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lint: don't warn about cast between union and one of its member types 

Seen in src/sbin/newfs_udf/udf_core.c for context.anchors.
This commit is contained in:
rillig 2023-04-22 17:42:29 +00:00
parent 0e61302acd
commit b847195210
2 changed files with 16 additions and 8 deletions
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9
tests/usr.bin/xlint/lint1/msg_247.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: msg_247.c,v 1.28 2023/04/22 17:30:35 rillig Exp $ */
/* $NetBSD: msg_247.c,v 1.29 2023/04/22 17:42:29 rillig Exp $ */
# 3 "msg_247.c"
// Test for message: pointer cast from '%s' to '%s' may be troublesome [247]
@ -367,20 +367,17 @@ conversions_from_and_to_union(void)
/* expect+1: warning: illegal combination of 'pointer to union typedef anything' and 'pointer to double', op '=' [124] */
p_anything = p_double;
/* FIXME: OK, since the union 'anything' has a 'double' member. */
/* expect+1: warning: pointer cast from 'pointer to double' to 'pointer to union typedef anything' may be troublesome [247] */
/* OK, since the union 'anything' has a 'double' member. */
p_anything = (anything *)p_double;
/* expect+1: warning: illegal combination of 'pointer to double' and 'pointer to union typedef anything', op '=' [124] */
p_double = p_anything;
/* FIXME: OK, since the union 'anything' has a 'double' member. */
/* expect+1: warning: pointer cast from 'pointer to union typedef anything' to 'pointer to double' may be troublesome [247] */
/* OK, since the union 'anything' has a 'double' member. */
p_double = (double *)p_anything;
/*
* Casting to an intermediate union does not make casting between two
* incompatible types better.
*/
/* expect+2: warning: pointer cast from 'pointer to int' to 'pointer to union typedef anything' may be troublesome [247] */
/* expect+1: warning: illegal combination of 'pointer to function(void) returning void' and 'pointer to union typedef anything', op '=' [124] */
p_function = (anything *)p_int;

15
usr.bin/xlint/lint1/tree.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: tree.c,v 1.515 2023/04/22 15:14:37 rillig Exp $ */
/* $NetBSD: tree.c,v 1.516 2023/04/22 17:42:29 rillig Exp $ */
/*
* Copyright (c) 1994, 1995 Jochen Pohl
@ -37,7 +37,7 @@
#include <sys/cdefs.h>
#if defined(__RCSID)
__RCSID("$NetBSD: tree.c,v 1.515 2023/04/22 15:14:37 rillig Exp $");
__RCSID("$NetBSD: tree.c,v 1.516 2023/04/22 17:42:29 rillig Exp $");
#endif
#include <float.h>
@ -3491,6 +3491,17 @@ should_warn_about_pointer_cast(const type_t *nstp, tspec_t nst,
return false;
}
if (nst == UNION || ost == UNION) {
const type_t *union_tp = nst == UNION ? nstp : ostp;
const type_t *other_tp = nst == UNION ? ostp : nstp;
for (const sym_t *mem = union_tp->t_str->sou_first_member;
mem != NULL; mem = mem->s_next) {
if (types_compatible(mem->s_type, other_tp,
true, false, NULL))
return false;
}
}
if (is_struct_or_union(nst) && nstp->t_str != ostp->t_str)
return true;