fix 'ignoring return value' compiler warnings

Various system functions like write() are marked with the
__warn_unused_result__ attribute, which causes an 'ignoring return value'
warning to be emitted, even if the function call result is cast to (void).

The generic solution seems to be

    int rc = write(...);
    PERL_UNUSED_VAR(rc);

1 files changed, 19 insertions, 10 deletions

diff --git a/pp_hot.c b/pp_hot.c
index 7ae8f3a019..31b6530958 100644
--- a/pp_hot.c
+++ b/pp_hot.c
@@ -1175,6 +1175,7 @@ PP(pp_aassign)
 	}
     }
     if (PL_delaymagic & ~DM_DELAY) {
+        int rc = 0;
 	/* Will be used to set PL_tainting below */
 	Uid_t tmp_uid  = PerlProc_getuid();
 	Uid_t tmp_euid = PerlProc_geteuid();
@@ -1183,65 +1184,73 @@ PP(pp_aassign)
 
 	if (PL_delaymagic & DM_UID) {
 #ifdef HAS_SETRESUID
-	    (void)setresuid((PL_delaymagic & DM_RUID) ? PL_delaymagic_uid  : (Uid_t)-1,
+	    rc = setresuid((PL_delaymagic & DM_RUID) ? PL_delaymagic_uid  : (Uid_t)-1,
 			    (PL_delaymagic & DM_EUID) ? PL_delaymagic_euid : (Uid_t)-1,
 			    (Uid_t)-1);
 #else
 #  ifdef HAS_SETREUID
-	    (void)setreuid((PL_delaymagic & DM_RUID) ? PL_delaymagic_uid  : (Uid_t)-1,
+	    rc = setreuid((PL_delaymagic & DM_RUID) ? PL_delaymagic_uid  : (Uid_t)-1,
 			   (PL_delaymagic & DM_EUID) ? PL_delaymagic_euid : (Uid_t)-1);
 #  else
 #    ifdef HAS_SETRUID
 	    if ((PL_delaymagic & DM_UID) == DM_RUID) {
-		(void)setruid(PL_delaymagic_uid);
+		rc = setruid(PL_delaymagic_uid);
 		PL_delaymagic &= ~DM_RUID;
 	    }
 #    endif /* HAS_SETRUID */
 #    ifdef HAS_SETEUID
 	    if ((PL_delaymagic & DM_UID) == DM_EUID) {
-		(void)seteuid(PL_delaymagic_euid);
+		rc = seteuid(PL_delaymagic_euid);
 		PL_delaymagic &= ~DM_EUID;
 	    }
 #    endif /* HAS_SETEUID */
 	    if (PL_delaymagic & DM_UID) {
 		if (PL_delaymagic_uid != PL_delaymagic_euid)
 		    DIE(aTHX_ "No setreuid available");
-		(void)PerlProc_setuid(PL_delaymagic_uid);
+		rc = PerlProc_setuid(PL_delaymagic_uid);
 	    }
 #  endif /* HAS_SETREUID */
 #endif /* HAS_SETRESUID */
+
+            /* XXX $> et al currently silently ignore failures */
+            PERL_UNUSED_VAR(rc);
+
 	    tmp_uid  = PerlProc_getuid();
 	    tmp_euid = PerlProc_geteuid();
 	}
 	if (PL_delaymagic & DM_GID) {
 #ifdef HAS_SETRESGID
-	    (void)setresgid((PL_delaymagic & DM_RGID) ? PL_delaymagic_gid  : (Gid_t)-1,
+	    rc = setresgid((PL_delaymagic & DM_RGID) ? PL_delaymagic_gid  : (Gid_t)-1,
 			    (PL_delaymagic & DM_EGID) ? PL_delaymagic_egid : (Gid_t)-1,
 			    (Gid_t)-1);
 #else
 #  ifdef HAS_SETREGID
-	    (void)setregid((PL_delaymagic & DM_RGID) ? PL_delaymagic_gid  : (Gid_t)-1,
+	    rc = setregid((PL_delaymagic & DM_RGID) ? PL_delaymagic_gid  : (Gid_t)-1,
 			   (PL_delaymagic & DM_EGID) ? PL_delaymagic_egid : (Gid_t)-1);
 #  else
 #    ifdef HAS_SETRGID
 	    if ((PL_delaymagic & DM_GID) == DM_RGID) {
-		(void)setrgid(PL_delaymagic_gid);
+		rc = setrgid(PL_delaymagic_gid);
 		PL_delaymagic &= ~DM_RGID;
 	    }
 #    endif /* HAS_SETRGID */
 #    ifdef HAS_SETEGID
 	    if ((PL_delaymagic & DM_GID) == DM_EGID) {
-		(void)setegid(PL_delaymagic_egid);
+		rc = setegid(PL_delaymagic_egid);
 		PL_delaymagic &= ~DM_EGID;
 	    }
 #    endif /* HAS_SETEGID */
 	    if (PL_delaymagic & DM_GID) {
 		if (PL_delaymagic_gid != PL_delaymagic_egid)
 		    DIE(aTHX_ "No setregid available");
-		(void)PerlProc_setgid(PL_delaymagic_gid);
+		rc = PerlProc_setgid(PL_delaymagic_gid);
 	    }
 #  endif /* HAS_SETREGID */
 #endif /* HAS_SETRESGID */
+
+            /* XXX $> et al currently silently ignore failures */
+            PERL_UNUSED_VAR(rc);
+
 	    tmp_gid  = PerlProc_getgid();
 	    tmp_egid = PerlProc_getegid();
 	}