'glyph' may be used uninitialized in 'kmscon_font_pango_render' (src/font_pango.c)

[Infinidoge]

I'm working to update the Nixpkgs version of kmscon (see NixOS/nixpkgs#178749), and I ran into an interesting warning thrown by the compiler:

[16/85] Compiling C object src/mod-pango.so.p/font_pango.c.o
FAILED: src/mod-pango.so.p/font_pango.c.o 
gcc -Isrc/mod-pango.so.p -Isrc -I../src -Iexternal -I../external -I/nix/store/fd9xgi1wnr21cf6r4g4wg0r1x3q1sfmp-libtsm-4.0.2//ni
x/store/fd9xgi1wnr21cf6r4g4wg0r1x3q1sfmp-libtsm-4.0.2/include -I/nix/store/h3rq434kc322x4jmzfzijfvvw4dn28q9-pango-1.50.7-dev/in
clude/pango-1.0 -I/nix/store/00gc9zv7daj8dx5nnv22klw8y09df1dp-fontconfig-2.13.94-dev/include -I/nix/store/0iyadd7k48mwx2g21rms1
4y6a8k13ca7-freetype-2.12.1-dev/include/freetype2 -I/nix/store/92p7s7grpcwx8jlbnjc7vhw2kqggr6xv-glib-2.72.1-dev/include -I/nix/store/92p7s7grpcwx8jlbnjc7vhw2kqggr6xv-glib-2.72.1-dev/include/glib-2.0 -I/nix/store/rk79fi264q6bc5mmvcabajh9kvqr7018-glib-2.72.1/lib/glib-2.0/include -I/nix/store/k1prvgi3vr3ln80wgh37ckaihwwg1w5a-harfbuzz-3.3.2-dev/include/harfbuzz -I/nix/store/ak01zssa4jdsswn6gixaxzdw6kjiqc3l-libxkbcommon-1.4.0-dev/include -I/nix/store/vb5r08wxkarnl9sqnz2888w99lvfwhzn-libglvnd-1.4.0-dev/include -fdiagnostics-color=always -D_FILE_OFFSET_BITS=64 -Wall -Winvalid-pch -Werror -std=gnu99 -O0 -ffast-math -fno-strict-aliasing -ffunction-sections -fdata-sections -fstack-protector -fvisibility=hidden -D_GNU_SOURCE -D_POSIX_C_SOURCE=200809L -include /build/source/build/config.h -fPIC -pthread -MD -MQ src/mod-pango.so.p/font_pango.c.o -MF src/mod-pango.so.p/font_pango.c.o.d -o src/mod-pango.so.p/font_pango.c.o -c ../src/font_pango.c
../src/font_pango.c: In function 'kmscon_font_pango_render':
../src/font_pango.c:436:14: error: 'glyph' may be used uninitialized in this function [-Werror=maybe-uninitialized]
  436 |         *out = glyph;
      |         ~~~~~^~~~~~~
cc1: all warnings being treated as errors

I don't have much experience with writing/debugging C code, so I was unsure if this was a nonissue, or if the code should be edited to remove the compiler warning. (Adding -Wno-error=maybe-uninitialized works to suppress the error, however.)

[Aetf]

I believe it's a false positive. glyph is initialized by get_glyph in

kmscon/src/font_pango.c

Line 432 in 90ed419

ret = get_glyph(font->data, &glyph, id, ch, len, &font->attr);

.

[Infinidoge]

Yeah thought so, will stick with the -Wno-error flag then. Out of curiosity, is there a way to signal to the compiler that that area is a known (and accounted for) issue, so as to not blanket-ignore the entire maybe-uninitialized category?

[Aetf]

There are #pragma directives, but I've never used them before... Not sure how portable they are.