Xcode: Fix support for source tree symlink inside build tree

Since commit 61495cdaae (Fix Xcode project references to the source
tree, 2009-09-22, v2.8.0~43) we force source file references to use
relative paths from the source tree.  If the source tree path is a
symbolic link inside the build tree, the relative `../` sequence
goes to the wrong place.  The problem with debug breakpoints motivating
that change does not seem to occur in modern Xcode versions, so update
the logic to use a relative path only when it does not need to start
in any `../` sequence.

1 files changed, 6 insertions, 4 deletions

diff --git a/Source/cmGlobalXCodeGenerator.cxx b/Source/cmGlobalXCodeGenerator.cxx
index b752c41..1e6624e 100644
--- a/Source/cmGlobalXCodeGenerator.cxx
+++ b/Source/cmGlobalXCodeGenerator.cxx
@@ -4695,10 +4695,12 @@ std::string cmGlobalXCodeGenerator::ConvertToRelativeForMake(
 
 std::string cmGlobalXCodeGenerator::RelativeToSource(const std::string& p)
 {
-  // We force conversion because Xcode breakpoints do not work unless
-  // they are in a file named relative to the source tree.
-  return cmSystemTools::ForceToRelativePath(
-    this->CurrentRootGenerator->GetCurrentSourceDirectory(), p);
+  std::string const& rootSrc =
+    this->CurrentRootGenerator->GetCurrentSourceDirectory();
+  if (cmSystemTools::IsSubDirectory(p, rootSrc)) {
+    return cmSystemTools::ForceToRelativePath(rootSrc, p);
+  }
+  return p;
 }
 
 std::string cmGlobalXCodeGenerator::RelativeToBinary(const std::string& p)