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List: cmake
Subject: [CMake] Handling of generated files in POST_BUILD custom commands
From: Pedro Navarro via CMake <cmake () cmake ! org>
Date: 2018-08-25 0:19:56
Message-ID: CAFSk+f6QHT1pZXeaWMz+rFkr5UXBRnDdct+i3zcbNyPe+sQfYA () mail ! gmail ! com
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Hi all,
I'm trying to build an executable that has its debug symbols in a separate
file. I implemented that with a POST_BUILD custom command:
add_executable(foo a.cpp)
add_custom_command(TARGET foo
POST_BUILD
COMMAND ${CMAKE_OBJCOPY} --only-keep-debug foo foo.sym
COMMAND ${CMAKE_OBJCOPY} --add-gnu-debuglink=foo.sym foo
COMMAND ${CMAKE_STRIP} --strip-debug foo
BYPRODUCTS foo.sym
COMMENT "Creating symbols"
)
The problem is that if I delete foo.sym, in order for it to be created
again it's not enough with running the custom command steps as we have
stripped the file and the debug symbols are gone: we need to relink the
executable so the debug information is available again.
The ninja generator makes this situation possible with the use of
byproducts. By adding BYPRODUCTS foo.sym to the custom command if I change
foo.sym the target is relinked. Unfortunately the GNU Makefiles generator
ignores byproducts, so I want to relink the executable I need to remove it.
Also the byproducts are added to ninja's clean target, but not for GNU
Makefiles.
I have tried to achieve the same result with a custom command:
add_custom_command(OUTPUT foo
DEPENDS foo
COMMAND ${CMAKE_OBJCOPY} --only-keep-debug foo foo.sym
COMMAND ${CMAKE_OBJCOPY} --add-gnu-debuglink=foo.sym foo
COMMAND ${CMAKE_STRIP} --strip-debug foo
BYPRODUCTS foo.sym
COMMENT "Creating symbols"
USES_TERMINAL
)
add_custom_target(foo_symbols ALL
DEPENDS foo.sym
)
But I get the same results, the target does not get relinked. Also, it
seems that there is an issue of some sort because every time I type make
the steps to create the file foo.sym are executed, resulting in an error
message from objcopy ('debuglink section already exists'). If I touch the
CMakeLists.txt file (by adding a space, removing it and saving), make after
that correctly does not execute the steps to create foo.sym. I understand
that targets created by add_custom_target are always out of date, but I
thought there shouldn't be a need to re-run the custom command.
*lgux-pnavarro4 ~/tests/cm2/b $ cmake --version*
cmake version 3.10.2
CMake suite maintained and supported by Kitware (kitware.com/cmake).
*lgux-pnavarro4 ~/tests/cm2/b $ rm -rf * && cmake -DCMAKE_BUILD_TYPE=Debug
..*
-- The C compiler identification is GNU 7.3.0
-- The CXX compiler identification is GNU 7.3.0
-- Check for working C compiler: /usr/local/bin/cc
-- Check for working C compiler: /usr/local/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/local/bin/c++
-- Check for working CXX compiler: /usr/local/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: /home/pnavarro/tests/cm2/b
*lgux-pnavarro4 ~/tests/cm2/b $ make*
make: Entering directory '/home/pnavarro/tests/cm2/b'
