[src/trunk]: src/usr.bin/xlint/lint1 lint: extract decision for warning about...

[rillig <rillig%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/b9e8ce4794ff
branches:  trunk
changeset: 1019951:b9e8ce4794ff
user:      rillig <rillig%NetBSD.org@localhost>
date:      Fri Mar 26 16:45:06 2021 +0000

description:
lint: extract decision for warning about pointer cast

This makes the code several lines longer but way more readable.  In the
previous dense expression it was hard to see what was going on at all
and that there are two completely separate situations in which this
warning applies.

No functional change.

diffstat:

 usr.bin/xlint/lint1/tree.c |  30 +++++++++++++++++++++---------
 1 files changed, 21 insertions(+), 9 deletions(-)

diffs (65 lines):

diff -r bf304ec23dec -r b9e8ce4794ff usr.bin/xlint/lint1/tree.c
--- a/usr.bin/xlint/lint1/tree.c        Fri Mar 26 16:19:43 2021 +0000
+++ b/usr.bin/xlint/lint1/tree.c        Fri Mar 26 16:45:06 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: tree.c,v 1.246 2021/03/22 15:29:43 rillig Exp $        */
+/*     $NetBSD: tree.c,v 1.247 2021/03/26 16:45:06 rillig Exp $        */
 
 /*
  * Copyright (c) 1994, 1995 Jochen Pohl
@@ -37,7 +37,7 @@
 
 #include <sys/cdefs.h>
 #if defined(__RCSID) && !defined(lint)
-__RCSID("$NetBSD: tree.c,v 1.246 2021/03/22 15:29:43 rillig Exp $");
+__RCSID("$NetBSD: tree.c,v 1.247 2021/03/26 16:45:06 rillig Exp $");
 #endif
 
 #include <float.h>
@@ -2222,6 +2222,21 @@
        }
 }
 
+static bool
+should_warn_about_pointer_cast(const type_t *tp, tspec_t nst,
+                              const tnode_t *tn, tspec_t ost)
+{
+       if (nst == STRUCT || nst == UNION)
+               if (tp->t_subt->t_str != tn->tn_type->t_subt->t_str)
+                       return true;
+
+       /*
+        * XXX: Why should it be ok to cast between arbitrary structs that
+        * just happen to be of the same size?
+        */
+       return portable_size_in_bits(nst) != portable_size_in_bits(ost);
+}
+
 /*
  * Print warnings for questionable pointer conversions.
  */
@@ -2238,6 +2253,7 @@
        if (op != CVT)
                return;
 
+       /* TODO: rename to 'nst' and 'ost' */
        nt = tp->t_subt->t_tspec;
        ot = tn->tn_type->t_subt->t_tspec;
 
@@ -2264,13 +2280,9 @@
                warning(135, type_name(tn->tn_type), type_name(tp));
        }
 
-       if (((nt == STRUCT || nt == UNION) &&
-            tp->t_subt->t_str != tn->tn_type->t_subt->t_str) ||
-           portable_size_in_bits(nt) != portable_size_in_bits(ot)) {
-               if (cflag) {
-                       /* pointer cast from '%s' to '%s' may be troublesome */
-                       warning(247, type_name(tn->tn_type), type_name(tp));
-               }
+       if (cflag && should_warn_about_pointer_cast(tp, nt, tn, ot)) {
+               /* pointer cast from '%s' to '%s' may be troublesome */
+               warning(247, type_name(tn->tn_type), type_name(tp));
        }
 }