Re: Warning annoyances in list_read.c

[Steve Kargl <sgk at troutmask dot apl dot washington dot edu>]

On Sun, Mar 26, 2017 at 06:45:07PM -0700, Jerry DeLisle wrote:
> On 03/26/2017 11:45 AM, Steve Kargl wrote:
> > On Sun, Mar 26, 2017 at 11:27:59AM -0700, Jerry DeLisle wrote:
> >>
> >> +#pragma GCC diagnostic push
> >> +#pragma GCC diagnostic ignored "-Wimplicit-fallthrough"
> > 
> > IMNSHO, the correct fix is to complain loudly to whomever
> > added -Wimplicit-fallthrough to compiler options.  It should
> > be removed (especially if is has been added to -Wall).
> > 
> > You can also probably add -Wno-implicit-fallthrough to 
> > libgfortran/configure.ac at 
> > 
> > # Add -Wall -fno-repack-arrays -fno-underscoring if we are using GCC.
> > if test "x$GCC" = "xyes"; then
> >   AM_FCFLAGS="-I . -Wall -Werror -fimplicit-none -fno-repack-arrays -fno-underscoring"
> > 
> 
> Problem I have is I don't know who to complain to. I think there is a bit of a
> glass wall going on here anyway, so what would be the point of complaining if
> the retrievers of the message all have the ON-OFF switch in the OFF position.
> (After all, I do not have a PHD, I am not a computer science graduate, why
> bother looking down ones nose at a low life such as myself, OMG its an engineer,
> what the hell does he know.)
> 
> Maybe these warnings are being turned on as a matter of policy, but truth is,
> when I build 50 times a day, the warnings flying by are masking the errors or
> other warnings that may be important. For example, I inadvertently passed a ptr
> to a function rather than the *ptr.
> 
> The warning that ensued flew by mixed in with all the other crap warnings and I
> did not see it. That cost me wasted cycle time (remember, I am not an expert and
> should not be expected to see such things. Hell, for that matter I should not
> even be doing any of this work. :)
> 

This option is clearly enforceing someone's preferred markup of
adding a comment to explicitly note a fall through.  Candidate
individual to complain to

2016-09-26  Marek Polacek  <polacek@redhat.com>

        PR c/7652
        * common.opt (Wimplicit-fallthrough): New option.
        * doc/extend.texi: Document statement attributes and the fallthrough
        attribute.
        * doc/invoke.texi: Document -Wimplicit-fallthrough.
        * gimple.h (gimple_call_internal_p): New function.
        * gimplify.c (struct gimplify_ctx): Add in_switch_expr.
        (struct label_entry): New struct.
        (find_label_entry): New function.
        (case_label_p): New function.
        (collect_fallthrough_labels): New function.
        (last_stmt_in_scope): New function.
        (should_warn_for_implicit_fallthrough): New function.
        (warn_implicit_fallthrough_r): New function.
        (maybe_warn_implicit_fallthrough): New function.
        (expand_FALLTHROUGH_r): New function.
        (expand_FALLTHROUGH): New function.
        (gimplify_switch_expr): Call maybe_warn_implicit_fallthrough and
        expand_FALLTHROUGH for the innermost GIMPLE_SWITCH.
        (gimplify_label_expr): New function.
        (gimplify_case_label_expr): Set location.
        (gimplify_expr): Call gimplify_label_expr.
        * internal-fn.c (expand_FALLTHROUGH): New function.
        * internal-fn.def (FALLTHROUGH): New internal function.
        * langhooks.c (lang_GNU_OBJC): New function.
        * langhooks.h (lang_GNU_OBJC): Declare.
        * system.h (gcc_fallthrough): Define.
        * tree-core.h: Add FALLTHROUGH_LABEL_P comment.
        * tree.h (FALLTHROUGH_LABEL_P): Define.

If he added a new option affecting libgfortran, then he should
fix up libgfortran.

-- 
Steve
20161221 https://www.youtube.com/watch?v=IbCHE-hONow