cmSystemTools: Revert GetRealPath implementation on Windows

The use of `uv_fs_realpath` introduced by commit v3.11.0-rc1~445^2~1
(cmSystemTools: Implement GetRealPath on Windows, 2017-10-02) causes
`subst` drives to be expanded on Windows, breaking existing use cases.
Revert its use until an alternative implementation can be chosen.

Preserve the behavior introduced by commit v3.11.0-rc1~445^2
(cmTimestamp: For symlinks switch to timestamp of resolved path,
2017-10-02) by retaining use of `uv_fs_realpath` in a function of
a different name.

Fixes: #18033
Issue: #17206

1 files changed, 6 insertions, 4 deletions

diff --git a/Source/cmSystemTools.h b/Source/cmSystemTools.h
index a53afde..4390c86 100644
--- a/Source/cmSystemTools.h
+++ b/Source/cmSystemTools.h
@@ -500,12 +500,14 @@ public:
     unsigned int Delay;
   };
   static WindowsFileRetry GetWindowsFileRetry();
-
-  /** Get the real path for a given path, removing all symlinks. */
-  static std::string GetRealPath(const std::string& path,
-                                 std::string* errorMessage = 0);
 #endif
 
+  /** Get the real path for a given path, removing all symlinks.
+      This variant of GetRealPath also works on Windows but will
+      resolve subst drives too.  */
+  static std::string GetRealPathResolvingWindowsSubst(
+    const std::string& path, std::string* errorMessage = nullptr);
+
   /** Perform one-time initialization of libuv.  */
   static void InitializeLibUV();