How do I debug CMakeLists.txt files?

Question

Is there a possibility to debug CMakeLists.txt files (at least listing of variables) except for the message statement?

Might be helpful, too: http://stackoverflow.com/a/38869455/2799037 — usr1234567, Jan 04 '17 at 14:24

Joe · Accepted Answer · 2019-01-22T11:18:09.537

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There is no interactive debugger for CMake, however there are also the flags -Wdev, --debug-output and --trace which might help. Also remember to check the log files CMakeFiles\CMakeOutput.log and CMakeFiles\CMakeError.log which mainly collect outputs of processes called by CMake (for example while checking for presence of a type or header).

Since version 3.7, CMake now officially supports a "server mode" so integration in IDEs is likely to improve in the near future. Initial support exists both in Qt Creator and Visual Studio 2017 RC

edited Jan 22 '19 at 11:18

answered Apr 02 '14 at 07:02

Joe

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Which one do we use to debug `if` statements in `CmakeList.txt`? `came --debug ...` and `cmake --debug-output ...` are not printing them. In Bash, the equivalent is `bash -x `. – jww Sep 14 '16 at 16:44
@jww I'm not 100% sure what you are trying to debug, but the output of `--trace` is usually quite extensive (redirect the output to a file!) – Joe Sep 15 '16 at 05:27
I was trying to debug the script and understand why certain code blocks were not being entered. But I found the problem: `string(STRIP ...)` was broken. Also see [How to strip trailing newline in Cmake variable?](http://stackoverflow.com/q/39496043/). My apologies if you did not know what `bash -x` does. – jww Sep 15 '16 at 05:44
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You shouldn't just mention checking the logs. You should explain how one goes about checking the logs. – Thomas Jay Rush Dec 22 '18 at 13:20
@ThomasJayRush I added information about the location and content of the log files. Anything beyond that depends on the specific issue. – Joe Jan 22 '19 at 11:19

score 12 · Answer 2 · answered Oct 10 '18 at 19:15

You can try using the new CMake Script Debugger provided by the VisualGDB tool. It uses an open-source fork of CMake that supports stepping through CMakeLists.txt files, setting code/data breakpoints, evaluating/changing variables, etc.

There's a detailed step-by-step tutorial on the new debugger here

score 7 · Answer 3 · answered Aug 27 '19 at 09:46

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I like to use variable_watch to "debug" my CMakeLists.txt files. Just set in top of my script:

variable_watch(SOME_MY_VAR)

answered Aug 27 '19 at 09:46

leanid.chaika

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usr1234567 · Answer 4 · 2017-01-04T14:23:03.420

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There are steveire's CMake Daemon Tools. I haven't used them myself, but they claim to offer possibilities for introspection that seem to be pretty close to a debugger.

Edit: They are now called CMake-server and are part of CMake 3.7.

edited Jan 04 '17 at 14:23

answered Aug 10 '16 at 09:43

usr1234567

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Eugene Gr. Philippov · Answer 5 · 2020-01-30T17:28:28.277

Also, read about the env var VERBOSE: https://cmake.org/cmake/help/latest/envvar/VERBOSE.html

I used it this way:

export VERBOSE=defined
make

and got some more verbosity.

In other cases, edit CMakeLists.txt file to include the following line:

set(CMAKE_VERBOSE_MAKEFILE ON)

(Some post on this is https://bytefreaks.net/programming-2/make-building-with-cmake-verbose ).

Also, there are useful cmake options controlling debug output, see the manpage: https://cmake.org/cmake/help/latest/manual/cmake.1.html

How do I debug CMakeLists.txt files?

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