21 byte memory leak in merge_styles (3 tiny leaks of 7 bytes)

Thanks for reporting your bug here! The following template will help with giving as much information as possible so that it's easier to diagnose and fix.

Upfront Information

Please provide the following information by running the command and providing the output.

Fvwm3 version (run: fvwm3 --version) 4405437b

fvwm3 1.0.3 (1.0.2-48-g356e327f)
with support for:  ReadLine, XPM, PNG, Shape, XShm, SM, Bidi text, XRandR, XRender, XCursor, XFT, NLS

Linux distribution or BSD name/version openSUSE 15.2 running on Windows Subsystem for Linux.
Platform (run: uname -sp) Linux x86_64
Expected Behaviour

Ideally no memory leaks reported by Valgrind What were you trying to do? Please explain the problem. Running valgrind on fvwm3 to find any more memory leaks to fix.

Actual Behaviour

merge_styles_leak.log

What should have happened, but didn't?

Enabling logging

fvwm3 has a means of logging what it's doing. Enabling this when reproducing the issue might help. To do this, either change the means fvwm3 is started by adding -v as in:

fvwm3 -v

or, once fvwm3 has loaded, send SIGUSR2 as in:

pkill -USR2 fvwm3

The resulting logfile can be found in $HOME/.fvwm/fvwm3-output.log

Steps to Reproduce

How can the problem be reproduced?

Compile fvwm3 revision 4405437b
valgrind --leak-check=full --track-origins=no --undef-value-errors=no --fullpath-after=$PWD/ --num-callers=200 --suppressions=fontconfig.supp fvwm/fvwm3 |& less
When Fvwm3 loads, click the background and click Quit then click Quit again from the confirmation dialog that pops up. For this, the following is helpful:

Reduce the problem to the smallest fvwm configuration example (where possible). Start with a blank config file (fvwm3 -f/dev/null) and go from there.
Does the problem also happen with Fvwm2?

Include your configuration with this issue. My fvwm config is the default fvwm3 config with this line added from a bugreport somewhere (I think from PR #429): *FvwmIconMan*action Mouse 1 N sendcommand "Iconify off", sendcommand "FlipFocus", sendcommand "Raise"

Does Fvwm3 crash?

Yes, it crashed several times when I was adding in the free_style calls but seems to be fine now.

If fvwm3 crashes then check your system for a corefile. This is platform dependant, however, check if:

corefiles are enabled (ulimit -c)
A corefile might be in $HOME or /tmp/.
If you're using Linux (with systemd), check coredumpctl list. coredumpctl may need installing separately.

If you find a corefile, install gdb and run:

gdb /path/to/fvwm3 /path/to/corefile

If you're using coredumpctl then use:

coredumpctl debug

Then from within the (gdb) prompt, issue:

bt full

... and include the output here.

Extra Information

Anything else we should know? X server: VcXsrv 1.20.8.1
Feel free to take a screen capture or video and upload to this issue if you feel it would help.
Attach $HOME/.fvwm/fvwm3-output.log from the step above. fvwm3-output.log

Fontconfig error suppression file (fontconfig.supp in the above Valgrind command):

{
   Fontconfig suppression
   Memcheck:Leak
   match-leak-kinds: definite
   fun:malloc
   ...
   obj:/usr/lib64/libfontconfig.so.1.10.1
   ...
}
{
   Fontconfig suppression 2
   Memcheck:Leak
   match-leak-kinds: definite
   fun:realloc
   ...
   obj:/usr/lib64/libfontconfig.so.1.10.1
   ...
}

fvwmorg / fvwm3