make[1]: Entering directory '/home/pnavarro/tests/cm2/b'
make[2]: Entering directory '/home/pnavarro/tests/cm2/b'
Scanning dependencies of target foo
make[2]: Leaving directory '/home/pnavarro/tests/cm2/b'
make[2]: Entering directory '/home/pnavarro/tests/cm2/b'
[ 33%] Building CXX object CMakeFiles/foo.dir/a.cpp.o
[ 66%] Linking CXX executable foo
make[2]: Leaving directory '/home/pnavarro/tests/cm2/b'
[ 66%] Built target foo
make[2]: Entering directory '/home/pnavarro/tests/cm2/b'
Scanning dependencies of target foo_symbols
make[2]: Leaving directory '/home/pnavarro/tests/cm2/b'
make[2]: Entering directory '/home/pnavarro/tests/cm2/b'
[100%] Creating symbols
make[2]: Leaving directory '/home/pnavarro/tests/cm2/b'
[100%] Built target foo_symbols
make[1]: Leaving directory '/home/pnavarro/tests/cm2/b'
make: Leaving directory '/home/pnavarro/tests/cm2/b'
*lgux-pnavarro4 ~/tests/cm2/b $ make*
make: Entering directory '/home/pnavarro/tests/cm2/b'
make[1]: Entering directory '/home/pnavarro/tests/cm2/b'
make[2]: Entering directory '/home/pnavarro/tests/cm2/b'
make[2]: Leaving directory '/home/pnavarro/tests/cm2/b'
[ 66%] Built target foo
make[2]: Entering directory '/home/pnavarro/tests/cm2/b'
make[2]: Leaving directory '/home/pnavarro/tests/cm2/b'
make[2]: Entering directory '/home/pnavarro/tests/cm2/b'
[100%] Creating symbols
/usr/bin/objcopy: stkkJQMo: debuglink section already exists
make[2]: Leaving directory '/home/pnavarro/tests/cm2/b'
[100%] Built target foo_symbols
make[1]: Leaving directory '/home/pnavarro/tests/cm2/b'
make: Leaving directory '/home/pnavarro/tests/cm2/b'
*lgux-pnavarro4 ~/tests/cm2/b $ *
*<touch CMakeLists.txt>*
*lgux-pnavarro4 ~/tests/cm2/b $ make*
make: Entering directory '/home/pnavarro/tests/cm2/b'
-- Configuring done
-- Generating done
-- Build files have been written to: /home/pnavarro/tests/cm2/b
make[1]: Entering directory '/home/pnavarro/tests/cm2/b'
make[2]: Entering directory '/home/pnavarro/tests/cm2/b'
make[2]: Leaving directory '/home/pnavarro/tests/cm2/b'
[ 66%] Built target foo
make[2]: Entering directory '/home/pnavarro/tests/cm2/b'
make[2]: Leaving directory '/home/pnavarro/tests/cm2/b'
[100%] Built target foo_symbols
make[1]: Leaving directory '/home/pnavarro/tests/cm2/b'
make: Leaving directory '/home/pnavarro/tests/cm2/b'
This leads me to the following questions:
1) Is is possible to achieve what I want (relink the target if a file
created after POST_BUILD is deleted) with GNU Make files?
2) As the documentation says that byproducts are ignored but the files
marked as GENERATED, shouldn't GENERATED files created by POST_BUILD be
added as a trigger for a new link?
3) Byproducts are added to the clean target in ninja, but in GNU Makefiles
you need to add them to ADDITIONAL_MAKE_CLEAN_FILES. Shouldn't GENERATED
files in POST_BUILD be automatically added to the make clean target? At
least it will give parity between ninja and make's behaviors.
4) Is my issue with foo_symbols not being executed after touching
CMakelists.txt a bug?
Thanks!
