Re: [RFA] Make macOS build warning-free

[Simon Marchi <simon dot marchi at ericsson dot com>]

On 2018-06-29 12:54 PM, Tom Tromey wrote:
> diff --git a/gdb/warning.m4 b/gdb/warning.m4
> index 632cc214ac0..17afc5455a1 100644
> --- a/gdb/warning.m4
> +++ b/gdb/warning.m4
> @@ -58,6 +58,17 @@ case "${host}" in
>      build_warnings="$build_warnings -Wno-unknown-pragmas"
>      # Solaris 11 <unistd.h> marks vfork deprecated.
>      build_warnings="$build_warnings -Wno-deprecated-declarations" ;;
> +  *-*-darwin*)
> +    # macOS deprecates syscall (needed by darwin-nat.c) and
> +    # sbrk (used only for some maint commands).
> +    build_warnings="$build_warnings -Wno-deprecated-declarations"
> +    # -Wformat-nonliteral doesn't work properly on macOS -- apparently
> +    # it does not interact properly with the format_arg attribute.
> +    # (libgnuintl.h disables this attribute for macOS, but re-enabling
> +    # it there did not work.)
> +    build_warnings="$build_warnings -Wno-format-nonliteral"
> +    build_warnings="$build_warnings -Wno-format-security"
> +    ;;
>    *) build_warnings="$build_warnings -Wformat-nonliteral" ;;
>  esac

About the gettext / non-literal warning, this is the patch I carry.  I tried
to dig up why gettext doesn't define _INTL_MAY_RETURN_STRING_ARG for __APPLE_CC__
but couldn't find it.  My guess is that in a distant past, the Apple compiler
did not know about that attribute.  You need another change to get rid of the warning
though.  Either:

1. Apply _INTL_MAY_RETURN_STRING_ARG to the gettext function (see patch below)
2. Remove the other __APPLE_CC__ guard that protects the _INTL_REDIRECT_ASM definition.
   It will make it so the used gettext declaration will be the one at line 138, which
   already has _INTL_MAY_RETURN_STRING_ARG.

Here's the diff I've been carrying for a while:

>From c40fdef23fb3c85e94454bb2e3e9559df02cb43c Mon Sep 17 00:00:00 2001
From: Simon Marchi <simon.marchi@polymtl.ca>
Date: Fri, 29 Jun 2018 17:20:06 -0400
Subject: [PATCH 1/2] Fix gettext warnings

---
 intl/libgnuintl.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/intl/libgnuintl.h b/intl/libgnuintl.h
index acc9093a9d..aae7947b84 100644
--- a/intl/libgnuintl.h
+++ b/intl/libgnuintl.h
@@ -115,7 +115,7 @@ extern "C" {
 /* _INTL_MAY_RETURN_STRING_ARG(n) declares that the given function may return
    its n-th argument literally.  This enables GCC to warn for example about
    printf (gettext ("foo %y")).  */
-#if __GNUC__ >= 3 && !(__APPLE_CC__ > 1 && defined __cplusplus)
+#if __GNUC__ >= 3
 # define _INTL_MAY_RETURN_STRING_ARG(n) __attribute__ ((__format_arg__ (n)))
 #else
 # define _INTL_MAY_RETURN_STRING_ARG(n)
@@ -127,7 +127,7 @@ extern "C" {
 #ifdef _INTL_REDIRECT_INLINE
 extern char *libintl_gettext (const char *__msgid)
        _INTL_MAY_RETURN_STRING_ARG (1);
-static inline char *gettext (const char *__msgid)
+static inline _INTL_MAY_RETURN_STRING_ARG (1) char *gettext (const char *__msgid)
 {
   return libintl_gettext (__msgid);
 }
-- 
2.13.1


Simon