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Date Submitted

Last Update

0011910

CMake

Modules

public

2011-03-01 03:58

2012-07-09 06:52

Reporter

Raymond Wan

Assigned To

Rolf Eike Beer

Priority

normal

Severity

minor

Reproducibility

always

Status

closed

Resolution

fixed

Platform

AMD64

Debian

OS Version

6.0

Product Version

CMake-2-8

Target Version

CMake 2.8.8

Fixed in Version

CMake 2.8.8

Summary

0011910: FindOpenMP.cmake requires both C and CXX

Description

If only CXX is enabled and not C, then many errors are produced that look like this (path shortened):

-- Performing Test OpenMP_FLAG_DETECTED
CMake Error: Unknown extension ".c" for file ".../build/CMakeFiles/CMakeTmp/src.c". TRY_COMPILE only works for enabled languages.
Currently enabled languages are: CXX
See PROJECT command for help enabling other languages.

Looking at the module, it seems that (1) it performs both the C and CXX tests unconditionally. So if C is not enabled, then the C tests will generate the above error. (2) Also, at the end of the module, the use of find_package_handle_standard_args() seems to require that both C and CXX flags have to be set.

Also, (3) there is a minor problem with the check_c_source_compiles () using the CXX source, and vice-versa. (As the two sources are identical, the effect is trivial.)

-----

Notes:
1) Debian 6.0 is using cmake 2.8.2 . However, looking at 2.8.4, it seems that the problem still persists.
2) A similar problem for an entirely different module appears to be described here: http://www.mail-archive.com/cmake@cmake.org/msg06043.html [^]]

Steps To Reproduce

Have a PROJECT () line with just CXX and no C enabled.

Additional Information

Attached is a diff file with changes that hopefully addresses the 3 problems above by performing the test only if either the C or CXX compiler is defined. The diff file is generated against the newer 2.8.4 and not the 2.8.2 that I'm using.

As I'm not experienced with cmake, hopefully it is correct and of some help.

Tags

No tags attached.

Attached Files

FindOpenMP.2-8-4.patch [^] (3,209 bytes) 2011-03-01 03:58 [Show Content] [Hide Content]

--- FindOpenMP.cmake.old	2011-03-01 17:34:59.000000000 +0900
+++ FindOpenMP.cmake.new	2011-03-01 17:35:26.000000000 +0900
@@ -72,41 +72,53 @@
 endif(DEFINED OpenMP_C_FLAGS AND DEFINED OpenMP_CXX_FLAGS)
 
 # check c compiler
-foreach(FLAG ${OpenMP_C_FLAG_CANDIDATES})
-  set(SAFE_CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}")
-  set(CMAKE_REQUIRED_FLAGS "${FLAG}")
-  unset(OpenMP_FLAG_DETECTED CACHE)
-  message(STATUS "Try OpenMP C flag = [${FLAG}]")
-  check_c_source_compiles("${OpenMP_CXX_TEST_SOURCE}" OpenMP_FLAG_DETECTED)
-  set(CMAKE_REQUIRED_FLAGS "${SAFE_CMAKE_REQUIRED_FLAGS}")
-  if(OpenMP_FLAG_DETECTED)
-    set(OpenMP_C_FLAGS_INTERNAL "${FLAG}")
-    break()
-  endif(OpenMP_FLAG_DETECTED) 
-endforeach(FLAG ${OpenMP_C_FLAG_CANDIDATES})
+IF (CMAKE_C_COMPILER)
+  foreach(FLAG ${OpenMP_C_FLAG_CANDIDATES})
+    set(SAFE_CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}")
+    set(CMAKE_REQUIRED_FLAGS "${FLAG}")
+    unset(OpenMP_FLAG_DETECTED CACHE)
+    message(STATUS "Try OpenMP C flag = [${FLAG}]")
+    check_c_source_compiles("${OpenMP_C_TEST_SOURCE}" OpenMP_FLAG_DETECTED)
+    set(CMAKE_REQUIRED_FLAGS "${SAFE_CMAKE_REQUIRED_FLAGS}")
+    if(OpenMP_FLAG_DETECTED)
+      set(OpenMP_C_FLAGS_INTERNAL "${FLAG}")
+      break()
+    endif(OpenMP_FLAG_DETECTED) 
+  endforeach(FLAG ${OpenMP_C_FLAG_CANDIDATES})
+ENDIF (CMAKE_C_COMPILER)
 
