llvm · Sirraide · Jul 12, 2025 · Jul 12, 2025
diff --git a/clang-tools-extra/test/clang-tidy/infrastructure/file-filter-symlinks.cpp b/clang-tools-extra/test/clang-tidy/infrastructure/file-filter-symlinks.cpp
@@ -12,9 +12,8 @@
 // RUN: clang-tidy -checks='-*,google-explicit-constructor' -header-filter='header\.h' %s -- -I %t 2>&1 | FileCheck --check-prefix=CHECK_HEADER %s
 // RUN: clang-tidy -checks='-*,google-explicit-constructor' -header-filter='header\.h' -quiet %s -- -I %t 2>&1 | FileCheck --check-prefix=CHECK_HEADER %s
 
-// `-header-filter` operates on the actual file path that the user provided in
-// the #include directive; however, Clang's path name simplification causes the
-// path to be printed in canonicalised form here.
+// Check that `-header-filter` operates on the same file paths as paths in
+// diagnostics printed by ClangTidy.
 #include "dir1/dir2/../header_alias.h"
-// CHECK_HEADER_ALIAS: dir1/header.h:1:11: warning: single-argument constructors
+// CHECK_HEADER_ALIAS: dir1/dir2/../header_alias.h:1:11: warning: single-argument constructors
 // CHECK_HEADER-NOT: warning:
diff --git a/clang/include/clang/Basic/SourceManager.h b/clang/include/clang/Basic/SourceManager.h
@@ -824,12 +824,6 @@ class SourceManager : public RefCountedBase<SourceManager> {
 
   mutable std::unique_ptr<SrcMgr::SLocEntry> FakeSLocEntryForRecovery;
 
-  /// Cache for filenames used in diagnostics. See 'getNameForDiagnostic()'.
-  mutable llvm::StringMap<StringRef> DiagNames;
-
-  /// Allocator for absolute/short names.
-  mutable llvm::BumpPtrAllocator DiagNameAlloc;
-
   /// Lazily computed map of macro argument chunks to their expanded
   /// source location.
   using MacroArgsMap = std::map<unsigned, SourceLocation>;
@@ -1854,16 +1848,6 @@ class SourceManager : public RefCountedBase<SourceManager> {
   /// \return Location of the top-level macro caller.
   SourceLocation getTopMacroCallerLoc(SourceLocation Loc) const;
 
-  /// Retrieve the name of a file suitable for diagnostics.
-  // 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;
   friend class ASTWriter;

diff --git a/clang/lib/Basic/SourceManager.cpp b/clang/lib/Basic/SourceManager.cpp
@@ -2390,75 +2390,3 @@ SourceManagerForFile::SourceManagerForFile(StringRef FileName,
   assert(ID.isValid());
   SourceMgr->setMainFileID(ID);
 }
-
-StringRef
-SourceManager::getNameForDiagnostic(StringRef Filename,
-                                    const DiagnosticOptions &Opts) const {
-  OptionalFileEntryRef File = getFileManager().getOptionalFileRef(Filename);
-  if (!File)
-    return Filename;
-
-  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.
-  StringRef &CacheEntry = DiagNames[Filename];
-  if (!CacheEntry.empty())
-    return CacheEntry;
-
-  // We want to print a simplified absolute path, i. e. without "dots".
-  //
-  // The hardest part here are the paths like "<part1>/<link>/../<part2>".
-  // On Unix-like systems, we cannot just collapse "<link>/..", because
-  // paths are resolved sequentially, and, thereby, the path
-  // "<part1>/<part2>" may point to a different location. That is why
-  // we use FileManager::getCanonicalName(), which expands all indirections
-  // with llvm::sys::fs::real_path() and caches the result.
-  //
-  // On the other hand, it would be better to preserve as much of the
-  // original path as possible, because that helps a user to recognize it.
-  // real_path() expands all links, which sometimes too much. Luckily,
-  // on Windows we can just use llvm::sys::path::remove_dots(), because,
-  // on that system, both aforementioned paths point to the same place.
-  SmallString<256> TempBuf;
-#ifdef _WIN32
-  TempBuf = File->getName();
-  llvm::sys::fs::make_absolute(TempBuf);
-  llvm::sys::path::native(TempBuf);
-  llvm::sys::path::remove_dots(TempBuf, /* remove_dot_dot */ true);
-#else
-  TempBuf = getFileManager().getCanonicalName(*File);
-#endif
-
-  // 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 (!Opts.AbsolutePath && TempBuf.size() > Filename.size())
-    CacheEntry = Filename;
-  else
-    CacheEntry = TempBuf.str().copy(DiagNameAlloc);
-
-  return CacheEntry;
-}
diff --git a/clang/lib/Frontend/SARIFDiagnostic.cpp b/clang/lib/Frontend/SARIFDiagnostic.cpp
@@ -163,7 +163,36 @@ SARIFDiagnostic::addDiagnosticLevelToRule(SarifRule Rule,
 
