Using GNU GCC to build the package mplayer 1.5 may result in an error during the compilation phase with the following output:
libvo/vo_aa.c: In function 'draw_frame':
libvo/vo_aa.c:360:17: error: passing argument 2 of 'sws_scale' from incompatible pointer type [-Wincompatible-pointer-types]
360 | sws_scale(sws,src,stride,0,src_height,image,image_stride);
| ^~~
| |
| uint8_t ** {aka unsigned char **}
In file included from libvo/vo_aa.c:42:
/usr/include/libswscale/swscale.h:224:58: note: expected 'const uint8_t * const*' {aka 'const unsigned char * const*'} but argument is of type 'uint8_t **' {aka 'unsigned char **'}
224 | int sws_scale(struct SwsContext *c, const uint8_t *const srcSlice[],
| ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~
libvo/vo_aa.c: In function 'draw_slice':
libvo/vo_aa.c:380:17: error: passing argument 2 of 'sws_scale' from incompatible pointer type [-Wincompatible-pointer-types]
380 | sws_scale(sws,src,stride,y,h,image,image_stride);
| ^~~
| |
| uint8_t ** {aka unsigned char **}
In version 14 if GNU GCC has been decided to throw an error by default (with standard >=C99) when there is a warning -Wincompatible-pointer-types. Some of the old software is not ready for such implementation, so using the older GNU GCC like version 13 or suppressing the error with CFLAGS=”-Wno-error=incompatible-pointer-types” should fix the error to warning and the compilation would not be interrupted.
Under Gentoo just switch back for this package to older GNU GCC with gcc-config tool:
srv ~ # gcc-config -l [1] x86_64-pc-linux-gnu-10.3.0 [2] x86_64-pc-linux-gnu-11.3.0 [3] x86_64-pc-linux-gnu-12 [4] x86_64-pc-linux-gnu-13 [5] x86_64-pc-linux-gnu-14 * srv ~ # gcc-config x86_64-pc-linux-gnu-13 * Switching native-compiler to x86_64-pc-linux-gnu-13 ... >>> Regenerating /etc/ld.so.cache... * If you intend to use the gcc from the new profile in an already * running shell, please remember to do: * . /etc/profile srv ~ # . /etc/profile srv ~ # emerge -v media-video/mplayer
List all available versions, select an older than 14 and reload the profile environments and then emerge the package. The compilation phase will only output a warning and package will be built and installed on the system.
If no older GNU GCC version is available just edit the CFLAGS to add “-Wno-error=incompatible-pointer-types” in /etc/portage/make.conf.
It is possible to tune the CFLAGS per a package by adding them before the emerge command, too:
srv ~ # CFLAGS="$CFLAGS -Wno-error=incompatible-pointer-types" emerge -v mplayer
The above line builds successfully the mplayer with GNU GCC 14, because it interprets the incompatible-pointer-types as a warning not error.
Check out a similar case – python 2.7 compilation failure -Wincompatible-pointer-types using GNU GCC 14 under Gentoo.