[clang-tidy] Improve "-quiet" option by suppressing "xxx warnings generated" #154012

vbvictor · 2025-08-17T11:28:53Z

Before this change, -quiet mode in clang-tidy generated meaningless messages xxx warnings generated in output:

// main.cpp
#include <iostream>

int main() {
  std::cout << 42;
}

> clang-tidy -checks='-*,readability-magic-numbers' -quiet main.cpp

82 warnings generated.
main.cpp:4:16: warning: 42 is a magic number; consider replacing it with a named constant [readability-magic-numbers]
    4 |   std::cout << 42;
      |                ^

As you can see, 82 warnings generated. does not say much quiet mode, this patch removes this message completely:

> ./build/bin/clang-tidy -p build -checks='-*,readability-magic-numbers' -quiet main.cpp

main.cpp:4:16: warning: 42 is a magic number; consider replacing it with a named constant [readability-magic-numbers]
    4 |   std::cout << 42;
      |                ^

In contrast, when running without quiet, It gives some meaningful information because we know how many messages were suppressed thus calculating total messages count:

> clang-tidy -checks='-*,readability-magic-numbers' main.cpp

82 warnings generated.
main.cpp:4:16: warning: 42 is a magic number; consider replacing it with a named constant [readability-magic-numbers]
    4 |   std::cout << 42;
      |                ^
Suppressed 81 warnings (81 in non-user code).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.

Fixes #47042

llvmbot · 2025-08-17T11:29:22Z

@llvm/pr-subscribers-clang-tidy

@llvm/pr-subscribers-clang-tools-extra

Author: Baranov Victor (vbvictor)

Changes

Before this change, -quiet mode in clang-tidy generated meaningless messages xxx warnings generated in output:

// main.cpp
#include &lt;iostream&gt;

int main() {
  std::cout &lt;&lt; 42;
}

&gt; clang-tidy -checks='-*,readability-magic-numbers' -quiet main.cpp

82 warnings generated.
main.cpp:4:16: warning: 42 is a magic number; consider replacing it with a named constant [readability-magic-numbers]
    4 |   std::cout &lt;&lt; 42;
      |                ^

As you can see, 82 warnings generated. does not say much quiet mode, this patch removes this message completely:

&gt; ./build/bin/clang-tidy -p build -checks='-*,readability-magic-numbers' -quiet main.cpp

main.cpp:4:16: warning: 42 is a magic number; consider replacing it with a named constant [readability-magic-numbers]
    4 |   std::cout &lt;&lt; 42;
      |                ^

In contrast, when running without quiet, It gives some meaningful information because we know how many messages were suppressed thus calculating total messages count:

&gt; clang-tidy -checks='-*,readability-magic-numbers' main.cpp

82 warnings generated.
main.cpp:4:16: warning: 42 is a magic number; consider replacing it with a named constant [readability-magic-numbers]
    4 |   std::cout &lt;&lt; 42;
      |                ^
Suppressed 81 warnings (81 in non-user code).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.

Full diff: https://github.com/llvm/llvm-project/pull/154012.diff

6 Files Affected:

(modified) clang-tools-extra/clang-tidy/ClangTidy.cpp (+8-4)
(modified) clang-tools-extra/clang-tidy/ClangTidy.h (+2-1)
(modified) clang-tools-extra/clang-tidy/tool/ClangTidyMain.cpp (+1-1)
(modified) clang-tools-extra/docs/ReleaseNotes.rst (+3)
(modified) clang-tools-extra/test/clang-tidy/infrastructure/file-filter-symlinks.cpp (+1-1)
(added) clang-tools-extra/test/clang-tidy/infrastructure/quiet-flag.cpp (+14)

diff --git a/clang-tools-extra/clang-tidy/ClangTidy.cpp b/clang-tools-extra/clang-tidy/ClangTidy.cpp
index 4ae2864d310d0..8f5728dea8c2a 100644
--- a/clang-tools-extra/clang-tidy/ClangTidy.cpp
+++ b/clang-tools-extra/clang-tidy/ClangTidy.cpp
@@ -540,7 +540,7 @@ runClangTidy(clang::tidy::ClangTidyContext &Context,
              ArrayRef<std::string> InputFiles,
              llvm::IntrusiveRefCntPtr<llvm::vfs::OverlayFileSystem> BaseFS,
              bool ApplyAnyFix, bool EnableCheckProfile,
-             llvm::StringRef StoreCheckProfile) {
+             llvm::StringRef StoreCheckProfile, bool Quiet) {
   ClangTool Tool(Compilations, InputFiles,
                  std::make_shared<PCHContainerOperations>(), BaseFS);
 
