Eclipse CDT - how to use an argfile for the linker for a too long command line - c

Question

I'm using Eclipse CDT 9 Neon with GCC 6.3 on Windows 7 for a STM32 project.
I have installed the GNU ARM Plug-in and use sh.exe for long command line management (cmd.exe from windows have a limite of 8192 char) for calling make.exe (GNU Coreutils date: 04.06.2009).
I'm working on a big project.
Without build exclusion my linker command line is over 33 000 char and generate an error on the linker command line.
With builds exclusions and a reduced version of my project, I have reduce the linker command line to 15 600 char, compilation worked fine and my binary file is operational.
At first, for the full version of my project, the linker command line is bigger than 20 000 char and generate an ACCESS VIOLATION on sh.exe.
With an other version of sh.exe (from Microsemi IDE) I have no more ACCESS VIOLATION on sh.exe and be able to link more file.
But for the full version of my project I have a link error :
make (e=87): Paramètre incorrect.
This error come from a to long command line (more than 32 000 char).
Other IDE (Winidea with GCC) use an argument file that combine linker file (.ld) and the obj files list to have a very short linker command line.
How can I configure GCC in Eclipse to use an argument file for the linker ?
I found a solution, not perfect but fully operational. I have writen an bat file to generate obj listing file.
Instructions to use it are in rem.
I have writen the file "gen__link_ld.bat" :
echo off
rem ***************************************************************************
rem Generate script file for the linker to go throuth linker command line too
rem long trouble under windows (32 000 char max)
rem ***************************************************************************
rem Lunch in pre-build step is not advised, this commande is run in paralel
rem with build step that can temporarie supress obj file need to run
rem compilation a 2nd time to have a script file up to date for the linker.
rem Run in pre-build step generate trouble in debug mode.
rem
rem Use manual lunch with 2 parameters :
rem create a .bat file per build with the folowing commande :
rem gen__link_ld.bat ./project relative path and .ld file name ./project relative build path
rem in linker commande line pattern replace {INPUT}
rem by -Xlinker --script=${ProjDirPath}/${ConfigName}/___link.ld
rem and add manualy librairie after ___link.ld, in this case library include
rem throuth graphical build setting don't work, they may use {INPUT} from the
rem standard commande
rem ***************************************************************************
echo **************************************************************************
echo ***************************** *****************************
echo ***************************** WARNING *****************************
echo ***************************** *****************************
echo **************************************************************************
echo Generate script file for the linker to go throuth linker command line too
echo long trouble under windows (32 000 char max)
echo
echo List only existing obj file.
echo The best way is to use manual lunch with one .bat file per build.
echo follow information in r e m above to use it.
echo
echo Run this commande evry time that obj liste is modified.
echo WARNING this function don't delete obj file for file recently exclude
echo frome build.
echo To secure the compilation need a clean to suppress all obj, run a first
echo build witch compile all file without error (with only linker error) to
echo generate an obj file listing up to date and run a second buid for a
echo successful linker step. When the OJB file listing is up to date, only
echo eclipse build commande is needed
echo **************************************************************************
echo Linker file use : %1
echo Build path use : %2
echo **************************************************************************
setlocal ENABLEDELAYEDEXPANSION
set destination=%2
set destination=%destination:/=\%
rem *** Generate obj file listing ***
echo INPUT(>%destination%\___link.ld
dir %destination%\*.o /s /b >>%destination%\___link.ld
echo )>>%destination%\___link.ld
rem *** Concatenat obj file listing with ld file from parameter 1 ***
set str=%1
set str=%str:/=\%
type %str%>>%destination%\___link.ld
echo *** OBJ file listing up to date
echo **************************************************************************
pause
Thanks

Answer 1

Here's a simple workaround I've found for the issue (using a small python script), on the same line of thought of separating the object listing in another file - note that these kind of files are called response files in the GNU world: https://gcc.gnu.org/wiki/Response_Files and they separate the entire command-line rather than only the object files and libraries.
Assuming you're using the GNU Make builder+GNU linker:
You'll need to create a python script and place it somewhere in your project, I'll assume the path to the script is build/link_with_rsp_file.py. Place in it the contents below.
Go to project properties -> C/C++ Build -> Settings. Make sure the appropriate build configuration is selected. You should find the toolchain settings there.
Select the linker item. Depending on your build configuration, you should have a Command/Command line pattern pair such as g++/${COMMAND} ${FLAGS} ${OUTPUT_FLAG} ${OUTPUT_PREFIX}${OUTPUT} ${INPUTS}. We'll assume it looks just like this, adjust accordingly.
Change the command-line pattern to #$(file >linkcl.rsp,${FLAGS} ${OUTPUT_FLAG} ${OUTPUT_PREFIX}${OUTPUT} ${INPUTS})python ../build/link_with_rsp_file.py linkcl.rsp ${COMMAND}. This effectively tells GNU make to take all the linker arguments, put them in the response file linkcl.rsp (using the $(file) function) and then run the linker (${COMMAND}) using the generated response file instead.
Python script:
import sys, subprocess
def cmd_exec(full_cmd):
print(full_cmd)
sys.stdout.flush(); sys.stderr.flush()
p = subprocess.Popen(full_cmd.split(' '))
p.communicate()
return p.returncode == 0
rsp_file, cmd = sys.argv[1], sys.argv[2:]
cmd = ' '.join(cmd)
# First replace all '\' with '/' in the response file (bash doesn't deal well with '\')
with open(rsp_file, "r") as f: linkcl = f.read()
linkcl = linkcl.replace('\\', '/')
with open(rsp_file, "w") as f: f.write(linkcl)
# Call the linker
cmd_exec("{cmd} #{rsp_file}".format(cmd=cmd, rsp_file=rsp_file))

Answer 2

I've improved the way in https://stackoverflow.com/a/61644057/5789722 :
Go to project properties -> C/C++ Build, and ensure Builder type is External builder and enable Generate Makefiles automatically
Go to project properties -> C/C++ Build -> Settings, select Tool Settings -> a linker like Cygwin C++ Linker
fill Command line pattern with:
#$(file >linkcl.rsp,$(subst \,/,${FLAGS}) ${OUTPUT_FLAG} ${OUTPUT_PREFIX}${OUTPUT} ${INPUTS}) ${COMMAND} #linkcl.rsp
here I use subst to replace \ with /, then link_with_rsp_file.py is not needed any more