Link with correct values-*.o files on Solaris (PR target/40411)

[Rainer Orth]

Hi Joseph,

> On Fri, 12 Jan 2018, Rainer Orth wrote:
>
>> At the same time, I had a new look at when values-Xc.o is used by the
>> Studio compilers.  It selects strict ISO C mode in a couple of cases,
>> and the latest Studio 12.6 cc, which is about to do away with the
>> previous -Xc option which enabled that mode in favour of gcc-compatible
>> -pedantic, uses the latter to control its use.  So I've changed gcc to
>> follow suit.
>
> gcc -pedantic is only ever a diagnostic option, not a semantic one; it's 
> incorrect to use it to change library semantics.  The relevant options for 
> strict ISO C (and C++) modes are -ansi, -std=c*, -std=iso9899:199409 and 
> aliases for those options.

that's what you get for changing your code at the eleventh hour ;-)
Before introducing -pedantic, I had

#define STARTFILE_ARCH_SPEC \
  "%{ansi|std=c90|std=iso9899\\:199409:values-Xc.o%s; :values-Xa.o%s} \

(which isn't correct either since it only handled C90 and C94).  I don't
think you need to handle the aliases explicitly: last time I checked
they never arrive in specs.

Prompted by the realization that -ansi applies to both C and C++ and I
only meant to affect C, I had a look at what the (then recently
released) Studio 12.6 compilers do, which strive for more GCC
compatibility.

I've now also checked the OpenSolaris libc and libm sources for uses of
_lib_version == strict_ansi (as is set in values-Xc.o).  libc has none,
and the uses in libm all follow this pattern (ignoring C Issue 4.2
compatibility mode handling no longer activated):

		if (lib_version == strict_ansi) {
			errno = EDOM;
		} else if (!matherr(&exc)) {
			errno = EDOM;
		}

The default implementation of matherr (overridable by the user) just returns 0.

So it seems the following snippet

#define STARTFILE_ARCH_SPEC \
[...]
     %{std=c9*|std=iso9899\\:199409|std=c1*:values-Xc.o%s; :values-Xa.o%s} \

seems like the right thing to do, as you said.

> -ansi is not defined as a .opt alias of -std=c90 (because the option it's 
> an alias for depends on whether C or C++ is being compiled), so I'd expect 
> the specs to need to handle it along with -std=c90.  I'd also expect 
> -std=iso9899:199409 to need to be handled there, supposing handling it 
> like -std=c90 is correct.  And what about C++ versions not based on C99 or 
> later?

I'm of mixed minds about whether or not to include -ansi in the above
list: for C it's correct, for C++ it's less clear.  AFAIK there's no way
to distinguish between different languages in specs (like via an -x
<lang> switch always passed in).  OTOH, it has always been there already.

The following patch implements the above with corresponding comment
adjustments.  I'm open to suggestions what to do about -ansi.

	Rainer

-- 
-----------------------------------------------------------------------------
Rainer Orth, Center for Biotechnology, Bielefeld University


2018-01-29  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>

	PR target/40411
	* config/sol2.h (STARTFILE_ARCH_SPEC): Use -std=c9*,
	-std=iso9899:199409, -std=c1* instead of -pedantic to select
	values-Xc.o.

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