Module Name: src
Committed By: rillig
Date: Sat Jan 9 22:55:36 UTC 2021
Modified Files:
src/tests/usr.bin/xlint/lint1: msg_116.c msg_116.exp
Log Message:
lint: add test for 116 "illegal pointer subtraction"
To generate a diff of this commit:
cvs rdiff -u -r1.2 -r1.3 src/tests/usr.bin/xlint/lint1/msg_116.c \
src/tests/usr.bin/xlint/lint1/msg_116.exp
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/tests/usr.bin/xlint/lint1/msg_116.c
diff -u src/tests/usr.bin/xlint/lint1/msg_116.c:1.2 src/tests/usr.bin/xlint/lint1/msg_116.c:1.3
--- src/tests/usr.bin/xlint/lint1/msg_116.c:1.2 Fri Jan 8 21:25:03 2021
+++ src/tests/usr.bin/xlint/lint1/msg_116.c Sat Jan 9 22:55:36 2021
@@ -1,10 +1,34 @@
-/* $NetBSD: msg_116.c,v 1.2 2021/01/08 21:25:03 rillig Exp $ */
+/* $NetBSD: msg_116.c,v 1.3 2021/01/09 22:55:36 rillig Exp $ */
# 3 "msg_116.c"
// Test for message: illegal pointer subtraction [116]
-unsigned long
+/*
+ * Subtracting an int pointer from a double pointer does not make sense.
+ * The result cannot be reasonably defined since it is "the difference of
+ * the subscripts of the two array elements" (C99 6.5.5p9), and these two
+ * pointers cannot point to the same array.
+ */
+_Bool
example(int *a, double *b)
{
- return a - b;
+ return a - b > 0;
+}
+
+/*
+ * Even though signed char and unsigned char have the same size,
+ * their pointer types are still considered incompatible.
+ *
+ * C99 6.5.5p9
+ */
+_Bool
+subtract_character_pointers(signed char *scp, unsigned char *ucp)
+{
+ return scp - ucp > 0;
+}
+
+_Bool
+subtract_const_pointer(const char *ccp, char *cp)
+{
+ return ccp - cp > 0;
}
Index: src/tests/usr.bin/xlint/lint1/msg_116.exp
diff -u src/tests/usr.bin/xlint/lint1/msg_116.exp:1.2 src/tests/usr.bin/xlint/lint1/msg_116.exp:1.3
--- src/tests/usr.bin/xlint/lint1/msg_116.exp:1.2 Fri Jan 8 21:25:03 2021
+++ src/tests/usr.bin/xlint/lint1/msg_116.exp Sat Jan 9 22:55:36 2021
@@ -1 +1,2 @@
-msg_116.c(9): illegal pointer subtraction [116]
+msg_116.c(15): illegal pointer subtraction [116]
+msg_116.c(27): illegal pointer subtraction [116]
