2 files changed, 39 insertions, 10 deletions
diff --git a/clang/lib/Lex/HeaderSearch.cpp b/clang/lib/Lex/HeaderSearch.cpp
index 99596b1..73f9678 100644
--- a/clang/lib/Lex/HeaderSearch.cpp
+++ b/clang/lib/Lex/HeaderSearch.cpp
@@ -255,18 +255,11 @@ std::string HeaderSearch::getCachedModuleFileNameImpl(StringRef ModuleName,
     //
     // To avoid false-negatives, we form as canonical a path as we can, and map
     // to lower-case in case we're on a case-insensitive file system.
-    std::string Parent =
-        std::string(llvm::sys::path::parent_path(ModuleMapPath));
-    if (Parent.empty())
-      Parent = ".";
-    auto Dir = FileMgr.getDirectory(Parent);
-    if (!Dir)
+    SmallString<128> CanonicalPath(ModuleMapPath);
+    if (getModuleMap().canonicalizeModuleMapPath(CanonicalPath))
       return {};
-    auto DirName = FileMgr.getCanonicalName(*Dir);
-    auto FileName = llvm::sys::path::filename(ModuleMapPath);
 
-    llvm::hash_code Hash =
-      llvm::hash_combine(DirName.lower(), FileName.lower());
+    llvm::hash_code Hash = llvm::hash_combine(CanonicalPath.str().lower());
 
     SmallString<128> HashStr;
     llvm::APInt(64, size_t(Hash)).toStringUnsigned(HashStr, /*Radix*/36);
diff --git a/clang/lib/Lex/ModuleMap.cpp b/clang/lib/Lex/ModuleMap.cpp
index dbb81dc..cbd3303f 100644
--- a/clang/lib/Lex/ModuleMap.cpp
+++ b/clang/lib/Lex/ModuleMap.cpp
@@ -1303,6 +1303,42 @@ void ModuleMap::setInferredModuleAllowedBy(Module *M, const FileEntry *ModMap) {
   InferredModuleAllowedBy[M] = ModMap;
 }
 
+std::error_code
+ModuleMap::canonicalizeModuleMapPath(SmallVectorImpl<char> &Path) {
+  StringRef Dir = llvm::sys::path::parent_path({Path.data(), Path.size()});
+
+  // Do not canonicalize within the framework; the module map parser expects
+  // Modules/ not Versions/A/Modules.
+  if (llvm::sys::path::filename(Dir) == "Modules") {
+    StringRef Parent = llvm::sys::path::parent_path(Dir);
+    if (Parent.endswith(".framework"))
+      Dir = Parent;
+  }
+
+  FileManager &FM = SourceMgr.getFileManager();
+  auto DirEntry = FM.getDirectory(Dir.empty() ? "." : Dir);
+  if (!DirEntry)
+    return DirEntry.getError();
+
+  // Canonicalize the directory.
+  StringRef CanonicalDir = FM.getCanonicalName(*DirEntry);
+  if (CanonicalDir != Dir) {
+    bool Done = llvm::sys::path::replace_path_prefix(Path, Dir, CanonicalDir);
+    (void)Done;
+    assert(Done && "Path should always start with Dir");
+  }
+
+  // In theory, the filename component should also be canonicalized if it
+  // on a case-insensitive filesystem. However, the extra canonicalization is
+  // expensive and if clang looked up the filename it will always be lowercase.
+
+  // Remove ., remove redundant separators, and switch to native separators.
+  // This is needed for separators between CanonicalDir and the filename.
+  llvm::sys::path::remove_dots(Path);
+
+  return std::error_code();
+}
+
 void ModuleMap::addAdditionalModuleMapFile(const Module *M,
                                            const FileEntry *ModuleMap) {
   AdditionalModMaps[M].insert(ModuleMap);