4 files changed, 39 insertions, 16 deletions
diff --git a/clang-tools-extra/clangd/FindSymbols.cpp b/clang-tools-extra/clangd/FindSymbols.cpp
index c1ee678977d..cc7f084f26a 100644
--- a/clang-tools-extra/clangd/FindSymbols.cpp
+++ b/clang-tools-extra/clangd/FindSymbols.cpp
@@ -193,7 +193,7 @@ public:
     const FileEntry *F = SM.getFileEntryForID(SM.getMainFileID());
     if (!F)
       return;
-    auto FilePath = getAbsoluteFilePath(F, SM);
+    auto FilePath = getRealPath(F, SM);
     if (FilePath)
       MainFileUri = URIForFile(*FilePath);
   }
diff --git a/clang-tools-extra/clangd/SourceCode.cpp b/clang-tools-extra/clangd/SourceCode.cpp
index 88ec2c95683..931ad3c0f20 100644
--- a/clang-tools-extra/clangd/SourceCode.cpp
+++ b/clang-tools-extra/clangd/SourceCode.cpp
@@ -185,18 +185,34 @@ std::vector<TextEdit> replacementsToEdits(StringRef Code,
   return Edits;
 }
 
-llvm::Optional<std::string>
-getAbsoluteFilePath(const FileEntry *F, const SourceManager &SourceMgr) {
-  SmallString<64> FilePath = F->tryGetRealPathName();
-  if (FilePath.empty())
-    FilePath = F->getName();
-  if (!llvm::sys::path::is_absolute(FilePath)) {
-    if (!SourceMgr.getFileManager().makeAbsolutePath(FilePath)) {
-      log("Could not turn relative path to absolute: {0}", FilePath);
+llvm::Optional<std::string> getRealPath(const FileEntry *F,
+                                        const SourceManager &SourceMgr) {
+  // Ideally, we get the real path from the FileEntry object.
+  SmallString<128> FilePath = F->tryGetRealPathName();
+  if (!FilePath.empty()) {
+    return FilePath.str().str();
+  }
+
+  // Otherwise, we try to compute ourselves.
+  vlog("FileEntry for {0} did not contain the real path.", F->getName());
+
+  llvm::SmallString<128> Path = F->getName();
+
+  if (!llvm::sys::path::is_absolute(Path)) {
+    if (!SourceMgr.getFileManager().makeAbsolutePath(Path)) {
+      log("Could not turn relative path to absolute: {0}", Path);
       return llvm::None;
     }
   }
-  return FilePath.str().str();
+
+  llvm::SmallString<128> RealPath;
+  if (SourceMgr.getFileManager().getVirtualFileSystem()->getRealPath(
+          Path, RealPath)) {
+    log("Could not compute real path: {0}", Path);
+    return Path.str().str();
+  }
+
+  return RealPath.str().str();
 }
 
 TextEdit toTextEdit(const FixItHint &FixIt, const SourceManager &M,
diff --git a/clang-tools-extra/clangd/SourceCode.h b/clang-tools-extra/clangd/SourceCode.h
index cb0c6728781..e633a1570d1 100644
--- a/clang-tools-extra/clangd/SourceCode.h
+++ b/clang-tools-extra/clangd/SourceCode.h
@@ -62,13 +62,20 @@ TextEdit replacementToEdit(StringRef Code, const tooling::Replacement &R);
 std::vector<TextEdit> replacementsToEdits(StringRef Code,
                                           const tooling::Replacements &Repls);
 
-/// Get the absolute file path of a given file entry.
-llvm::Optional<std::string> getAbsoluteFilePath(const FileEntry *F,
-                                                const SourceManager &SourceMgr);
-
 TextEdit toTextEdit(const FixItHint &FixIt, const SourceManager &M,
                     const LangOptions &L);
 
+/// Get the real/canonical path of \p F.  This means:
+///
+///   - Absolute path
+///   - Symlinks resolved
+///   - No "." or ".." component
+///   - No duplicate or trailing directory separator
+///
+/// This function should be used when sending paths to clients, so that paths
+/// are normalized as much as possible.
+llvm::Optional<std::string> getRealPath(const FileEntry *F,
+                                        const SourceManager &SourceMgr);
 } // namespace clangd
 } // namespace clang
 #endif
diff --git a/clang-tools-extra/clangd/XRefs.cpp b/clang-tools-extra/clangd/XRefs.cpp
index e95730ba7e8..f5e2b1e12da 100644
--- a/clang-tools-extra/clangd/XRefs.cpp
+++ b/clang-tools-extra/clangd/XRefs.cpp
@@ -192,7 +192,7 @@ makeLocation(ParsedAST &AST, const SourceRange &ValSourceRange) {
   Range R = {Begin, End};
   Location L;
 
-  auto FilePath = getAbsoluteFilePath(F, SourceMgr);
+  auto FilePath = getRealPath(F, SourceMgr);
   if (!FilePath) {
     log("failed to get path!");
     return llvm::None;
@@ -286,7 +286,7 @@ std::vector<Location> findDefinitions(ParsedAST &AST, Position Pos,
     std::string HintPath;
     const FileEntry *FE =
         SourceMgr.getFileEntryForID(SourceMgr.getMainFileID());
-    if (auto Path = getAbsoluteFilePath(FE, SourceMgr))
+    if (auto Path = getRealPath(FE, SourceMgr))
       HintPath = *Path;
     // Query the index and populate the empty slot.
     Index->lookup(