
while (!Lex->LexFromRawLexer(Tok) && Tok.isNot(tok::TokenKind::l_brace)) {
return Tok.isNot(tok::TokenKind::l_brace)
? SourceLocation()
: Tok.getEndLoc().getLocWithOffset(1);
// Stores information about a moved namespace in `MoveNamespaces` and leaves
// the actual movement to `onEndOfTranslationUnit()`.
void ChangeNamespaceTool::moveOldNamespace(
const ast_matchers::MatchFinder::MatchResult &Result,
const NamespaceDecl *NsDecl) {
// If the namespace is empty, do nothing.
if (Decl::castToDeclContext(NsDecl)->decls_empty())
const SourceManager &SM = *Result.SourceManager;
// Get the range of the code in the old namespace.
SourceLocation Start =
getLocAfterNamespaceLBrace(NsDecl, SM, Result.Context->getLangOpts());
assert(Start.isValid() && "Can't find l_brace for namespace.");
MoveNamespace MoveNs;
MoveNs.Offset = SM.getFileOffset(Start);
// The range of the moved namespace is from the location just past the left
// brace to the location right before the right brace.
MoveNs.Length = SM.getFileOffset(NsDecl->getRBraceLoc()) - MoveNs.Offset;
// Insert the new namespace after `DiffOldNamespace`. For example, if
// `OldNamespace` is "a::b::c" and `NewNamespace` is `a::x::y`, then
// "x::y" will be inserted inside the existing namespace "a" and after "a::b".
// `OuterNs` is the first namespace in `DiffOldNamespace`, e.g. "namespace b"
// in the above example.
// If there is no outer namespace (i.e. DiffOldNamespace is empty), the new
// namespace will be a nested namespace in the old namespace.
const NamespaceDecl *OuterNs = getOuterNamespace(NsDecl, DiffOldNamespace);
SourceLocation InsertionLoc = Start;
if (OuterNs) {
SourceLocation LocAfterNs = getStartOfNextLine(
OuterNs->getRBraceLoc(), SM, Result.Context->getLangOpts());
assert(LocAfterNs.isValid() &&
"Failed to get location after DiffOldNamespace");
InsertionLoc = LocAfterNs;
MoveNs.InsertionOffset = SM.getFileOffset(SM.getSpellingLoc(InsertionLoc));
MoveNs.FID = SM.getFileID(Start);
MoveNs.SourceMgr = Result.SourceManager;
// Removes a class forward declaration from the code in the moved namespace and
// creates an `InsertForwardDeclaration` to insert the forward declaration back
// into the old namespace after moving code from the old namespace to the new
// namespace.
// For example, changing "a" to "x":
// Old code:
// namespace a {
// class FWD;
// class A { FWD *fwd; }
// } // a
// New code:
// namespace a {
// class FWD;
// } // a
// namespace x {
// class A { a::FWD *fwd; }
// } // x
void ChangeNamespaceTool::moveClassForwardDeclaration(
const ast_matchers::MatchFinder::MatchResult &Result,
const NamedDecl *FwdDecl) {
SourceLocation Start = FwdDecl->getBeginLoc();
SourceLocation End = FwdDecl->getEndLoc();
const SourceManager &SM = *Result.SourceManager;
SourceLocation AfterSemi = Lexer::findLocationAfterToken(
End, tok::semi, SM, Result.Context->getLangOpts(),
if (AfterSemi.isValid())
End = AfterSemi.getLocWithOffset(-1);
// Delete the forward declaration from the code to be moved.
addReplacementOrDie(Start, End, "", SM, &FileToReplacements);
llvm::StringRef Code = Lexer::getSourceText(
SM, Result.Context->getLangOpts());
// Insert the forward declaration back into the old namespace after moving the
// code from old namespace to new namespace.
// Insertion information is stored in `InsertFwdDecls` and actual
// insertion will be performed in `onEndOfTranslationUnit`.