Pedro
[Attachment #5 (text/html)]
<div dir="ltr"><div class="gmail_default" style="font-family:"trebuchet \
ms",sans-serif">Hi all,</div><div class="gmail_default" \
style="font-family:"trebuchet ms",sans-serif"><br></div><div \
class="gmail_default" style="font-family:"trebuchet ms",sans-serif">I'm \
trying to build an executable that has its debug symbols in a separate file. I \
implemented that with a POST_BUILD custom command:</div><div \
class="gmail_default"><span style="font-family:"trebuchet \
ms",sans-serif"><br></span></div><div class="gmail_default"><font \
face="monospace, monospace">add_executable(foo a.cpp)</font></div><div \
class="gmail_default"><font face="monospace, monospace">add_custom_command(TARGET \
foo</font></div><div class="gmail_default"><font face="monospace, monospace"> \
POST_BUILD</font></div><div class="gmail_default"><font face="monospace, monospace"> \
COMMAND ${CMAKE_OBJCOPY} --only-keep-debug foo foo.sym</font></div><div \
class="gmail_default"><font face="monospace, monospace"> COMMAND \
${CMAKE_OBJCOPY} --add-gnu-debuglink=foo.sym foo</font></div><div \
class="gmail_default"><font face="monospace, monospace"> COMMAND ${CMAKE_STRIP} \
--strip-debug foo</font></div><div class="gmail_default"><font face="monospace, \
monospace"> BYPRODUCTS foo.sym</font></div><div class="gmail_default"><font \
face="monospace, monospace"> COMMENT "Creating \
symbols"</font></div><div class="gmail_default"><font face="monospace, \
monospace">)</font></div><div class="gmail_default"><font face="trebuchet ms, \
sans-serif"><br></font></div><div class="gmail_default"><font face="trebuchet ms, \
sans-serif">The problem is that if I delete foo.sym, in order for it to be created \
again it's not enough with running the custom command steps as we have stripped \
the file and the debug symbols are gone: we need to relink the executable so the \
debug information is available again.</font></div><div class="gmail_default"><font \
face="trebuchet ms, sans-serif"><br></font></div><div class="gmail_default"><font \
face="trebuchet ms, sans-serif">The ninja generator makes this situation possible \
with the use of byproducts. By adding </font><font face="monospace, \
monospace">BYPRODUCTS foo.sym</font><font face="trebuchet ms, sans-serif"> to the \
custom command if I change foo.sym the target is relinked. Unfortunately the GNU \
Makefiles generator ignores byproducts, so I want to relink the executable I need to \
remove it. Also the byproducts are added to ninja's clean target, but not for GNU \
Makefiles.</font></div><div class="gmail_default"><font face="trebuchet ms, \
sans-serif"><br></font></div><div class="gmail_default"><font face="trebuchet ms, \
sans-serif">I have tried to achieve the same result with a custom \
command:</font></div><div class="gmail_default"><font face="trebuchet ms, \
sans-serif"><br></font></div><div class="gmail_default"><div \
class="gmail_default"><font face="monospace, monospace">add_custom_command(OUTPUT \
foo</font></div><div class="gmail_default"><font face="monospace, monospace"> \
DEPENDS foo</font></div><div class="gmail_default"><font face="monospace, monospace"> \
COMMAND ${CMAKE_OBJCOPY} --only-keep-debug foo foo.sym</font></div><div \
class="gmail_default"><font face="monospace, monospace"> COMMAND \
${CMAKE_OBJCOPY} --add-gnu-debuglink=foo.sym foo</font></div><div \
class="gmail_default"><font face="monospace, monospace"> COMMAND ${CMAKE_STRIP} \
--strip-debug foo</font></div><div class="gmail_default"><font face="monospace, \
monospace"> BYPRODUCTS foo.sym</font></div><div class="gmail_default"><font \
face="monospace, monospace"> COMMENT "Creating \
symbols"</font></div><div class="gmail_default"><font face="monospace, \
monospace"> USES_TERMINAL</font></div><div class="gmail_default"><font \
face="monospace, monospace">)</font></div><div class="gmail_default"><font \
face="monospace, monospace"><br></font></div><div class="gmail_default"><font \
face="monospace, monospace">add_custom_target(foo_symbols ALL<br></font></div><div \
class="gmail_default"><font face="monospace, monospace"> DEPENDS \
foo.sym</font></div><div class="gmail_default"><font face="monospace, \
monospace">)</font></div><div style="font-family:"trebuchet \
ms",sans-serif"><br></div></div><div class="gmail_default"><font face="trebuchet \
ms, sans-serif">But I get the same results, the target does not get relinked. Also, \
it seems that there is an issue of some sort because every time I type </font><font \
