Make clang's rewrite engine a core feature

The rewrite facility's footprint is small so it's not worth going to these
lengths to support disabling at configure time, particularly since key compiler
features now depend on it.

Meanwhile the Objective-C rewriters have been moved under the
ENABLE_CLANG_ARCMT umbrella for now as they're comparatively heavy and still
potentially worth excluding from lightweight builds.

Tests are now passing with any combination of feature flags. The flags
historically haven't been tested by LLVM's build servers so caveat emptor.

llvm-svn: 213171

1 files changed, 200 insertions, 0 deletions

diff --git a/clang/lib/Frontend/Rewrite/FixItRewriter.cpp b/clang/lib/Frontend/Rewrite/FixItRewriter.cpp
new file mode 100644
index 00000000000..8b7af7166c8
--- /dev/null
+++ b/clang/lib/Frontend/Rewrite/FixItRewriter.cpp
@@ -0,0 +1,200 @@
+//===--- FixItRewriter.cpp - Fix-It Rewriter Diagnostic Client --*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This is a diagnostic client adaptor that performs rewrites as
+// suggested by code modification hints attached to diagnostics. It
+// then forwards any diagnostics to the adapted diagnostic client.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Rewrite/Frontend/FixItRewriter.h"
+#include "clang/Basic/FileManager.h"
+#include "clang/Basic/SourceLocation.h"
+#include "clang/Basic/SourceManager.h"
+#include "clang/Edit/Commit.h"
+#include "clang/Edit/EditsReceiver.h"
+#include "clang/Frontend/FrontendDiagnostic.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/raw_ostream.h"
+#include <cstdio>
+#include <memory>
+
+using namespace clang;
+
+FixItRewriter::FixItRewriter(DiagnosticsEngine &Diags, SourceManager &SourceMgr,
+                             const LangOptions &LangOpts,
+                             FixItOptions *FixItOpts)
+  : Diags(Diags),
+    Editor(SourceMgr, LangOpts),
+    Rewrite(SourceMgr, LangOpts),
+    FixItOpts(FixItOpts),
+    NumFailures(0),
+    PrevDiagSilenced(false) {
+  OwnsClient = Diags.ownsClient();
+  Client = Diags.takeClient();
+  Diags.setClient(this);
+}
+
+FixItRewriter::~FixItRewriter() {
+  Diags.takeClient();
+  Diags.setClient(Client, OwnsClient);
+}
+
+bool FixItRewriter::WriteFixedFile(FileID ID, raw_ostream &OS) {
+  const RewriteBuffer *RewriteBuf = Rewrite.getRewriteBufferFor(ID);
+  if (!RewriteBuf) return true;
+  RewriteBuf->write(OS);
+  OS.flush();
+  return false;
+}
+
+namespace {
+
+class RewritesReceiver : public edit::EditsReceiver {
+  Rewriter &Rewrite;
+
+public:
+  RewritesReceiver(Rewriter &Rewrite) : Rewrite(Rewrite) { }
+
+  void insert(SourceLocation loc, StringRef text) override {
+    Rewrite.InsertText(loc, text);
+  }
+  void replace(CharSourceRange range, StringRef text) override {
+    Rewrite.ReplaceText(range.getBegin(), Rewrite.getRangeSize(range), text);
+  }
+};
+
+}
+
+bool FixItRewriter::WriteFixedFiles(
+            std::vector<std::pair<std::string, std::string> > *RewrittenFiles) {
+  if (NumFailures > 0 && !FixItOpts->FixWhatYouCan) {
+    Diag(FullSourceLoc(), diag::warn_fixit_no_changes);
+    return true;
+  }
+
+  RewritesReceiver Rec(Rewrite);
+  Editor.applyRewrites(Rec);
+
+  for (iterator I = buffer_begin(), E = buffer_end(); I != E; ++I) {
+    const FileEntry *Entry = Rewrite.getSourceMgr().getFileEntryForID(I->first);
+    int fd;
+    std::string Filename = FixItOpts->RewriteFilename(Entry->getName(), fd);
+    std::string Err;
+    std::unique_ptr<llvm::raw_fd_ostream> OS;
+    if (fd != -1) {
+      OS.reset(new llvm::raw_fd_ostream(fd, /*shouldClose=*/true));
