esp-idf/components/driver/component.mk

#
# Component Makefile
#

COMPONENT_ADD_INCLUDEDIRS := include

COMPONENT_PRIV_INCLUDEDIRS := include/driver

ifeq ($(GCC_NOT_5_2_0), 1)
# uses C11 atomic feature
spi_master.o: CFLAGS += -std=gnu11
endif
add gpio driver code 2016-09-19 17:33:21 +08:00			`#`
			`# Component Makefile`
			`#`

			`COMPONENT_ADD_INCLUDEDIRS := include`

			`COMPONENT_PRIV_INCLUDEDIRS := include/driver`

spi_master: compile as C11 due to use of stdatomic.h stdatomic.h is available both in newlib and GCC include directories. Normally (if you invoke the compiler without any flags) GCC include directories are first on the list, so GCC’s stdatomic.h is used. In IDF, we used to pass newlib include path as an extra include directory, so newlib’s stdint.h got included instead. Newlib 2.2.0 stdatomic implementation is compatible with -std=gnu99 but incompatible with -std=gnu11. And GCC doesn’t support atomic_load with -std=gnu99 (it’s a C11 feature). So when we used atomic_load with -std=gnu99, it worked due to newlib’s header. Since we are no longer going to be including newlib headers into IDF, GCC stdatomic will be used instead. Hence, add -std=gnu11 for source files which use atomic features. 2019-03-08 14:57:00 +08:00			`ifeq ($(GCC_NOT_5_2_0), 1)`
			`# uses C11 atomic feature`
			`spi_master.o: CFLAGS += -std=gnu11`
			`endif`