Author: Younan Zhang Date: 2025-04-15T09:16:55+08:00 New Revision: 83344da69145a648aad3e0cd88eab4aaf60b2142
URL: https://github.com/llvm/llvm-project/commit/83344da69145a648aad3e0cd88eab4aaf60b2142 DIFF: https://github.com/llvm/llvm-project/commit/83344da69145a648aad3e0cd88eab4aaf60b2142.diff LOG: [Clang] Fix dependent local class instantiation bugs (#134038) This patch fixes two long-standing bugs that prevent Clang from instantiating local class members inside a dependent context. These bugs were introduced in commits 21eb1af469c3 and 919df9d75a. 21eb1af469c3 introduced a concept called eligible methods such that it did an attempt to skip past ineligible method instantiation when instantiating class members. Unfortunately, this broke the instantiation chain for local classes - getTemplateInstantiationPattern() would fail to find the correct definition pattern if the class was defined within a partially transformed dependent context. 919df9d75a introduced a separate issue by incorrectly copying the DeclarationNameInfo during function definition instantiation from the template pattern, even though that DNI might contain a transformed TypeSourceInfo. Since that TSI was already updated when the declaration was instantiated, this led to inconsistencies. As a result, the final instantiated function could lose track of the transformed declarations, hence we crash: https://compiler-explorer.com/z/vjvoG76Tf. This PR corrects them by 1. Removing the bypass logic for method instantiation. The eligible flag is independent of instantiation and can be updated properly afterward, so skipping instantiation is unnecessary. 2. Carefully handling TypeSourceInfo by creating a new instance that preserves the pattern's source location while using the already transformed type. Fixes https://github.com/llvm/llvm-project/issues/59734 Fixes https://github.com/llvm/llvm-project/issues/132208 Added: clang/test/CodeGenCXX/local-class-instantiation.cpp Modified: clang/docs/ReleaseNotes.rst clang/lib/Sema/SemaTemplateInstantiate.cpp clang/lib/Sema/SemaTemplateInstantiateDecl.cpp Removed: ################################################################################ diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 7ca04d9ebd44c..d551de0d4aabd 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -434,6 +434,7 @@ Bug Fixes to C++ Support by template argument deduction. - Clang is now better at instantiating the function definition after its use inside of a constexpr lambda. (#GH125747) +- Fixed a local class member function instantiation bug inside dependent lambdas. (#GH59734), (#GH132208) - Clang no longer crashes when trying to unify the types of arrays with certain diff erences in qualifiers (this could happen during template argument deduction or when building a ternary operator). (#GH97005) diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp index d2408a94ad0ab..0e81804f8c1e7 100644 --- a/clang/lib/Sema/SemaTemplateInstantiate.cpp +++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp @@ -4126,9 +4126,6 @@ Sema::InstantiateClassMembers(SourceLocation PointOfInstantiation, if (FunctionDecl *Pattern = Function->getInstantiatedFromMemberFunction()) { - if (Function->isIneligibleOrNotSelected()) - continue; - if (Function->getTrailingRequiresClause()) { ConstraintSatisfaction Satisfaction; if (CheckFunctionConstraints(Function, Satisfaction) || diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp index 5c80077f294c6..bf5a882ba4f12 100644 --- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp +++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp @@ -5597,7 +5597,61 @@ void Sema::InstantiateFunctionDefinition(SourceLocation PointOfInstantiation, Function->setLocation(PatternDecl->getLocation()); Function->setInnerLocStart(PatternDecl->getInnerLocStart()); Function->setRangeEnd(PatternDecl->getEndLoc()); - Function->setDeclarationNameLoc(PatternDecl->getNameInfo().getInfo()); + // Let the instantiation use the Pattern's DeclarationNameLoc, due to the + // following awkwardness: + // + // 1. There are out-of-tree users of getNameInfo().getSourceRange(), who + // expect the source range of the instantiated declaration to be set to + // point to the definition. + // + // 2. That getNameInfo().getSourceRange() might return the TypeLocInfo's + // location