[fixit] Use overwriteChangedFiles() to deal with Windows mapped files

Fixes one instance of PR17960.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@239920 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Rewrite/Frontend/FixItRewriter.h

@@ -27,7 +27,7 @@ class FileEntry;
 
 class FixItOptions {
 public:
-  FixItOptions() : FixWhatYouCan(false),
+  FixItOptions() : InPlace(false), FixWhatYouCan(false),
                    FixOnlyWarnings(false), Silent(false) { }
 
   virtual ~FixItOptions();
@@ -41,6 +41,10 @@ public:
   ///
   virtual std::string RewriteFilename(const std::string &Filename, int &fd) = 0;
 
+  /// True if files should be updated in place. RewriteFilename is only called
+  /// if this is false.
+  bool InPlace;
+
   /// \brief Whether to abort fixing a file when not all errors could be fixed.
   bool FixWhatYouCan;
 

lib/Frontend/Rewrite/FixItRewriter.cpp

@@ -81,6 +81,13 @@ bool FixItRewriter::WriteFixedFiles(
   RewritesReceiver Rec(Rewrite);
   Editor.applyRewrites(Rec);
 
+  if (FixItOpts->InPlace) {
+    // Overwriting open files on Windows is tricky, but the rewriter can do it
+    // for us.
+    Rewrite.overwriteChangedFiles();
+    return false;
+  }
+
   for (iterator I = buffer_begin(), E = buffer_end(); I != E; ++I) {
     const FileEntry *Entry = Rewrite.getSourceMgr().getFileEntryForID(I->first);
     int fd;

lib/Frontend/Rewrite/FrontendActions.cpp

@@ -48,9 +48,10 @@ FixItAction::CreateASTConsumer(CompilerInstance &CI, StringRef InFile) {
 namespace {
 class FixItRewriteInPlace : public FixItOptions {
 public:
+  FixItRewriteInPlace() { InPlace = true; }
+
   std::string RewriteFilename(const std::string &Filename, int &fd) override {
-    fd = -1;
-    return Filename;
+    llvm_unreachable("don't call RewriteFilename for inplace rewrites");
   }
 };