Re: How to get autoconf to respect CC="gcc -std=c89"?

[Niels Möller]

Niels Möller <nisse@lysator.liu.se> writes:

> "Zack Weinberg" <zack@owlfolio.org> writes:
>
>> This is currently not possible, but you are not the only person who has
>> asked for it to be made possible, and it's on our near-future list.
>> However, none of the core Autoconf developers currently have time to work
>> on it.  Might you be willing to put some time into it? 
>
> I can have a look; I would hope it's not too difficult (I'm familiar
> with m4 and sh programming, but not with autoconf-specifics, like how
> AC_REQUIRE/AC_PROVIDE really works). I think this is the right piece of
> code that needs a bit of configurability, in lib/autoconf/c.m4:
>
>   AC_DEFUN([_AC_PROG_CC_STDC_EDITION],
>   [ac_prog_cc_stdc=no
>   m4_map([_AC_PROG_CC_STDC_EDITION_TRY], [[11], [99], [89]])])

Below is an initial patch, it seems to work with a little manual
testing, and it does the simplest thing I could come up with. No idea
how proper tests should be done. Cc:ing autoconf-patches, since
README-hacking says that's the right forum.

Is this on the right track?

Regards,
/Niels

diff --git a/lib/autoconf/c.m4 b/lib/autoconf/c.m4
index 77ff1af8..83eb4bea 100644
--- a/lib/autoconf/c.m4
+++ b/lib/autoconf/c.m4
@@ -1561,6 +1561,14 @@ m4_define([_AC_C_C11_OPTIONS], [
     -std=gnu11
 ])
 
+AC_DEFUN([AC_C_STANDARD_VERSION], [
+  m4_ifdef([_AC_C_STANDARD_VERSION_LIST],
+    [m4_fatal([AC_PROG_C_STANDARD_VERSION should only be used once], 1)])
+  m4_define([_AC_C_STANDARD_VERSION_LIST],
+    m4_if([$1], [c89], 89, [$1], [c99], 99, [$1], [c11], 11,
+      [$1], [], [m4_fatal([C language revision not specified], 1)],
+      [m4_fatal([Unknown C language revision $1], 1)]))
+])
 
 # _AC_PROG_CC_STDC_EDITION_TRY(EDITION)
 # -------------------------------------
@@ -1623,7 +1631,9 @@ AS_IF([test "x$ac_cv_prog_cc_c$1" = xno],
 # variable ac_prog_cc_stdc to indicate the edition.
 AC_DEFUN([_AC_PROG_CC_STDC_EDITION],
 [ac_prog_cc_stdc=no
-m4_map([_AC_PROG_CC_STDC_EDITION_TRY], [[11], [99], [89]])])
+m4_ifndef([_AC_C_STANDARD_VERSION_LIST],
+  [m4_define([_AC_C_STANDARD_VERSION_LIST], [[11], [99], [89]])])
+m4_map([_AC_PROG_CC_STDC_EDITION_TRY], [_AC_C_STANDARD_VERSION_LIST])])
 
 
 # _AC_PROG_CC_C89(ACTION-IF-SUPPORTED, ACTION-IF-NOT-SUPPORTED)

-- 
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