it tracked. + // + // 3. Function might come from an (implicit) declaration, while the pattern + // comes from a definition. In these cases, we need the PatternDecl's source + // location. + // + // To that end, we need to more or less tweak the DeclarationNameLoc. However, + // we can't blindly copy the DeclarationNameLoc from the PatternDecl to the + // function, since it contains associated TypeLocs that should have already + // been transformed. So, we rebuild the TypeLoc for that purpose. Technically, + // we should create a new function declaration and assign everything we need, + // but InstantiateFunctionDefinition updates the declaration in place. + auto NameLocPointsToPattern = [&] { + DeclarationNameInfo PatternName = PatternDecl->getNameInfo(); + DeclarationNameLoc PatternNameLoc = PatternName.getInfo(); + switch (PatternName.getName().getNameKind()) { + case DeclarationName::CXXConstructorName: + case DeclarationName::CXXDestructorName: + case DeclarationName::CXXConversionFunctionName: + break; + default: + // Cases where DeclarationNameLoc doesn't matter, as it merely contains a + // source range. + return PatternNameLoc; + } + + TypeSourceInfo *TSI = Function->getNameInfo().getNamedTypeInfo(); + // TSI might be null if the function is named by a constructor template id. + // E.g. S<T>() {} for class template S with a template parameter T. + if (!TSI) { + // We don't care about the DeclarationName of the instantiated function, + // but only the DeclarationNameLoc. So if the TypeLoc is absent, we do + // nothing. + return PatternNameLoc; + } + + QualType InstT = TSI->getType(); + // We want to use a TypeLoc that reflects the transformed type while + // preserving the source location from the pattern. + TypeLocBuilder TLB; + TLB.pushTrivial( + Context, InstT, + PatternNameLoc.getNamedTypeInfo()->getTypeLoc().getBeginLoc()); + return DeclarationNameLoc::makeNamedTypeLoc( + TLB.getTypeSourceInfo(Context, InstT)); + }; + Function->setDeclarationNameLoc(NameLocPointsToPattern()); EnterExpressionEvaluationContext EvalContext( *this, Sema::ExpressionEvaluationContext::PotentiallyEvaluated); diff --git a/clang/test/CodeGenCXX/local-class-instantiation.cpp b/clang/test/CodeGenCXX/local-class-instantiation.cpp new file mode 100644 index 0000000000000..34103a1ee55ef --- /dev/null +++ b/clang/test/CodeGenCXX/local-class-instantiation.cpp @@ -0,0 +1,64 @@ +// RUN: %clang_cc1 -std=c++17 %s -emit-llvm -triple %itanium_abi_triple -o - | FileCheck %s + +namespace LambdaContainingLocalClasses { + +template <typename F> +void GH59734() { + [&](auto param) { + struct Guard { + Guard() { + // Check that we're able to create DeclRefExpr to param at this point. + static_assert(__is_same(decltype(param), int), ""); + } + ~Guard() { + static_assert(__is_same(decltype(param), int), ""); + } + operator decltype(param)() { + return decltype(param)(); + } + }; + Guard guard; + param = guard; + }(42); +} + +// Guard::Guard(): +// CHECK-DAG: define {{.*}} @_ZZZN28LambdaContainingLocalClasses7GH59734IiEEvvENKUlT_E_clIiEEDaS1_EN5GuardC2Ev +// Guard::operator int(): +// CHECK-DAG: define {{.*}} @_ZZZN28LambdaContainingLocalClasses7GH59734IiEEvvENKUlT_E_clIiEEDaS1_EN5GuardcviEv +// Guard::~Guard(): +// CHECK-DAG: define {{.*}} @_ZZZN28LambdaContainingLocalClasses7GH59734IiEEvvENKUlT_E_clIiEEDaS1_EN5GuardD2Ev + +struct S {}; + +template <class T = void> +auto GH132208 = [](auto param) { + struct OnScopeExit { + OnScopeExit() { + static_assert(__is_same(decltype(param), S), ""); + } + ~OnScopeExit() { + static_assert(__is_same(decltype(param), S), ""); + } + operator decltype(param)() { + return decltype(param)(); + } + } pending; + + param = pending; +}; + +void bar() { + GH59734<int>(); + + GH132208<void>(S{}); +} + +// OnScopeExit::OnScopeExit(): +// CHECK-DAG: define {{.*}} @_ZZNK28LambdaContainingLocalClasses8GH132208IvEMUlT_E_clINS_1SEEEDaS2_EN11OnScopeExitC2Ev +// OnScopeExit::operator S(): +// CHECK-DAG: define {{.*}} @_ZZNK28LambdaContainingLocalClasses8GH132208IvEMUlT_E_clINS_1SEEEDaS2_EN11OnScopeExitcvS5_Ev +// OnScopeExit::~OnScopeExit(): +// CHECK-DAG: define {{.*}} @_ZZNK28LambdaContainingLocalClasses8GH132208IvEMUlT_E_clINS_1SEEEDaS2_EN11OnScopeExitD2Ev + +} // namespace LambdaContainingLocalClasses _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
