Re: refactoring comment.c

Robert Haas <robertmhaas@gmail.com> writes:
> What's a bit odd about this is that I do get warnings for this kind of
> thing in general, which get turned into errors since I compile with
> -Werror; and in fact the version of the patch that I committed has no
> fewer than four places where there is a comment that says "placate
> compiler".  But for some reason the compiler I used to develop this
> patch (gcc-4.2.1 i686-apple-darwin10) did not complain about this
> case, for reasons that are not quite clear to me.

gcc has been able to detect possibly-uninitialized scalar variables
for many years, but only fairly-recent versions seem to apply the
same type of logic to fields of local structs.  I've also noticed
that sometimes it can only spot the potential problem after inlining
a function that sets the local variable, and so a more recent version
and/or a more aggressive -O setting can also affect whether you get
a warning.  In short: this warning is a lot more context sensitive
than you might guess.
        regards, tom lane