llvmorg-github-actions[bot] wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-clang Author: Akshay Kumar Dubey (akshaydubey05) <details> <summary>Changes</summary> When reconstructing an LValue from an APValue, findMostDerivedSubobject was resetting ArraySize = 0 and IsArray = false when encountering a base class path entry. A base class subobject is not a most-derived object and should inherit the most-derived object's properties (IsArray, ArraySize, MostDerivedType, and MostDerivedPathLength) from the containing most-derived object, matching SubobjectDesignator::addDeclUnchecked. Fixes #<!-- -->223064 --- Full diff: https://github.com/llvm/llvm-project/pull/223663.diff 3 Files Affected: - (modified) clang/docs/ReleaseNotes.md (+2) - (modified) clang/lib/AST/ExprConstant.cpp (+3-4) - (modified) clang/test/SemaCXX/constant-expression-cxx11.cpp (+22) ``````````diff diff --git a/clang/docs/ReleaseNotes.md b/clang/docs/ReleaseNotes.md index 043a0ddae2a6c..875f59ff9853a 100644 --- a/clang/docs/ReleaseNotes.md +++ b/clang/docs/ReleaseNotes.md @@ -554,6 +554,8 @@ features cannot lower the translation-unit ABI level; #### Bug Fixes to C++ Support +- Fixed a bug where constant evaluation lost track of most-derived array information + when reconstructing an lvalue referring to a base subobject of an array element. (#GH223064) - Fixed false-positive module ODR diagnostics when a type is found through a using-declaration in one definition and directly in another. ODR hashing also now distinguishes differently qualified uses of types found through diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp index 1286c77ad1c69..014d1a6b1b0e6 100644 --- a/clang/lib/AST/ExprConstant.cpp +++ b/clang/lib/AST/ExprConstant.cpp @@ -235,11 +235,10 @@ namespace { ArraySize = 0; MostDerivedLength = I + 1; IsArray = false; - } else { - // Path[I] describes a base class. - ArraySize = 0; - IsArray = false; } + // Otherwise, Path[I] describes a base class. It inherits the most-derived + // properties (IsArray, ArraySize, Type, MostDerivedLength) from the + // containing most-derived object. } return MostDerivedLength; } diff --git a/clang/test/SemaCXX/constant-expression-cxx11.cpp b/clang/test/SemaCXX/constant-expression-cxx11.cpp index 7b483a4238652..dc5d2def4aebd 100644 --- a/clang/test/SemaCXX/constant-expression-cxx11.cpp +++ b/clang/test/SemaCXX/constant-expression-cxx11.cpp @@ -2747,3 +2747,25 @@ namespace GH154567 { constexpr S s{}; static_assert(s.val.i == 0, ""); } + +namespace GH223064 { + struct A { int n; }; + struct B : A {} b[2]; + + constexpr int *f() { + A *p = b; + return &static_cast<B*>(p)[1].n; + } + static_assert(f() == &b[1].n, ""); + + struct Base1 { int x; }; + struct Base2 : Base1 { int y; }; + struct Derived : Base2 { int z; } arr[3]; + + constexpr int *g() { + Base1 *p = arr; + return &static_cast<Derived*>(p)[2].z; + } + static_assert(g() == &arr[2].z, ""); +} + `````````` </details> https://github.com/llvm/llvm-project/pull/223663 _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
