stdint.h: make redefinition of stdint types optional

PR zephyrproject-rtos#16645 streamlined stdint.h type definitions. This has an unfortunate
side effect that any legacy code which assumed default, compiler
provided types will now generate warnings any time type mismatch is
detected during the compilation process. Redefining stdint types also
significantly increases porting effort when building an existing
bare metal application with Zephyr.

This PR makes redefinition of stdint types optional.

Signed-off-by: Piotr Mienkowski <[email protected]>

Author: mnkp

CMakeLists.txt

@@ -236,7 +236,9 @@ zephyr_compile_options(
 
 # @Intent: Enforce standard integer type correspondance to match Zephyr usage.
 # (must be after compiler specific flags)
+if(CONFIG_ZEPHYR_STDINT)
 toolchain_cc_imacros(${ZEPHYR_BASE}/include/toolchain/zephyr_stdint.h)
+endif()
 
 # Common toolchain-agnostic assembly flags
 zephyr_compile_options(

lib/libc/Kconfig

@@ -83,4 +83,12 @@ config MINIMAL_LIBC_LL_PRINTF
 	  Build with long long printf enabled. This will increase the size of
 	  the image.
 
+config ZEPHYR_STDINT
+	bool "Enforce standard integer types to match Zephyr usage"
+	default y
+	help
+	  This option enforces standard integer types such as uint32_t, int16_t
+	  to match Zephyr usage. When disabled default definitions provided by
+	  the compiler are used.
+
 endmenu