 llvm::StringRef SARIFDiagnostic::emitFilename(StringRef Filename,
                                               const SourceManager &SM) {
-  return SM.getNameForDiagnostic(Filename, DiagOpts);
+  if (DiagOpts.AbsolutePath) {
+    auto File = SM.getFileManager().getOptionalFileRef(Filename);
+    if (File) {
+      // We want to print a simplified absolute path, i. e. without "dots".
+      //
+      // The hardest part here are the paths like "<part1>/<link>/../<part2>".
+      // On Unix-like systems, we cannot just collapse "<link>/..", because
+      // paths are resolved sequentially, and, thereby, the path
+      // "<part1>/<part2>" may point to a different location. That is why
+      // we use FileManager::getCanonicalName(), which expands all indirections
+      // with llvm::sys::fs::real_path() and caches the result.
+      //
+      // On the other hand, it would be better to preserve as much of the
+      // original path as possible, because that helps a user to recognize it.
+      // real_path() expands all links, which is sometimes too much. Luckily,
+      // on Windows we can just use llvm::sys::path::remove_dots(), because,
+      // on that system, both aforementioned paths point to the same place.
+#ifdef _WIN32
+      SmallString<256> TmpFilename = File->getName();
+      llvm::sys::fs::make_absolute(TmpFilename);
+      llvm::sys::path::native(TmpFilename);
+      llvm::sys::path::remove_dots(TmpFilename, /* remove_dot_dot */ true);
+      Filename = StringRef(TmpFilename.data(), TmpFilename.size());
+#else
+      Filename = SM.getFileManager().getCanonicalName(*File);
+#endif
+    }
+  }
+
+  return Filename;
 }
 
 /// Print out the file/line/column information and include trace.

diff --git a/clang/lib/Frontend/TextDiagnostic.cpp b/clang/lib/Frontend/TextDiagnostic.cpp
@@ -738,7 +738,39 @@ void TextDiagnostic::printDiagnosticMessage(raw_ostream &OS,
 }
 
 void TextDiagnostic::emitFilename(StringRef Filename, const SourceManager &SM) {
-  OS << SM.getNameForDiagnostic(Filename, DiagOpts);
+#ifdef _WIN32
+  SmallString<4096> TmpFilename;
+#endif
+  if (DiagOpts.AbsolutePath) {
+    auto File = SM.getFileManager().getOptionalFileRef(Filename);
+    if (File) {
+      // We want to print a simplified absolute path, i. e. without "dots".
+      //
+      // The hardest part here are the paths like "<part1>/<link>/../<part2>".
+      // On Unix-like systems, we cannot just collapse "<link>/..", because
+      // paths are resolved sequentially, and, thereby, the path
+      // "<part1>/<part2>" may point to a different location. That is why
+      // we use FileManager::getCanonicalName(), which expands all indirections
+      // with llvm::sys::fs::real_path() and caches the result.
+      //
+      // On the other hand, it would be better to preserve as much of the
+      // original path as possible, because that helps a user to recognize it.
+      // real_path() expands all links, which sometimes too much. Luckily,
+      // on Windows we can just use llvm::sys::path::remove_dots(), because,
+      // on that system, both aforementioned paths point to the same place.
+#ifdef _WIN32
+      TmpFilename = File->getName();
+      llvm::sys::fs::make_absolute(TmpFilename);
+      llvm::sys::path::native(TmpFilename);
+      llvm::sys::path::remove_dots(TmpFilename, /* remove_dot_dot */ true);
+      Filename = StringRef(TmpFilename.data(), TmpFilename.size());
+#else
+      Filename = SM.getFileManager().getCanonicalName(*File);
+#endif
+    }
+  }
+
+  OS << Filename;
 }
 
 /// Print out the file/line/column information and include trace.

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

diff --git a/clang/test/Frontend/simplify-paths.c b/clang/test/Frontend/simplify-paths.c