From df8372da0926a0a6fd995e50fc378bd699ea54dd Mon Sep 17 00:00:00 2001
From: Cristian Adam <cristian.adam@gmail.com>
Date: Fri, 29 Nov 2019 17:59:52 +0100
Subject: PCH: Do not add #pragma system_header for Xcode generator

Fixes: #20039
---
 Modules/Compiler/Clang.cmake | 4 +++-
 Modules/Compiler/GNU.cmake   | 4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/Modules/Compiler/Clang.cmake b/Modules/Compiler/Clang.cmake
index ea5a3b3583..5cc93284b9 100644
--- a/Modules/Compiler/Clang.cmake
+++ b/Modules/Compiler/Clang.cmake
@@ -98,7 +98,9 @@ else()
     )
 
     set(CMAKE_PCH_EXTENSION .pch)
-    set(CMAKE_PCH_PROLOGUE "#pragma clang system_header")
+    if (NOT CMAKE_GENERATOR MATCHES "Xcode")
+      set(CMAKE_PCH_PROLOGUE "#pragma clang system_header")
+    endif()
     set(CMAKE_${lang}_COMPILE_OPTIONS_USE_PCH -Xclang -include-pch -Xclang <PCH_FILE>)
     set(CMAKE_${lang}_COMPILE_OPTIONS_CREATE_PCH -Xclang -emit-pch -Xclang -include -Xclang <PCH_HEADER>)
   endmacro()
diff --git a/Modules/Compiler/GNU.cmake b/Modules/Compiler/GNU.cmake
index 6960571db8..1c050a297e 100644
--- a/Modules/Compiler/GNU.cmake
+++ b/Modules/Compiler/GNU.cmake
@@ -111,7 +111,9 @@ macro(__compiler_gnu lang)
   list(APPEND CMAKE_${lang}_COMPILER_PREDEFINES_COMMAND "-dM" "-E" "-c" "${CMAKE_ROOT}/Modules/CMakeCXXCompilerABI.cpp")
 
   set(CMAKE_PCH_EXTENSION .gch)
-  set(CMAKE_PCH_PROLOGUE "#pragma GCC system_header")
+  if (NOT CMAKE_GENERATOR MATCHES "Xcode")
+    set(CMAKE_PCH_PROLOGUE "#pragma GCC system_header")
+  endif()
   set(CMAKE_${lang}_COMPILE_OPTIONS_USE_PCH -Winvalid-pch -include <PCH_HEADER>)
   set(CMAKE_${lang}_COMPILE_OPTIONS_CREATE_PCH -Winvalid-pch -x ${__pch_header_${lang}} -include <PCH_HEADER>)
 endmacro()
-- 
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