[PATCH] D59415: Do not resolve directory junctions for `-fdiagnostics-absolute-paths` on Windows.

[Igor Kudrin via Phabricator via cfe-commits]

ikudrin created this revision.
ikudrin added reviewers: ioeric, bkramer, hans, thakis, rsmith, zturner.
Herald added a project: clang.

This patch partially reverts D46942 <https://reviews.llvm.org/D46942>.

If the source file path contains directory junctions, and we resolve them when printing
diagnostic messages, these paths look independent for an IDE. For example, both Visual
Studio and Visual Studio Code open separate editors for such paths, which is not only
inconvenient but might even result in loss of the changes made in one of them.


Repository:
  rC Clang

https://reviews.llvm.org/D59415

Files:
  lib/Basic/FileManager.cpp
  test/Frontend/absolute-paths-windows.test
  test/Frontend/lit.local.cfg


Index: test/Frontend/lit.local.cfg
===================================================================
--- test/Frontend/lit.local.cfg
+++ test/Frontend/lit.local.cfg
@@ -1 +1 @@
-config.suffixes = ['.c', '.cpp', '.m', '.mm', '.ll', '.cl']
+config.suffixes = ['.c', '.cpp', '.m', '.mm', '.ll', '.cl', '.test']
Index: test/Frontend/absolute-paths-windows.test
===================================================================
--- /dev/null
+++ test/Frontend/absolute-paths-windows.test
@@ -0,0 +1,9 @@
+// REQUIRES: system-windows
+// RUN: rm -rf %t.dir
+// RUN: mkdir -p %t.dir\real
+// RUN: cmd /c mklink /j %t.dir\junc %t.dir\real
+// RUN: echo "wrong code" > %t.dir\real\foo.cpp
+// RUN: not %clang_cc1 -fsyntax-only -fdiagnostics-absolute-paths %t.dir\junc\foo.cpp 2>&1 | FileCheck %s
+
+// CHECK-NOT: .dir\real\foo.cpp
+// CHECK: .dir\junc\foo.cpp
Index: lib/Basic/FileManager.cpp
===================================================================
--- lib/Basic/FileManager.cpp
+++ lib/Basic/FileManager.cpp
@@ -497,8 +497,22 @@
   StringRef CanonicalName(Dir->getName());
 
   SmallString<4096> CanonicalNameBuf;
+#ifdef _WIN32
+  CanonicalNameBuf = CanonicalName;
+  llvm::sys::fs::make_absolute(CanonicalNameBuf);
+  llvm::sys::path::native(CanonicalNameBuf);
+  // We've run into needing to remove '..' here in the wild though, so
+  // remove it.
+  // On Windows, symlinks are significantly less prevalent, so removing
+  // '..' is pretty safe.
+  // Ideally we'd have an equivalent of `realpath` and could implement
+  // sys::fs::canonical across all the platforms.
+  llvm::sys::path::remove_dots(CanonicalNameBuf, /* remove_dot_dot */ true);
+  CanonicalName = StringRef(CanonicalNameBuf).copy(CanonicalNameStorage);
+#else
   if (!FS->getRealPath(Dir->getName(), CanonicalNameBuf))
     CanonicalName = StringRef(CanonicalNameBuf).copy(CanonicalNameStorage);
+#endif
 
   CanonicalDirNames.insert({Dir, CanonicalName});
   return CanonicalName;


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