// Get the (old) namespace that contains the forward declaration.
const auto *NsDecl = Result.Nodes.getNodeAs<NamespaceDecl>("ns_decl");
// The namespace contains the forward declaration, so it must not be empty.
const auto Insertion = createInsertion(
getLocAfterNamespaceLBrace(NsDecl, SM, Result.Context->getLangOpts()),
Code, SM);
InsertForwardDeclaration InsertFwd;
InsertFwd.InsertionOffset = Insertion.getOffset();
InsertFwd.ForwardDeclText = Insertion.getReplacementText().str();
// Replaces a qualified symbol (in \p DeclCtx) that refers to a declaration \p
// FromDecl with the shortest qualified name possible when the reference is in
// `NewNamespace`.
void ChangeNamespaceTool::replaceQualifiedSymbolInDeclContext(
const ast_matchers::MatchFinder::MatchResult &Result,
const DeclContext *DeclCtx, SourceLocation Start, SourceLocation End,
const NamedDecl *FromDecl) {
const auto *NsDeclContext = DeclCtx->getEnclosingNamespaceContext();
if (llvm::isa<TranslationUnitDecl>(NsDeclContext)) {
// This should not happen in usual unless the TypeLoc is in function type
// parameters, e.g `std::function<void(T)>`. In this case, DeclContext of
// `T` will be the translation unit. We simply use fully-qualified name
// here.
// Note that `FromDecl` must not be defined in the old namespace (according
// to `DeclMatcher`), so its fully-qualified name will not change after
// changing the namespace.
addReplacementOrDie(Start, End, FromDecl->getQualifiedNameAsString(),
*Result.SourceManager, &FileToReplacements);
const auto *NsDecl = llvm::cast<NamespaceDecl>(NsDeclContext);
// Calculate the name of the `NsDecl` after it is moved to new namespace.
std::string OldNs = NsDecl->getQualifiedNameAsString();
llvm::StringRef Postfix = OldNs;
bool Consumed = Postfix.consume_front(OldNamespace);
assert(Consumed && "Expect OldNS to start with OldNamespace.");
const std::string NewNs = (NewNamespace + Postfix).str();
llvm::StringRef NestedName = Lexer::getSourceText(
*Result.SourceManager, Result.Context->getLangOpts());
std::string FromDeclName = FromDecl->getQualifiedNameAsString();
for (llvm::Regex &RE : AllowedSymbolRegexes)
if (RE.match(FromDeclName))
std::string ReplaceName =
getShortestQualifiedNameInNamespace(FromDeclName, NewNs);
// Checks if there is any using namespace declarations that can shorten the
// qualified name.
for (const auto *UsingNamespace : UsingNamespaceDecls) {
if (!isDeclVisibleAtLocation(*Result.SourceManager, UsingNamespace, DeclCtx,
StringRef FromDeclNameRef = FromDeclName;
if (FromDeclNameRef.consume_front(UsingNamespace->getNominatedNamespace()
->getQualifiedNameAsString())) {
FromDeclNameRef = FromDeclNameRef.drop_front(2);
if (FromDeclNameRef.size() < ReplaceName.size())
ReplaceName = std::string(FromDeclNameRef);
// Checks if there is any namespace alias declarations that can shorten the
// qualified name.
for (const auto *NamespaceAlias : NamespaceAliasDecls) {
if (!isDeclVisibleAtLocation(*Result.SourceManager, NamespaceAlias, DeclCtx,
StringRef FromDeclNameRef = FromDeclName;
if (FromDeclNameRef.consume_front(
NamespaceAlias->getNamespace()->getQualifiedNameAsString() +
"::")) {
std::string AliasName = NamespaceAlias->getNameAsString();
std::string AliasQualifiedName =
// We only consider namespace aliases define in the global namespace or
// in namespaces that are directly visible from the reference, i.e.
