[clang-tools-extra] [clang-tidy] Fix loading clang-tidy as a Clang frontend plugin (PR #221961)
Zeyi Xu via cfe-commits
cfe-commits at lists.llvm.org
Tue Sep 8 09:51:09 PDT 2026
https://github.com/zeyi2 updated https://github.com/llvm/llvm-project/pull/221961
>From ad2515a915fc57525fa27d633495e6927d367bff Mon Sep 17 00:00:00 2001
From: Zeyi Xu <mitchell.xu2 at gmail.com>
Date: Tue, 8 Sep 2026 19:09:29 +0800
Subject: [PATCH 1/2] [clang-tidy] Fix loading clang-tidy as a Clang frontend
plugin
---
.../clang-tidy/plugin/CMakeLists.txt | 10 +++++++++-
.../clang-tidy/plugin/ClangTidyPlugin.cpp | 20 ++++++++++++-------
.../clang-tidy/plugin/ClangTidyPlugin.exports | 1 +
clang-tools-extra/docs/ReleaseNotes.md | 3 +++
clang-tools-extra/test/CMakeLists.txt | 10 ++++++++++
.../infrastructure/clang-plugin-analyzer.cpp | 8 ++++++++
.../infrastructure/clang-plugin.cpp | 14 +++++++++++++
clang-tools-extra/test/lit.cfg.py | 2 ++
clang-tools-extra/test/lit.site.cfg.py.in | 1 +
9 files changed, 61 insertions(+), 8 deletions(-)
create mode 100644 clang-tools-extra/clang-tidy/plugin/ClangTidyPlugin.exports
create mode 100644 clang-tools-extra/test/clang-tidy/infrastructure/clang-plugin-analyzer.cpp
create mode 100644 clang-tools-extra/test/clang-tidy/infrastructure/clang-plugin.cpp
diff --git a/clang-tools-extra/clang-tidy/plugin/CMakeLists.txt b/clang-tools-extra/clang-tidy/plugin/CMakeLists.txt
index aff2018b693b1..899c9fb057c52 100644
--- a/clang-tools-extra/clang-tidy/plugin/CMakeLists.txt
+++ b/clang-tools-extra/clang-tidy/plugin/CMakeLists.txt
@@ -1,6 +1,14 @@
-add_clang_library(clangTidyPlugin STATIC
+if(NOT CLANG_PLUGIN_SUPPORT OR NOT CLANG_LINK_CLANG_DYLIB OR
+ NOT LLVM_LINK_LLVM_DYLIB)
+ return()
+endif()
+
+set(LLVM_EXPORTED_SYMBOL_FILE ${CMAKE_CURRENT_SOURCE_DIR}/ClangTidyPlugin.exports)
+add_llvm_library(clangTidyPlugin MODULE
ClangTidyPlugin.cpp
+ PLUGIN_TOOL clang
+
LINK_LIBS
clangTidy
${ALL_CLANG_TIDY_CHECKS}
diff --git a/clang-tools-extra/clang-tidy/plugin/ClangTidyPlugin.cpp b/clang-tools-extra/clang-tidy/plugin/ClangTidyPlugin.cpp
index 4431333906f7b..87869a3af4b94 100644
--- a/clang-tools-extra/clang-tidy/plugin/ClangTidyPlugin.cpp
+++ b/clang-tools-extra/clang-tidy/plugin/ClangTidyPlugin.cpp
@@ -8,10 +8,16 @@
#include "../ClangTidy.h"
#include "../ClangTidyDiagnosticConsumer.h"
+#include "../ClangTidyForceLinker.h" // IWYU pragma: keep
#include "../ClangTidyModule.h"
#include "clang/Frontend/CompilerInstance.h"
#include "clang/Frontend/FrontendPluginRegistry.h"
#include "clang/Frontend/MultiplexConsumer.h"
+#include "clang/StaticAnalyzer/Frontend/CheckerRegistry.h"
+
+// NOLINTNEXTLINE(readability-identifier-naming)
+extern "C" const char clang_analyzerAPIVersionString[] =
+ CLANG_ANALYZER_API_VERSION_STRING;
namespace clang::tidy {
namespace {
@@ -32,6 +38,8 @@ class ClangTidyPluginAction : public PluginASTAction {
std::vector<std::unique_ptr<ASTConsumer>> Consumer)
: MultiplexConsumer(std::move(Consumer)), Context(std::move(Context)),
DiagEngine(std::move(DiagEngine)) {}
+
+ ~WrapConsumer() override { DiagEngine->getClient()->EndSourceFile(); }
};
public:
@@ -44,6 +52,8 @@ class ClangTidyPluginAction : public PluginASTAction {
auto DiagEngine = std::make_unique<DiagnosticsEngine>(
DiagnosticIDs::create(), *DiagOpts, DiagConsumer);
Context->setDiagnosticsEngine(std::move(DiagOpts), DiagEngine.get());
+ DiagConsumer->BeginSourceFile(Compiler.getLangOpts(),
+ &Compiler.getPreprocessor());
// Create the AST consumer.
