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Re: [patch] cse.c: gcc_assertify an "if" statement whose conditionis always false.
On Thu, 2005-01-27 at 11:40 -0800, Mark Mitchell wrote:
> Kazu Hirata wrote:
> > Hi Mark,
> >>I dunno, I like asserts -- they document the assumption. But, there's
> >>no point in guarding ggc_assert with ENABLE_CHECKING, as ggc_assert
> >>already is conditionalized on that macro. OK with that change.
> > Actually, gcc_assert is guarded with ENABLE_ASSERT_CHECKING, not
> > ENABLE_CHECKING. In other words, if we don't guard this gcc_assert
> > with ENABLE_CHECKING, a release version of GCC would basically have
> > if (x == 0)
> > fancy_abort (...);
> > The idea is to keep the assertion while we are developing GCC and omit
> > it when we release it, so I'd like to go with either my original patch
> > or Jakub's idea of droping the whole "if" statement.
> > --enable-checking=release, which will presumably be default on a
> > release, will have ENABLE_ASSERT_CHECKING, but not ENABLE_CHECKING.
> I think that was a compromise; people wanted to keep assertions in
> releases for historical reasons. There's no intrinsic difference
> between a gcc_assert() and something guarded by ENABLE_CHECING.
> In any case, I think that guarding asserts with ENABLE_CHECKING is
> weird; if you want to guard it with ENABLE_CHECING, then don't use
> What do other people think?
Well, I definitely prefer having the assert vs just removing the code
as Jakub suggested.
The assert states pretty clearly that if we get into this code with
x == 0 that the problem lies elsewhere -- ie, if the caller might
pass in a null value, then the caller is at fault.
As to whether or not we wrap the assert into an ENABLE_CHECKING or
not. I don't really care, particularly since 99.9% of my builds
are with checking-enabled compilers.