Question

How can I strip leading whitespace from parameters passed to user defined functions with gnu-make?

For example:

define FOO
# --- some build rules

# run the built target
/home/user/dir/bin/$(1)

endef

The following call works correctly, since there is no leading whitespace:

$(eval $(call FOO,my_test ) )

Unfortunately the following fails, because $(1) has a leadning space

$(eval $(call FOO, my_test ) )
                  ^
                Additional space to 'prettier' formatting

this ends up expanding to:

/home/user/dir/bin/ $(1)
                   ^
                 Leading whitespace

How can I strip leading whitespace from arguments passed to user defined functions?

Is it bad form to do this or should I simply assume that arguments are passed without leading whitespace?

Answer 1

Use the strip function:

define FOO
# ...
/home/user/dir/bin/$(strip $(1))
endef

For details, see Text Functions. Because of this, and to avoid using strip everywhere, it is best to avoid spaces after commas when passing arguments to functions.