On Sat, Sep 30, 2017 at 04:14:50PM -0700, Nick Desaulniers wrote: > On Thu, Sep 28, 2017 at 07:52:35PM +0900, Masahiro Yamada wrote: > > 2017-09-26 11:28 GMT+09:00 Nick Desaulniers <nick.desaulni...@gmail.com>: > > > HOSTCFLAGS := -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 \ > > > + $(call hostcc-option,-fno-delete-null-pointer-checks) \ > > > -fomit-frame-pointer -std=gnu89 $(HOST_LFS_CFLAGS) > > > > You call hostcc-option > > before Kbuild.include is included around line 341. > > > > So, $(call hostcc-option, ...) returns always an empty string here > > whether the compiler supports the option or not. > > So calling a yet-to-be defined variable results in an empty string > rather than a loud failure? Chalk that up there with language features > no one ever asked for. That kind of implicit conversion gets languages > like JavaScript (with its loose type system, not that C is without its > own implicit type conversions/promotions) in a lot of hot water.
make --warn-undefined-variables (and it warns all over the place during a kernel build -- having undefined variables expand to the empty string is a useful feature, too, not just a trap for the unwary). Segher
