[analyzer][CTU] Correctly signal in the function index generation tool if there was an error

[xazax.hun]

Summary

Do not always return 0 to the OS. This will make it easier for orchestration tools like CodeChecker to detect errors.
Also small NFC cleanups along the way.

[xazax.hun]

• Remove yet another dependency from the tool that is no longer used.

[martong]

Looks good to me. It is great to see that we can get rid of so many header and lib dependencies.

[Szelethus]

Makes sense!

tools/clang-func-mapping/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
   ${LLVM_TARGETS_TO_BUILD}
-  asmparser
   support
-  mc
   )
 
 add_clang_executable(clang-func-mapping
   ClangFnMapGen.cpp
   )
 
 target_link_libraries(clang-func-mapping
   PRIVATE
   clangAST
   clangBasic
   clangCrossTU
   clangFrontend
-  clangIndex
   clangTooling
   )
 
 install(TARGETS clang-func-mapping
   RUNTIME DESTINATION bin)

tools/clang-func-mapping/ClangFnMapGen.cpp

 //===- ClangFnMapGen.cpp -----------------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===--------------------------------------------------------------------===//
 //
 // Clang tool which creates a list of defined functions and the files in which
 // they are defined.
 //
 //===--------------------------------------------------------------------===//
 
 #include "clang/AST/ASTConsumer.h"
 #include "clang/AST/ASTContext.h"
-#include "clang/AST/GlobalDecl.h"
-#include "clang/AST/Mangle.h"
-#include "clang/AST/StmtVisitor.h"
 #include "clang/Basic/SourceManager.h"
-#include "clang/Basic/TargetInfo.h"
 #include "clang/CrossTU/CrossTranslationUnit.h"
 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/Frontend/FrontendActions.h"
-#include "clang/Index/USRGeneration.h"
 #include "clang/Tooling/CommonOptionsParser.h"
 #include "clang/Tooling/Tooling.h"
 #include "llvm/Support/CommandLine.h"
-#include "llvm/Support/Path.h"
 #include "llvm/Support/Signals.h"
 #include <sstream>
 #include <string>
-#include <vector>
 
 using namespace llvm;
 using namespace clang;
 using namespace clang::cross_tu;
 using namespace clang::tooling;
 
 static cl::OptionCategory ClangFnMapGenCategory("clang-fnmapgen options");
 
 class MapFunctionNamesConsumer : public ASTConsumer {
 public:
-  MapFunctionNamesConsumer(ASTContext &Context) : Ctx(Context) {}
+  MapFunctionNamesConsumer(ASTContext &Context)
+      : SM(Context.getSourceManager()) {}
 
   ~MapFunctionNamesConsumer() {
     // Flush results to standard output.
     llvm::outs() << createCrossTUIndexString(Index);
   }
 
-  virtual void HandleTranslationUnit(ASTContext &Ctx) {
+  void HandleTranslationUnit(ASTContext &Ctx) override {
     handleDecl(Ctx.getTranslationUnitDecl());
   }
 
 private:
   void handleDecl(const Decl *D);
 
-  ASTContext &Ctx;
+  SourceManager &SM;
   llvm::StringMap<std::string> Index;
   std::string CurrentFileName;
 };
 
 void MapFunctionNamesConsumer::handleDecl(const Decl *D) {
   if (!D)
     return;
 
   if (const auto *FD = dyn_cast<FunctionDecl>(D)) {
     if (FD->isThisDeclarationADefinition()) {
       if (const Stmt *Body = FD->getBody()) {
-        std::string LookupName = CrossTranslationUnitContext::getLookupName(FD);
-        const SourceManager &SM = Ctx.getSourceManager();
         if (CurrentFileName.empty()) {
           CurrentFileName =
               SM.getFileEntryForID(SM.getMainFileID())->tryGetRealPathName();
           if (CurrentFileName.empty())
             CurrentFileName = "invalid_file";
         }
 
         switch (FD->getLinkageInternal()) {
         case ExternalLinkage:
         case VisibleNoLinkage:
         case UniqueExternalLinkage:
-          if (SM.isInMainFile(Body->getBeginLoc()))
+          if (SM.isInMainFile(Body->getBeginLoc())) {
+            std::string LookupName =
+                CrossTranslationUnitContext::getLookupName(FD);
             Index[LookupName] = CurrentFileName;
+          }
         default:
           break;
         }
       }
     }
   }
 
   if (const auto *DC = dyn_cast<DeclContext>(D))
     for (const Decl *D : DC->decls())
       handleDecl(D);
 }
 
 class MapFunctionNamesAction : public ASTFrontendAction {
 protected:
   std::unique_ptr<ASTConsumer> CreateASTConsumer(CompilerInstance &CI,
                                                  llvm::StringRef) {
-    std::unique_ptr<ASTConsumer> PFC(
-        new MapFunctionNamesConsumer(CI.getASTContext()));
-    return PFC;
+    return llvm::make_unique<MapFunctionNamesConsumer>(CI.getASTContext());
   }
 };
 
 static cl::extrahelp CommonHelp(CommonOptionsParser::HelpMessage);
 
 int main(int argc, const char **argv) {
   // Print a stack trace if we signal out.
   sys::PrintStackTraceOnErrorSignal(argv[0], false);
   PrettyStackTraceProgram X(argc, argv);
 
   const char *Overview = "\nThis tool collects the USR name and location "
                          "of all functions definitions in the source files "
                          "(excluding headers).\n";
   CommonOptionsParser OptionsParser(argc, argv, ClangFnMapGenCategory,
                                     cl::ZeroOrMore, Overview);
 
   ClangTool Tool(OptionsParser.getCompilations(),
                  OptionsParser.getSourcePathList());
-  Tool.run(newFrontendActionFactory<MapFunctionNamesAction>().get());
-  return 0;
+  
+  return Tool.run(newFrontendActionFactory<MapFunctionNamesAction>().get());
 }