Make idiom using colon (:) and percent (%) in variable expansion [closed]

What does the KBuild expression:

FOO := $(BAR:"%"=%) 

do as part of a Linux kernel Makefile?

1 Answer

It's a substitution reference. In this specific case, its intent appears to be to remove quotes from the variable. Ex. given

BAR := "quotedstring"
FOO := $(BAR:"%"=%)
all: $(info $$BAR is $(BAR)) $(info $$FOO is $(FOO))

then

$ make
$BAR is "quotedstring"
$FOO is quotedstring
make: 'all' is up to date.

See also How to Convert a Quoted String to a Normal One in Makefile?