@@ -577,8 +577,9 @@ runClangTidy(clang::tidy::ClangTidyContext &Context,
   class ActionFactory : public FrontendActionFactory {
   public:
     ActionFactory(ClangTidyContext &Context,
-                  IntrusiveRefCntPtr<llvm::vfs::OverlayFileSystem> BaseFS)
-        : ConsumerFactory(Context, std::move(BaseFS)) {}
+                  IntrusiveRefCntPtr<llvm::vfs::OverlayFileSystem> BaseFS,
+                  bool Quiet)
+        : ConsumerFactory(Context, std::move(BaseFS)), Quiet(Quiet) {}
     std::unique_ptr<FrontendAction> create() override {
       return std::make_unique<Action>(&ConsumerFactory);
     }
@@ -589,6 +590,8 @@ runClangTidy(clang::tidy::ClangTidyContext &Context,
                        DiagnosticConsumer *DiagConsumer) override {
       // Explicitly ask to define __clang_analyzer__ macro.
       Invocation->getPreprocessorOpts().SetUpStaticAnalyzer = true;
+      if (Quiet)
+        Invocation->getDiagnosticOpts().ShowCarets = false;
       return FrontendActionFactory::runInvocation(
           Invocation, Files, PCHContainerOps, DiagConsumer);
     }
@@ -607,9 +610,10 @@ runClangTidy(clang::tidy::ClangTidyContext &Context,
     };
 
     ClangTidyASTConsumerFactory ConsumerFactory;
+    bool Quiet;
   };
 
-  ActionFactory Factory(Context, std::move(BaseFS));
+  ActionFactory Factory(Context, std::move(BaseFS), Quiet);
   Tool.run(&Factory);
   return DiagConsumer.take();
 }
diff --git a/clang-tools-extra/clang-tidy/ClangTidy.h b/clang-tools-extra/clang-tidy/ClangTidy.h
index 454261bbd6840..d37d68ec0a5b9 100644
--- a/clang-tools-extra/clang-tidy/ClangTidy.h
+++ b/clang-tools-extra/clang-tidy/ClangTidy.h
@@ -94,7 +94,8 @@ runClangTidy(clang::tidy::ClangTidyContext &Context,
              ArrayRef<std::string> InputFiles,
              llvm::IntrusiveRefCntPtr<llvm::vfs::OverlayFileSystem> BaseFS,
              bool ApplyAnyFix, bool EnableCheckProfile = false,
-             llvm::StringRef StoreCheckProfile = StringRef());
+             llvm::StringRef StoreCheckProfile = StringRef(),
+             bool Quiet = false);
 
 /// Controls what kind of fixes clang-tidy is allowed to apply.
 enum FixBehaviour {
diff --git a/clang-tools-extra/clang-tidy/tool/ClangTidyMain.cpp b/clang-tools-extra/clang-tidy/tool/ClangTidyMain.cpp
index df3a8b22b1e24..bef3b938b5afd 100644
--- a/clang-tools-extra/clang-tidy/tool/ClangTidyMain.cpp
+++ b/clang-tools-extra/clang-tidy/tool/ClangTidyMain.cpp
@@ -717,7 +717,7 @@ int clangTidyMain(int argc, const char **argv) {
                            EnableModuleHeadersParsing);
   std::vector<ClangTidyError> Errors =
       runClangTidy(Context, OptionsParser->getCompilations(), PathList, BaseFS,
-                   FixNotes, EnableCheckProfile, ProfilePrefix);
+                   FixNotes, EnableCheckProfile, ProfilePrefix, Quiet);
   bool FoundErrors = llvm::any_of(Errors, [](const ClangTidyError &E) {
     return E.DiagLevel == ClangTidyError::Error;
   });
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index b481c56c262c4..e4b470026ef08 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -112,6 +112,9 @@ Improvements to clang-tidy
 - Improved documentation of the `-line-filter` command-line flag of
   :program:`clang-tidy` and :program:`run-clang-tidy.py`.
 
+- Improved :program:`clang-tidy` option `quiet` to suppresses diagnostic count
+  messages.
+
 New checks
 ^^^^^^^^^^
 
diff --git a/clang-tools-extra/test/clang-tidy/infrastructure/file-filter-symlinks.cpp b/clang-tools-extra/test/clang-tidy/infrastructure/file-filter-symlinks.cpp
index 7efa7d070f69f..58f3b23cb1dbf 100644
--- a/clang-tools-extra/test/clang-tidy/infrastructure/file-filter-symlinks.cpp
+++ b/clang-tools-extra/test/clang-tidy/infrastructure/file-filter-symlinks.cpp
@@ -10,7 +10,7 @@
 // RUN: clang-tidy -checks='-*,google-explicit-constructor' -header-filter='header_alias\.h' %s -- -I %t 2>&1 | FileCheck --check-prefix=CHECK_HEADER_ALIAS %s
 // RUN: clang-tidy -checks='-*,google-explicit-constructor' -header-filter='header_alias\.h' -quiet %s -- -I %t 2>&1 | FileCheck --check-prefix=CHECK_HEADER_ALIAS %s
 // RUN: clang-tidy -checks='-*,google-explicit-constructor' -header-filter='header\.h' %s -- -I %t 2>&1 | FileCheck --check-prefix=CHECK_HEADER %s
-// RUN: clang-tidy -checks='-*,google-explicit-constructor' -header-filter='header\.h' -quiet %s -- -I %t 2>&1 | FileCheck --check-prefix=CHECK_HEADER %s
+// RUN: clang-tidy -checks='-*,google-explicit-constructor' -header-filter='header\.h' -quiet %s -- -I %t 2>&1 | FileCheck --check-prefix=CHECK_HEADER --allow-empty %s
 
