From 9b7c8b9f98bf3693b375d2316847bffefba73125 Mon Sep 17 00:00:00 2001
From: Jon Siwek <jsiwek@ncsa.illinois.edu>
Date: Tue, 19 Apr 2011 10:44:44 -0500
Subject: [PATCH] Fix CheckTypes.cmake from generating different config.h's
 between CMake runs.

Changing a file that causes CMake to re-run would incorrectly use
leftover state to arrive at the wrong conclusion about whether the
system has a given type.
---
 cmake/CheckTypes.cmake | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/cmake/CheckTypes.cmake b/cmake/CheckTypes.cmake
index 8346487e2c..1fab29e3f8 100644
--- a/cmake/CheckTypes.cmake
+++ b/cmake/CheckTypes.cmake
@@ -7,12 +7,15 @@ check_type_size("void *" SIZEOF_VOID_P)
 # checks existence of ${_type}, and if it does not, sets CMake variable ${_var}
 # to alternative type, ${_alt_type}
 macro(CheckType _type _alt_type _var)
-    check_type_size(${_type} ${_var})
-    if (NOT ${_var})
-        set(${_var} ${_alt_type})
-    else ()
-        unset(${_var})
-        unset(${_var} CACHE)
+    # don't perform check if we have a result from a previous CMake run
+    if (NOT HAVE_${_var})
+        check_type_size(${_type} ${_var})
+        if (NOT ${_var})
+            set(${_var} ${_alt_type})
+        else ()
+            unset(${_var})
+            unset(${_var} CACHE)
+        endif ()
     endif ()
 endmacro(CheckType _type _alt_type _var)