[include-cleaner] Use RAV instead of ASTMatchers in LocateSymbolTest

[kadircet]

Summary

ASTMatchers are pulling in lots of dependencies that we don't really
need for just finding a decl based on name. So use a simple RAV instead.

[sammccall]

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

60

you might want to EXPECT_EQ(Out, nullptr) first to ensure only a single match

(A single match for a name may not generalize well, but the matching would have to be made more specific regardless in that case)

[kadircet]

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

60

we expect to see multiple declarations for the same entity anyway though, so instead of asserting null, i'll assert same canonical or null.

clang-tools-extra/include-cleaner/unittests/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
-  FrontendOpenMP
   Support
   TestingSupport
   )
 
 add_custom_target(ClangIncludeCleanerUnitTests)
 add_unittest(ClangIncludeCleanerUnitTests ClangIncludeCleanerTests
   AnalysisTest.cpp
   FindHeadersTest.cpp
   LocateSymbolTest.cpp
   RecordTest.cpp
   TypesTest.cpp
   WalkASTTest.cpp
 )
 
 target_include_directories(ClangIncludeCleanerTests
   PRIVATE
   ${CMAKE_CURRENT_SOURCE_DIR}/../lib)
 
 clang_target_link_libraries(ClangIncludeCleanerTests
   PRIVATE
   clangAST
-  clangASTMatchers
   clangBasic
   clangFrontend
   clangLex
   clangToolingInclusionsStdlib
   )
 
 target_link_libraries(ClangIncludeCleanerTests
   PRIVATE
   clangIncludeCleaner
   clangTesting
   LLVMTestingSupport
   )
 

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

 //===--- LocateSymbolTest.cpp -------------------------------------- C++-*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 #include "AnalysisInternal.h"
 #include "clang-include-cleaner/Types.h"
 #include "clang/AST/Decl.h"
 #include "clang/AST/DeclBase.h"
-#include "clang/ASTMatchers/ASTMatchFinder.h"
-#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/AST/RecursiveASTVisitor.h"
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Testing/TestAST.h"
 #include "clang/Tooling/Inclusions/StandardLibrary.h"
 #include "llvm/ADT/StringRef.h"
-#include "llvm/Support/Casting.h"
 #include "llvm/Testing/Support/Annotations.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 #include <cstddef>
 #include <memory>
 #include <unordered_map>
 #include <utility>
 #include <variant>
public:
   LocateExample(llvm::StringRef AnnotatedCode)
       : Target(AnnotatedCode), AST([this] {
           TestInputs Inputs(Target.code());
           Inputs.ExtraArgs.push_back("-std=c++17");
           return Inputs;
         }()) {}
 
   const Decl &findDecl(llvm::StringRef SymbolName) {
-    const NamedDecl *DeclToLocate;
-    struct MatchCB : public ast_matchers::MatchFinder::MatchCallback {
-      MatchCB(const NamedDecl *&Out) : Out(Out) {}
-      void run(const ast_matchers::MatchFinder::MatchResult &Result) override {
-        Out = Result.Nodes.getNodeAs<NamedDecl>("id");
-        assert(Out);
-        Out = llvm::cast<NamedDecl>(Out->getCanonicalDecl());
-      }
-      const NamedDecl *&Out;
-    } CB(DeclToLocate);
-    ast_matchers::MatchFinder Finder;
-    Finder.addMatcher(ast_matchers::namedDecl(
-                          ast_matchers::unless(ast_matchers::isImplicit()),
-                          ast_matchers::hasName(SymbolName))
-                          .bind("id"),
-                      &CB);
-    Finder.matchAST(AST.context());
-    if (!DeclToLocate)
+    struct Visitor : RecursiveASTVisitor<Visitor> {
+      llvm::StringRef NameToFind;
+      const NamedDecl *Out = nullptr;
+      bool VisitNamedDecl(const NamedDecl *ND) {
+        if (ND->getName() != NameToFind)
+          return true;
+        Out = ND;
+        return false;
+      }
+    };
+    Visitor V;
+    V.NameToFind = SymbolName;
+    V.TraverseDecl(AST.context().getTranslationUnitDecl());
+    if (!V.Out)
       ADD_FAILURE() << "Couldn't find any decls with name: " << SymbolName;
-    assert(DeclToLocate);
-    return *DeclToLocate;
+    assert(V.Out);
+    return *V.Out;
   }
 
   Macro findMacro(llvm::StringRef Name) {
     auto &PP = AST.preprocessor();
     auto *II = PP.getIdentifierInfo(Name);
     if (!II || !II->hasMacroDefinition()) {
       ADD_FAILURE() << "Couldn't find any macros with name: " << Name;
       return {};