Tue Jan 5 22:38:51 2021 UTC ()
lint: add test for "suggest cast" [324]
This warning is the only one that calls print_tnode, which in turn uses
the redundant operator names in str_op_t.
There is another list of operator names in ops.c, but those names
include more clutter, for example "p + p" instead of a simple "+".
Using those operator names would therefore rather be confusing. These
two lists should be merged, to remove unnecessary redundancy.
(rillig)
diff -r1.1 -r1.2 src/tests/usr.bin/xlint/lint1/msg_324.c
diff -r1.1 -r1.2 src/tests/usr.bin/xlint/lint1/msg_324.exp
--- src/tests/usr.bin/xlint/lint1/msg_324.c 2021/01/02 10:22:44 1.1
+++ src/tests/usr.bin/xlint/lint1/msg_324.c 2021/01/05 22:38:51 1.2
@@ -1,7 +1,40 @@
-/* $NetBSD: msg_324.c,v 1.1 2021/01/02 10:22:44 rillig Exp $ */
+/* $NetBSD: msg_324.c,v 1.2 2021/01/05 22:38:51 rillig Exp $ */
# 3 "msg_324.c"
// Test for message: suggest cast from '%s' to '%s' on op %s to avoid overflow [324]
-TODO: "Add example code that triggers the above message."
+/*
-TODO: "Add example code that almost triggers the above message."
+ * This warning applies to binary operators if the result of the operator
+ * is converted to a type that is bigger than the operands' result type
+ * after the usual arithmetic promotions.
+ *
+ * In such a case, the operator's result would be truncated to the operator's
+ * result type (invoking undefined behavior for signed integers), and that
+ * truncated value would then be converted. At that point, a few bits may
+ * have been lost.
+ */
+
+/* lint1-flags: -g -S -w -P */
+
+void
+example(char c, int i, unsigned u)
+{
+ long l;
+ unsigned long ul;
+
+ l = c + i;
+ l = i - c;
+ ul = c * u;
+ ul = u + c;
+ ul = i - u;
+ ul = u * i;
+ l = i << c;
+
+ /*
+ * The operators SHR, DIV and MOD cannot produce an overflow,
+ * therefore no warning is necessary for them.
+ */
+ l = i >> c;
+ ul = u / c;
+ ul = u % c;
+}
--- src/tests/usr.bin/xlint/lint1/Attic/msg_324.exp 2021/01/02 10:22:44 1.1
+++ src/tests/usr.bin/xlint/lint1/Attic/msg_324.exp 2021/01/05 22:38:51 1.2
@@ -1 +1,7 @@
-msg_324.c(6): syntax error ':' [249]
+msg_324.c(25): warning: suggest cast from 'int' to 'long' on op + to avoid overflow [324]
+msg_324.c(26): warning: suggest cast from 'int' to 'long' on op - to avoid overflow [324]
+msg_324.c(27): warning: suggest cast from 'unsigned int' to 'unsigned long' on op * to avoid overflow [324]
+msg_324.c(28): warning: suggest cast from 'unsigned int' to 'unsigned long' on op + to avoid overflow [324]
+msg_324.c(29): warning: suggest cast from 'unsigned int' to 'unsigned long' on op - to avoid overflow [324]
+msg_324.c(30): warning: suggest cast from 'unsigned int' to 'unsigned long' on op * to avoid overflow [324]
+msg_324.c(31): warning: suggest cast from 'int' to 'long' on op << to avoid overflow [324]