Martin Storsjö : configure: Downgrade -Wincompatible-function-pointer-types to a warning on ARM.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 59b5b79c0c9ca6589f02f707328d849b08c89a73
URL:    https://gitlab.winehq.org/wine/wine/-/commit/59b5b79c0c9ca6589f02f707328d849b08c89a73

Author: Martin Storsjö <martin at martin.st>
Date:   Thu Aug 11 14:26:31 2022 +0300

configure: Downgrade -Wincompatible-function-pointer-types to a warning on ARM.

Clang 16 is defaulting -Wincompatible-function-pointer-types to
an error instead of a warning. This isn't an issue for most of Wine,
but the error shows up in a lot of cases if doing a non-PE build for
ARM (32 bit, 64 has no such issues), in particular around the integration
of libxml2 and faudio.

The root cause of the issue is that some functions are specified with
e.g. __attribute__((pcs("aapcs-vfp"))) - which is equal to the
default calling convention when compiling with -mfloat-abi=hard - but
Clang's warning doesn't treat such function pointers as equal. (This
could maybe be considered a bug or limitation in Clang though.)

There's also some smaller amount of cases where our attributes
actually do conflict, where we mix __attribute__((pcs("aapcs"))), i.e.
arm softfloat calling convention, with the default calling convention
(which is set to hardfloat), but they drown in the noise from the
other ones.

Therefore, on arm, try to downgrade this diagnostic back to a warning,
not an error - while keeping the warnings visible.

Signed-off-by: Martin Storsjö <martin at martin.st>

---

 configure    | 29 +++++++++++++++++++++++++++++
 configure.ac |  2 ++
 2 files changed, 31 insertions(+)

diff --git a/configure b/configure
index 51946122dae..9a426b619bb 100755
--- a/configure
+++ b/configure
@@ -19413,6 +19413,35 @@ printf "%s\n" "$ac_cv_mabi_ms" >&6; }
            fi
            MSVCRTFLAGS="$MSVCRTFLAGS -mabi=ms" ;;
       esac ;;
+    arm*)
+      { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether the compiler supports -Wincompatible-function-pointer-types" >&5
+printf %s "checking whether the compiler supports -Wincompatible-function-pointer-types... " >&6; }
+if test ${ac_cv_cflags__Wincompatible_function_pointer_types+y}
+then :
+  printf %s "(cached) " >&6
+else $as_nop
+  ac_wine_try_cflags_saved=$CFLAGS
+CFLAGS="$CFLAGS -Wincompatible-function-pointer-types"
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+int main(int argc, char **argv) { return 0; }
+_ACEOF
+if ac_fn_c_try_link "$LINENO"
+then :
+  ac_cv_cflags__Wincompatible_function_pointer_types=yes
+else $as_nop
+  ac_cv_cflags__Wincompatible_function_pointer_types=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam \
+    conftest$ac_exeext conftest.$ac_ext
+CFLAGS=$ac_wine_try_cflags_saved
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_cflags__Wincompatible_function_pointer_types" >&5
+printf "%s\n" "$ac_cv_cflags__Wincompatible_function_pointer_types" >&6; }
+if test "x$ac_cv_cflags__Wincompatible_function_pointer_types" = xyes
+then :
+  EXTRACFLAGS="$EXTRACFLAGS -Wno-error=incompatible-function-pointer-types"
+fi ;;
   esac
 
   CFLAGS=$saved_CFLAGS
diff --git a/configure.ac b/configure.ac
index dd4abd39e32..560d66c46de 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1931,6 +1931,8 @@ int a(int b, ...) { __builtin_ms_va_list list; __builtin_ms_va_start(list,b); }]
            fi
            MSVCRTFLAGS="$MSVCRTFLAGS -mabi=ms" ;;
       esac ;;
+    arm*)
+      WINE_TRY_CFLAGS([-Wincompatible-function-pointer-types],[EXTRACFLAGS="$EXTRACFLAGS -Wno-error=incompatible-function-pointer-types"]) ;;
   esac
 
   CFLAGS=$saved_CFLAGS