From 10c88c433766cb9b4d3e6f95a96788559ff4136f Mon Sep 17 00:00:00 2001
From: Brad King <brad.king@kitware.com>
Date: Tue, 2 Jun 2020 08:16:49 -0400
Subject: PCH: Do not enable GNU or Intel PCH settings for Fortran

The PCH settings are shared by C and CXX languages but do not make sense
for Fortran.  In particular, `CMAKE_PCH_EXTENSION` should not be set
because it can overwrite the value set for C/C++ languages, which may
have a different compiler vendor than the Fortran compiler.

Fixes: #20752
---
 Modules/Compiler/GNU.cmake   | 12 +++++++-----
 Modules/Compiler/Intel.cmake | 14 ++++++++------
 2 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/Modules/Compiler/GNU.cmake b/Modules/Compiler/GNU.cmake
index 1c050a2..a68bb6c 100644
--- a/Modules/Compiler/GNU.cmake
+++ b/Modules/Compiler/GNU.cmake
@@ -110,10 +110,12 @@ macro(__compiler_gnu lang)
   endif()
   list(APPEND CMAKE_${lang}_COMPILER_PREDEFINES_COMMAND "-dM" "-E" "-c" "${CMAKE_ROOT}/Modules/CMakeCXXCompilerABI.cpp")
 
-  set(CMAKE_PCH_EXTENSION .gch)
-  if (NOT CMAKE_GENERATOR MATCHES "Xcode")
-    set(CMAKE_PCH_PROLOGUE "#pragma GCC system_header")
+  if(NOT "x${lang}" STREQUAL "xFortran")
+    set(CMAKE_PCH_EXTENSION .gch)
+    if (NOT CMAKE_GENERATOR MATCHES "Xcode")
+      set(CMAKE_PCH_PROLOGUE "#pragma GCC system_header")
+    endif()
+    set(CMAKE_${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>)
   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()
diff --git a/Modules/Compiler/Intel.cmake b/Modules/Compiler/Intel.cmake
index d895ed0..56a3078 100644
--- a/Modules/Compiler/Intel.cmake
+++ b/Modules/Compiler/Intel.cmake
@@ -33,11 +33,13 @@ else()
     endif()
     list(APPEND CMAKE_${lang}_COMPILER_PREDEFINES_COMMAND "-QdM" "-P" "-Za" "${CMAKE_ROOT}/Modules/CMakeCXXCompilerABI.cpp")
 
-    # Precompile Headers
-    set(CMAKE_PCH_EXTENSION .pchi)
-    set(CMAKE_LINK_PCH ON)
-    set(CMAKE_PCH_EPILOGUE "#pragma hdrstop")
-    set(CMAKE_${lang}_COMPILE_OPTIONS_USE_PCH -Winvalid-pch -Wno-pch-messages -pch-use <PCH_FILE> -include <PCH_HEADER>)
-    set(CMAKE_${lang}_COMPILE_OPTIONS_CREATE_PCH -Winvalid-pch -Wno-pch-messages -pch-create <PCH_FILE> -include <PCH_HEADER>)
+    if(NOT "x${lang}" STREQUAL "xFortran")
+      # Precompile Headers
+      set(CMAKE_PCH_EXTENSION .pchi)
+      set(CMAKE_LINK_PCH ON)
+      set(CMAKE_PCH_EPILOGUE "#pragma hdrstop")
+      set(CMAKE_${lang}_COMPILE_OPTIONS_USE_PCH -Winvalid-pch -Wno-pch-messages -pch-use <PCH_FILE> -include <PCH_HEADER>)
+      set(CMAKE_${lang}_COMPILE_OPTIONS_CREATE_PCH -Winvalid-pch -Wno-pch-messages -pch-create <PCH_FILE> -include <PCH_HEADER>)
+    endif()
   endmacro()
 endif()
-- 
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