https://github.com/frederick-vs-ja created https://github.com/llvm/llvm-project/pull/140246
Since P2280R4 Unknown references and pointers was implemented, HandleLValueBase now has to deal with referneces: D.MostDerivedType->getAsCXXRecordDecl() will return a nullptr if D.MostDerivedType is a ReferenceType. The fix is to use getNonReferenceType() to obtain the Pointee Type if we have a reference. (cherry picked from commit 136f2ba2a7bca015ef831c91fb0db5e5e31b7632) >From 6ae8c79ed2c7d1deeb686f1d6e1c48b633e86c61 Mon Sep 17 00:00:00 2001 From: Shafik Yaghmour <shafik.yaghm...@intel.com> Date: Thu, 15 May 2025 16:04:37 -0700 Subject: [PATCH] [Clang][AST] Fix HandleLValueBase to deal with references (#140105) Since P2280R4 Unknown references and pointers was implemented, HandleLValueBase now has to deal with referneces: D.MostDerivedType->getAsCXXRecordDecl() will return a nullptr if D.MostDerivedType is a ReferenceType. The fix is to use getNonReferenceType() to obtain the Pointee Type if we have a reference. Fixes: https://github.com/llvm/llvm-project/issues/139452 (cherry picked from commit 136f2ba2a7bca015ef831c91fb0db5e5e31b7632) # Conflicts: # clang/docs/ReleaseNotes.rst --- clang/docs/ReleaseNotes.rst | 2 ++ clang/lib/AST/ExprConstant.cpp | 6 +++++- .../SemaCXX/constant-expression-p2280r4.cpp | 21 +++++++++++++++++++ 3 files changed, 28 insertions(+), 1 deletion(-) diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 47ef2f80ac3f2..2f43dc4021fd8 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -909,6 +909,8 @@ Bug Fixes in This Version being deleted has a potentially throwing destructor (#GH118660). - Clang now outputs correct values when #embed data contains bytes with negative signed char values (#GH102798). +- Fix crash due to unknown references and pointer implementation and handling of + base classes. (GH139452) Bug Fixes to Compiler Builtins ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp index 23602362eaa79..e0746f4532245 100644 --- a/clang/lib/AST/ExprConstant.cpp +++ b/clang/lib/AST/ExprConstant.cpp @@ -3311,7 +3311,11 @@ static bool HandleLValueBase(EvalInfo &Info, const Expr *E, LValue &Obj, return false; // Extract most-derived object and corresponding type. - DerivedDecl = D.MostDerivedType->getAsCXXRecordDecl(); + // FIXME: After implementing P2280R4 it became possible to get references + // here. We do MostDerivedType->getAsCXXRecordDecl() in several other + // locations and if we see crashes in those locations in the future + // it may make more sense to move this fix into Lvalue::set. + DerivedDecl = D.MostDerivedType.getNonReferenceType()->getAsCXXRecordDecl(); if (!CastToDerivedClass(Info, E, Obj, DerivedDecl, D.MostDerivedPathLength)) return false; diff --git a/clang/test/SemaCXX/constant-expression-p2280r4.cpp b/clang/test/SemaCXX/constant-expression-p2280r4.cpp index 6c9a87267109c..87beeb4d3dc84 100644 --- a/clang/test/SemaCXX/constant-expression-p2280r4.cpp +++ b/clang/test/SemaCXX/constant-expression-p2280r4.cpp @@ -179,3 +179,24 @@ namespace extern_reference_used_as_unknown { int y; constinit int& g = (x,y); // expected-warning {{left operand of comma operator has no effect}} } + +namespace GH139452 { +struct Dummy { + explicit operator bool() const noexcept { return true; } +}; + +struct Base { int error; }; +struct Derived : virtual Base { }; + +template <class R> +constexpr R get_value() { + const auto& derived_val = Derived{}; + if (derived_val.error != 0) + /* nothing */; + return R{}; +} + +int f() { + return !get_value<Dummy>(); // contextually convert the function call result to bool +} +} _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
