linux-stable/scripts/Kconfig.include

# Kconfig helper macros

# Convenient variables
comma       := ,
quote       := "
squote      := '
empty       :=
space       := $(empty) $(empty)
dollar      := $
right_paren := )
left_paren  := (

# $(if-success,<command>,<then>,<else>)
# Return <then> if <command> exits with 0, <else> otherwise.
if-success = $(shell,{ $(1); } >/dev/null 2>&1 && echo "$(2)" || echo "$(3)")

# $(success,<command>)
# Return y if <command> exits with 0, n otherwise
success = $(if-success,$(1),y,n)

# $(failure,<command>)
# Return n if <command> exits with 0, y otherwise
failure = $(if-success,$(1),n,y)

# $(cc-option,<flag>)
# Return y if the compiler supports <flag>, n otherwise
cc-option = $(success,$(CC) -Werror $(1) -E -x c /dev/null -o /dev/null)

# $(ld-option,<flag>)
# Return y if the linker supports <flag>, n otherwise
ld-option = $(success,$(LD) -v $(1))

# check if $(CC) and $(LD) exist
$(error-if,$(failure,command -v $(CC)),compiler '$(CC)' not found)
$(error-if,$(failure,command -v $(LD)),linker '$(LD)' not found)

# gcc version including patch level
gcc-version := $(shell,$(srctree)/scripts/gcc-version.sh $(CC))