[clang-format] [RELAND] Remove the dependency on frontend

[MyDeveloperDay]

Summary

relanding D68969: [clang-format] Remove the dependency on frontend after it failed UBSAN build caused by the passing of an invalid SMLoc() (nullptr)

[merge_guards_bot]

Build result: fail - 33803 tests passed, 1 failed and 462 were skipped.

failed: LLVM.Object/macho-invalid.test

Log files: console-log.txt, CMakeCache.txt

[MyDeveloperDay]

In D69854#1734222, @merge_guards_bot wrote:

Build result: fail - 33803 tests passed, 1 failed and 462 were skipped.

failed: LLVM.Object/macho-invalid.test

Log files: console-log.txt, CMakeCache.txt

pretty sure this pre merge failure is unrelated.

[thakis]

Thanks! One comment (the stale pointer one) and a more general suggestion (potentially for a future change) below, else I think this is good to go.

clang/tools/clang-format/ClangFormat.cpp

310

Maybe not for this change, but do you need all this machinery up here? SMDiagnostics takes a pointer and a file name, so yu can just pass Code->getBufferStart() + R.getOffset() for the pointer and you don't need the FileManager, the SourceManager, createInMemoryFile(), the PresumedLoc, translateFileLineCol.

You can either try to use SourceMgr::getLineAndColumn() or compute line/col yourself -- either should be a lot less code than the current machinery here.

335

I think the idea is that you have a llvm::SourceMgr() hanging around (above the loop or somewhere). SMDiagnostic stores a pointer to this argument, and you pass in a temporary. The SourceMgr needs to outlive the Diags object. (In practice, the pointer is not used by anything so it happens to work, but having the object store a stale pointer seems like potential future trouble, and it's easy to prevent -- just put the SourceMgr on the stack).

Also, probably "Diag", not "Diags"?

[MyDeveloperDay]

clang/tools/clang-format/ClangFormat.cpp

310

So I definitely agree here, I'm afraid I shamelessly copied this from elsewhere.. but I see there should be a better way, let me work on that separately and if its ok I'll send a later review your way.

For now let me reland the frontEnd removal, with your suggested change before.

335

I made the suggested changes just prior to landing, hope that is ok.

clang/tools/clang-format/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS support)
 
 add_clang_tool(clang-format
   ClangFormat.cpp
   )
 
 set(CLANG_FORMAT_LIB_DEPS
   clangBasic
   clangFormat
-  clangFrontend
   clangRewrite
   clangToolingCore
   )
 
 clang_target_link_libraries(clang-format
   PRIVATE
   ${CLANG_FORMAT_LIB_DEPS}
   )

clang/tools/clang-format/ClangFormat.cpp

 //===----------------------------------------------------------------------===//
 
 #include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/DiagnosticOptions.h"
 #include "clang/Basic/FileManager.h"
 #include "clang/Basic/SourceManager.h"
 #include "clang/Basic/Version.h"
 #include "clang/Format/Format.h"
-#include "clang/Frontend/TextDiagnosticPrinter.h"
 #include "clang/Rewrite/Core/Rewriter.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/InitLLVM.h"
 #include "llvm/Support/Process.h"
 
 using namespace llvm;
 using clang::tooling::Replacements;
emitReplacementWarnings(const Replacements &Replaces, StringRef AssumedFileName,
                         const std::unique_ptr<llvm::MemoryBuffer> &Code) {
   if (Replaces.empty()) {
     return false;
   }
 
   IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
   DiagOpts->ShowColors = (ShowColors && !NoShowColors);
 
-  TextDiagnosticPrinter *DiagsBuffer =
-      new TextDiagnosticPrinter(llvm::errs(), &*DiagOpts, false);
-
   IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
   IntrusiveRefCntPtr<DiagnosticsEngine> Diags(
-      new DiagnosticsEngine(DiagID, &*DiagOpts, DiagsBuffer));
+      new DiagnosticsEngine(DiagID, &*DiagOpts));
 
   IntrusiveRefCntPtr<llvm::vfs::InMemoryFileSystem> InMemoryFileSystem(
       new llvm::vfs::InMemoryFileSystem);
   FileManager Files(FileSystemOptions(), InMemoryFileSystem);
   SourceManager Sources(*Diags, Files);
   FileID FileID = createInMemoryFile(AssumedFileName, Code.get(), Sources,
                                      Files, InMemoryFileSystem.get());
 
-  const unsigned ID = Diags->getCustomDiagID(
-      WarningsAsErrors ? clang::DiagnosticsEngine::Error
-                       : clang::DiagnosticsEngine::Warning,
-      "code should be clang-formatted [-Wclang-format-violations]");
+  FileManager &FileMgr = Sources.getFileManager();
+  llvm::ErrorOr<const FileEntry *> FileEntryPtr =
+      FileMgr.getFile(AssumedFileName);
 
   unsigned Errors = 0;
-  DiagsBuffer->BeginSourceFile(LangOptions(), nullptr);
   if (WarnFormat && !NoWarnFormat) {
+    llvm::SourceMgr Mgr;
     for (const auto &R : Replaces) {
-      Diags->Report(
-          Sources.getLocForStartOfFile(FileID).getLocWithOffset(R.getOffset()),
-          ID);
+      PresumedLoc PLoc = Sources.getPresumedLoc(
+          Sources.getLocForStartOfFile(FileID).getLocWithOffset(R.getOffset()));
+
+      SourceLocation LineBegin =
+          Sources.translateFileLineCol(FileEntryPtr.get(), PLoc.getLine(), 1);
+      SourceLocation NextLineBegin = Sources.translateFileLineCol(
+          FileEntryPtr.get(), PLoc.getLine() + 1, 1);
+
+      const char *StartBuf = Sources.getCharacterData(LineBegin);
+      const char *EndBuf = Sources.getCharacterData(NextLineBegin);
+
+      StringRef Line(StartBuf, (EndBuf - StartBuf) - 1);
+
+      SMDiagnostic Diag(
+          Mgr, SMLoc::getFromPointer(StartBuf), AssumedFileName,
+          PLoc.getLine(), PLoc.getColumn(),
+          WarningsAsErrors ? SourceMgr::DiagKind::DK_Error
+                           : SourceMgr::DiagKind::DK_Warning,
+          "code should be clang-formatted [-Wclang-format-violations]", Line,
+          ArrayRef<std::pair<unsigned, unsigned>>());
+
+      Diag.print(nullptr, llvm::errs(), (ShowColors && !NoShowColors));
       Errors++;
       if (ErrorLimit && Errors >= ErrorLimit)
         break;
     }
   }
-  DiagsBuffer->EndSourceFile();
   return WarningsAsErrors;
 }
 
 static void outputXML(const Replacements &Replaces,
                       const Replacements &FormatChanges,
                       const FormattingAttemptStatus &Status,
                       const cl::opt<unsigned> &Cursor,
                       unsigned CursorPosition) {