Unbreak bootstrap with GCC 4.3 (PR bootstrap/77751)

GCC 4.3 stupidly errors on this with
error: unrecognized command line option "-Wno-implicit-fallthrough"
so use -Wno-error instead.

Bootstrapped on x86_64-linux, ok for trunk?

2016-09-27  Marek Polacek  <polacek@redhat.com>

	PR bootstrap/77751
	* Makefile.in (insn-attrtab.o-warn, insn-dfatab.o-warn,
	insn-latencytab.o-warn, insn-output.o-warn, insn-emit.o-warn): Use
	-Wno-error instead of -Wno-implicit-fallthrough.


	Marek

On Tue, Sep 27, 2016 at 11:40:19AM +0200, Marek Polacek wrote:
> GCC 4.3 stupidly errors on this with
> error: unrecognized command line option "-Wno-implicit-fallthrough"
> so use -Wno-error instead.

I'm not sure I like this, then we'll see even during stage2/stage3 lots of
warnings in those files and other kinds of errors will not be reported.
And, the surrounding lines show that we already use -Wno-unused or
-Wno-strict-aliasing on other files.

My preference would be configure test for whether -Wno-implicit-fallthrough
works, and using @W_NO_IMPLICIT_FALLTHROUGH@ in there or something similar
(or stick that into a make variable and use $(W_NO_IMPLICIT_FALLTHROUGH)).
> 
> Bootstrapped on x86_64-linux, ok for trunk?
> 
> 2016-09-27  Marek Polacek  <polacek@redhat.com>
> 
> 	PR bootstrap/77751
> 	* Makefile.in (insn-attrtab.o-warn, insn-dfatab.o-warn,
> 	insn-latencytab.o-warn, insn-output.o-warn, insn-emit.o-warn): Use
> 	-Wno-error instead of -Wno-implicit-fallthrough.
> 
> diff --git gcc/Makefile.in gcc/Makefile.in
> index e8559cb..ff12908 100644
> --- gcc/Makefile.in
> +++ gcc/Makefile.in
> @@ -218,11 +218,11 @@ libgcov-merge-tool.o-warn = -Wno-error
>  gimple-match.o-warn = -Wno-unused
>  generic-match.o-warn = -Wno-unused
>  dfp.o-warn = -Wno-strict-aliasing
> -insn-attrtab.o-warn = -Wno-implicit-fallthrough
> -insn-dfatab.o-warn = -Wno-implicit-fallthrough
> -insn-latencytab.o-warn = -Wno-implicit-fallthrough
> -insn-output.o-warn = -Wno-implicit-fallthrough
> -insn-emit.o-warn = -Wno-implicit-fallthrough
> +insn-attrtab.o-warn = -Wno-error
> +insn-dfatab.o-warn = -Wno-error
> +insn-latencytab.o-warn = -Wno-error
> +insn-output.o-warn = -Wno-error
> +insn-emit.o-warn = -Wno-error
>  
>  # All warnings have to be shut off in stage1 if the compiler used then
>  # isn't gcc; configure determines that.  WARN_CFLAGS will be either
> 
> 	Marek

	Jakub

On Sep 27 2016, Jakub Jelinek <jakub@redhat.com> wrote:

> On Tue, Sep 27, 2016 at 11:40:19AM +0200, Marek Polacek wrote:
>> GCC 4.3 stupidly errors on this with
>> error: unrecognized command line option "-Wno-implicit-fallthrough"
>> so use -Wno-error instead.
>
> I'm not sure I like this, then we'll see even during stage2/stage3 lots of
> warnings in those files and other kinds of errors will not be reported.
> And, the surrounding lines show that we already use -Wno-unused or
> -Wno-strict-aliasing on other files.
>
> My preference would be configure test for whether -Wno-implicit-fallthrough
> works, and using @W_NO_IMPLICIT_FALLTHROUGH@ in there or something similar
> (or stick that into a make variable and use $(W_NO_IMPLICIT_FALLTHROUGH)).

Perhaps some general construct that suppresses -Wno-foo in stage1 only?

Andreas.

On Tue, Sep 27, 2016 at 11:40 AM, Marek Polacek <polacek@redhat.com> wrote:
> GCC 4.3 stupidly errors on this with
> error: unrecognized command line option "-Wno-implicit-fallthrough"
> so use -Wno-error instead.
>
> Bootstrapped on x86_64-linux, ok for trunk?

Ok for trunk now to unbreak peoples bootstrap.  We can improve on this
later if we want.

Richard.

> 2016-09-27  Marek Polacek  <polacek@redhat.com>
>
>         PR bootstrap/77751
>         * Makefile.in (insn-attrtab.o-warn, insn-dfatab.o-warn,
>         insn-latencytab.o-warn, insn-output.o-warn, insn-emit.o-warn): Use
>         -Wno-error instead of -Wno-implicit-fallthrough.
>
> diff --git gcc/Makefile.in gcc/Makefile.in
> index e8559cb..ff12908 100644
> --- gcc/Makefile.in
> +++ gcc/Makefile.in
> @@ -218,11 +218,11 @@ libgcov-merge-tool.o-warn = -Wno-error
>  gimple-match.o-warn = -Wno-unused
>  generic-match.o-warn = -Wno-unused
>  dfp.o-warn = -Wno-strict-aliasing
> -insn-attrtab.o-warn = -Wno-implicit-fallthrough
> -insn-dfatab.o-warn = -Wno-implicit-fallthrough
> -insn-latencytab.o-warn = -Wno-implicit-fallthrough
> -insn-output.o-warn = -Wno-implicit-fallthrough
> -insn-emit.o-warn = -Wno-implicit-fallthrough
> +insn-attrtab.o-warn = -Wno-error
> +insn-dfatab.o-warn = -Wno-error
> +insn-latencytab.o-warn = -Wno-error
> +insn-output.o-warn = -Wno-error
> +insn-emit.o-warn = -Wno-error
>
>  # All warnings have to be shut off in stage1 if the compiler used then
>  # isn't gcc; configure determines that.  WARN_CFLAGS will be either
>
>         Marek

On Tue, Sep 27, 2016 at 12:24:23PM +0200, Richard Biener wrote:
> On Tue, Sep 27, 2016 at 11:40 AM, Marek Polacek <polacek@redhat.com> wrote:
> > GCC 4.3 stupidly errors on this with
> > error: unrecognized command line option "-Wno-implicit-fallthrough"
> > so use -Wno-error instead.
> >
> > Bootstrapped on x86_64-linux, ok for trunk?
> 
> Ok for trunk now to unbreak peoples bootstrap.  We can improve on this
> later if we want.

Committed.  I'll look into the configure test check now.

	Marek