https://github.com/Rajveer100 updated https://github.com/llvm/llvm-project/pull/96301
>From 1a25f021b797e5591f1ae324c8a8b5244047d5f4 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 | 88 +++++++++++++++++++++++++++++++ clang/include/clang/AST/DeclCXX.h | 3 +- clang/lib/AST/DeclCXX.cpp | 9 +++- clang/test/SemaCXX/GH95854.cpp | 21 ++++++++ 4 files changed, 119 insertions(+), 2 deletions(-) create mode 100644 clang/test/SemaCXX/GH95854.cpp diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 351b41b1c0c588..2927888b31f47c 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -192,6 +192,94 @@ Bug Fixes in This Version - Fixed a crash when diagnosing format strings and encountering an empty delimited escape sequence (e.g., ``"\o{}"``). #GH102218 +- Fixed missing warnings when comparing mismatched enumeration constants + in C (#GH29217) + +- Clang now accepts elaborated-type-specifiers that explicitly specialize + a member class template for an implicit instantiation of a class template. + +- Fixed missing warnings when doing bool-like conversions in C23 (#GH79435). +- Clang's ``-Wshadow`` no longer warns when an init-capture is named the same as + a class field unless the lambda can capture this. + Fixes (#GH71976) + +- Clang now accepts qualified partial/explicit specializations of variable templates that + are not nominable in the lookup context of the specialization. + +- Clang now doesn't produce false-positive warning `-Wconstant-logical-operand` + for logical operators in C23. + Fixes (#GH64356). + +- ``__is_trivially_relocatable`` no longer returns ``false`` for volatile-qualified types. + Fixes (#GH77091). + +- Clang no longer produces a false-positive `-Wunused-variable` warning + for variables created through copy initialization having side-effects in C++17 and later. + Fixes (#GH64356) (#GH79518). + +- Fix value of predefined macro ``__FUNCTION__`` in MSVC compatibility mode. + Fixes (#GH66114). + +- Clang now emits errors for explicit specializations/instatiations of lambda call + operator. + Fixes (#GH83267). + +- Fix crash on ill-formed partial specialization with CRTP. + Fixes (#GH89374). + +- Clang now correctly generates overloads for bit-precise integer types for + builtin operators in C++. Fixes #GH82998. + +- Fix crash when destructor definition is preceded with an equals sign. + Fixes (#GH89544). + +- When performing mixed arithmetic between ``_Complex`` floating-point types and integers, + Clang now correctly promotes the integer to its corresponding real floating-point + type only rather than to the complex type (e.g. ``_Complex float / int`` is now evaluated + as ``_Complex float / float`` rather than ``_Complex float / _Complex float``), as mandated + by the C standard. This significantly improves codegen of `*` and `/` especially. + Fixes #GH31205. + +- Fixes an assertion failure on invalid code when trying to define member + functions in lambdas. + +- Fixed a regression in CTAD that a friend declaration that befriends itself may cause + incorrect constraint substitution. (#GH86769). + +- Fixed an assertion failure on invalid InitListExpr in C89 mode (#GH88008). + +- Fixed missing destructor calls when we branch from middle of an expression. + This could happen through a branch in stmt-expr or in an expression containing a coroutine + suspension. Fixes (#GH63818) (#GH88478). + +- Clang will no longer diagnose an erroneous non-dependent ``switch`` condition + during instantiation, and instead will only diagnose it once, during checking + of the function template. + +- Clang now allows the value of unroll count to be zero in ``#pragma GCC unroll`` and ``#pragma unroll``. + The values of 0 and 1 block any unrolling of the loop. This keeps the same behavior with GCC. + Fixes (`#88624 <https://github.com/llvm/llvm-project/issues/88624>`_). + +- Clang will no longer emit a duplicate -Wunused-value warning for an expression + `(A, B)` which evaluates to glvalue `B` that can be converted to non ODR-use. (#GH45783) + +- Clang now correctly disallows VLA type compound literals, e.g. ``(int[size]){}``, + as the C standard mandates. (#GH89835) + +- ``__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). + +- Correctly reject declarations where a statement is required in C. + Fixes #GH92775 + +- Fixed `static_cast` to array of unknown bound. Fixes (#GH62863). + Bug Fixes to Compiler Builtins ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ diff --git a/clang/include/clang/AST/DeclCXX.h b/clang/include/clang/AST/DeclCXX.h index bf6a5ce92d438d..9988a4c84ad008 100644 --- a/clang/include/clang/AST/DeclCXX.h +++ b/clang/include/clang/AST/DeclCXX.h @@ -1395,7 +1395,8 @@ class CXXRecordDecl : public RecordDecl { bool allowConstDefaultInit() const { return !data().HasUninitializedFields || !(data().HasDefaultedDefaultConstructor || - needsImplicitDefaultConstructor()); + needsImplicitDefaultConstructor()) || + (isUnion() && isEmpty()); } /// Determine whether this class has a destructor which has no diff --git a/clang/lib/AST/DeclCXX.cpp b/clang/lib/AST/DeclCXX.cpp index 9a3ede426e9143..e8597adcf6fd4a 100644 --- a/clang/lib/AST/DeclCXX.cpp +++ b/clang/lib/AST/DeclCXX.cpp @@ -1057,6 +1057,9 @@ void CXXRecordDecl::addedMember(Decl *D) { if (isUnion() && !Field->isAnonymousStructOrUnion()) data().HasVariantMembers = true; + if (isUnion() && IsFirstField) + data().HasUninitializedFields = true; + // C++0x [class]p9: // A POD struct is a class that is both a trivial class and a // standard-layout class, and has no non-static data members of type @@ -1125,7 +1128,11 @@ void CXXRecordDecl::addedMember(Decl *D) { data().DefaultedCopyConstructorIsDeleted = true; } - if (!Field->hasInClassInitializer() && !Field->isMutable()) { + if (isUnion() && !Field->isMutable()) { + if (Field->hasInClassInitializer()) { + data().HasUninitializedFields = false; + } + } else if (!Field->hasInClassInitializer() && !Field->isMutable()) { if (CXXRecordDecl *FieldType = T->getAsCXXRecordDecl()) { if (FieldType->hasDefinition() && !FieldType->allowConstDefaultInit()) data().HasUninitializedFields = true; diff --git a/clang/test/SemaCXX/GH95854.cpp b/clang/test/SemaCXX/GH95854.cpp new file mode 100644 index 00000000000000..62ae549f2496f0 --- /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; // expected-error {{default initialization of an object of const type 'const B' without a user-provided default constructor}} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
