Re: [PATCH for 7.2] Fix broken configure with -Wunused-parameter

[Daniel P . Berrangé]

On Wed, Nov 02, 2022 at 09:22:58PM +0100, Stefan Weil via wrote:
> The configure script fails because it tries to compile small C programs
> with a main function which is declared with arguments argc and argv
> although those arguments are unused.
> 
> Running `configure -extra-cflags=-Wunused-parameter` triggers the problem.
> configure for a native build does abort but shows the error in config.log.
> A cross build configure for Windows with Debian stable aborts with an
> error.
> 
> Avoiding unused arguments fixes this.

I'm not convinced that we should allow -extra-cflags to influence
the configure compile checks at all, as there are likely more cases
where arbitrary -W$warn flag will impact the checks, potentially
causing configure to silently take the wrong action.

> 
> Signed-off-by: Stefan Weil <sw@weilnetz.de>
> ---
> 
> See https://gitlab.com/qemu-project/qemu/-/issues/1295.
> 
> I noticed the problem because I often compile with -Wextra.
> 
> Stefan
> 
>  configure | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/configure b/configure
> index 4275f5419f..1106c04fea 100755
> --- a/configure
> +++ b/configure
> @@ -1258,6 +1258,7 @@ if test "$stack_protector" != "no"; then
>    cat > $TMPC << EOF
>  int main(int argc, char *argv[])
>  {
> +    (void)argc;
>      char arr[64], *p = arr, *c = argv[0];
>      while (*c) {
>          *p++ = *c++;
> @@ -1607,7 +1608,7 @@ fi
>  
>  if test "$safe_stack" = "yes"; then
>  cat > $TMPC << EOF
> -int main(int argc, char *argv[])
> +int main(void)
>  {
>  #if ! __has_feature(safe_stack)
>  #error SafeStack Disabled
> @@ -1629,7 +1630,7 @@ EOF
>    fi
>  else
>  cat > $TMPC << EOF
> -int main(int argc, char *argv[])
> +int main(void)
>  {
>  #if defined(__has_feature)
>  #if __has_feature(safe_stack)
> @@ -1675,7 +1676,7 @@ static const int Z = 1;
>  #define TAUT(X) ((X) == Z)
>  #define PAREN(X, Y) (X == Y)
>  #define ID(X) (X)
> -int main(int argc, char *argv[])
> +int main(void)
>  {
>      int x = 0, y = 0;
>      x = ID(x);
> -- 
> 2.30.2
> 
> 

With regards,
Daniel
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