From 1d12853ed3c2b3307714c8556f261df70350a980 Mon Sep 17 00:00:00 2001
From: Marc Chevrier <marc.chevrier@gmail.com>
Date: Sun, 19 Mar 2023 13:32:02 +0100
Subject: file(REAL_PATH): Ensure same behavior as
 get_filename_component(REALPATH)

Fixes: #24605
---
 Source/cmFileCommand.cxx            |  7 +++----
 Tests/RunCMake/file/REAL_PATH.cmake | 16 ++++++++++++++++
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/Source/cmFileCommand.cxx b/Source/cmFileCommand.cxx
index 00a68a8..45fba8b 100644
--- a/Source/cmFileCommand.cxx
+++ b/Source/cmFileCommand.cxx
@@ -30,7 +30,6 @@
 
 #include "cmArgumentParser.h"
 #include "cmArgumentParserTypes.h"
-#include "cmCMakePath.h"
 #include "cmCryptoHash.h"
 #include "cmELF.h"
 #include "cmExecutionStatus.h"
@@ -1278,9 +1277,9 @@ bool HandleRealPathCommand(std::vector<std::string> const& args,
     }
   }
 
-  cmCMakePath path(input, cmCMakePath::auto_format);
-  path = path.Absolute(*arguments.BaseDirectory).Normal();
-  auto realPath = cmSystemTools::GetRealPath(path.GenericString());
+  auto realPath =
+    cmSystemTools::CollapseFullPath(input, *arguments.BaseDirectory);
+  realPath = cmSystemTools::GetRealPath(realPath);
 
   status.GetMakefile().AddDefinition(args[2], realPath);
 
diff --git a/Tests/RunCMake/file/REAL_PATH.cmake b/Tests/RunCMake/file/REAL_PATH.cmake
index 0b5d3c0..9c5d4ea 100644
--- a/Tests/RunCMake/file/REAL_PATH.cmake
+++ b/Tests/RunCMake/file/REAL_PATH.cmake
@@ -34,3 +34,19 @@ file(REAL_PATH "~/test.txt" real_path EXPAND_TILDE)
 if (NOT real_path STREQUAL "${HOME_DIR}/test.txt")
   message(SEND_ERROR "real path is \"${real_path}\", should be \"${HOME_DIR}/test.txt\"")
 endif()
+
+if (WIN32)
+  cmake_policy(SET CMP0139 NEW)
+
+  set(in "${CMAKE_CURRENT_BINARY_DIR}/AbC.TxT")
+
+  file(REMOVE "${in}")
+  file(TOUCH "${in}")
+
+  string(TOLOWER "${in}" low)
+  file(REAL_PATH "${low}" out)
+
+  if(NOT "${out}" PATH_EQUAL "${in}")
+    message(SEND_ERROR "real path is \"${out}\", should be \"${in}\"")
+  endif()
+endif()
-- 
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