ClangTidyASTConsumerFactory Factory(*Context);
@@ -54,7 +64,7 @@ class ClangTidyPluginAction : public PluginASTAction {
std::move(Context), std::move(DiagEngine), std::move(Vec));
}
- bool ParseArgs(const CompilerInstance &,
+ bool ParseArgs(const CompilerInstance &Compiler,
const std::vector<std::string> &Args) override {
const ClangTidyGlobalOptions GlobalOptions;
const ClangTidyOptions DefaultOptions;
@@ -67,7 +77,8 @@ class ClangTidyPluginAction : public PluginASTAction {
OverrideOptions.Checks = std::string(Arg.substr(strlen("-checks=")));
auto Options = std::make_unique<FileOptionsProvider>(
- GlobalOptions, DefaultOptions, OverrideOptions);
+ GlobalOptions, DefaultOptions, OverrideOptions,
+ Compiler.getVirtualFileSystemPtr());
Context = std::make_unique<ClangTidyContext>(std::move(Options));
return true;
}
@@ -79,10 +90,5 @@ class ClangTidyPluginAction : public PluginASTAction {
} // namespace
} // namespace clang::tidy
-// This anchor is used to force the linker to link in the generated object file
-// and thus register the clang-tidy plugin.
-// NOLINTNEXTLINE(misc-use-internal-linkage)
-volatile int ClangTidyPluginAnchorSource = 0;
-
static clang::FrontendPluginRegistry::Add<clang::tidy::ClangTidyPluginAction>
X("clang-tidy", "clang-tidy");
diff --git a/clang-tools-extra/clang-tidy/plugin/ClangTidyPlugin.exports b/clang-tools-extra/clang-tidy/plugin/ClangTidyPlugin.exports
new file mode 100644
index 0000000000000..b5289dac3fca8
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/plugin/ClangTidyPlugin.exports
@@ -0,0 +1 @@
+clang_analyzerAPIVersionString
diff --git a/clang-tools-extra/docs/ReleaseNotes.md b/clang-tools-extra/docs/ReleaseNotes.md
index 70dd45eb3297c..6d9bc92ffe7e2 100644
--- a/clang-tools-extra/docs/ReleaseNotes.md
+++ b/clang-tools-extra/docs/ReleaseNotes.md
@@ -96,6 +96,9 @@ infrastructure are described first, followed by tool-specific sections.
### Improvements to clang-tidy
+- Improved clang-tidy by fixing its use as a Clang plugin, allowing checks to
+ run during normal compilation when Clang and LLVM are built as shared libraries.
+
- Improved {program}`check_clang_tidy.py` by adding support of
`-std=cXX-or-earlier` values, mirroring the existing `-std=cXX-or-later`.
New construct expands to the given standard and every earlier one.
diff --git a/clang-tools-extra/test/CMakeLists.txt b/clang-tools-extra/test/CMakeLists.txt
index 22f227a891f82..e94879b655643 100644
--- a/clang-tools-extra/test/CMakeLists.txt
+++ b/clang-tools-extra/test/CMakeLists.txt
@@ -7,10 +7,16 @@
set(CLANG_TOOLS_SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/..")
set(CLANG_TOOLS_BINARY_DIR "${CMAKE_CURRENT_BINARY_DIR}/..")
+set(CLANG_TIDY_PLUGIN_AVAILABLE OFF)
+if(TARGET clangTidyPlugin)
+ set(CLANG_TIDY_PLUGIN_AVAILABLE ON)
+endif()
+
llvm_canonicalize_cmake_booleans(
CLANG_TIDY_ENABLE_STATIC_ANALYZER
CLANG_TIDY_ENABLE_QUERY_BASED_CUSTOM_CHECKS
CLANG_PLUGIN_SUPPORT
+ CLANG_TIDY_PLUGIN_AVAILABLE
LLVM_INSTALL_TOOLCHAIN_ONLY
)
@@ -76,6 +82,10 @@ if(TARGET CTTestTidyModule)
endif()
endif()
+if(TARGET clangTidyPlugin)
+ list(APPEND CLANG_TOOLS_TEST_DEPS clangTidyPlugin)
+endif()
+
add_lit_testsuite(check-clang-extra "Running clang-tools-extra/test"
${CMAKE_CURRENT_BINARY_DIR}
DEPENDS ${CLANG_TOOLS_TEST_DEPS}
diff --git a/clang-tools-extra/test/clang-tidy/infrastructure/clang-plugin-analyzer.cpp b/clang-tools-extra/test/clang-tidy/infrastructure/clang-plugin-analyzer.cpp
new file mode 100644
index 0000000000000..347ac29d3e53d
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/infrastructure/clang-plugin-analyzer.cpp
@@ -0,0 +1,8 @@
+// REQUIRES: clang-plugin, static-analyzer
+// RUN: %clang_cc1 -load %llvmshlibdir/clangTidyPlugin%pluginext -add-plugin clang-tidy -plugin-arg-clang-tidy -checks=-*,clang-analyzer-core.DivideZero %s -verify
+
+int divide() {