+    } else {
+      OS.reset(new llvm::raw_fd_ostream(Filename.c_str(), Err,
+                                        llvm::sys::fs::F_None));
+    }
+    if (!Err.empty()) {
+      Diags.Report(clang::diag::err_fe_unable_to_open_output)
+          << Filename << Err;
+      continue;
+    }
+    RewriteBuffer &RewriteBuf = I->second;
+    RewriteBuf.write(*OS);
+    OS->flush();
+
+    if (RewrittenFiles)
+      RewrittenFiles->push_back(std::make_pair(Entry->getName(), Filename));
+  }
+
+  return false;
+}
+
+bool FixItRewriter::IncludeInDiagnosticCounts() const {
+  return Client ? Client->IncludeInDiagnosticCounts() : true;
+}
+
+void FixItRewriter::HandleDiagnostic(DiagnosticsEngine::Level DiagLevel,
+                                     const Diagnostic &Info) {
+  // Default implementation (Warnings/errors count).
+  DiagnosticConsumer::HandleDiagnostic(DiagLevel, Info);
+
+  if (!FixItOpts->Silent ||
+      DiagLevel >= DiagnosticsEngine::Error ||
+      (DiagLevel == DiagnosticsEngine::Note && !PrevDiagSilenced) ||
+      (DiagLevel > DiagnosticsEngine::Note && Info.getNumFixItHints())) {
+    Client->HandleDiagnostic(DiagLevel, Info);
+    PrevDiagSilenced = false;
+  } else {
+    PrevDiagSilenced = true;
+  }
+
+  // Skip over any diagnostics that are ignored or notes.
+  if (DiagLevel <= DiagnosticsEngine::Note)
+    return;
+  // Skip over errors if we are only fixing warnings.
+  if (DiagLevel >= DiagnosticsEngine::Error && FixItOpts->FixOnlyWarnings) {
+    ++NumFailures;
+    return;
+  }
+
+  // Make sure that we can perform all of the modifications we
+  // in this diagnostic.
+  edit::Commit commit(Editor);
+  for (unsigned Idx = 0, Last = Info.getNumFixItHints();
+       Idx < Last; ++Idx) {
+    const FixItHint &Hint = Info.getFixItHint(Idx);
+
+    if (Hint.CodeToInsert.empty()) {
+      if (Hint.InsertFromRange.isValid())
+        commit.insertFromRange(Hint.RemoveRange.getBegin(),
+                           Hint.InsertFromRange, /*afterToken=*/false,
+                           Hint.BeforePreviousInsertions);
+      else
+        commit.remove(Hint.RemoveRange);
+    } else {
+      if (Hint.RemoveRange.isTokenRange() ||
+          Hint.RemoveRange.getBegin() != Hint.RemoveRange.getEnd())
+        commit.replace(Hint.RemoveRange, Hint.CodeToInsert);
+      else
+        commit.insert(Hint.RemoveRange.getBegin(), Hint.CodeToInsert,
+                    /*afterToken=*/false, Hint.BeforePreviousInsertions);
+    }
+  }
+  bool CanRewrite = Info.getNumFixItHints() > 0 && commit.isCommitable();
+
+  if (!CanRewrite) {
+    if (Info.getNumFixItHints() > 0)
+      Diag(Info.getLocation(), diag::note_fixit_in_macro);
+
+    // If this was an error, refuse to perform any rewriting.
+    if (DiagLevel >= DiagnosticsEngine::Error) {
+      if (++NumFailures == 1)
+        Diag(Info.getLocation(), diag::note_fixit_unfixed_error);
+    }
+    return;
+  }
+  
+  if (!Editor.commit(commit)) {
+    ++NumFailures;
+    Diag(Info.getLocation(), diag::note_fixit_failed);
+    return;
+  }
+
+  Diag(Info.getLocation(), diag::note_fixit_applied);
+}
+
+/// \brief Emit a diagnostic via the adapted diagnostic client.
+void FixItRewriter::Diag(SourceLocation Loc, unsigned DiagID) {
+  // When producing this diagnostic, we temporarily bypass ourselves,
+  // clear out any current diagnostic, and let the downstream client
+  // format the diagnostic.
+  Diags.takeClient();
+  Diags.setClient(Client);
+  Diags.Clear();
+  Diags.Report(Loc, DiagID);
+  Diags.takeClient();
+  Diags.setClient(this);
+}
+
+FixItOptions::~FixItOptions() {}