Re: Will autoconf work with -Werror=implicit-int and -Werror=implicit-function-declaration ?

[Paul Eggert]

On 12/11/23 07:55, David A. Wheeler wrote:
> Will the latest version of autoconf work by default when the compiler has these 
> options enabled?:
> -Werror=implicit-int
> -Werror=implicit-function-declaration

Although it'll be helpful for Autoconf to work by default with those two 
options, it's not essential because it's bad advice for builders to 
*configure* with all the options suggested in "Compiler Options 
Hardening Guide for C and C++"[1]. The advice should merely be to 
*build* with those options.

This is because the recommended options include controversial ones like 
-Wconversion that can be harmful in C code. The only way to pacify 
-Wconversion is to complicate the code by inserting casts that can lower 
code safety and quality. Even Gnulib, which goes far beyond [1] in 
recommending warning options, disables -Wconversion.

For controversial options like -Wconversion we shouldn't expect 
'configure' scripts to pacify compilers in all cases. And since we 
shouldn't expect that, we shouldn't recommend builders to use all the 
options in [1] when configuring.


[1]: 
https://best.openssf.org/Compiler-Hardening-Guides/Compiler-Options-Hardening-Guide-for-C-and-C++