How to ignore a specific warning

[spacemoose]

Just trying out flycheck, and find it awesome. Thanks for the great work.

Regarding my issue: Concretely, I get a warning (both gcc and clang) "#pragma once in main file" for all my header files that are included in a file providing main. This is incorrect, and from googling around seems to be a clang/gcc issue.

I would like to disable the warning -- have flycheck ignore this warning, and potentially others. How can I go about doing this?

Sorry if creating an issue is the wrong approach to answering my question, i tried stackexchange first...

[swsnr]

You can't. Flycheck does not have its own way to ignore warnings, but relies on syntax checker to be able to ignore warnings on their own.

In other words, you'll need to find Clang's warning flag responsible for this warning, and add it to flycheck-clang-warnings or flycheck-clang-args. It's a Clang issue really, so closing.

[jcoffland]

I've changed flycheck-clang-warnings from the default value of ("all", "extra") to ("all") which should eliminate the #pragma once in main file warning but the warning persists. If I run clang or gcc on the command line I only get this warning with -Wextra. It appears that setting flycheck-clang-warnings or flycheck-gcc-warnings has no effect. Any idea how to fix this?

[cpitclaudel]

Can you try running C-c ! C-c? It should show you exactly what command line flycheck ran.

[jcoffland]

That was very helpful. Here's what I got:

gcc -fshow-column -iquote /home/jcoffland/projects/camotics/git/master/src/gcode/plan/ -x c\+\+  -o /dev/null - < /home/jcoffland/projects/camotics/git/master/src/gcode/plan/Planner.h
<stdin>:21:9: warning: #pragma once in main file
In file included from <stdin>:23:0:
/home/jcoffland/projects/camotics/git/master/src/gcode/plan/PlannerConfig.h:23:10: fatal error: gcode/Axes.h: No such file or directory
 #include <gcode/Axes.h>
          ^~~~~~~~~~~~~~
compilation terminated.

There are two problems. One, I don't have my include paths setup correctly. Two, because of the way gcc is called it considers Planner.h to be a "main file" not a header. This causes it to emit the warning warning: #pragma once in main file. I cannot find any way to disable this warning in gcc but clang has -Wno-pragma-once-outside-header. So I'll just use clang with this option.

Now I just need to figure out how to get flycheck to use all of my project's include paths.