llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-clang Author: cor3ntin (cor3ntin) <details> <summary>Changes</summary> We document libstdc++4.8 as the minimum supported version, and we carried a hack for `include/tr1/hashtable.h` fixed in 4.7. Cleanup some libstdc++ compatibility comments. --- Full diff: https://github.com/llvm/llvm-project/pull/139693.diff 4 Files Affected: - (modified) clang/lib/Parse/ParseDecl.cpp (+4-3) - (modified) clang/lib/Sema/SemaInit.cpp (+9-29) - (removed) clang/test/SemaCXX/libstdcxx_gets_hack.cpp (-28) - (removed) clang/test/SemaCXX/libstdcxx_pointer_return_false_hack.cpp (-34) ``````````diff diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp index 4fe3565687905..02b3a14134873 100644 --- a/clang/lib/Parse/ParseDecl.cpp +++ b/clang/lib/Parse/ParseDecl.cpp @@ -4024,13 +4024,14 @@ void Parser::ParseDeclarationSpecifiers( } case tok::kw___is_signed: - // GNU libstdc++ 4.4 uses __is_signed as an identifier, but Clang - // typically treats it as a trait. If we see __is_signed as it appears - // in libstdc++, e.g., + // HACK: before 2022-12, libstdc++ uses __is_signed as an identifier, + // but Clang typically treats it as a trait. + // If we see __is_signed as it appears in libstdc++, e.g., // // static const bool __is_signed; // // then treat __is_signed as an identifier rather than as a keyword. + // This was fixed by libstdc++ in December 2022. if (DS.getTypeSpecType() == TST_bool && DS.getTypeQualifiers() == DeclSpec::TQ_const && DS.getStorageClassSpec() == DeclSpec::SCS_static) diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp index e5670dab03cb0..dc12bacc0158b 100644 --- a/clang/lib/Sema/SemaInit.cpp +++ b/clang/lib/Sema/SemaInit.cpp @@ -637,11 +637,11 @@ ExprResult InitListChecker::PerformEmptyInit(SourceLocation Loc, } InitializationSequence InitSeq(SemaRef, Entity, Kind, SubInit); - // libstdc++4.6 marks the vector default constructor as explicit in - // _GLIBCXX_DEBUG mode, so recover using the C++03 logic in that case. - // stlport does so too. Look for std::__debug for libstdc++, and for - // std:: for stlport. This is effectively a compiler-side implementation of - // LWG2193. + // HACK: libstdc++ prior to 4.9 marks the vector default constructor + // as explicit in _GLIBCXX_DEBUG mode, so recover using the C++03 logic + // in that case. stlport does so too. + // Look for std::__debug for libstdc++, and for std:: for stlport. + // This is effectively a compiler-side implementation of LWG2193. if (!InitSeq && EmptyInitList && InitSeq.getFailureKind() == InitializationSequence::FK_ExplicitConstructor) { OverloadCandidateSet::iterator Best; @@ -6240,24 +6240,6 @@ static void TryUserDefinedConversion(Sema &S, } } -/// An egregious hack for compatibility with libstdc++-4.2: in <tr1/hashtable>, -/// a function with a pointer return type contains a 'return false;' statement. -/// In C++11, 'false' is not a null pointer, so this breaks the build of any -/// code using that header. -/// -/// Work around this by treating 'return false;' as zero-initializing the result -/// if it's used in a pointer-returning function in a system header. -static bool isLibstdcxxPointerReturnFalseHack(Sema &S, - const InitializedEntity &Entity, - const Expr *Init) { - return S.getLangOpts().CPlusPlus11 && - Entity.getKind() == InitializedEntity::EK_Result && - Entity.getType()->isPointerType() && - isa<CXXBoolLiteralExpr>(Init) && - !cast<CXXBoolLiteralExpr>(Init)->getValue() && - S.getSourceManager().isInSystemHeader(Init->getExprLoc()); -} - /// The non-zero enum values here are indexes into diagnostic alternatives. enum InvalidICRKind { IIK_okay, IIK_nonlocal, IIK_nonscalar }; @@ -6943,12 +6925,10 @@ void InitializationSequence::InitializeFrom(Sema &S, AddPassByIndirectCopyRestoreStep(DestType, ShouldCopy); } else if (ICS.isBad()) { - if (isLibstdcxxPointerReturnFalseHack(S, Entity, Initializer)) - AddZeroInitializationStep(Entity.getType()); - else if (DeclAccessPair Found; - Initializer->getType() == Context.OverloadTy && - !S.ResolveAddressOfOverloadedFunction(Initializer, DestType, - /*Complain=*/false, Found)) + if (DeclAccessPair Found; + Initializer->getType() == Context.OverloadTy && + !S.ResolveAddressOfOverloadedFunction(Initializer, DestType, + /*Complain=*/false, Found)) SetFailed(InitializationSequence::FK_AddressOfOverloadFailed); else if (Initializer->getType()->isFunctionType() && isExprAnUnaddressableFunction(S, Initializer)) diff --git a/clang/test/SemaCXX/libstdcxx_gets_hack.cpp b/clang/test/SemaCXX/libstdcxx_gets_hack.cpp deleted file mode 100644 index 0d915d01474c3..0000000000000 --- a/clang/test/SemaCXX/libstdcxx_gets_hack.cpp +++ /dev/null @@ -1,28 +0,0 @@ -// RUN: %clang_cc1 -fsyntax-only %s -std=c++14 -verify - -// This is a test for an egregious hack in Clang that works around -// an issue with libstdc++'s detection of whether glibc provides a -// ::gets function. If there is no ::gets, ignore -// using ::gets; -// in namespace std. -// -// See PR18402 and gcc.gnu.org/PR77795 for more details. - -#ifdef BE_THE_HEADER - -#pragma GCC system_header -namespace std { - using ::gets; - using ::getx; // expected-error {{no member named 'getx'}} -} - -#else - -#define BE_THE_HEADER -#include "libstdcxx_pointer_return_false_hack.cpp" - -namespace foo { - using ::gets; // expected-error {{no member named 'gets'}} -} - -#endif diff --git a/clang/test/SemaCXX/libstdcxx_pointer_return_false_hack.cpp b/clang/test/SemaCXX/libstdcxx_pointer_return_false_hack.cpp deleted file mode 100644 index 17e1548ac50d6..0000000000000 --- a/clang/test/SemaCXX/libstdcxx_pointer_return_false_hack.cpp +++ /dev/null @@ -1,34 +0,0 @@ -// RUN: %clang_cc1 -fsyntax-only %s -std=c++11 -verify - -// This is a test for an egregious hack in Clang that works around -// an issue with libstdc++-4.2's <tr1/hashtable> implementation. -// The code in question returns 'false' from a function with a pointer -// return type, which is ill-formed in C++11. - -#ifdef BE_THE_HEADER - -#pragma GCC system_header -namespace std { - namespace tr1 { - template<typename T> struct hashnode; - template<typename T> struct hashtable { - typedef hashnode<T> node; - node *find_node() { - // This is ill-formed in C++11, per core issue 903, but we accept - // it anyway in a system header. - return false; - } - }; - } -} - -#else - -#define BE_THE_HEADER -#include "libstdcxx_pointer_return_false_hack.cpp" - -auto *test1 = std::tr1::hashtable<int>().find_node(); - -void *test2() { return false; } // expected-error {{cannot initialize}} - -#endif `````````` </details> https://github.com/llvm/llvm-project/pull/139693 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
