Move unittest helpers to a shared location

[gribozavr]

Summary

unittests/AST/Language.h defines some helpers that we would like to
reuse in other tests, for example, in tests for syntax trees.

[gribozavr]

Removed some refactoring leftovers.

[gribozavr]

Added a modulemap entry for the new Clang library.

[gribozavr]

Fixed a clang-tidy warning about header guard format.

clang/include/clang/Testing/CommandLineArgs.h

-//===------ unittest/AST/Language.h - AST unit test support ---------------===//
+//===--- CommandLineArgs.h ------------------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 //
-//  This file defines language options for AST unittests.
+//  This file defines language options for Clang unittests.
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef LLVM_CLANG_UNITTESTS_AST_LANGUAGE_H
-#define LLVM_CLANG_UNITTESTS_AST_LANGUAGE_H
+#ifndef LLVM_CLANG_TESTING_COMMANDLINEARGS_H
+#define LLVM_CLANG_TESTING_COMMANDLINEARGS_H
 
-#include <vector>
 #include <string>
+#include <vector>
 
 namespace clang {
 
 enum TestLanguage {
   Lang_C,
   Lang_C89,
   Lang_CXX,
   Lang_CXX11,

clang/include/clang/module.modulemap

 }
 
 module Clang_StaticAnalyzer_Frontend {
   requires cplusplus
   umbrella "StaticAnalyzer/Frontend"
   module * { export * }
 }
 
+module Clang_Testing {
+  requires cplusplus
+  umbrella "Testing"
+  module * { export * }
+}
+
 module Clang_Tooling {
   requires cplusplus umbrella "Tooling" module * { export * }
   // FIXME: Exclude these headers to avoid pulling all of the AST matchers
   // library into clang-format. Due to inline key functions in the headers,
   // importing the AST matchers library gives a link dependency on the AST
   // matchers (and thus the AST), which clang-format should not have.
   exclude header "Tooling/RefactoringCallbacks.h"
 }

clang/lib/CMakeLists.txt

 add_subdirectory(FrontendTool)
 add_subdirectory(Tooling)
 add_subdirectory(DirectoryWatcher)
 add_subdirectory(Index)
 if(CLANG_ENABLE_STATIC_ANALYZER)
   add_subdirectory(StaticAnalyzer)
 endif()
 add_subdirectory(Format)
+add_subdirectory(Testing)

clang/lib/Testing/CMakeLists.txt

+set(LLVM_LINK_COMPONENTS
+  Support
+  )
+
+add_clang_library(clangTesting
+  CommandLineArgs.cpp
+  )

clang/lib/Testing/CommandLineArgs.cpp

-//===------ unittest/AST/Language.cpp - AST unit test support -------------===//
+//===--- CommandLineArgs.cpp ----------------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
-//
-//  This file defines language options for AST unittests.
-//
-//===----------------------------------------------------------------------===//
 
-#include "Language.h"
+#include "clang/Testing/CommandLineArgs.h"
 #include "llvm/Support/ErrorHandling.h"
 
 namespace clang {
 
 std::vector<std::string> getCommandLineArgsForTesting(TestLanguage Lang) {
   std::vector<std::string> Args;
   // Test with basic arguments.
   switch (Lang) {

clang/unittests/AST/ASTImporterFixtures.h

 #ifndef LLVM_CLANG_UNITTESTS_AST_IMPORTER_FIXTURES_H
 #define LLVM_CLANG_UNITTESTS_AST_IMPORTER_FIXTURES_H
 
 #include "gmock/gmock.h"
 
 #include "clang/AST/ASTImporter.h"
 #include "clang/AST/ASTImporterSharedState.h"
 #include "clang/Frontend/ASTUnit.h"
+#include "clang/Testing/CommandLineArgs.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/ErrorHandling.h"
 
 #include "DeclMatcher.h"
-#include "Language.h"
 
 #include <sstream>
 
 namespace clang {
 
 class ASTImporter;
 class ASTImporterSharedState;
 class ASTUnit;

clang/unittests/AST/CMakeLists.txt

add_clang_unittest(ASTTests
   CommentLexer.cpp
   CommentParser.cpp
   CommentTextTest.cpp
   DataCollectionTest.cpp
   DeclPrinterTest.cpp
   DeclTest.cpp
   EvaluateAsRValueTest.cpp
   ExternalASTSourceTest.cpp
-  Language.cpp
   NamedDeclPrinterTest.cpp
   RecursiveASTVisitorTest.cpp
   SizelessTypesTest.cpp
   SourceLocationTest.cpp
   StmtPrinterTest.cpp
   StructuralEquivalenceTest.cpp
   )
 
 clang_target_link_libraries(ASTTests
   PRIVATE
   clangAST
   clangASTMatchers
   clangBasic
   clangFrontend
   clangSerialization
+  clangTesting
   clangTooling
   )
 
 target_link_libraries(ASTTests
   PRIVATE
   LLVMTestingSupport
 )

clang/unittests/AST/MatchVerifier.h

 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CLANG_UNITTESTS_AST_MATCHVERIFIER_H
 #define LLVM_CLANG_UNITTESTS_AST_MATCHVERIFIER_H
 
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/Testing/CommandLineArgs.h"
 #include "clang/Tooling/Tooling.h"
-#include "Language.h"
 #include "gtest/gtest.h"
 
 namespace clang {
 namespace ast_matchers {
 
 /// \brief Base class for verifying some property of nodes found by a matcher.
 template <typename NodeType>
 class MatchVerifier : public MatchFinder::MatchCallback {

clang/unittests/AST/StructuralEquivalenceTest.cpp

 #include "clang/AST/ASTContext.h"
 #include "clang/AST/ASTStructuralEquivalence.h"
 #include "clang/ASTMatchers/ASTMatchers.h"
 #include "clang/Frontend/ASTUnit.h"
+#include "clang/Testing/CommandLineArgs.h"
 #include "clang/Tooling/Tooling.h"
 #include "llvm/Support/Host.h"
 
-#include "Language.h"
 #include "DeclMatcher.h"
 
 #include "gtest/gtest.h"
 
 namespace clang {
 namespace ast_matchers {
 
 using std::get;