https://github.com/Rajveer100 updated https://github.com/llvm/llvm-project/pull/96301
>From b964923b9610c9cd53e4d1de8f5d51d8fcebc78c Mon Sep 17 00:00:00 2001 From: Rajveer <rajveer.develo...@icloud.com> Date: Fri, 21 Jun 2024 18:26:36 +0530 Subject: [PATCH] [clang] Allow class with anonymous union member to be const-default-constructible even if a union member has a default member initializer (#95854) Resolves #95854 Clang incorrectly considers a class with an anonymous union member to not be const-default-constructible even if a union member has a default member initializer. This is valid as per ``8.3`` in `Draft C++ Standard <https://eel.is/c++draft/dcl.init#general-8.3>`_. The ``allowConstDefaultInit`` member function in ``CXXRecordDecl`` needs special-case unions to handle the rule. (#GH95854). ``` struct A { union { int n = 0; int m; }; }; const A a; ``` -- As per https://eel.is/c++draft/dcl.init#general-8.3 --- clang/docs/ReleaseNotes.rst | 6 ++++++ clang/include/clang/AST/DeclCXX.h | 4 +++- clang/test/SemaCXX/GH95854.cpp | 21 +++++++++++++++++++++ 3 files changed, 30 insertions(+), 1 deletion(-) create mode 100644 clang/test/SemaCXX/GH95854.cpp diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 45676a02b760b..c107304ea95f7 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -624,6 +624,12 @@ Bug Fixes in This Version - ``__is_array`` and ``__is_bounded_array`` no longer return ``true`` for zero-sized arrays. Fixes (#GH54705). + +- Clang incorrectly considers a class with an anonymous union member to not be + const-default-constructible even if a union member has a default member initializer. + This is valid as per ``8.3`` in `Draft C++ Standard <https://eel.is/c++draft/dcl.init#general-8.3>`_. + The ``allowConstDefaultInit`` member function in ``CXXRecordDecl`` needs + special-case unions to handle the rule. (#GH95854). Bug Fixes to Compiler Builtins ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ diff --git a/clang/include/clang/AST/DeclCXX.h b/clang/include/clang/AST/DeclCXX.h index fb52ac804849d..e4dc50c9b9e00 100644 --- a/clang/include/clang/AST/DeclCXX.h +++ b/clang/include/clang/AST/DeclCXX.h @@ -1392,7 +1392,9 @@ class CXXRecordDecl : public RecordDecl { bool allowConstDefaultInit() const { return !data().HasUninitializedFields || !(data().HasDefaultedDefaultConstructor || - needsImplicitDefaultConstructor()); + needsImplicitDefaultConstructor()) || + (!hasUninitializedReferenceMember() && isUnion() && + hasInClassInitializer()); } /// Determine whether this class has a destructor which has no diff --git a/clang/test/SemaCXX/GH95854.cpp b/clang/test/SemaCXX/GH95854.cpp new file mode 100644 index 0000000000000..820cf15e68287 --- /dev/null +++ b/clang/test/SemaCXX/GH95854.cpp @@ -0,0 +1,21 @@ +// RUN: %clang_cc1 -std=c++23 -fsyntax-only -verify %s +// +// expected-no-diagnostics + +struct A { + union { + int n = 0; + int m; + }; +}; +const A a; + +struct B { + union { + struct { + int n = 5; + int m; + }; + }; +}; +const B b; _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
