[cmake-developers] [CMake 0015650]: Linking large files on OS X can result in linker failing with "command line too long" error

[Mantis Bug Tracker]

The following issue has been SUBMITTED. 
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http://www.cmake.org/Bug/view.php?id=15650 
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Reported By:                Abigail
Assigned To:                
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Project:                    CMake
Issue ID:                   15650
Category:                   CMake
Reproducibility:            always
Severity:                   major
Priority:                   normal
Status:                     new
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Date Submitted:             2015-07-14 07:07 EDT
Last Modified:              2015-07-14 07:07 EDT
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Summary:                    Linking large files on OS X can result in linker
failing with "command line too long" error
Description: 
When a project contains sufficiently many source files - the one I'm compiling
has 1689 .cpp files - the linker will fail, with the message "Error running link
command: Argument list too long".

When using response lists (via set(CMAKE_CXX_USE_RESPONSE_FILE_FOR_OBJECTS 1)),
the issue still occurs. This is because the response file is specified as a
linker flag with @ResponseFile.rsp syntax, which is expanded by the compiler
driver rather than being passed through and then expanded internally by the
linker.

OS X's linker, ld64, doesn't support the @ResponseFile.rsp syntax, so it's not
possible to work around this with set(CMAKE_CXX_RESPONSE_FILE_LINK_FLAG
"-Wl,@"). However, it does support -filelist, but this requires the file to be
newline-separated rather than space-separated.

Steps to Reproduce: 
In an empty directory:

for i in {0000..9999}; echo "void f$i() {}" >> $i.c
find . > files.txt
cat << EOF > CMakeLists.txt
cmake_minimum_required(VERSION 2.8)
project(long_file_test)
file(STRINGS "files.txt" files)
add_executable(long_file_test ${files})
EOF
cmake . && cmake --build . -- -j 24

...This will compile everything correctly, and then at the end emit:

[100%] Linking C executable long_file_test
Error running link command: Argument list too long
make[2]: *** [long_file_test] Error 2
make[1]: *** [CMakeFiles/long_file_test.dir/all] Error 2
make: *** [all] Error 2
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Issue History 
Date Modified    Username       Field                    Change               
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2015-07-14 07:07 Abigail        New Issue                                    
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