The Makefile race condition report included a link to a log file
of the build attempt, and it contained this:
makedefs.c: In function 'do_grep_control':
makedefs.c:611:26: warning: suggest parentheses around operand of '!'
or change '|' to '||' or '!' to '~' [-Wparentheses]
#define ST_LD(old, opp) (!!(old) | (!!(opp) << 1))
^
makedefs.c:722:37: note: in expansion of macro 'ST_LD'
grep_stack[++grep_sp] = ST_LD(grep_writing, !isif);
^
They're using a more recent version of gcc than I am, because my
CFLAGS includes -Wparentheses (via -Wall) and I don't get that.
It's a little confusing, but I think it's whining that we might
have meant !!((old) | (!!(opp) << 1))
rather than (!!(old)) | (!!(opp) << 1).
The latter is what we get (and what we intended--no bug here).
I changed it to something that more directly reflects the intent
since it's not bit twiddling within some crucial innermost loop.
9e0a9d96f9