[cmake-developers] [CMake 0015872]: Programs with Fortran entry point (but calls into C) don't link correctly using Intel or PGI compilers

[Mantis Bug Tracker]

The following issue has been SUBMITTED. 
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https://public.kitware.com/Bug/view.php?id=15872 
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Reported By:                Ben Matthews
Assigned To:                
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Project:                    CMake
Issue ID:                   15872
Category:                   CMake
Reproducibility:            always
Severity:                   major
Priority:                   normal
Status:                     new
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Date Submitted:             2015-12-06 21:39 MST
Last Modified:              2015-12-06 21:39 MST
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Summary:                    Programs with Fortran entry point (but calls into C)
don't link correctly using Intel or PGI compilers
Description: 
CMake always seems to link mixed language programs using the C++ compiler. Intel
and PGI link libcrt, which wants to have a main(). Programs with a Fortran entry
point typically won't have main(). Setting the linker_language property doesn't
seem to make a difference. 

Using the GNU compilers, CMake still uses the C++ compiler, but it gets the
libraries right and everything works as expected. 

Steps to Reproduce: 
git clone https://github.com/matthb2/cmake_f90_entry_bug.git
cd cmake_f90_entry_bug
mkdir build
cd build
CC=icc CXX=icpc FC=ifort cmake ../
make

####
make
Scanning dependencies of target testprog
[ 50%] Building Fortran object CMakeFiles/testprog.dir/test.f90.o
[100%] Linking CXX executable testprog
/usr/lib/gcc/x86_64-pc-linux-gnu/4.9.3/../../../../lib64/crt1.o: In function
`_start':
(.text+0x20): undefined reference to `main'
CMakeFiles/testprog.dir/build.make:94: recipe for target 'testprog' failed
make[2]: *** [testprog] Error 1
CMakeFiles/Makefile2:67: recipe for target 'CMakeFiles/testprog.dir/all' failed
make[1]: *** [CMakeFiles/testprog.dir/all] Error 2
Makefile:83: recipe for target 'all' failed
make: *** [all] Error 2


Additional Information: 
Note that the example code is a bit of a simplified/contrived example. It will
work fine if you remove the HAS_CXX property, but real cases also incorporate
C/C++ modules and require that libc/libstdc++ be present. 

icc -V
Intel(R) C Intel(R) 64 Compiler XE for applications running on Intel(R) 64,
Version 13.0.0.079 Build 20120731
Copyright (C) 1985-2012 Intel Corporation.  All rights reserved.
FOR NON-COMMERCIAL USE ONLY

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Issue History 
Date Modified    Username       Field                    Change               
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2015-12-06 21:39 Ben Matthews   New Issue                                    
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