[include-cleaner] Ignore the ParmVarDecl itself in WalkAST.cpp

[hokein]

Summary

This will fix a false positive where a ParamVarDecl happend to be the
same name of some C standard symbol and has a global namespace.

using A = int(int time); // we suggest <ctime> for the `int time`.

[kadircet]

thanks!

clang-tools-extra/include-cleaner/lib/WalkAST.cpp

219

s/isa/llvm::isa/

clang-tools-extra/include-cleaner/unittests/AnalysisTest.cpp

101

no need for this one, as we already have a param in bar. can you just move the comment near that one instead?

clang-tools-extra/include-cleaner/lib/WalkAST.cpp

public:
 
   bool VisitFunctionDecl(FunctionDecl *FD) {
     // Mark declaration from definition as it needs type-checking.
     if (FD->isThisDeclarationADefinition())
       report(FD->getLocation(), FD);
     return true;
   }
   bool VisitVarDecl(VarDecl *VD) {
+    // Ignore the parameter decl itself (its children were handled elsewhere),
+    // as they don't contribute to the main-file #include.
+    if (isa<ParmVarDecl>(VD))
+      return true;
     // Mark declaration from definition as it needs type-checking.
     if (VD->isThisDeclarationADefinition())
       report(VD->getLocation(), VD);
     return true;
   }
 
   bool VisitEnumDecl(EnumDecl *D) {
     // Definition of an enum with an underlying type references declaration for

clang-tools-extra/include-cleaner/unittests/AnalysisTest.cpp

protected:
   }
 };
 
 TEST_F(WalkUsedTest, Basic) {
   llvm::Annotations Code(R"cpp(
   #include "header.h"
   #include "private.h"
 
-  void $bar^bar($private^Private $p^p) {
+  void $bar^bar($private^Private p) {
     $foo^foo();
     std::$vector^vector $vconstructor^$v^v;
     $builtin^__builtin_popcount(1);
     std::$move^move(3);
   }
+  // No reference reported for the Parameter.
+  using A = int(int time);
   )cpp");
   Inputs.Code = Code.code();
   Inputs.ExtraFiles["header.h"] = guard(R"cpp(
   void foo();
   namespace std { class vector {}; int&& move(int&&); }
   )cpp");
   Inputs.ExtraFiles["private.h"] = guard(R"cpp(
     // IWYU pragma: private, include "path/public.h"
     class Private {};
   )cpp");
 
   TestAST AST(Inputs);
   auto &SM = AST.sourceManager();
   auto HeaderFile = Header(AST.fileManager().getFile("header.h").get());
   auto PrivateFile = Header(AST.fileManager().getFile("private.h").get());
   auto PublicFile = Header("\"path/public.h\"");
   auto MainFile = Header(SM.getFileEntryForID(SM.getMainFileID()));
   auto VectorSTL = Header(*tooling::stdlib::Header::named("<vector>"));
   auto UtilitySTL = Header(*tooling::stdlib::Header::named("<utility>"));
   EXPECT_THAT(
       offsetToProviders(AST, SM),
       UnorderedElementsAre(
           Pair(Code.point("bar"), UnorderedElementsAre(MainFile)),
-          Pair(Code.point("p"), UnorderedElementsAre(MainFile)),
           Pair(Code.point("private"),
                UnorderedElementsAre(PublicFile, PrivateFile)),
           Pair(Code.point("foo"), UnorderedElementsAre(HeaderFile)),
           Pair(Code.point("vector"), UnorderedElementsAre(VectorSTL)),
           Pair(Code.point("vconstructor"), UnorderedElementsAre(VectorSTL)),
           Pair(Code.point("v"), UnorderedElementsAre(MainFile)),
           Pair(Code.point("builtin"), testing::IsEmpty()),
           Pair(Code.point("move"), UnorderedElementsAre(UtilitySTL))));