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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.
This commit is contained in:
rillig 2021-01-05 22:38:51 +00:00
parent a1d6d60c3f
commit 3796e6d449
2 changed files with 43 additions and 4 deletions
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39
tests/usr.bin/xlint/lint1/msg_324.c
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@ -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;
}

8
tests/usr.bin/xlint/lint1/msg_324.exp
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@ -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]