From b6c022eaa27abcc265a5961b22e5e0c44df88752 Mon Sep 17 00:00:00 2001
From: Ben Boeckel <ben.boeckel@kitware.com>
Date: Tue, 2 Mar 2021 14:51:22 -0500
Subject: [PATCH] ExternalData: use `file(CREATE_LINK)`

This avoids spawning a new CMake command which isn't necessary.
---
 Modules/ExternalData.cmake | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Modules/ExternalData.cmake b/Modules/ExternalData.cmake
index 032e423c09..1850e74625 100644
--- a/Modules/ExternalData.cmake
+++ b/Modules/ExternalData.cmake
@@ -941,7 +941,8 @@ function(_ExternalData_link_or_copy src dst)
         file(RELATIVE_PATH tgt "${dst_dir}" "${src}")
       endif()
     endif()
-    execute_process(COMMAND "${CMAKE_COMMAND}" -E create_symlink "${tgt}" "${tmp}" RESULT_VARIABLE result)
+    # Create link (falling back to copying if there's a problem).
+    file(CREATE_LINK "${tgt}" "${tmp}" RESULT result COPY_ON_ERROR SYMBOLIC)
   else()
     # Create a copy.
     file(COPY_FILE "${src}" "${tmp}" RESULT result)