1 files changed, 21 insertions, 3 deletions
diff --git a/clang/lib/Frontend/ModuleDependencyCollector.cpp b/clang/lib/Frontend/ModuleDependencyCollector.cpp
index 5fa0e13c770..3546508a89f 100644
--- a/clang/lib/Frontend/ModuleDependencyCollector.cpp
+++ b/clang/lib/Frontend/ModuleDependencyCollector.cpp
@@ -97,6 +97,24 @@ struct ModuleDependencyMMCallbacks : public ModuleMapCallbacks {
 
 }
 
+// TODO: move this to Support/Path.h and check for HAVE_REALPATH?
+static bool real_path(StringRef SrcPath, SmallVectorImpl<char> &RealPath) {
+#ifdef LLVM_ON_UNIX
+  char CanonicalPath[PATH_MAX];
+
+  // TODO: emit a warning in case this fails...?
+  if (!realpath(SrcPath.str().c_str(), CanonicalPath))
+    return false;
+
+  SmallString<256> RPath(CanonicalPath);
+  RealPath.swap(RPath);
+  return true;
+#else
+  // FIXME: Add support for systems without realpath.
+  return false;
+#endif
+}
+
 void ModuleDependencyCollector::attachToASTReader(ASTReader &R) {
   R.addListener(llvm::make_unique<ModuleDependencyListener>(*this));
 }
@@ -111,7 +129,7 @@ void ModuleDependencyCollector::attachToPreprocessor(Preprocessor &PP) {
 static bool isCaseSensitivePath(StringRef Path) {
   SmallString<256> TmpDest = Path, UpperDest, RealDest;
   // Remove component traversals, links, etc.
-  if (llvm::sys::fs::real_path(Path, TmpDest))
+  if (!real_path(Path, TmpDest))
     return true; // Current default value in vfs.yaml
   Path = TmpDest;
 
@@ -121,7 +139,7 @@ static bool isCaseSensitivePath(StringRef Path) {
   // already expects when sensitivity isn't setup.
   for (auto &C : Path)
     UpperDest.push_back(toUppercase(C));
-  if (!llvm::sys::fs::real_path(UpperDest, RealDest) && Path.equals(RealDest))
+  if (real_path(UpperDest, RealDest) && Path.equals(RealDest))
     return false;
   return true;
 }
@@ -171,7 +189,7 @@ bool ModuleDependencyCollector::getRealPath(StringRef SrcPath,
   // Computing the real path is expensive, cache the search through the
   // parent path directory.
   if (DirWithSymLink == SymLinkMap.end()) {
-    if (llvm::sys::fs::real_path(Dir, RealPath))
+    if (!real_path(Dir, RealPath))
       return false;
     SymLinkMap[Dir] = RealPath.str();
   } else {