CVS commit: src/sys/sys

["Taylor R Campbell" <riastradh%netbsd.org@localhost>]

Module Name:    src
Committed By:   riastradh
Date:           Sun Apr 30 08:45:48 UTC 2023

Modified Files:
        src/sys/sys: cdefs.h

Log Message:
sys/cdefs.h: New __MACROUSE for macros to type-check arguments.

This way, if there's a macro F(x) with a conditional definition --
e.g., conditional on DIAGNOSTIC or KDTRACE_HOOKS -- it can do
__MACROUSE(x) in the definition that's supposed to compile away,
without triggering `variable set but not used' errors, while still
catching type errors in the expression x.  But there's no cost or
side effects incurred in the generated code because the value is not
computed.

This should be the same as __USE, but I haven't figured out how to
make it work for both bit fields (which are likely to appear in macro
arguments) and aggregates (structs/unions, which are likely to appear
as variable declarations), so for now we use two separate macros.


To generate a diff of this commit:
cvs rdiff -u -r1.159 -r1.160 src/sys/sys/cdefs.h

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.