From ac7290bedd859af35ac785e9ea7c76863b1e4b32 Mon Sep 17 00:00:00 2001
From: Chad Loder <cloder@cvs.openbsd.org>
Date: Thu, 15 Dec 2005 05:49:50 +0000
Subject: Add a new warning message: conversion of %s return value from '%s' to
 '%s'. Lint now warns when a function's return value is converted to a smaller
 (or differently signed) type.  These conversions can happen when doing an
 assignment, when passing a function's return value as an argument to another
 function, or when initializing a variable.  Currently this produces useless
 warnings on tolower() and toupper() because they return ints but are usually
 assigned to chars.

---
 usr.bin/xlint/lint1/err.c  |  5 +++--
 usr.bin/xlint/lint1/tree.c | 13 +++++++++++--
 2 files changed, 14 insertions(+), 4 deletions(-)

(limited to 'usr.bin')

diff --git a/usr.bin/xlint/lint1/err.c b/usr.bin/xlint/lint1/err.c
index ba64269c3eb..a46486bceae 100644
--- a/usr.bin/xlint/lint1/err.c
+++ b/usr.bin/xlint/lint1/err.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: err.c,v 1.15 2005/12/14 22:09:40 kjell Exp $	*/
+/*	$OpenBSD: err.c,v 1.16 2005/12/15 05:49:48 cloder Exp $	*/
 /*	$NetBSD: err.c,v 1.8 1995/10/02 17:37:00 jpo Exp $	*/
 
 /*
@@ -33,7 +33,7 @@
  */
 
 #ifndef lint
-static char rcsid[] = "$OpenBSD: err.c,v 1.15 2005/12/14 22:09:40 kjell Exp $";
+static char rcsid[] = "$OpenBSD: err.c,v 1.16 2005/12/15 05:49:48 cloder Exp $";
 #endif
 
 /* number of errors found */
@@ -366,6 +366,7 @@ const	char *msgs[] = {
 	"right shift of %d-bit quantity by %d bits",		      /* 310 */
 	"case ranges are illegal in ANSI C",			      /* 311 */
 	"suspicious operator for sizeof: %s",			      /* 312 */
+	"conversion of %s return value from '%s' to '%s'",	      /* 313 */
 };
 
 /*
diff --git a/usr.bin/xlint/lint1/tree.c b/usr.bin/xlint/lint1/tree.c
index dc8e5aa6313..92a32b3b93f 100644
--- a/usr.bin/xlint/lint1/tree.c
+++ b/usr.bin/xlint/lint1/tree.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: tree.c,v 1.25 2005/12/14 22:09:40 kjell Exp $	*/
+/*	$OpenBSD: tree.c,v 1.26 2005/12/15 05:49:49 cloder Exp $	*/
 /*	$NetBSD: tree.c,v 1.12 1995/10/02 17:37:57 jpo Exp $	*/
 
 /*
@@ -33,7 +33,7 @@
  */
 
 #ifndef lint
-static char rcsid[] = "$OpenBSD: tree.c,v 1.25 2005/12/14 22:09:40 kjell Exp $";
+static char rcsid[] = "$OpenBSD: tree.c,v 1.26 2005/12/15 05:49:49 cloder Exp $";
 #endif
 
 #include <stdlib.h>
@@ -1193,6 +1193,15 @@ asgntypok(op_t op, int arg, tnode_t *ln, tnode_t *rn)
 		rst = (rstp = rtp->t_subt)->t_tspec;
 	mp = &modtab[op];
 
+	/* be picky about conversion of function return types */
+	if (rn->tn_op == CALL) {
+		if (size(lt) < size(rt) ||
+		    (size(lt) == size(rt) && isutyp(lt) && !isutyp(rt))) {
+			warning(313, rn->tn_left->tn_left->tn_sym->s_name,
+			    tyname(rn->tn_type), tyname(ln->tn_type));
+		}
+	}
+
 	if (isatyp(lt) && isatyp(rt))
 		return (1);
 
-- 
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