https://github.com/llvmbot created https://github.com/llvm/llvm-project/pull/219097
Backport dc222c2de55988f5359262a0e29fed5c14e824e7 Requested by: @ChuanqiXu9 >From 8ff757c089a6af50a4c600801be7b79d1954b3d8 Mon Sep 17 00:00:00 2001 From: AZero13 <[email protected]> Date: Wed, 26 Aug 2026 23:10:57 -0400 Subject: [PATCH] [NFC][clang][Serialization] Fix std::set_difference sorting mismatch in ASTReader (#219053) Fixes a `std::set_difference` sorting violation in `ASTReader::checkTargetOptions` that causes a crash when building clang with `LLVM_ENABLE_EXPENSIVE_CHECKS` on libstdc++. `accumulateFeaturesAsWritten` sorts target features using a custom comparator that strips the `+`/`-` prefix (i.e. comparing `A.substr(1) < B.substr(1)`). However, `std::set_difference` was being called with the default `std::string::operator<` comparator, which does not match the sorting order because `+` (ASCII 0x2B) is less than `-` (ASCII 0x2D). For example, `["-cx16", "+sse2"]` is correctly sorted according to the custom comparator, but incorrectly sorted according to the default lexicographical comparator. This patch fixes the issue by passing the same custom comparator used for sorting to both `std::set_difference` calls. Fixes #219046. (cherry picked from commit dc222c2de55988f5359262a0e29fed5c14e824e7) --- clang/lib/Serialization/ASTReader.cpp | 13 ++++++++---- clang/test/Modules/merge-target-features.cpp | 22 ++++++++++++++++++++ 2 files changed, 31 insertions(+), 4 deletions(-) diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp index 4d3816d686730..1a437f3ebab98 100644 --- a/clang/lib/Serialization/ASTReader.cpp +++ b/clang/lib/Serialization/ASTReader.cpp @@ -523,13 +523,18 @@ static bool checkTargetOptions(const TargetOptions &TargetOpts, // We compute the set difference in both directions explicitly so that we can // diagnose the differences differently. + auto FeatureLess = [](StringRef A, StringRef B) { + return A.substr(1) < B.substr(1); + }; + SmallVector<StringRef, 4> UnmatchedExistingFeatures, UnmatchedReadFeatures; - std::set_difference( - ExistingFeatures.begin(), ExistingFeatures.end(), ReadFeatures.begin(), - ReadFeatures.end(), std::back_inserter(UnmatchedExistingFeatures)); + std::set_difference(ExistingFeatures.begin(), ExistingFeatures.end(), + ReadFeatures.begin(), ReadFeatures.end(), + std::back_inserter(UnmatchedExistingFeatures), + FeatureLess); std::set_difference(ReadFeatures.begin(), ReadFeatures.end(), ExistingFeatures.begin(), ExistingFeatures.end(), - std::back_inserter(UnmatchedReadFeatures)); + std::back_inserter(UnmatchedReadFeatures), FeatureLess); // If we are allowing compatible differences and the read feature set is // a strict subset of the existing feature set, there is nothing to diagnose. diff --git a/clang/test/Modules/merge-target-features.cpp b/clang/test/Modules/merge-target-features.cpp index c3678cbea11cb..f008492b7e341 100644 --- a/clang/test/Modules/merge-target-features.cpp +++ b/clang/test/Modules/merge-target-features.cpp @@ -148,6 +148,28 @@ // RUN: -fsyntax-only merge-target-features.cpp 2>&1 \ // RUN: | FileCheck --allow-empty --check-prefix=IGNORED2 %s // IGNORED2-NOT: error: +// +// RUN: %clang_cc1 -fmodules -x c++ -fmodules-cache-path=%t \ +// RUN: -iquote Inputs/merge-target-features \ +// RUN: -fno-implicit-modules \ +// RUN: -fmodule-map-file-home-is-cwd \ +// RUN: -emit-module -fmodule-name=foo -o %t/foo-order.pcm \ +// RUN: -triple i386-unknown-unknown \ +// RUN: -target-cpu i386 -target-feature -cx16 -target-feature +sse2 \ +// RUN: Inputs/merge-target-features/module.modulemap +// +// RUN: not %clang_cc1 -fmodules -x c++ -fmodules-cache-path=%t \ +// RUN: -iquote Inputs/merge-target-features \ +// RUN: -fno-implicit-modules \ +// RUN: -fmodule-map-file-home-is-cwd \ +// RUN: -fmodule-map-file=Inputs/merge-target-features/module.modulemap \ +// RUN: -fmodule-file=%t/foo-order.pcm \ +// RUN: -triple i386-unknown-unknown \ +// RUN: -target-cpu i386 -target-feature +sse2 \ +// RUN: -fsyntax-only merge-target-features.cpp 2>&1 \ +// RUN: | FileCheck --check-prefix=ORDER --implicit-check-not=error: %s +// ORDER: error: precompiled file '{{.*}}foo-order.pcm' was compiled with the target feature '-cx16' but the current translation unit is not +// ORDER: error: {{.*}} configuration mismatch #include "foo.h" _______________________________________________ llvm-branch-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
