diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 10644c9854270..ab69e9737c5c7 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -477,6 +477,8 @@ Bug Fixes to C++ Support conformance of explicit instantiation behaviour with MSVC. (#GH111266) - Fixed a bug in constraint expression comparison where the ``sizeof...`` expression was not handled properly in certain friend declarations. (#GH93099) +- Clang now instantiates the correct lambda call operator when a lambda's class type is + merged across modules. (#GH110401) Bug Fixes to AST Handling ^^^^^^^^^^^^^^^^^^^^^^^^^ diff --git a/clang/lib/AST/DeclCXX.cpp b/clang/lib/AST/DeclCXX.cpp index f5a0aa8f82512..1364ccc745ba0 100644 --- a/clang/lib/AST/DeclCXX.cpp +++ b/clang/lib/AST/DeclCXX.cpp @@ -1631,13 +1631,42 @@ static bool allLookupResultsAreTheSame(const DeclContext::lookup_result &R) { static NamedDecl* getLambdaCallOperatorHelper(const CXXRecordDecl &RD) { if (!RD.isLambda()) return nullptr; DeclarationName Name = - RD.getASTContext().DeclarationNames.getCXXOperatorName(OO_Call); - DeclContext::lookup_result Calls = RD.lookup(Name); + RD.getASTContext().DeclarationNames.getCXXOperatorName(OO_Call); + DeclContext::lookup_result Calls = RD.lookup(Name); assert(!Calls.empty() && "Missing lambda call operator!"); assert(allLookupResultsAreTheSame(Calls) && "More than one lambda call operator!"); - return Calls.front(); + + // FIXME: If we have multiple call operators, we might be in a situation + // where we merged this lambda with one from another module; in that + // case, return our method (instead of that of the other lambda). + // + // This avoids situations where, given two modules A and B, if we + // try to instantiate A's call operator in a function in B, anything + // in the call operator that relies on local decls in the surrounding + // function will crash because it tries to find A's decls, but we only + // instantiated B's: + // + // template + // void f() { + // using T = int; // We only instantiate B's version of this. + // auto L = [](T) { }; // But A's call operator would want A's here. + // } + // + // Walk the call operator’s redecl chain to find the one that belongs + // to this module. + // + // TODO: We need to fix this properly (see + // https://github.com/llvm/llvm-project/issues/90154). + Module *M = RD.getOwningModule(); + for (Decl *D : Calls.front()->redecls()) { + auto *MD = cast(D); + if (MD->getOwningModule() == M) + return MD; + } + + llvm_unreachable("Couldn't find our call operator!"); } FunctionTemplateDecl* CXXRecordDecl::getDependentLambdaCallOperator() const { diff --git a/clang/test/Modules/gh110401.cppm b/clang/test/Modules/gh110401.cppm new file mode 100644 index 0000000000000..6b335eb5ba9d5 --- /dev/null +++ b/clang/test/Modules/gh110401.cppm @@ -0,0 +1,44 @@ +// RUN: rm -rf %t +// RUN: mkdir %t +// RUN: split-file %s %t +// +// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux -emit-module-interface %t/a.cppm -o %t/A.pcm +// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux -emit-module-interface -fprebuilt-module-path=%t %t/b.cppm -o %t/B.pcm + +// Just check that this doesn't crash. + +//--- a.cppm +module; + +template +void __do_visit(_Visitor &&__visitor) { + using _V0 = int; + [](_V0 __v) -> _V0 { return __v; } (1); +} + +export module A; + +void g() { + struct Visitor { }; + __do_visit(Visitor()); +} + +//--- b.cppm +module; + +template +void __do_visit(_Visitor &&__visitor) { + using _V0 = int; + + // Check that we instantiate this lambda's call operator in 'f' below + // instead of the one in 'a.cppm' here; otherwise, we won't find a + // corresponding instantiation of the using declaration above. + [](_V0 __v) -> _V0 { return __v; } (1); +} + +export module B; +import A; + +void f() { + __do_visit(1); +}