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I'm using CMake with the GNU Make generator on a project of mine, and then want to build it - verbosely.

I'm interested in lines which actually produce things, and not interested in lines such as:

gmake[2]: Entering directory '/some/where'
gmake[2]: Leaving directory '/some/other/place'

nor the lines saying:

cd /some/where && /path/to/cmake/bin/cmake -E cmake_link_script CMakeFiles/some.dir/link.txt --verbose=1

as those are "wrapping" the actual work that will happen when cmake runs that script (e.g. calls a linker executable such as gcc).

I don't mind very much the percentage headers such as:

[ 97%] Building CXX object /path/to/proj/CMakeFiles/something.dir/foo.o

i.e. if your solution removes them, then fine, if it keeps them - also fine.

I've read answers and comments on this question: Using CMake with GNU Make: How can I see the exact commands?, and the best I've come up with so far is:

MAKEFLAGS="$MAKEFLAGS --no-print-dir" cmake --build build_dir/  --verbose

The --verbose gives you maximum (?) verbosity, with everything you don't want. Then, the --no-print-dir is picked up by GNU Make, making it avoid the Entering/Leaving Directory messages.

Can I do better, and actually avoid the cd and the cmake -E commands?

Notes:

  • I realize I can use maximum verbosity, then filter using grep. That's not what I want - I want the lines not to be emitted in the first place.
  • Nothing may be hard-coded into the CMakeLists.txt file; everything must be done via the command-line, after CMake configuration.
einpoklum
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  • I'm sure that `MAKEFLAGS+="--no-print-dir"` is a typo and you meant `MAKEFLAGS="--no-print-dir"`. – MadScientist Nov 03 '21 at 15:24
  • @MadScientist: Well, it depends on whether I have other stuff in my MAKEFLAGS, but ok. – einpoklum Nov 03 '21 at 15:40
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    This is reason number #289465 why I use Ninja instead. – Alex Reinking Nov 03 '21 at 16:43
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    The POSIX shell doesn't define any such operator as `+=`; using it is a syntax error. The portable way to write this while preserving pre-existing values is `MAKEFLAGS="$MAKEFLAGS --no-print-dir"`. Some shells (like bash) do support `+=` as a specific operator, others don't. – MadScientist Nov 03 '21 at 18:07
  • There's no particular reason that these lines have to be printed: that's just how cmake decided to generate its makefiles. cmake could easily have generated makefiles that did better here, and I'm sure cmake could (maybe even does) generate ninja files that don't work exactly how some people would like. – MadScientist Nov 03 '21 at 18:09

1 Answers1

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You can discover for yourself that there is no way to do what you want.

Since cmake is just generating makefiles, and it's make that is actually running the recipes and printing the output, you need to look at the makefile and see how the rules are constructed. If you find a sample rule for a link line for example you will see it looks like this:

myexecutable: ...
        @$(CMAKE_COMMAND) -E cmake_echo_color --switch=$(COLOR) --green --bold --progress-dir=/mydir/CMakeFiles --progress-num=$(CMAKE_PROGRESS_2) "Linking CXX executable myexecutable"
        cd /mydir && $(CMAKE_COMMAND) -E cmake_link_script CMakeFiles/myexecutable.dir/link.txt --verbose=$(VERBOSE)

Note that there is no special variable, or token, or anything appearing in this recipe before the cd /mydir ... text.

So, there is absolutely no way to control how this particular recipe is printed, separately from how all the other recipes are printed. You either get them all, or you get none of them.

MadScientist
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