Re: How can Autoconf help with the transition to stricter compilation defaults?

[Bob Friesenhahn]

On Thu, 10 Nov 2022, Zack Weinberg wrote:

> The biggest remaining (potential) problem, that I’m aware of, is that
> AC_CHECK_FUNC unconditionally declares the function we’re probing for
> as ‘char NAME (void)’, and asks the compiler to call it with no
> arguments, regardless of what its prototype actually is.  It is not

This does seem like the biggest problem since it would appear to 
require that new macros are used and that the configure.ac developer 
would need to supply additional syntax (where syntax does not 
currently exist) in order to succeed with linking.  It is not possible 
for Autoconf itself to anticipate the function names used by libraries 
and assume some specific prototype.

There was already the issue that when testing for functions in static 
libraries (or libraries which otherwise require full linkage) that it 
is necessary to supply the library dependencies at the same time.  It 
might also be necessary to provide the linker search paths as well.

While GCC is GNU's compiler, there is too much focus on GCC here.  Any 
compiler currently usable with Autoconf might change to conform with 
the standard such that configure scripts no longer work with it.

The only reassurance is that GCC/Clang authors can not do what they 
want to do without providing a means for Autoconf and other similar 
test-based systems to work as is since Autoconf is so important.

Bob
--
Bob Friesenhahn
bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/
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