https://github.com/t-a-james created https://github.com/llvm/llvm-project/pull/215239
Finds uses of `#pragma comment` and, for `lib` or `linker` comments, suggests using the build system for improved portability. `#pragma comment` is not widely supported outside of MSVC. Clang supports the use of `#pragma comment` to link libraries on both Windows and Linux, but other kinds are only supported on Windows. Using `pragma comment` to change link flags may be unexpected in projects that prefer to set these flags in the build system. >From 5c76f8d1f42b643dc4f6a8b912d798af210e745a Mon Sep 17 00:00:00 2001 From: Tom James <[email protected]> Date: Mon, 10 Aug 2026 11:52:40 +0100 Subject: [PATCH] [clang-tidy] New portability-avoid-pragma-comment Finds uses of `#pragma comment` and, for `lib` or `linker` comments, suggests using the build system for improved portability. `#pragma comment` is not widely supported outside of MSVC. Clang supports the use of `#pragma comment` to link libraries on both Windows and Linux, but other kinds are only supported on Windows. Using `pragma comment` to change link flags may be unexpected in projects that prefer to set these flags in the build system. --- .../portability/AvoidPragmaCommentCheck.cpp | 50 +++++++++++++++++++ .../portability/AvoidPragmaCommentCheck.h | 37 ++++++++++++++ .../clang-tidy/portability/CMakeLists.txt | 1 + .../portability/PortabilityTidyModule.cpp | 3 ++ clang-tools-extra/docs/ReleaseNotes.md | 6 +++ .../docs/clang-tidy/checks/list.md | 1 + .../portability/avoid-pragma-comment.rst | 23 +++++++++ .../avoid-pragma-comment-linux.cpp | 21 ++++++++ .../avoid-pragma-comment-windows.cpp | 42 ++++++++++++++++ 9 files changed, 184 insertions(+) create mode 100644 clang-tools-extra/clang-tidy/portability/AvoidPragmaCommentCheck.cpp create mode 100644 clang-tools-extra/clang-tidy/portability/AvoidPragmaCommentCheck.h create mode 100644 clang-tools-extra/docs/clang-tidy/checks/portability/avoid-pragma-comment.rst create mode 100644 clang-tools-extra/test/clang-tidy/checkers/portability/avoid-pragma-comment-linux.cpp create mode 100644 clang-tools-extra/test/clang-tidy/checkers/portability/avoid-pragma-comment-windows.cpp diff --git a/clang-tools-extra/clang-tidy/portability/AvoidPragmaCommentCheck.cpp b/clang-tools-extra/clang-tidy/portability/AvoidPragmaCommentCheck.cpp new file mode 100644 index 0000000000000..1b2f5d92687b8 --- /dev/null +++ b/clang-tools-extra/clang-tidy/portability/AvoidPragmaCommentCheck.cpp @@ -0,0 +1,50 @@ +//===----------------------------------------------------------------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// + +#include "AvoidPragmaCommentCheck.h" +#include "clang/ASTMatchers/ASTMatchFinder.h" + +#include <string> + +using namespace clang::ast_matchers; + +namespace clang::tidy::portability { + +static const internal::VariadicDynCastAllOfMatcher<Decl, PragmaCommentDecl> + // All other node matchers declared in this way are camelCase + // NOLINTNEXTLINE(readability-identifier-naming) + pragmaCommentDecl; + +void AvoidPragmaCommentCheck::registerMatchers(MatchFinder *Finder) { + Finder->addMatcher(pragmaCommentDecl().bind("pragma"), this); +} + +void AvoidPragmaCommentCheck::check(const MatchFinder::MatchResult &Result) { + const auto *Pragma = Result.Nodes.getNodeAs<PragmaCommentDecl>("pragma"); + + std::string Msg{"avoid 'pragma comment' directive"}; + + // We can give specific advice about comments that add linker flags, but other + // kinds are too generic + const PragmaMSCommentKind &Kind = Pragma->getCommentKind(); + switch (Kind) { + case PragmaMSCommentKind::PCK_Lib: + Msg.append("; use the build system to link libraries"); + break; + case PragmaMSCommentKind::PCK_Linker: + Msg.append("; use the build system to set linker options"); + break; + case PragmaMSCommentKind::PCK_Unknown: + llvm_unreachable("unexpected pragma comment kind"); + default: + break; + } + diag(Pragma->getBeginLoc(), Msg); +} + +} // namespace clang::tidy::portability diff --git a/clang-tools-extra/clang-tidy/portability/AvoidPragmaCommentCheck.h b/clang-tools-extra/clang-tidy/portability/AvoidPragmaCommentCheck.h new file mode 100644 index 0000000000000..47f326374b97a --- /dev/null +++ b/clang-tools-extra/clang-tidy/portability/AvoidPragmaCommentCheck.h @@ -0,0 +1,37 @@ +//===----------------------------------------------------------------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_PORTABILITY_AVOIDPRAGMACOMMENTCHECK_H +#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_PORTABILITY_AVOIDPRAGMACOMMENTCHECK_H + +#include "../ClangTidyCheck.h" + +namespace clang::tidy::portability { + +/// Finds uses of ``#pragma comment`` and for ``lib`` or ``linker`` comments +/// suggests using the build system for improved portability. +/// +/// Only the "lib" pragma comment type is implemented on Linux, the rest are +/// Windows-only and should be caught by "-Wunknown-pragmas" on Linux. +/// +/// For the user-facing documentation see: +/// https://clang.llvm.org/extra/clang-tidy/checks/portability/avoid-pragma-comment.html +class AvoidPragmaCommentCheck : public ClangTidyCheck { +public: + AvoidPragmaCommentCheck(StringRef Name, ClangTidyContext *Context) + : ClangTidyCheck(Name, Context) {} + void registerMatchers(ast_matchers::MatchFinder *Finder) override; + void check(const ast_matchers::MatchFinder::MatchResult &Result) override; + bool isLanguageVersionSupported(const LangOptions &LangOpts) const override { + return LangOpts.CPlusPlus; + } +}; + +} // namespace clang::tidy::portability + +#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_PORTABILITY_AVOIDPRAGMACOMMENTCHECK_H diff --git a/clang-tools-extra/clang-tidy/portability/CMakeLists.txt b/clang-tools-extra/clang-tidy/portability/CMakeLists.txt index 170fedf52130e..f9bcb149b8145 100644 --- a/clang-tools-extra/clang-tidy/portability/CMakeLists.txt +++ b/clang-tools-extra/clang-tidy/portability/CMakeLists.txt @@ -5,6 +5,7 @@ set(LLVM_LINK_COMPONENTS ) add_clang_library(clangTidyPortabilityModule STATIC + AvoidPragmaCommentCheck.cpp AvoidPragmaOnceCheck.cpp NoAssemblerCheck.cpp PortabilityTidyModule.cpp diff --git a/clang-tools-extra/clang-tidy/portability/PortabilityTidyModule.cpp b/clang-tools-extra/clang-tidy/portability/PortabilityTidyModule.cpp index 1f2340502f685..c12ef3d20e871 100644 --- a/clang-tools-extra/clang-tidy/portability/PortabilityTidyModule.cpp +++ b/clang-tools-extra/clang-tidy/portability/PortabilityTidyModule.cpp @@ -8,6 +8,7 @@ #include "../ClangTidy.h" #include "../ClangTidyModule.h" +#include "AvoidPragmaCommentCheck.h" #include "AvoidPragmaOnceCheck.h" #include "NoAssemblerCheck.h" #include "RestrictSystemIncludesCheck.h" @@ -22,6 +23,8 @@ namespace { class PortabilityModule : public ClangTidyModule { public: void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override { + CheckFactories.registerCheck<AvoidPragmaCommentCheck>( + "portability-avoid-pragma-comment"); CheckFactories.registerCheck<AvoidPragmaOnceCheck>( "portability-avoid-pragma-once"); CheckFactories.registerCheck<NoAssemblerCheck>("portability-no-assembler"); diff --git a/clang-tools-extra/docs/ReleaseNotes.md b/clang-tools-extra/docs/ReleaseNotes.md index 29de9aef9e4b6..0f1dcf1ed20de 100644 --- a/clang-tools-extra/docs/ReleaseNotes.md +++ b/clang-tools-extra/docs/ReleaseNotes.md @@ -106,6 +106,12 @@ infrastructure are described first, followed by tool-specific sections. Finds calls to `value_or` (and alternative spellings `valueOr`, `ValueOr`) on optional types where the return type is expensive to copy. +- New {doc}`portability-avoid-pragma-comment + <clang-tidy/checks/portability/avoid-pragma-comment>` check. + + Finds uses of `#pragma comment` and, for `lib` or `linker` comments, suggests + using the build system for improved portability. + #### New check aliases #### Changes in existing checks diff --git a/clang-tools-extra/docs/clang-tidy/checks/list.md b/clang-tools-extra/docs/clang-tidy/checks/list.md index 77c9eafa7835c..5d279824714e7 100644 --- a/clang-tools-extra/docs/clang-tidy/checks/list.md +++ b/clang-tools-extra/docs/clang-tidy/checks/list.md @@ -372,6 +372,7 @@ readability/* | {doc}`performance-unnecessary-copy-initialization <performance/unnecessary-copy-initialization>` | Yes | | {doc}`performance-unnecessary-value-param <performance/unnecessary-value-param>` | Yes | | {doc}`performance-use-std-move <performance/use-std-move>` | Yes | +| {doc}`portability-avoid-pragma-comment <portability/avoid-pragma-comment>` | | | {doc}`portability-avoid-pragma-once <portability/avoid-pragma-once>` | | | {doc}`portability-no-assembler <portability/no-assembler>` | | | {doc}`portability-restrict-system-includes <portability/restrict-system-includes>` | Yes | diff --git a/clang-tools-extra/docs/clang-tidy/checks/portability/avoid-pragma-comment.rst b/clang-tools-extra/docs/clang-tidy/checks/portability/avoid-pragma-comment.rst new file mode 100644 index 0000000000000..d38541710ac3c --- /dev/null +++ b/clang-tools-extra/docs/clang-tidy/checks/portability/avoid-pragma-comment.rst @@ -0,0 +1,23 @@ +.. title:: clang-tidy - portability-avoid-pragma-comment + +portability-avoid-pragma-comment +================================ + +Finds uses of ``#pragma comment`` and, for ``lib`` or ``linker`` comments, +suggests using the build system for improved portability. + +``#pragma comment`` is not widely supported outside of MSVC. Clang supports the +use of ``#pragma comment`` to link libraries on both Windows and Linux, but +other kinds are only supported on Windows. Using ``pragma comment`` to change +link flags may be unexpected in projects that prefer to set these flags in the +build system. + +.. code:: c++ + // Clang supports the `lib` kind on Windows and Linux, but setting link flags + // outside the build system may be unexpected + #pragma comment(lib, "some_lib") + #pragma comment(linker, "some_linker_flag") + + // Clang only supports the `compiler` and `user` kinds when targeting Windows + #pragma comment(compiler) + #pragma comment(user, "Some string") \ No newline at end of file diff --git a/clang-tools-extra/test/clang-tidy/checkers/portability/avoid-pragma-comment-linux.cpp b/clang-tools-extra/test/clang-tidy/checkers/portability/avoid-pragma-comment-linux.cpp new file mode 100644 index 0000000000000..165371be06933 --- /dev/null +++ b/clang-tools-extra/test/clang-tidy/checkers/portability/avoid-pragma-comment-linux.cpp @@ -0,0 +1,21 @@ +// Only the "lib" pragma comment type is implemented on Linux, the rest are +// Windows-only. Therefore, this file always targets linux. +// RUN: %check_clang_tidy %s portability-avoid-pragma-comment %t -- -- -target x86_64-unknown-linux-gnu + +#pragma comment(lib, "some_lib") +// CHECK-MESSAGES: :[[@LINE-1]]:9: warning: avoid 'pragma comment' directive; use the build system to link libraries [portability-avoid-pragma-comment] + +_Pragma("comment(lib, \"some_lib\")") +// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: avoid 'pragma comment' directive; use the build system to link libraries [portability-avoid-pragma-comment] + +// Only the "lib" pragma comment type is implemented on Linux, the rest are +// Windows-only and should be caught by "-Wunknown-pragmas" or +// "-Wignored-pragmas" on Linux. They won't show up in the Linux AST, so +// portability-avoid-pragma-comment won't detect the below instances. +#pragma comment(linker, "some_linker_flag") +#pragma comment(compiler) +#pragma comment(user, "Some string") + +_Pragma("comment(linker, \"some_linker_flag\")") +_Pragma("comment(compiler)") +_Pragma("comment(user, \"Some string\")") diff --git a/clang-tools-extra/test/clang-tidy/checkers/portability/avoid-pragma-comment-windows.cpp b/clang-tools-extra/test/clang-tidy/checkers/portability/avoid-pragma-comment-windows.cpp new file mode 100644 index 0000000000000..24166898c0691 --- /dev/null +++ b/clang-tools-extra/test/clang-tidy/checkers/portability/avoid-pragma-comment-windows.cpp @@ -0,0 +1,42 @@ +// Only the "lib" pragma comment type is implemented on Linux, the rest are +// Windows-only. Therefore, this file always targets windows-msvc. +// RUN: %check_clang_tidy %s portability-avoid-pragma-comment %t -- -- -target x86_64-pc-windows-msvc + + +#pragma comment(lib, "some_lib") +// CHECK-MESSAGES: :[[@LINE-1]]:9: warning: avoid 'pragma comment' directive; use the build system to link libraries [portability-avoid-pragma-comment] + +_Pragma("comment(lib, \"some_lib\")") +// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: avoid 'pragma comment' directive; use the build system to link libraries [portability-avoid-pragma-comment] + + +#pragma comment(linker, "some_linker_flag") +// CHECK-MESSAGES: :[[@LINE-1]]:9: warning: avoid 'pragma comment' directive; use the build system to set linker options [portability-avoid-pragma-comment] + +#pragma comment(compiler) +// CHECK-MESSAGES: :[[@LINE-1]]:9: warning: avoid 'pragma comment' directive [portability-avoid-pragma-comment] + +#pragma comment(user, "Some string") +// CHECK-MESSAGES: :[[@LINE-1]]:9: warning: avoid 'pragma comment' directive [portability-avoid-pragma-comment] + +// __pragma() is a Microsoft-specific extension +__pragma(comment(lib, "some_lib")) +// CHECK-MESSAGES: :[[@LINE-1]]:10: warning: avoid 'pragma comment' directive; use the build system to link libraries [portability-avoid-pragma-comment] + +__pragma(comment(linker, "some_linker_flag")) +// CHECK-MESSAGES: :[[@LINE-1]]:10: warning: avoid 'pragma comment' directive; use the build system to set linker options [portability-avoid-pragma-comment] + +__pragma(comment(compiler)) +// CHECK-MESSAGES: :[[@LINE-1]]:10: warning: avoid 'pragma comment' directive [portability-avoid-pragma-comment] + +__pragma(comment(user, "Some string")) +// CHECK-MESSAGES: :[[@LINE-1]]:10: warning: avoid 'pragma comment' directive [portability-avoid-pragma-comment] + +_Pragma("comment(linker, \"some_linker_flag\")") +// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: avoid 'pragma comment' directive; use the build system to set linker options [portability-avoid-pragma-comment] + +_Pragma("comment(compiler)") +// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: avoid 'pragma comment' directive [portability-avoid-pragma-comment] + +_Pragma("comment(user, \"Some string\")") +// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: avoid 'pragma comment' directive [portability-avoid-pragma-comment] \ No newline at end of file _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