face="monospace, monospace">make</font><font face="trebuchet ms, sans-serif"> the \
steps to create the file foo.sym are executed, resulting in an error message from \
objcopy ('debuglink section already exists'). If I touch the CMakeLists.txt \
file (by adding a space, removing it and saving), make after that correctly does not \
execute the steps to create foo.sym. I understand that targets created by \
add_custom_target are always out of date, but I thought there shouldn't be a need \
to re-run the custom command.</font></div><div class="gmail_default"><br></div><div \
class="gmail_default"><div class="gmail_default"><font face="monospace, \
monospace"><b>lgux-pnavarro4 ~/tests/cm2/b $ cmake --version</b></font></div><div \
class="gmail_default"><font face="monospace, monospace">cmake version \
3.10.2</font></div><div class="gmail_default"><font face="monospace, \
monospace"><br></font></div><div class="gmail_default"><font face="monospace, \
monospace">CMake suite maintained and supported by Kitware (<a \
href="http://kitware.com/cmake">kitware.com/cmake</a>).</font></div></div><div \
class="gmail_default"><div class="gmail_default"><font face="monospace, \
monospace"><b>lgux-pnavarro4 ~/tests/cm2/b $ rm -rf * && cmake \
-DCMAKE_BUILD_TYPE=Debug ..</b></font></div><div class="gmail_default"><font \
face="monospace, monospace">-- The C compiler identification is GNU \
7.3.0</font></div><div class="gmail_default"><font face="monospace, monospace">-- The \
CXX compiler identification is GNU 7.3.0</font></div><div class="gmail_default"><font \
face="monospace, monospace">-- Check for working C compiler: \
/usr/local/bin/cc</font></div><div class="gmail_default"><font face="monospace, \
monospace">-- Check for working C compiler: /usr/local/bin/cc -- \
works</font></div><div class="gmail_default"><font face="monospace, monospace">-- \
Detecting C compiler ABI info</font></div><div class="gmail_default"><font \
face="monospace, monospace">-- Detecting C compiler ABI info - done</font></div><div \
class="gmail_default"><font face="monospace, monospace">-- Detecting C compile \
features</font></div><div class="gmail_default"><font face="monospace, monospace">-- \
Detecting C compile features - done</font></div><div class="gmail_default"><font \
face="monospace, monospace">-- Check for working CXX compiler: \
/usr/local/bin/c++</font></div><div class="gmail_default"><font face="monospace, \
monospace">-- Check for working CXX compiler: /usr/local/bin/c++ -- \
works</font></div><div class="gmail_default"><font face="monospace, monospace">-- \
Detecting CXX compiler ABI info</font></div><div class="gmail_default"><font \
face="monospace, monospace">-- Detecting CXX compiler ABI info - \
done</font></div><div class="gmail_default"><font face="monospace, monospace">-- \
Detecting CXX compile features</font></div><div class="gmail_default"><font \
face="monospace, monospace">-- Detecting CXX compile features - done</font></div><div \
class="gmail_default"><font face="monospace, monospace">-- Configuring \
done</font></div><div class="gmail_default"><font face="monospace, monospace">-- \
Generating done</font></div><div class="gmail_default"><font face="monospace, \
monospace">-- Build files have been written to: \
/home/pnavarro/tests/cm2/b</font></div><div class="gmail_default"><font \
face="monospace, monospace"><b>lgux-pnavarro4 ~/tests/cm2/b $ \
make</b></font></div><div class="gmail_default"><font face="monospace, \
monospace">make: Entering directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace">make[1]: Entering directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace">make[2]: Entering directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace">Scanning dependencies of target foo</font></div><div \
class="gmail_default"><font face="monospace, monospace">make[2]: Leaving directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace">make[2]: Entering directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace">[ 33%] Building CXX object \
CMakeFiles/foo.dir/a.cpp.o</font></div><div class="gmail_default"><font \
face="monospace, monospace">[ 66%] Linking CXX executable foo</font></div><div \
class="gmail_default"><font face="monospace, monospace">make[2]: Leaving directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace">[ 66%] Built target foo</font></div><div \
class="gmail_default"><font face="monospace, monospace">make[2]: Entering directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace">Scanning dependencies of target \
foo_symbols</font></div><div class="gmail_default"><font face="monospace, \
