Unable to build LVGL with picolibc from source/module

[aescolar]

Describe the bug

When attempting to build LVGL with the Picolibc source module things fail to compile badly.

Regression

• This is a regression.

Steps to reproduce

1. mkdir build && cd build
2. cmake -GNinja -DBOARD=native_sim ../samples/modules/lvgl/demos/ -DCONFIG_PICOLIBC=y
3. ninja
4. see errors

Relevant log output

In file included from zephyr/build/modules/picolibc/picolibc/include/ssp/string.h:35,
                 from zephyr/build/modules/picolibc/picolibc/include/string.h:240,
                 from zephyr/modules/lvgl/include/lv_conf.h:12,
                 from modules/lib/gui/lvgl/demos/music/assets/../../../src/lv_conf_internal.h:56,
                 from modules/lib/gui/lvgl/demos/music/assets/../../../src/lv_init.h:16,
                 from modules/lib/gui/lvgl/demos/music/assets/../../../lvgl.h:21,
                 from modules/lib/gui/lvgl/demos/music/assets/../../lv_demos.h:16,
                 from modules/lib/gui/lvgl/demos/music/assets/../lv_demo_music.h:16,
                 from modules/lib/gui/lvgl/demos/music/assets/img_lv_demo_music_cover_3.c:1:
zephyr/modules/lvgl/include/lv_conf.h:41:35: error: expected declaration specifiers or ‘...’ before numeric constant
   41 | #define lv_memcpy                 memcpy
      |                                   ^~~~~~
modules/lib/gui/lvgl/demos/music/assets/../../../src/stdlib/lv_string.h:39:8: note: in expansion of macro ‘lv_memcpy’
   39 | void * lv_memcpy(void * dst, const void * src, size_t len);
      |        ^~~~~~~~~
zephyr/modules/lvgl/include/lv_conf.h:41:35: error: expected ‘)’ before ‘!=’ token
   41 | #define lv_memcpy                 memcpy
      |                                   ^~~~~~
modules/lib/gui/lvgl/demos/music/assets/../../../src/stdlib/lv_string.h:39:8: note: in expansion of macro ‘lv_memcpy’
   39 | void * lv_memcpy(void * dst, const void * src, size_t len);
      |        ^~~~~~~~~

(between many others)

Impact

Annoyance – Minor irritation; no significant impact on usability or functionality.

Environment

• Linux Ubuntu 24.04
• host gcc 14.2
• zephyr version main as of now: 52bf8fb

Additional Context

Related to

• modules: lvgl: Use Zephyr builtins instead of LVGL stdlib/string impls #92898
• Unable to build LVGL samples on Ubuntu 22.04 for native_sim #93943

Note the picolibc source module and the one prebuilt with the SDK are not the same picolibc version in general

Note this was worsened by 47c4e3d, but it was failing before, since before v4.1.0, similarly on snprintf and vsnprintf:

In file included from build/modules/picolibc/picolibc/include/stdio.h:573,
                 from include/zephyr/sys/printk.h:65,
                 from include/zephyr/kernel_includes.h:35,
                 from include/zephyr/kernel.h:17,
                 from samples/modules/lvgl/demos/src/main.c:7:
modules/lvgl/include/lv_conf.h:30:35: error: expected declaration specifiers or ‘...’ before numeric constant
   30 | #define lv_snprintf               snprintf
      |                                   ^~~~~~~~
/scratch/zephyrproject/modules/lib/gui/lvgl/src/../src/stdlib/lv_sprintf.h:52:5: note: in expansion of macro ‘lv_snprintf’
   52 | int lv_snprintf(char * buffer, size_t count, const char * format, ...);
      |     ^~~~~~~~~~~
In file included from build/modules/picolibc/picolibc/include/ssp/string.h:35,
                 from build/modules/picolibc/picolibc/include/string.h:240,
                 from include/zephyr/sys/util.h:31,
                 from include/zephyr/sys/atomic.h:18,
                 from include/zephyr/kernel_includes.h:25:
modules/lvgl/include/lv_conf.h:30:35: error: expected declaration specifiers or ‘...’ before ‘__builtin_dynamic_object_size’
   30 | #define lv_snprintf               snprintf
      |                                   ^~~~~~~~
/scratch/zephyrproject/modules/lib/gui/lvgl/src/../src/stdlib/lv_sprintf.h:52:5: note: in expansion of macro ‘lv_snprintf’
   52 | int lv_snprintf(char * buffer, size_t count, const char * format, ...);
      |     ^~~~~~~~~~~
modules/lvgl/include/lv_conf.h:31:35: error: expected declaration specifiers or ‘...’ before numeric constant
   31 | #define lv_vsnprintf              vsnprintf
      |                                   ^~~~~~~~~
/scratch/zephyrproject/modules/lib/gui/lvgl/src/../src/stdlib/lv_sprintf.h:54:5: note: in expansion of macro ‘lv_vsnprintf’
   54 | int lv_vsnprintf(char * buffer, size_t count, const char * format, va_list va);
      |     ^~~~~~~~~~~~
modules/lvgl/include/lv_conf.h:31:35: error: expected declaration specifiers or ‘...’ before ‘__builtin_dynamic_object_size’
   31 | #define lv_vsnprintf              vsnprintf
      |                                   ^~~~~~~~~
/scratch/zephyrproject/modules/lib/gui/lvgl/src/../src/stdlib/lv_sprintf.h:54:5: note: in expansion of macro ‘lv_vsnprintf’
   54 | int lv_vsnprintf(char * buffer, size_t count, const char * format, va_list va);
      |     ^~~~~~~~~~~~

Neither of this issues were present on the 4.0 release