// ancestor of the `OldNs`. Note that declarations in ancestor namespaces
// but not visible in the new namespace is filtered out by
// "IsVisibleInNewNs" matcher.
if (AliasQualifiedName != AliasName) {
// The alias is defined in some namespace.
assert(StringRef(AliasQualifiedName).endswith("::" + AliasName));
llvm::StringRef AliasNs =
StringRef(AliasQualifiedName).drop_back(AliasName.size() + 2);
if (!llvm::StringRef(OldNs).startswith(AliasNs))
std::string NameWithAliasNamespace =
(AliasName + "::" + FromDeclNameRef).str();
if (NameWithAliasNamespace.size() < ReplaceName.size())
ReplaceName = NameWithAliasNamespace;
// Checks if there is any using shadow declarations that can shorten the
// qualified name.
bool Matched = false;
for (const UsingDecl *Using : UsingDecls) {
if (Matched)
if (isDeclVisibleAtLocation(*Result.SourceManager, Using, DeclCtx, Start)) {
for (const auto *UsingShadow : Using->shadows()) {
const auto *TargetDecl = UsingShadow->getTargetDecl();
if (TargetDecl->getQualifiedNameAsString() ==
FromDecl->getQualifiedNameAsString()) {
ReplaceName = FromDecl->getNameAsString();
Matched = true;
bool Conflict = conflictInNamespace(DeclCtx->getParentASTContext(),
ReplaceName, NewNamespace);
// If the new nested name in the new namespace is the same as it was in the
// old namespace, we don't create replacement unless there can be ambiguity.
if ((NestedName == ReplaceName && !Conflict) ||
(NestedName.startswith("::") && NestedName.drop_front(2) == ReplaceName))
// If the reference need to be fully-qualified, add a leading "::" unless
// NewNamespace is the global namespace.
if (ReplaceName == FromDeclName && !NewNamespace.empty() && Conflict)
ReplaceName = "::" + ReplaceName;
addReplacementOrDie(Start, End, ReplaceName, *Result.SourceManager,
// Replace the [Start, End] of `Type` with the shortest qualified name when the
// `Type` is in `NewNamespace`.
void ChangeNamespaceTool::fixTypeLoc(
const ast_matchers::MatchFinder::MatchResult &Result, SourceLocation Start,
SourceLocation End, TypeLoc Type) {
// FIXME: do not rename template parameter.
if (Start.isInvalid() || End.isInvalid())
// Types of CXXCtorInitializers do not need to be fixed.
if (llvm::is_contained(BaseCtorInitializerTypeLocs, Type))
if (isTemplateParameter(Type))
// The declaration which this TypeLoc refers to.
const auto *FromDecl = Result.Nodes.getNodeAs<NamedDecl>("from_decl");
// `hasDeclaration` gives underlying declaration, but if the type is
// a typedef type, we need to use the typedef type instead.
auto IsInMovedNs = [&](const NamedDecl *D) {
if (!llvm::StringRef(D->getQualifiedNameAsString())
.startswith(OldNamespace + "::"))
return false;
auto ExpansionLoc = Result.SourceManager->getExpansionLoc(D->getBeginLoc());
if (ExpansionLoc.isInvalid())
return false;
llvm::StringRef Filename = Result.SourceManager->getFilename(ExpansionLoc);
return FilePatternRE.match(Filename);
// Make `FromDecl` the immediate declaration that `Type` refers to, i.e. if
// `Type` is an alias type, we make `FromDecl` the type alias declaration.
// Also, don't fix the \p Type if it refers to a type alias decl in the moved
// namespace since the alias decl will be moved along with the type reference.
if (auto *Typedef = Type.getType()->getAs<TypedefType>()) {
FromDecl = Typedef->getDecl();
if (IsInMovedNs(FromDecl))
} else if (auto *TemplateType =
Type.getType()->getAs<TemplateSpecializationType>()) {
if (TemplateType->isTypeAlias()) {
FromDecl = TemplateType->getTemplateName().getAsTemplateDecl();
if (IsInMovedNs(FromDecl))
const auto *DeclCtx = Result.Nodes.getNodeAs<Decl>("dc");
assert(DeclCtx && "Empty decl context.");
replaceQualifiedSymbolInDeclContext(Result, DeclCtx->getDeclContext(), Start,
End, FromDecl);
void ChangeNamespaceTool::fixUsingShadowDecl(
const ast_matchers::MatchFinder::MatchResult &Result,
const UsingDecl *UsingDeclaration) {
SourceLocation Start = UsingDeclaration->getBeginLoc();
SourceLocation End = UsingDeclaration->getEndLoc();
if (Start.isInvalid() || End.isInvalid())
assert(UsingDeclaration->shadow_size() > 0);
// FIXME: it might not be always accurate to use the first using-decl.
const NamedDecl *TargetDecl =
std::string TargetDeclName = TargetDecl->getQualifiedNameAsString();
// FIXME: check if target_decl_name is in moved ns, which doesn't make much
// sense. If this happens, we need to use name with the new namespace.
