Bug 223180

Summary: Bug in kmod.mk when SRCS is empty/not defined
Product: Base System Reporter: Johannes Lundberg <johalun0>
Component: confAssignee: freebsd-bugs (Nobody) <bugs>
Status: New ---    
Severity: Affects Only Me CC: emaste
Priority: ---    
Version: CURRENT   
Hardware: Any   
OS: Any   

Description Johannes Lundberg 2017-10-23 07:58:39 UTC
I discovered a bug/flaw in kmod.mk when building a kernel module where I do not have any c source files. Objects files are built using Rust and specified in OBJS variable.

If SRCS is empty/not defined these lines

# Conditionally include SRCS based on kernel config options.
.for _o in ${KERN_OPTS}

generate an entry in SRCS with one space: SRCS=" "

Causing this line to add a " .o" to OBJS. 

OBJS+=	${SRCS:N*.h:R:S/$/.o/g}

Which of course cause the make command to fail since there is no ".o" file.

By replacing it with these lines I could temporary fix the problem.

.for _o in ${SRCS}
Comment 1 Johannes Lundberg 2018-01-31 15:42:12 UTC
It should of course be

.for _o in ${SRCS:N*.h}

The previous suggestion breaks buildkernel (and maybe even buildworld).