[include-cleaner] Handle decls/refs to concepts.

[sammccall]

I think we're not *that* far away from landing the AST change, and changing RecursiveASTVisitor now is probably confusing and not worth the churn.
So I'd prefer to wait for now...

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

249

after D155858 this can be VisitConceptReference

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

217 ↗

(On Diff #553448)

to complete the set I think you want

void foo(Bar auto x) (abbreviated template param) and Bar auto x = 1 (deduced type).

Though these may not pass yet

[usaxena95]

Rebased over AST changes.

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

217 ↗

(On Diff #553448)

For some reason, Bar auto x = 1 is still failing; investigating.

[sammccall]

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

244

I don't know why we're doing this, decls in general are not considered references to themselves.

Function/Var/Enum are in some cases, because their definition should be typechecked against a forward-declaration in the header. But that doesn't apply here: you can't forward-declare a concept.

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

201 ↗

(On Diff #554955)

AFAICT these are just normal AST nodes, so should be tested in WalkASTTest which is narrower and lighter-weight.

The tests in this file run a bit more code, and none of it seems specifically relevant to concepts.

[usaxena95]

Addressed comments.

[sammccall]

LGTM

Unclear to me whether the FIXME will be addressed by an AST bug or a local change, either way continuing to look into it SG but this is fine to land as-is.

[usaxena95]

closed by ac2d2652db8de9ea2b750dd2bf1232941039dffe

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

public:
   bool VisitEnumDecl(EnumDecl *D) {
     // Definition of an enum with an underlying type references declaration for
     // type-checking purposes.
     if (D->isThisDeclarationADefinition() && D->getIntegerTypeSourceInfo())
       report(D->getLocation(), D);
     return true;
   }
 
+  bool VisitConceptReference(const ConceptReference *CR) {
+    report(CR->getConceptNameLoc(), CR->getFoundDecl());
+    return true;
+  }
+
   // Report a reference from explicit specializations to the specialized
   // template. Implicit ones are filtered out by RAV and explicit instantiations
   // are already traversed through typelocs.
   bool
   VisitClassTemplateSpecializationDecl(ClassTemplateSpecializationDecl *CTSD) {
     if (CTSD->isExplicitSpecialization())
       report(CTSD->getLocation(),
              CTSD->getSpecializedTemplate()->getTemplatedDecl());
     return true;

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

TEST(WalkAST, InitializerList) {
   testWalk(R"cpp(
        namespace std {
         template <typename T> struct $implicit^initializer_list {};
        })cpp",
            R"cpp(
        const char* s = "";
        auto sx = ^{s};)cpp");
 }
+
+TEST(WalkAST, Concepts) {
+  std::string Concept = "template<typename T> concept $explicit^Foo = true;";
+  testWalk(Concept, "template<typename T>concept Bar = ^Foo<T> && true;");
+  testWalk(Concept, "template<^Foo T>void func() {}");
+  testWalk(Concept, "template<typename T> requires ^Foo<T> void func() {}");
+  testWalk(Concept, "template<typename T> void func() requires ^Foo<T> {}");
+  testWalk(Concept, "void func(^Foo auto x) {}");
+  // FIXME: Foo should be explicitly referenced.
+  testWalk("template<typename T> concept Foo = true;", "void func() { ^Foo auto x = 1; }");
+}
 } // namespace
 } // namespace clang::include_cleaner