// Use fully qualified name in UsingDecl for now.
addReplacementOrDie(Start, End, "using ::" + TargetDeclName,
*Result.SourceManager, &FileToReplacements);
void ChangeNamespaceTool::fixDeclRefExpr(
const ast_matchers::MatchFinder::MatchResult &Result,
const DeclContext *UseContext, const NamedDecl *From,
const DeclRefExpr *Ref) {
SourceRange RefRange = Ref->getSourceRange();
replaceQualifiedSymbolInDeclContext(Result, UseContext, RefRange.getBegin(),
RefRange.getEnd(), From);
void ChangeNamespaceTool::onEndOfTranslationUnit() {
// Move namespace blocks and insert forward declaration to old namespace.
for (const auto &FileAndNsMoves : MoveNamespaces) {
auto &NsMoves = FileAndNsMoves.second;
if (NsMoves.empty())
const std::string &FilePath = FileAndNsMoves.first;
auto &Replaces = FileToReplacements[FilePath];
auto &SM = *NsMoves.begin()->SourceMgr;
llvm::StringRef Code = SM.getBufferData(NsMoves.begin()->FID);
auto ChangedCode = tooling::applyAllReplacements(Code, Replaces);
if (!ChangedCode) {
llvm::errs() << llvm::toString(ChangedCode.takeError()) << "\n";
// Replacements on the changed code for moving namespaces and inserting
// forward declarations to old namespaces.
tooling::Replacements NewReplacements;
// Cut the changed code from the old namespace and paste the code in the new
// namespace.
for (const auto &NsMove : NsMoves) {
// Calculate the range of the old namespace block in the changed
// code.
const unsigned NewOffset = Replaces.getShiftedCodePosition(NsMove.Offset);
const unsigned NewLength =
Replaces.getShiftedCodePosition(NsMove.Offset + NsMove.Length) -
tooling::Replacement Deletion(FilePath, NewOffset, NewLength, "");
std::string MovedCode = ChangedCode->substr(NewOffset, NewLength);
std::string MovedCodeWrappedInNewNs =
wrapCodeInNamespace(DiffNewNamespace, MovedCode);
// Calculate the new offset at which the code will be inserted in the
// changed code.
unsigned NewInsertionOffset =
tooling::Replacement Insertion(FilePath, NewInsertionOffset, 0,
addOrMergeReplacement(Deletion, &NewReplacements);
addOrMergeReplacement(Insertion, &NewReplacements);
// After moving namespaces, insert forward declarations back to old
// namespaces.
const auto &FwdDeclInsertions = InsertFwdDecls[FilePath];
for (const auto &FwdDeclInsertion : FwdDeclInsertions) {
unsigned NewInsertionOffset =
tooling::Replacement Insertion(FilePath, NewInsertionOffset, 0,
addOrMergeReplacement(Insertion, &NewReplacements);
// Add replacements referring to the changed code to existing replacements,
// which refers to the original code.
Replaces = Replaces.merge(NewReplacements);
auto Style =
format::getStyle(format::DefaultFormatStyle, FilePath, FallbackStyle);
if (!Style) {
llvm::errs() << llvm::toString(Style.takeError()) << "\n";
// Clean up old namespaces if there is nothing in it after moving.
auto CleanReplacements =
format::cleanupAroundReplacements(Code, Replaces, *Style);
if (!CleanReplacements) {
llvm::errs() << llvm::toString(CleanReplacements.takeError()) << "\n";
FileToReplacements[FilePath] = *CleanReplacements;
// Make sure we don't generate replacements for files that do not match
// FilePattern.
for (auto &Entry : FileToReplacements)
if (!FilePatternRE.match(Entry.first))
} // namespace change_namespace
} // namespace clang