 // Check that `-header-filter` operates on the same file paths as paths in
 // diagnostics printed by ClangTidy.
diff --git a/clang-tools-extra/test/clang-tidy/infrastructure/quiet-flag.cpp b/clang-tools-extra/test/clang-tidy/infrastructure/quiet-flag.cpp
new file mode 100644
index 0000000000000..0e3d6164163a4
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/infrastructure/quiet-flag.cpp
@@ -0,0 +1,14 @@
+// RUN: clang-tidy -checks=-*,readability-magic-numbers %t.cpp -- 2>&1 | FileCheck %s --check-prefix=CHECK-NORMAL
+// RUN: clang-tidy -checks=-*,readability-magic-numbers -quiet %t.cpp -- 2>&1 | FileCheck %s --check-prefix=CHECK-QUIET
+
+// Normal mode should show warning count
+// CHECK-NORMAL: 1 warning generated
+// CHECK-NORMAL: warning: 42 is a magic number
+
+// Quiet mode should suppress warning count 
+// CHECK-QUIET-NOT: 1 warning generated
+// CHECK-QUIET: warning: 42 is a magic number
+
+int main() {
+  int x = 42;
+}

carlosgalvezp

LGTM, thanks for fixing!

It might be worth double-checking the comment I wrote about this carets option (which I guess is equivalent to passing the command line flag):

#47042 (comment)

In particular the fact that part of the diagnostic is removed. But perhaps it's only for compiler warnings and it's not a problem for clang-tidy.

vbvictor · 2025-08-17T20:55:38Z

LGTM, thanks for fixing!

It might be worth double-checking the comment I wrote about this carets option (which I guess is equivalent to passing the command line flag):

#47042 (comment)

In particular the fact that part of the diagnostic is removed. But perhaps it's only for compiler warnings and it's not a problem for clang-tidy.

Thanks for the issue link and concerns!

Yes, it looks to don't affect clang-tidy because there are 2 separate DiagnosticOptions we can set in clang-tidy.
The first ClangTidyDiagnosticConsumer that has one set of DiagnosticOptions is left unchanged:

llvm-project/clang-tools-extra/clang-tidy/ClangTidy.cpp

Lines 574 to 578 in a10773c

    
           ClangTidyDiagnosticConsumer DiagConsumer(Context, nullptr, true, ApplyAnyFix); 
        
           auto DiagOpts = std::make_unique<DiagnosticOptions>(); 
        
           DiagnosticsEngine DE(DiagnosticIDs::create(), *DiagOpts, &DiagConsumer, 
        
                                /*ShouldOwnClient=*/false); 
        
           Context.setDiagnosticsEngine(std::move(DiagOpts), &DE);

And second one for CompilerInvocation that handles warnings generated but passes all actual diagnostics to consumer. This part I changed in PR and it handles.

I've added tests with carets (hopefully correctly) so this feature will be tracked in the future.

vbvictor · 2025-08-17T21:04:47Z

P.S.
One of the comments in the original issue was right about annoyance with CI integration.
I started tinkering with clang-tidy CI for LLVM and stumbled upon this. I'd need to also enhance -quiet mode in scripts because for now it gives such output:

Running clang-tidy for 446 files out of 5099 in compilation database ...
[  1/446][3.6s] clang-tidy-21 -p=build/ -quiet /home/victor/llvm2/llvm-project/clang-tools-extra/clang-tidy/misc/ConfusableTable/BuildConfusableTable.cpp
33046 warnings generated.

The last string will be suppressed in this PR and the first and second lines should be suppressed inside run-clang-tidy

carlosgalvezp · 2025-08-18T19:22:33Z

Great, thanks for checking and adding this use case to the unit test! LGTM

[clang-tidy] Improve "-quiet" option by suppressing warnings count

09a1f8e

vbvictor requested review from 5chmidti, HerrCai0907, PiotrZSL and carlosgalvezp August 17, 2025 11:28

llvmbot added clang-tools-extra clang-tidy labels Aug 17, 2025

vbvictor added 2 commits August 17, 2025 14:31

[clang-tidy] improve release notes of "-quiet"

d4f3ed2

fix test

3f410e8

vbvictor changed the title ~~[clang-tidy] Improve "-quiet" option by suppressing warnings generated count~~ [clang-tidy] Improve "-quiet" option by suppressing "xxx warnings generated" Aug 17, 2025

carlosgalvezp approved these changes Aug 17, 2025

View reviewed changes

[clang-tidy] add test with carets

1237346

vbvictor merged commit ed26993 into llvm:main Aug 19, 2025
10 checks passed

vbvictor deleted the suppress-xxx-warnings-generated-in-quite-mode branch August 19, 2025 18:47

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