Re: avoiding obsolete macros like AC_TRY_RUN

[Paolo Bonzini]

>     Drawbacks of AC_*_IFELSE:
>       - Unmnemonic naming of the macros. Macros and procedure names should 
> follow
>         the convention of "verb" or "verb_noun", so that they can better be
>         remembered by people who are familiar with English grammar.

Well, the common name was already taken. :-(

>       - Danger if a single level of quoting is used instead of double quoting:
>         Array declarations and array accesses get silently botched in that
>         case. The autoconf manual uses double-quoting in the examples of
>         AC_LANG_SOURCE and AC_LANG_PROGRAM, which is good. But some advocates 
> like
>         you propagate single-quoting.

That's not why Ralf used single quoting.  He did so to achieve 
consistency, where only the ultimate caller uses double quoting of 
arguments.  You're welcome to write

  AC_LANG_SOURCE([[
    #include <stdio.h>
    extern char foo[];
    int main ()
    {
      ]$1[
    }]])

where most of the argument is double quoted, but the arguments are 
expanded single-quoted.

>     The macros gt_CHECK_VAR_DECL, gt_CHECK_DECL, gl_MINMAX_IN_HEADER,
>     gl_FLOATTYPE_SIGN_LOCATION are not public: all possible invocations are
>     found in these *.m4 files. Therefore they are correct as is.

Well, the argument can be reversed.  Therefore they can also use 
consistent quoting.

>     The macro AC_LIB_HAVE_LINKFLAGS is meant to be called with literal
>     arguments. Calling it with complex expressions is not supported. In
>     particular, one of its arguments is 'testcode', which may contain
>     array declarations. If you remove a level of quoting here, you introduce
>     a bug.

You introduce a change, not a bug.  It may be a good reason to let this 
one go, though.

> 3) Indentation:
>
> > -          AC_TRY_RUN([
> > +          AC_RUN_IFELSE([AC_LANG_SOURCE([[
> >   #include<stddef.h>
> >   #include<stdio.h>
> >   int main ()
> >   {
> >     return fopen ("conftest.sl/", "w") != NULL;
> > -}], [gl_cv_func_fopen_slash=yes], [gl_cv_func_fopen_slash=no],
> > +}]])], [gl_cv_func_fopen_slash=yes], [gl_cv_func_fopen_slash=no],
>
>     Lines of code are not *that* expensive that it would warrant
>       - opening two macro invocations on the same line, without closing
>         the second one on the same line,

Well, this is customary M4 indentation (opening macros on the same line 
as its caller if they are the first argument).

The only change I'd make to Ralf's indentation would be to do like

}]])],
             [gl_cv_func_fopen_slash=yes],
             [gl_cv_func_fopen_slash=no]

>       - putting 5 closing brackets/braces/parentheses in a row, like if
>         you were programming Forth.

You mean Lisp?  However, note that ]])] is quite common, it's only the 
first } that is additional.

Context is everything.  If you see the gl_cv_func_fopen_slash assignment 
after it, you understand what is closed.  And since this is C code 
without unmatched parentheses a la case, for a five line argument you 
can use electric parens or paren matching commands (such as, in 
vi/VIPER, the % command).

Paolo