[build sytem] many system wide macros injected more than once #21966
Description
Description
The build system provides a number of predefined preprocessor macros (e.g. RIOT_VERSION, RIOT_CPU, RIOT_BOARD, ...). There are two ways the build system passes those preprocessor macros to the compiler:
- Via
CFLAGS(e.g.-DRIOT_APPLICATION=\"default\") - Via
-include riotbuild.h, whereriotbuild.hcontains lots of generated macros
Steps to reproduce the issue
- Run
make BOARD=nucleo-f767zi QUIET=0 -C examples/basic/default/ - Check the console output above for
-D...arguments passed to GCC. (Looking at a single GCC call is sufficient) - Check the contents of
examples/basic/default/bin/nucleo-f767zi/riotbuild/riotbuild.h
Expected results
- Each system wide macro is injected exactly once using either
riotbuild.hor-D... - There is some reasoning and strategy behind using
riotbuild.hover-D
Actual results
- Most macros are injected with both ways, one macro (
-DCONFIG_GNRC_PKTBUF_SIZE=512) is injected three times with both ways - Modules are only provided via
riotbuild.h, other than that it looks like complete chaos
Evaluation that lead to above conclusion
When building with QUIET=0 I get the following command for compiling e.g. assert.c:
ccache arm-none-eabi-gcc \
-DRIOT_FILE_RELATIVE=\"core/lib/assert.c\" \
-DRIOT_FILE_NOPATH=\"assert.c\" \
-DDEVELHELP -Werror -DCONFIG_GNRC_PKTBUF_SIZE=512 -DCONFIG_GNRC_PKTBUF_SIZE=512 -DCONFIG_GNRC_PKTBUF_SIZE=512 -DCPU_FAM_STM32F7 -DSTM32F767xx -DCPU_LINE_STM32F767xx -DSTM32_FLASHSIZE=2097152U -D__SYSTEM_STM32F7XX_H -DSYSTEM_STM32F7XX_H -mno-thumb-interwork -mcpu=cortex-m7 -mlittle-endian -mthumb -mfloat-abi=hard -mfpu=fpv5-sp-d16 -ffunction-sections -fdata-sections -fshort-enums -ggdb -g3 -Os -DCPU_MODEL_STM32F767ZI -DCPU_CORE_CORTEX_M7 -DCPU_HAS_BACKUP_RAM=1 --param=min-pagesize=0 -DRIOT_APPLICATION=\"default\" -DBOARD_NUCLEO_F767ZI=\"nucleo-f767zi\" -DRIOT_BOARD=BOARD_NUCLEO_F767ZI -DCPU_STM32=\"stm32\" -DRIOT_CPU=CPU_STM32 -std=c11 -fwrapv -Wstrict-overflow -fno-common -ffunction-sections -fdata-sections -Wall -Wextra -Wmissing-include-dirs -fno-delete-null-pointer-checks -fdiagnostics-color -Wstrict-prototypes -Wold-style-definition -gz -Wformat=2 -Wformat-overflow -Wformat-truncation -fmacro-prefix-map=$REPOPATH/= -Wcast-align -DCPU_RAM_BASE=0x20000000 -DCPU_RAM_SIZE=0x80000 -DRTT_FREQUENCY=RTT_MAX_FREQUENCY -D__int64_t_defined=1 -include '$REPOPATH/examples/basic/default/bin/nucleo-f767zi/riotbuild/riotbuild.h' -isystem /usr/include/newlib/nano -I$REPOPATH/examples/basic/default -I$REPOPATH/core/lib/include -I$REPOPATH/core/include -I$REPOPATH/drivers/include -I$REPOPATH/sys/include -I$REPOPATH/boards/nucleo-f767zi/include -I$REPOPATH/boards/common/nucleo/include -I$REPOPATH/boards/common/stm32/include -I$REPOPATH/boards/common/nucleo144/include -I$REPOPATH/cpu/stm32/include -I/home/[email protected]/.cache/RIOT/stm32/cmsis/f7/Include -I$REPOPATH/cpu/stm32/include/clk -I$REPOPATH/cpu/cortexm_common/include -I$REPOPATH/sys/libc/include -isystem/home/[email protected]/.cache/RIOT/pkg/cmsis/CMSIS/Core/Include -I$REPOPATH/sys/net/gnrc/pktbuf/include -I$REPOPATH/sys/net/gnrc/pktbuf_static/include -I$REPOPATH/sys/net/link_layer/eui_provider/include -I$REPOPATH/sys/auto_init/include -I$REPOPATH/examples/basic/default/bin/nucleo-f767zi/preprocessor -MQ '$REPOPATH/examples/basic/default/bin/nucleo-f767zi/core_lib/assert.o' -MD -MP -c -o $REPOPATH/examples/basic/default/bin/nucleo-f767zi/core_lib/assert.o $REPOPATH/core/lib/assert.c
Filtering out only the macros in that command and sorting them, I get:
-DBOARD_NUCLEO_F767ZI=\"nucleo-DRIOT_BOARD=BOARD_NUCLEO_F767ZI
-DCONFIG_GNRC_PKTBUF_SIZE=512
-DCONFIG_GNRC_PKTBUF_SIZE=512
-DCONFIG_GNRC_PKTBUF_SIZE=512
-DCPU_CORE_CORTEX_M7
-DCPU_FAM_STM32F7
-DCPU_HAS_BACKUP_RAM=1
-DCPU_LINE_STM32F767xx
-DCPU_MODEL_STM32F767ZI
-DCPU_RAM_BASE=0x20000000
-DCPU_RAM_SIZE=0x80000
-DCPU_STM32=\"stm32\"
-DDEVELHELP
-D__int64_t_defined=1
-DRIOT_APPLICATION=\"default\"
-DRIOT_CPU=CPU_STM32
-DRIOT_FILE_NOPATH=\"assert.c\"
-DRIOT_FILE_RELATIVE=\"core/lib/assert.c\"
-DRTT_FREQUENCY=RTT_MAX_FREQUENCY
-DSTM32F767xx
-DSTM32_FLASHSIZE=2097152U
-D__SYSTEM_STM32F7XX_H
-DSYSTEM_STM32F7XX_H
Sorting the contents of riotbuild.h, filtering out the #ifdef DOXYGEN ... #endif and all instances of #define MODULE_..., I have:
#define BOARD_NUCLEO_F767ZI "nucleo-f767zi"
#define CONFIG_GNRC_PKTBUF_SIZE 512
#define CONFIG_GNRC_PKTBUF_SIZE 512
#define CONFIG_GNRC_PKTBUF_SIZE 512
#define CPU_CORE_CORTEX_M7 1
#define CPU_FAM_STM32F7 1
#define CPU_HAS_BACKUP_RAM 1
#define CPU_LINE_STM32F767xx 1
#define CPU_MODEL_STM32F767ZI 1
#define CPU_RAM_BASE 0x20000000
#define CPU_RAM_SIZE 0x80000
#define CPU_STM32 "stm32"
#define DEVELHELP 1
#define __int64_t_defined 1
#define RIOT_APPLICATION "default"
#define RIOT_BOARD BOARD_NUCLEO_F767ZI
#define RIOT_CPU CPU_STM32
#define RIOT_MCU MACRO_DEPRECATED RIOT_CPU
#define RIOT_VERSION "2026.01-devel-302-g2bd24"
#define RIOT_VERSION_CODE RIOT_VERSION_NUM(2026,01,0,0)
#define RTT_FREQUENCY RTT_MAX_FREQUENCY
#define STM32F767xx 1
#define STM32_FLASHSIZE 2097152U
#define __SYSTEM_STM32F7XX_H 1
#define SYSTEM_STM32F7XX_H 1
So we see that:
- Every
-D....from$(CFLAGS)is injected a second time with-include riotbuild.h - Some macros (e.g.
CONFIG_GNRC_PKTBUF_SIZE) are provided multiple times with either method.
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