monospace">make[2]: Leaving directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace">make[2]: Entering directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace" color="#0000ff">[100%] Creating symbols</font></div><div \
class="gmail_default"><font face="monospace, monospace">make[2]: Leaving directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace">[100%] Built target foo_symbols</font></div><div \
class="gmail_default"><font face="monospace, monospace">make[1]: Leaving directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace">make: Leaving directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace"><b>lgux-pnavarro4 ~/tests/cm2/b $ \
make</b></font></div><div class="gmail_default"><font face="monospace, \
monospace">make: Entering directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace">make[1]: Entering directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace">make[2]: Entering directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace">make[2]: Leaving directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace">[ 66%] Built target foo</font></div><div \
class="gmail_default"><font face="monospace, monospace">make[2]: Entering directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace">make[2]: Leaving directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace">make[2]: Entering directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace" color="#0000ff">[100%] Creating symbols</font></div><div \
class="gmail_default"><font face="monospace, monospace" \
color="#ff0000">/usr/bin/objcopy: stkkJQMo: debuglink section already \
exists</font></div><div class="gmail_default"><font face="monospace, \
monospace">make[2]: Leaving directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace">[100%] Built target foo_symbols</font></div><div \
class="gmail_default"><font face="monospace, monospace">make[1]: Leaving directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace">make: Leaving directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace"><b>lgux-pnavarro4 ~/tests/cm2/b $ </b></font></div><div \
style="font-family:"trebuchet ms",sans-serif"><br></div></div><div \
class="gmail_default"><i style=""><font face="monospace, monospace"><touch \
CMakeLists.txt></font></i></div><div class="gmail_default"><font face="trebuchet \
ms, sans-serif"><br></font></div><div class="gmail_default"><div \
class="gmail_default"><font face="monospace, monospace"><b>lgux-pnavarro4 \
~/tests/cm2/b $ make</b></font></div><div class="gmail_default"><font \
face="monospace, monospace">make: Entering directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace">-- Configuring done</font></div><div \
class="gmail_default"><font face="monospace, monospace">-- Generating \
done</font></div><div class="gmail_default"><font face="monospace, monospace">-- \
Build files have been written to: /home/pnavarro/tests/cm2/b</font></div><div \
class="gmail_default"><font face="monospace, monospace">make[1]: Entering directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace">make[2]: Entering directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace">make[2]: Leaving directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace">[ 66%] Built target foo</font></div><div \
class="gmail_default"><font face="monospace, monospace">make[2]: Entering directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace">make[2]: Leaving directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace">[100%] Built target foo_symbols</font></div><div \
class="gmail_default"><font face="monospace, monospace">make[1]: Leaving directory \
'/home/pnavarro/tests/cm2/b'</font></div><div class="gmail_default"><font \
face="monospace, monospace">make: Leaving directory \
'/home/pnavarro/tests/cm2/b'</font></div><div \
style="font-family:"trebuchet ms",sans-serif"><br></div></div><div \
class="gmail_default"><font face="trebuchet ms, sans-serif"><br></font></div><div \
class="gmail_default"><font face="trebuchet ms, sans-serif">This leads me to the \
following questions:</font></div><div class="gmail_default"><font face="trebuchet ms, \
sans-serif">1) Is is possible to achieve what I want (relink the target if a file \
created after POST_BUILD is deleted) with GNU Make files?</font></div><div \
class="gmail_default"><font face="trebuchet ms, sans-serif">2) As the documentation \
says that byproducts are ignored but the files marked as GENERATED, shouldn't \
--
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