[clang] [clang-tools-extra] [clang-tidy] [Modules] Skip checking decls in clang-tidy (PR #145630)

[Chuanqi Xu via cfe-commits]

https://github.com/ChuanqiXu9 updated https://github.com/llvm/llvm-project/pull/145630

>From b54a054a957c7b7d59cd8783230a7683f997636d Mon Sep 17 00:00:00 2001
From: Chuanqi Xu <chuanqi.xcq at alibaba-inc.com>
Date: Wed, 17 Jan 2024 13:22:10 +0800
Subject: [PATCH] [clang-tidy] [Modules] Skip checking decls in clang-tidy

---
 clang-tools-extra/clang-tidy/ClangTidy.cpp    |  3 ++
 .../infrastructure/cxx20-modules.cppm         | 29 +++++++++++++++++++
 clang-tools-extra/test/lit.cfg.py             |  1 +
 .../clang/ASTMatchers/ASTMatchFinder.h        |  2 ++
 clang/lib/ASTMatchers/ASTMatchFinder.cpp      |  4 +++
 5 files changed, 39 insertions(+)
 create mode 100644 clang-tools-extra/test/clang-tidy/infrastructure/cxx20-modules.cppm

diff --git a/clang-tools-extra/clang-tidy/ClangTidy.cpp b/clang-tools-extra/clang-tidy/ClangTidy.cpp
index 60f4823d930c1..0e5f8fbda631a 100644
--- a/clang-tools-extra/clang-tidy/ClangTidy.cpp
+++ b/clang-tools-extra/clang-tidy/ClangTidy.cpp
@@ -434,6 +434,9 @@ ClangTidyASTConsumerFactory::createASTConsumer(CompilerInstance &Compiler,
 
   ast_matchers::MatchFinder::MatchFinderOptions FinderOptions;
 
+  // We should always skip the declarations in modules.
+  FinderOptions.SkipDeclsInModules = true;
+
   std::unique_ptr<ClangTidyProfiling> Profiling;
   if (Context.getEnableProfiling()) {
     Profiling =
diff --git a/clang-tools-extra/test/clang-tidy/infrastructure/cxx20-modules.cppm b/clang-tools-extra/test/clang-tidy/infrastructure/cxx20-modules.cppm
new file mode 100644
index 0000000000000..663df0104fd0a
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/infrastructure/cxx20-modules.cppm
@@ -0,0 +1,29 @@
+// RUN: rm -fr %t
+// RUN: mkdir %t
+// RUN: split-file %s %t
+// RUN: mkdir %t/tmp
+//
+// RUN: %check_clang_tidy -std=c++20 -check-suffix=DEFAULT %t/a.cpp \
+// RUN:   cppcoreguidelines-narrowing-conversions %t/a.cpp -- \
+// RUN:   -config='{}'
+
+// RUN: clang -std=c++20 -x c++-module %t/a.cpp --precompile -o %t/a.pcm
+
+// RUN: %check_clang_tidy -std=c++20 -check-suffix=DEFAULT %t/use.cpp \
+// RUN:   cppcoreguidelines-narrowing-conversions %t/a.cpp -- \
+// RUN:   -config='{}' -- -fmodule-file=a=%t/a.pcm 
+
+//--- a.cpp
+export module a;
+export void most_narrowing_is_not_ok() {
+  int i;
+  long long ui;
+  i = ui;
+  // CHECK-MESSAGES-DEFAULT: :[[@LINE-1]]:7: warning: narrowing conversion from 'long long' to signed type 'int' is implementation-defined [cppcoreguidelines-narrowing-conversions]
+}
+
+//--- use.cpp
+import a;
+void use() {
+  most_narrowing_is_not_ok();
+}
diff --git a/clang-tools-extra/test/lit.cfg.py b/clang-tools-extra/test/lit.cfg.py
index c39ea29329674..c075650ff7a73 100644
--- a/clang-tools-extra/test/lit.cfg.py
+++ b/clang-tools-extra/test/lit.cfg.py
@@ -27,6 +27,7 @@
 config.suffixes = [
     ".c",
     ".cpp",
+    ".cppm",
     ".hpp",
     ".m",
     ".mm",
diff --git a/clang/include/clang/ASTMatchers/ASTMatchFinder.h b/clang/include/clang/ASTMatchers/ASTMatchFinder.h
index 2d36e8c4fae1c..b0ccbf22a4269 100644
--- a/clang/include/clang/ASTMatchers/ASTMatchFinder.h
+++ b/clang/include/clang/ASTMatchers/ASTMatchFinder.h
@@ -144,6 +144,8 @@ class MatchFinder {
 
     /// Avoids matching declarations in system headers.
     bool IgnoreSystemHeaders{false};
+
+    bool SkipDeclsInModules{false};
   };
 
   MatchFinder(MatchFinderOptions Options = MatchFinderOptions());
diff --git a/clang/lib/ASTMatchers/ASTMatchFinder.cpp b/clang/lib/ASTMatchers/ASTMatchFinder.cpp
index 83ffae65c67d4..004a02c279099 100644
--- a/clang/lib/ASTMatchers/ASTMatchFinder.cpp
+++ b/clang/lib/ASTMatchers/ASTMatchFinder.cpp
@@ -20,6 +20,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/DeclCXX.h"
 #include "clang/AST/RecursiveASTVisitor.h"
+#include "clang/Basic/Module.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/StringMap.h"
@@ -1511,6 +1512,9 @@ bool MatchASTVisitor::TraverseDecl(Decl *DeclNode) {
   if (shouldSkipNode(DeclNode))
     return true;
 
+  if (Options.SkipDeclsInModules && DeclNode->isInAnotherModuleUnit())
+    return true;
+
   bool ScopedTraversal =
       TraversingASTNodeNotSpelledInSource || DeclNode->isImplicit();
   bool ScopedChildren = TraversingASTChildrenNotSpelledInSource;