 # check cxx compiler
-foreach(FLAG ${OpenMP_CXX_FLAG_CANDIDATES})
-  set(SAFE_CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}")
-  set(CMAKE_REQUIRED_FLAGS "${FLAG}")
-  unset(OpenMP_FLAG_DETECTED CACHE)
-  message(STATUS "Try OpenMP CXX flag = [${FLAG}]")
-  check_cxx_source_compiles("${OpenMP_C_TEST_SOURCE}" OpenMP_FLAG_DETECTED)
-  set(CMAKE_REQUIRED_FLAGS "${SAFE_CMAKE_REQUIRED_FLAGS}")
-  if(OpenMP_FLAG_DETECTED)
-    set(OpenMP_CXX_FLAGS_INTERNAL "${FLAG}")
-    break()
-  endif(OpenMP_FLAG_DETECTED)
-endforeach(FLAG ${OpenMP_CXX_FLAG_CANDIDATES})
+IF (CMAKE_CXX_COMPILER)
+  foreach(FLAG ${OpenMP_CXX_FLAG_CANDIDATES})
+    set(SAFE_CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}")
+    set(CMAKE_REQUIRED_FLAGS "${FLAG}")
+    unset(OpenMP_FLAG_DETECTED CACHE)
+    message(STATUS "Try OpenMP CXX flag = [${FLAG}]")
+    check_cxx_source_compiles("${OpenMP_CXX_TEST_SOURCE}" OpenMP_FLAG_DETECTED)
+    set(CMAKE_REQUIRED_FLAGS "${SAFE_CMAKE_REQUIRED_FLAGS}")
+    if(OpenMP_FLAG_DETECTED)
+      set(OpenMP_CXX_FLAGS_INTERNAL "${FLAG}")
+      break()
+    endif(OpenMP_FLAG_DETECTED)
+  endforeach(FLAG ${OpenMP_CXX_FLAG_CANDIDATES})
+ENDIF (CMAKE_CXX_COMPILER)
 
 set(OpenMP_C_FLAGS "${OpenMP_C_FLAGS_INTERNAL}"
   CACHE STRING "C compiler flags for OpenMP parallization")
 
 set(OpenMP_CXX_FLAGS "${OpenMP_CXX_FLAGS_INTERNAL}"
   CACHE STRING "C++ compiler flags for OpenMP parallization")
+
 # handle the standard arguments for find_package
-find_package_handle_standard_args(OpenMP DEFAULT_MSG 
-  OpenMP_C_FLAGS OpenMP_CXX_FLAGS )
+IF (CMAKE_C_COMPILER)
+  find_package_handle_standard_args(OpenMP DEFAULT_MSG 
+    OpenMP_C_FLAGS )
+ENDIF (CMAKE_C_COMPILER)
+
+IF (CMAKE_CXX_COMPILER)
+  find_package_handle_standard_args(OpenMP DEFAULT_MSG 
+    OpenMP_CXX_FLAGS )
+ENDIF (CMAKE_CXX_COMPILER)
 
 mark_as_advanced(
   OpenMP_C_FLAGS

Relationships

Notes
(0028515) Justin (reporter) 2012-02-06 07:42	Patch works fine, please apply.

(0028525) Rolf Eike Beer (developer) 2012-02-08 13:04	Pushed fix to next: http://cmake.org/gitweb?p=cmake.git;a=commitdiff;h=81228e9d1d94cb55fa0a75b474c5a3283b39551a [^] It's not your one, but does the same.

(0029964) David Cole (manager) 2012-07-09 06:52	Closing resolved issues that have not been updated in more than 4 months.

Issue History
Date Modified	Username	Field	Change
2011-03-01 03:58	Raymond Wan	New Issue
2011-03-01 03:58	Raymond Wan	File Added: FindOpenMP.2-8-4.patch
2012-02-06 07:42	Justin	Note Added: 0028515
2012-02-08 13:04	Rolf Eike Beer	Note Added: 0028525
2012-02-08 13:04	Rolf Eike Beer	Assigned To	=> Rolf Eike Beer
2012-02-08 13:04	Rolf Eike Beer	Status	new => resolved
2012-02-08 13:04	Rolf Eike Beer	Resolution	open => fixed
2012-02-08 13:04	Rolf Eike Beer	Fixed in Version	=> CMake 2.8.8
2012-02-08 13:04	Rolf Eike Beer	Target Version	=> CMake 2.8.8
2012-07-09 06:52	David Cole	Note Added: 0029964
2012-07-09 06:52	David Cole	Status	resolved => closed