[src/trunk]: src/tests/usr.bin/xlint/lint1 lint: add test for message 329, un...

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

details:   https://anonhg.NetBSD.org/src/rev/71d5d4d33920
branches:  trunk
changeset: 958914:71d5d4d33920
user:      rillig <rillig%NetBSD.org@localhost>
date:      Sun Jan 24 17:44:37 2021 +0000

description:
lint: add test for message 329, union cast with incompatible type

diffstat:

 tests/usr.bin/xlint/lint1/msg_329.c   |  39 ++++++++++++++++++++++++++++++++--
 tests/usr.bin/xlint/lint1/msg_329.exp |   2 +-
 2 files changed, 37 insertions(+), 4 deletions(-)

diffs (53 lines):

diff -r bd9a1429eacb -r 71d5d4d33920 tests/usr.bin/xlint/lint1/msg_329.c
--- a/tests/usr.bin/xlint/lint1/msg_329.c       Sun Jan 24 17:44:16 2021 +0000
+++ b/tests/usr.bin/xlint/lint1/msg_329.c       Sun Jan 24 17:44:37 2021 +0000
@@ -1,7 +1,40 @@
-/*     $NetBSD: msg_329.c,v 1.1 2021/01/02 10:22:44 rillig Exp $       */
+/*     $NetBSD: msg_329.c,v 1.2 2021/01/24 17:44:37 rillig Exp $       */
 # 3 "msg_329.c"
 
 // Test for message: type '%s' is not a member of '%s' [329]
 
-TODO: "Add example code that triggers the above message."
-TODO: "Add example code that almost triggers the above message."
+union u {
+       int i1;
+       int i2;
+       void *vp;
+};
+
+void
+example(void)
+{
+       /*
+        * A type cast to a union type is valid if the source type is any
+        * member type of the union.  Since all union members with the same
+        * type have the same representation, the name of the union member
+        * doesn't matter.
+        *
+        * XXX: could there be padding bits or other tricky details that are
+        * settable per-member?  These could make the type alone insufficient
+        * for determining the exact representation.
+        *
+        * C99 6.5.4 "Cast operators" does not mention a union cast.  On the
+        * contrary, it says that the type name shall specify a scalar type.
+        *
+        * C11 6.5.4 "Cast operators" differs from C99 but still requires
+        * scalar types for both the target type and the source value.
+        *
+        * This is a GCC extension.
+        * See https://gcc.gnu.org/onlinedocs/gcc/Cast-to-Union.html.
+        *
+        * FIXME: lint says in message 328 that "union cast is a C9X feature",
+        *  but that is wrong.  It is a GCC feature.
+        */
+       union u u_i1 = (union u)3;
+       union u u_vp = (union u)(void *)0;
+       union u u_cp = (union u)(char *)0;      /* expect: 329 */
+}
diff -r bd9a1429eacb -r 71d5d4d33920 tests/usr.bin/xlint/lint1/msg_329.exp
--- a/tests/usr.bin/xlint/lint1/msg_329.exp     Sun Jan 24 17:44:16 2021 +0000
+++ b/tests/usr.bin/xlint/lint1/msg_329.exp     Sun Jan 24 17:44:37 2021 +0000
@@ -1,1 +1,1 @@
-msg_329.c(6): syntax error ':' [249]
+msg_329.c(39): type 'pointer to char' is not a member of 'union u' [329]