Author: Antonio Frighetto Date: 2023-09-14T08:48:59+02:00 New Revision: 660876a4019b81b5a7427a3dcec5ce8c39cd1ee0
URL: https://github.com/llvm/llvm-project/commit/660876a4019b81b5a7427a3dcec5ce8c39cd1ee0 DIFF: https://github.com/llvm/llvm-project/commit/660876a4019b81b5a7427a3dcec5ce8c39cd1ee0.diff LOG: [clang] Bail out when handling union access with virtual inheritance An assertion issue that arose when handling union member access with virtual base class has been addressed. As pointed out by @zygoloid, there is no need for further derived-to-base analysis in this instance, so we can bail out upon encountering a virtual base class. Minor refinement on the function name as we might not be handling a union. Reported-By: ormris Fixes: https://github.com/llvm/llvm-project/issues/65982 Added: clang/test/SemaCXX/cxx2a-virtual-base-used.cpp Modified: clang/lib/AST/ExprConstant.cpp Removed: ################################################################################ diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp index dfa48e9c030b6a3..fea06b97259fe31 100644 --- a/clang/lib/AST/ExprConstant.cpp +++ b/clang/lib/AST/ExprConstant.cpp @@ -6062,8 +6062,9 @@ const AccessKinds StartLifetimeOfUnionMemberHandler::AccessKind; /// operator whose left-hand side might involve a union member access. If it /// does, implicitly start the lifetime of any accessed union elements per /// C++20 [class.union]5. -static bool HandleUnionActiveMemberChange(EvalInfo &Info, const Expr *LHSExpr, - const LValue &LHS) { +static bool MaybeHandleUnionActiveMemberChange(EvalInfo &Info, + const Expr *LHSExpr, + const LValue &LHS) { if (LHS.InvalidBase || LHS.Designator.Invalid) return false; @@ -6118,8 +6119,14 @@ static bool HandleUnionActiveMemberChange(EvalInfo &Info, const Expr *LHSExpr, break; // Walk path backwards as we walk up from the base to the derived class. for (const CXXBaseSpecifier *Elt : llvm::reverse(ICE->path())) { + if (Elt->isVirtual()) { + // A class with virtual base classes never has a trivial default + // constructor, so S(E) is empty in this case. + E = nullptr; + break; + } + --PathLength; - (void)Elt; assert(declaresSameEntity(Elt->getType()->getAsCXXRecordDecl(), LHS.Designator.Entries[PathLength] .getAsBaseOrMember().getPointer())); @@ -7806,7 +7813,7 @@ class ExprEvaluatorBase // per C++20 [class.union]5. if (Info.getLangOpts().CPlusPlus20 && OCE && OCE->getOperator() == OO_Equal && MD->isTrivial() && - !HandleUnionActiveMemberChange(Info, Args[0], ThisVal)) + !MaybeHandleUnionActiveMemberChange(Info, Args[0], ThisVal)) return false; Args = Args.slice(1); @@ -8679,7 +8686,7 @@ bool LValueExprEvaluator::VisitBinAssign(const BinaryOperator *E) { return false; if (Info.getLangOpts().CPlusPlus20 && - !HandleUnionActiveMemberChange(Info, E->getLHS(), Result)) + !MaybeHandleUnionActiveMemberChange(Info, E->getLHS(), Result)) return false; return handleAssignment(this->Info, E, Result, E->getLHS()->getType(), diff --git a/clang/test/SemaCXX/cxx2a-virtual-base-used.cpp b/clang/test/SemaCXX/cxx2a-virtual-base-used.cpp new file mode 100644 index 000000000000000..196a3ab05564b96 --- /dev/null +++ b/clang/test/SemaCXX/cxx2a-virtual-base-used.cpp @@ -0,0 +1,11 @@ +// RUN: %clang_cc1 -std=c++20 -verify=cxx20 -triple=x86_64-linux-gnu %s +// Fixes assertion triggered by https://github.com/llvm/llvm-project/issues/65982 + +struct A { int y; }; +struct B : virtual public A {}; +struct X : public B {}; + +void member_with_virtual_inheritance() { + X x; + x.B::y = 1; +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
