On 07/30/18 17:49, Joseph Myers wrote:
> On Mon, 30 Jul 2018, Bernd Edlinger wrote:
>
>> Hi,
>>
>> this is how I would like to handle the over length strings issue in the C FE.
>> If the string constant is exactly the right length and ends in one explicit
>> NUL character, shorten it by one character.
>
> I don't think shortening should be limited to that case. I think the case
> where the constant is longer than that (and so gets an unconditional
> pedwarn) should also have it shortened - any constant that doesn't fit in
> the object being initialized should be shortened to fit, whether diagnosed
> or not, we should define GENERIC / GIMPLE to disallow too-large string
> constants in initializers, and should add an assertion somewhere in the
> middle-end that no too-large string constants reach it.
>
Okay, there is an update following your suggestion.
Bootstrapped and reg-tested on x86_64-pc-linux-gnu.
Is it OK for trunk?
Thanks
Bernd.
2018-08-01 Bernd Edlinger <bernd.edlin...@hotmail.de>
* c-typeck.c (digest_init): Fix overlength strings.
diff -pur gcc/c/c-typeck.c gcc/c/c-typeck.c
--- gcc/c/c-typeck.c 2018-06-20 18:35:15.000000000 +0200
+++ gcc/c/c-typeck.c 2018-07-31 18:49:50.757586625 +0200
@@ -7435,29 +7435,52 @@ digest_init (location_t init_loc, tree t
}
}
- TREE_TYPE (inside_init) = type;
if (TYPE_DOMAIN (type) != NULL_TREE
&& TYPE_SIZE (type) != NULL_TREE
&& TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST)
{
unsigned HOST_WIDE_INT len = TREE_STRING_LENGTH (inside_init);
+ unsigned unit = TYPE_PRECISION (typ1) / BITS_PER_UNIT;
/* Subtract the size of a single (possibly wide) character
because it's ok to ignore the terminating null char
that is counted in the length of the constant. */
- if (compare_tree_int (TYPE_SIZE_UNIT (type),
- (len - (TYPE_PRECISION (typ1)
- / BITS_PER_UNIT))) < 0)
- pedwarn_init (init_loc, 0,
- ("initializer-string for array of chars "
- "is too long"));
- else if (warn_cxx_compat
- && compare_tree_int (TYPE_SIZE_UNIT (type), len) < 0)
- warning_at (init_loc, OPT_Wc___compat,
- ("initializer-string for array chars "
- "is too long for C++"));
+ if (compare_tree_int (TYPE_SIZE_UNIT (type), len - unit) < 0)
+ {
+ pedwarn_init (init_loc, 0,
+ ("initializer-string for array of chars "
+ "is too long"));
+ if (tree_fits_uhwi_p (TYPE_SIZE_UNIT (type)))
+ {
+ unsigned HOST_WIDE_INT size
+ = tree_to_uhwi (TYPE_SIZE_UNIT (type));
+ const char *p = TREE_STRING_POINTER (inside_init);
+ char *q = (char *)xmalloc (size + unit);
+
+ memcpy (q, p, size);
+ memset (q + size, 0, unit);
+ inside_init = build_string (size + unit, q);
+ free (q);
+ }
+ }
+ else if (compare_tree_int (TYPE_SIZE_UNIT (type), len) < 0)
+ {
+ if (warn_cxx_compat)
+ warning_at (init_loc, OPT_Wc___compat,
+ ("initializer-string for array chars "
+ "is too long for C++"));
+ if (len >= 2 * unit)
+ {
+ const char *p = TREE_STRING_POINTER (inside_init);
+
+ len -= unit;
+ if (memcmp (p + len - unit, "\0\0\0\0", unit) == 0)
+ inside_init = build_string (len, p);
+ }
+ }
}
+ TREE_TYPE (inside_init) = type;
return inside_init;
}
else if (INTEGRAL_TYPE_P (typ1))
