[clang-tidy] Simplify function complexity check

[steveire]

Summary

Update test to note use of lambda instead of the invisible operator().

[njames93]

clang-tools-extra/clang-tidy/readability/FunctionCognitiveComplexityCheck.cpp

508

Am I right in assuming lambdas need to be explicitly matched because in the traversal mode their operator() isn't matched as a functionDecl?

[steveire]

clang-tools-extra/clang-tidy/readability/FunctionCognitiveComplexityCheck.cpp

508

Yes.

[njames93]

Can you have a look at the failed tests, they seem to be related.

[steveire]

Trigger rebuild

[steveire]

Fix test

clang-tools-extra/clang-tidy/readability/FunctionCognitiveComplexityCheck.h

 /// http://clang.llvm.org/extra/clang-tidy/checks/readability-function-cognitive-complexity.html
 class FunctionCognitiveComplexityCheck : public ClangTidyCheck {
 public:
   FunctionCognitiveComplexityCheck(StringRef Name, ClangTidyContext *Context);
 
   void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
   void registerMatchers(ast_matchers::MatchFinder *Finder) override;
   void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+  llvm::Optional<TraversalKind> getCheckTraversalKind() const override {
+    return TK_IgnoreUnlessSpelledInSource;
+  }
 
 private:
   const unsigned Threshold;
 };
 
 } // namespace readability
 } // namespace tidy
 } // namespace clang
 
 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_FUNCTIONCOGNITIVECOMPLEXITYCHECK_H

clang-tools-extra/clang-tidy/readability/FunctionCognitiveComplexityCheck.cpp

 void FunctionCognitiveComplexityCheck::storeOptions(
     ClangTidyOptions::OptionMap &Opts) {
   Options.store(Opts, "Threshold", Threshold);
 }
 
 void FunctionCognitiveComplexityCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(
       functionDecl(isDefinition(),
-                   unless(anyOf(isDefaulted(), isDeleted(), isImplicit(),
-                                isInstantiated(), isWeak())))
+                   unless(anyOf(isDefaulted(), isDeleted(), isWeak())))
           .bind("func"),
       this);
+  Finder->addMatcher(lambdaExpr().bind("lambda"), this);
 }
 
 void FunctionCognitiveComplexityCheck::check(
     const MatchFinder::MatchResult &Result) {
-  const auto *Func = Result.Nodes.getNodeAs<FunctionDecl>("func");
-  assert(Func->hasBody() && "The matchers should only match the functions that "
-                            "have user-provided body.");
 
   FunctionASTVisitor Visitor;
-  Visitor.TraverseDecl(const_cast<FunctionDecl *>(Func), true);
+  SourceLocation Loc;
+
+  const auto *TheDecl = Result.Nodes.getNodeAs<FunctionDecl>("func");
+  const auto *TheLambdaExpr = Result.Nodes.getNodeAs<LambdaExpr>("lambda");
+  if (TheDecl) {
+    assert(TheDecl->hasBody() &&
+           "The matchers should only match the functions that "
+           "have user-provided body.");
+    Loc = TheDecl->getLocation();
+    Visitor.TraverseDecl(const_cast<FunctionDecl *>(TheDecl), true);
+  } else {
+    Loc = TheLambdaExpr->getBeginLoc();
+    Visitor.TraverseLambdaExpr(const_cast<LambdaExpr *>(TheLambdaExpr));
+  }
 
   if (Visitor.CC.Total <= Threshold)
     return;
 
-  diag(Func->getLocation(),
-       "function %0 has cognitive complexity of %1 (threshold %2)")
-      << Func << Visitor.CC.Total << Threshold;
+  if (TheDecl)
+    diag(Loc, "function %0 has cognitive complexity of %1 (threshold %2)")
+        << TheDecl << Visitor.CC.Total << Threshold;
+  else
+    diag(Loc, "lambda has cognitive complexity of %0 (threshold %1)")
+        << Visitor.CC.Total << Threshold;
 
   // Output all the basic increments of complexity.
   for (const auto &Detail : Visitor.CC.Details) {
     unsigned MsgId;          // The id of the message to output.
     unsigned short Increase; // How much of an increment?
     std::tie(MsgId, Increase) = Detail.process();
     assert(MsgId < Msgs.size() && "MsgId should always be valid");
     // Increase, on the other hand, can be 0.

clang-tools-extra/test/clang-tidy/checkers/readability-function-cognitive-complexity.cpp

// CHECK-NOTES: :[[@LINE-1]]:6: warning: function 'unittest_b2_08_02' has cognitive complexity of 2 (threshold 0) [readability-function-cognitive-complexity]
   CC100;
 
   auto fun = []() {
 // CHECK-NOTES: :[[@LINE-1]]:14: note: nesting level increased to 1{{$}}
     if (true) {
 // CHECK-NOTES: :[[@LINE-1]]:5: note: +2, including nesting penalty of 1, nesting level increased to 2{{$}}
     }
   };
-// CHECK-NOTES: :[[@LINE-6]]:14: warning: function 'operator()' has cognitive complexity of 1 (threshold 0) [readability-function-cognitive-complexity]
+// CHECK-NOTES: :[[@LINE-6]]:14: warning: lambda has cognitive complexity of 1 (threshold 0) [readability-function-cognitive-complexity]
 // CHECK-NOTES: :[[@LINE-5]]:5: note: +1, including nesting penalty of 0, nesting level increased to 1{{$}}
 }
 
 void unittest_b2_09() {
 // CHECK-NOTES: :[[@LINE-1]]:6: warning: function 'unittest_b2_09' has cognitive complexity of 2 (threshold 0) [readability-function-cognitive-complexity]
   CC100;
 
   ({