Fix crash and disable nfs check on windows

Author: Sirraide

clang/include/clang/Basic/SourceManager.h

@@ -1854,7 +1854,14 @@ class SourceManager : public RefCountedBase<SourceManager> {
   SourceLocation getTopMacroCallerLoc(SourceLocation Loc) const;
 
   /// Retrieve the name of a file suitable for diagnostics.
-  StringRef getNameForDiagnostic(StringRef Filename) const;
+  // FIXME: Passing in the DiagnosticOptions here is a workaround for the
+  // fact that installapi does some weird things with DiagnosticsEngines,
+  // which causes the 'Diag' member of SourceManager (or at least the
+  // DiagnosticsOptions member thereof) to be a dangling reference
+  // sometimes. We should probably fix that or decouple the two classes
+  // to avoid this issue entirely.
+  StringRef getNameForDiagnostic(StringRef Filename,
+                                 const DiagnosticOptions &Opts) const;
 
 private:
   friend class ASTReader;

clang/lib/Basic/SourceManager.cpp

@@ -2404,19 +2404,36 @@ SourceManagerForFile::SourceManagerForFile(StringRef FileName,
   SourceMgr->setMainFileID(ID);
 }
 
-StringRef SourceManager::getNameForDiagnostic(StringRef Filename) const {
+StringRef
+SourceManager::getNameForDiagnostic(StringRef Filename,
+                                    const DiagnosticOptions &Opts) const {
   OptionalFileEntryRef File = getFileManager().getOptionalFileRef(Filename);
   if (!File)
     return Filename;
 
-  // Try to simplify paths that contain '..' in any case since paths to
-  // standard library headers especially tend to get quite long otherwise.
-  // Only do that for local filesystems though to avoid slowing down
-  // compilation too much.
-  bool Absolute = Diag.getDiagnosticOptions().AbsolutePath;
-  bool AlwaysSimplify = File->getName().contains("..") &&
-                        llvm::sys::fs::is_local(File->getName());
-  if (!Absolute && !AlwaysSimplify)
+  bool SimplifyPath = [&] {
+    if (Opts.AbsolutePath)
+      return true;
+
+    // Try to simplify paths that contain '..' in any case since paths to
+    // standard library headers especially tend to get quite long otherwise.
+    // Only do that for local filesystems though to avoid slowing down
+    // compilation too much.
+    if (!File->getName().contains(".."))
+      return false;
+
+    // If we're not on Windows, check if we're on a network file system and
+    // avoid simplifying the path in that case since that can be slow. On
+    // Windows, the check for a local filesystem is already slow, so skip it.
+#ifndef _WIN32
+    if (!llvm::sys::fs::is_local(File->getName()))
+      return false;
+#endif
+
+    return true;
+  }();
+
+  if (!SimplifyPath)
     return Filename;
 
   // This may involve computing canonical names, so cache the result.
@@ -2451,7 +2468,7 @@ StringRef SourceManager::getNameForDiagnostic(StringRef Filename) const {
   // In some cases, the resolved path may actually end up being longer (e.g.
   // if it was originally a relative path), so just retain whichever one
   // ends up being shorter.
-  if (!Absolute && TempBuf.size() > Filename.size())
+  if (!Opts.AbsolutePath && TempBuf.size() > Filename.size())
     CacheEntry = Filename;
   else
     CacheEntry = TempBuf.str().copy(DiagNameAlloc);

clang/lib/Frontend/SARIFDiagnostic.cpp

@@ -163,7 +163,7 @@ SARIFDiagnostic::addDiagnosticLevelToRule(SarifRule Rule,
 
 llvm::StringRef SARIFDiagnostic::emitFilename(StringRef Filename,
                                               const SourceManager &SM) {
-  return SM.getNameForDiagnostic(Filename);
+  return SM.getNameForDiagnostic(Filename, DiagOpts);
 }
 
 /// Print out the file/line/column information and include trace.

clang/lib/Frontend/TextDiagnostic.cpp

@@ -738,7 +738,7 @@ void TextDiagnostic::printDiagnosticMessage(raw_ostream &OS,
 }
 
 void TextDiagnostic::emitFilename(StringRef Filename, const SourceManager &SM) {
-  OS << SM.getNameForDiagnostic(Filename);
+  OS << SM.getNameForDiagnostic(Filename, DiagOpts);
 }
 
 /// Print out the file/line/column information and include trace.

clang/test/Frontend/absolute-paths.c

@@ -8,9 +8,9 @@
 
 #include "absolute-paths.h"
 
-// Check whether the diagnostic from the header above includes the dummy
-// directory in the path.
-// NORMAL: SystemHeaderPrefix
+// Check that the bogus prefix we added is stripped out even if absolute paths
+// are disabled.
+// NORMAL-NOT: SystemHeaderPrefix
 // ABSOLUTE-NOT: SystemHeaderPrefix
 // CHECK: warning: non-void function does not return a value