+ return 1 / 0; // expected-warning {{division by zero is undefined}}
+ // expected-warning at -1 {{Division by zero [clang-analyzer-core.DivideZero]}}
+ // expected-note at -2 {{Division by zero}}
+}
diff --git a/clang-tools-extra/test/clang-tidy/infrastructure/clang-plugin.cpp b/clang-tools-extra/test/clang-tidy/infrastructure/clang-plugin.cpp
new file mode 100644
index 0000000000000..e946f9379ae5e
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/infrastructure/clang-plugin.cpp
@@ -0,0 +1,14 @@
+// REQUIRES: clang-plugin
+// RUN: %clang_cc1 -load %llvmshlibdir/clangTidyPlugin%pluginext -add-plugin clang-tidy -plugin-arg-clang-tidy -checks=-*,modernize-use-nullptr,bugprone-narrowing-conversions %s -std=c++11 -verify
+// RUN: %clang -Xclang -load -Xclang %llvmshlibdir/clangTidyPlugin%pluginext -Xclang -add-plugin -Xclang clang-tidy -Xclang -plugin-arg-clang-tidy -Xclang -checks=-*,modernize-use-nullptr,bugprone-narrowing-conversions -Xclang -verify %s -std=c++11 -S -emit-llvm -o - | FileCheck %s
+// RUN: %clang_cc1 -load %llvmshlibdir/clangTidyPlugin%pluginext -add-plugin clang-tidy -plugin-arg-clang-tidy -checks=-* %s -std=c++11 -verify=disabled
+// disabled-no-diagnostics
+
+extern "C" {
+int *p = 0; // expected-warning {{use nullptr [modernize-use-nullptr]}}
+}
+// CHECK: @p = {{.*}}global ptr null
+
+int narrow(double value) {
+ return value; // expected-warning {{narrowing conversion from 'double' to 'int' [bugprone-narrowing-conversions]}}
+}
diff --git a/clang-tools-extra/test/lit.cfg.py b/clang-tools-extra/test/lit.cfg.py
index be484b4ff217d..28c6b9bbfbd84 100644
--- a/clang-tools-extra/test/lit.cfg.py
+++ b/clang-tools-extra/test/lit.cfg.py
@@ -76,6 +76,8 @@
# Plugins (loadable modules)
if config.has_plugins and config.llvm_plugin_ext:
config.available_features.add("plugins")
+if config.has_clang_tidy_plugin:
+ config.available_features.add("clang-plugin")
# It is not realistically possible to account for all options that could
# possibly be present in system and user configuration files, so disable
diff --git a/clang-tools-extra/test/lit.site.cfg.py.in b/clang-tools-extra/test/lit.site.cfg.py.in
index 152ea6be2771c..03535a9ae770e 100644
--- a/clang-tools-extra/test/lit.site.cfg.py.in
+++ b/clang-tools-extra/test/lit.site.cfg.py.in
@@ -12,6 +12,7 @@ config.host_triple = "@LLVM_HOST_TRIPLE@"
config.clang_tidy_staticanalyzer = @CLANG_TIDY_ENABLE_STATIC_ANALYZER@
config.clang_tidy_custom_check = @CLANG_TIDY_ENABLE_QUERY_BASED_CUSTOM_CHECKS@
config.has_plugins = @CLANG_PLUGIN_SUPPORT@
+config.has_clang_tidy_plugin = @CLANG_TIDY_PLUGIN_AVAILABLE@
# Support substitution of the tools and libs dirs with user parameters. This is
# used when we can't determine the tool dir at configuration time.
config.llvm_tools_dir = lit_config.substitute("@LLVM_TOOLS_DIR@")
>From 50b42f202c13ad44b29d3074e051d6c76498e087 Mon Sep 17 00:00:00 2001
From: Zeyi Xu <mitchell.xu2 at gmail.com>
Date: Wed, 9 Sep 2026 00:50:59 +0800
Subject: [PATCH 2/2] Update clang-tools-extra/docs/ReleaseNotes.md
Co-authored-by: EugeneZelenko <eugene.zelenko at gmail.com>
---
clang-tools-extra/docs/ReleaseNotes.md | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/clang-tools-extra/docs/ReleaseNotes.md b/clang-tools-extra/docs/ReleaseNotes.md
index 6d9bc92ffe7e2..1397e1ec5b468 100644
--- a/clang-tools-extra/docs/ReleaseNotes.md
+++ b/clang-tools-extra/docs/ReleaseNotes.md
@@ -96,7 +96,7 @@ infrastructure are described first, followed by tool-specific sections.
### Improvements to clang-tidy
-- Improved clang-tidy by fixing its use as a Clang plugin, allowing checks to
+- Improved {program}`clang-tidy` by fixing its use as a Clang plugin, allowing checks to
run during normal compilation when Clang and LLVM are built as shared libraries.
- Improved {program}`check_clang_tidy.py` by adding support of
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