From 4b85141f8373f24ecace6d12afaaa56adf60273c Mon Sep 17 00:00:00 2001
From: Craig Scott <craig.scott@crascit.com>
Date: Fri, 2 Dec 2022 15:19:48 +1100
Subject: FetchContent: Don't pass SYSTEM through to sub-build

If we don't filter out SYSTEM from the arguments we pass
through to ExternalProject_Add(), it gets appended as a
list item to whatever arguments precede it because
ExternalProject_Add() doesn't recognize it as a keyword.

Fixes: #24201
---
 Modules/FetchContent.cmake | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Modules/FetchContent.cmake b/Modules/FetchContent.cmake
index ac3918c..25b0683 100644
--- a/Modules/FetchContent.cmake
+++ b/Modules/FetchContent.cmake
@@ -1427,6 +1427,9 @@ function(__FetchContent_directPopulate contentName)
 
   set(options
       QUIET
+      # SYSTEM has no meaning for ExternalProject, it is only used by us in
+      # FetchContent_MakeAvailable(). We need to parse and discard it here.
+      SYSTEM
   )
   set(oneValueArgs
       SUBBUILD_DIR
-- 
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