Hello,
CheckStructHasMember does not support C++ only structs. If headers
required to check if a struct has a member can be compiled with C++
compiler only, the check will fail, because the C compiler will fail. As
a consequence, the result variable is set to false, even if the struct
has that particular member.
The attached patch adds 2 new macros:
- CHECK_CXX_STRUCT_HAS_MEMBER (similar to CHECK_STRUCT_HAS_MEMBER but
uses the C++ compiler)
- CHECK_C_STRUCT_HAS_MEMBER (identical to CHECK_STRUCT_HAS_MEMBER,
added for symmetry)
that can be used to check a struct, choosing the compiler to use.
I'm not sure if this is the right way to fix this (i.e. if
CHECK_C_STRUCT_HAS_MEMBER is required), or if it is a better idea to add
a parameter to the existing macro.
What do you think?
Cheers,
Daniele
>From d9467221a4caba2ade591f858c3c45dbfb15d871 Mon Sep 17 00:00:00 2001
From: "Daniele E. Domenichelli" <daniele.domeniche...@iit.it>
Date: Fri, 20 Sep 2013 15:10:40 +0200
Subject: [PATCH] [CheckStructHasMember] Add support for C++
If headers required to check if a struct has a member can be compiled
with C++ compiler only, the check will fail, because the C compiler
will fail.
As a consequence, the result variable is set to false, even if the
struct has that particular member.
This patch adds 2 new macros:
- CHECK_C_STRUCT_HAS_MEMBER (identical to CHECK_STRUCT_HAS_MEMBER)
- CHECK_CXX_STRUCT_HAS_MEMBER (similar, but uses the C++ compiler)
---
Modules/CheckStructHasMember.cmake | 22 +++++++++++++++++++++-
1 file changed, 21 insertions(+), 1 deletion(-)
diff --git a/Modules/CheckStructHasMember.cmake b/Modules/CheckStructHasMember.cmake
index ea2891c..f9032ce 100644
--- a/Modules/CheckStructHasMember.cmake
+++ b/Modules/CheckStructHasMember.cmake
@@ -1,5 +1,7 @@
# - Check if the given struct or class has the specified member variable
# CHECK_STRUCT_HAS_MEMBER (STRUCT MEMBER HEADER VARIABLE)
+# CHECK_C_STRUCT_HAS_MEMBER (STRUCT MEMBER HEADER VARIABLE)
+# CHECK_CXX_STRUCT_HAS_MEMBER (STRUCT MEMBER HEADER VARIABLE)
#
# STRUCT - the name of the struct or class you are interested in
# MEMBER - the member which existence you want to check
@@ -29,8 +31,10 @@
# License text for the above reference.)
include(CheckCSourceCompiles)
+include(CheckCXXSourceCompiles)
+
+macro (_CHECK_STRUCT_HAS_MEMBER_BASE _STRUCT _MEMBER _HEADER _RESULT)
-macro (CHECK_STRUCT_HAS_MEMBER _STRUCT _MEMBER _HEADER _RESULT)
set(_INCLUDE_FILES)
foreach (it ${_HEADER})
set(_INCLUDE_FILES "${_INCLUDE_FILES}#include <${it}>\n")
@@ -45,7 +49,23 @@ int main()
return 0;
}
")
+
+endmacro ()
+
+
+macro (CHECK_STRUCT_HAS_MEMBER _STRUCT _MEMBER _HEADER _RESULT)
+ _CHECK_STRUCT_HAS_MEMBER_BASE(${ARGN})
CHECK_C_SOURCE_COMPILES("${_CHECK_STRUCT_MEMBER_SOURCE_CODE}" ${_RESULT})
+endmacro ()
+
+macro (CHECK_C_STRUCT_HAS_MEMBER _STRUCT _MEMBER _HEADER _RESULT)
+ _CHECK_STRUCT_HAS_MEMBER_BASE(${ARGN})
+ CHECK_C_SOURCE_COMPILES("${_CHECK_STRUCT_MEMBER_SOURCE_CODE}" ${_RESULT})
endmacro ()
+
+macro (CHECK_CXX_STRUCT_HAS_MEMBER _STRUCT _MEMBER _HEADER _RESULT)
+ _CHECK_STRUCT_HAS_MEMBER_BASE(${ARGN})
+ CHECK_CXX_SOURCE_COMPILES("${_CHECK_STRUCT_MEMBER_SOURCE_CODE}" ${_RESULT})
+endmacro ()
--
1.8.4.rc3
--
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