Author: Fabian Wolff Date: 2022-04-20T16:55:29+02:00 New Revision: f25935a000917f2c06b52bbc7273e20a82543782
URL: https://github.com/llvm/llvm-project/commit/f25935a000917f2c06b52bbc7273e20a82543782 DIFF: https://github.com/llvm/llvm-project/commit/f25935a000917f2c06b52bbc7273e20a82543782.diff LOG: [clang-tidy] Fix `altera-struct-pack-align` check for empty structs Fixes https://github.com/llvm/llvm-project/issues/50962. Reviewed By: whisperity, aaron.ballman Differential Revision: https://reviews.llvm.org/D114292 Added: Modified: clang-tools-extra/clang-tidy/altera/StructPackAlignCheck.cpp clang-tools-extra/docs/ReleaseNotes.rst clang-tools-extra/test/clang-tidy/checkers/altera-struct-pack-align.cpp Removed: ################################################################################ diff --git a/clang-tools-extra/clang-tidy/altera/StructPackAlignCheck.cpp b/clang-tools-extra/clang-tidy/altera/StructPackAlignCheck.cpp index 6ae53512fca5e..b5f8d082d8877 100644 --- a/clang-tools-extra/clang-tidy/altera/StructPackAlignCheck.cpp +++ b/clang-tools-extra/clang-tidy/altera/StructPackAlignCheck.cpp @@ -77,7 +77,8 @@ void StructPackAlignCheck::check(const MatchFinder::MatchResult &Result) { uint64_t CharSize = Result.Context->getCharWidth(); CharUnits CurrSize = Result.Context->getASTRecordLayout(Struct).getSize(); CharUnits MinByteSize = - CharUnits::fromQuantity(ceil((float)TotalBitSize / CharSize)); + CharUnits::fromQuantity(std::max<clang::CharUnits::QuantityType>( + ceil(static_cast<float>(TotalBitSize) / CharSize), 1)); CharUnits MaxAlign = CharUnits::fromQuantity( ceil((float)Struct->getMaxAlignment() / CharSize)); CharUnits CurrAlign = diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst index 50d5b8ecc72c1..491bc92f4ef38 100644 --- a/clang-tools-extra/docs/ReleaseNotes.rst +++ b/clang-tools-extra/docs/ReleaseNotes.rst @@ -170,6 +170,9 @@ Changes in existing checks <clang-tidy/checks/performance-inefficient-vector-operation>` to work when the vector is a member of a structure. +- Fixed nonsensical suggestion of :doc:`altera-struct-pack-align + <clang-tidy/checks/altera-struct-pack-align>` check for empty structs. + Removed checks ^^^^^^^^^^^^^^ diff --git a/clang-tools-extra/test/clang-tidy/checkers/altera-struct-pack-align.cpp b/clang-tools-extra/test/clang-tidy/checkers/altera-struct-pack-align.cpp index 615b6cafe87a2..472372ffe35c1 100644 --- a/clang-tools-extra/test/clang-tidy/checkers/altera-struct-pack-align.cpp +++ b/clang-tools-extra/test/clang-tidy/checkers/altera-struct-pack-align.cpp @@ -99,3 +99,22 @@ void no_trigger_on_instantiation() { struct bad_align3 instantiated { 'a', 0.001, 'b' }; } +// Make sure that we don't recommend aligning an empty struct to zero bytes (PR#51620) +struct StructWithNoFields {}; + +struct ContainsStructWithNoFields { + StructWithNoFields s; +}; + +// Make sure that an empty struct is treated like "char" for padding and alignment purposes +struct ContainsStructWithNoFields2 { + StructWithNoFields s; + double d; + StructWithNoFields t; +}; +// CHECK-MESSAGES: :[[@LINE-5]]:8: warning: accessing fields in struct 'ContainsStructWithNoFields2' is inefficient due to padding; only needs 10 bytes but is using 24 bytes [altera-struct-pack-align] +// CHECK-MESSAGES: :[[@LINE-6]]:8: note: use "__attribute__((packed))" to reduce the amount of padding applied to struct 'ContainsStructWithNoFields2' +// CHECK-MESSAGES: :[[@LINE-7]]:8: warning: accessing fields in struct 'ContainsStructWithNoFields2' is inefficient due to poor alignment; currently aligned to 8 bytes, but recommended alignment is 16 bytes [altera-struct-pack-align] +// CHECK-MESSAGES: :[[@LINE-8]]:8: note: use "__attribute__((aligned(16)))" to align struct 'ContainsStructWithNoFields2' to 16 bytes +// CHECK-FIXES: __attribute__((packed)) +// CHECK-FIXES: __attribute__((aligned(16))); _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
