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 thought Martin would be working on it, but as this is a really simple fix,
I would dare to send it to gcc-patches anyway, hope you don't mind...
The patch is relative to the other patch here:
https://gcc.gnu.org/ml/gcc-patches/2018-07/msg01800.html
Bootstrapped and reg-tested on x86_64-pc-linux-gnu.
Is it OK for trunk?
Thanks
Bernd.
gcc/c:
2018-07-30 Bernd Edlinger <bernd.edlin...@hotmail.de>
* c-typeck.c (digest_init): Fix overlength strings.
testsuite:
2018-07-30 Bernd Edlinger <bernd.edlin...@hotmail.de>
* gcc.dg/strlenopt-49.c: Adjust test expectations.
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 2018-07-30 12:17:34.175481372 +0200
@@ -7435,29 +7435,38 @@ 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)
+ 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"));
- 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++"));
+ 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))
diff -pur gcc/testsuite/gcc.dg/strlenopt-49.c gcc/testsuite/gcc.dg/strlenopt-49.c
--- gcc/testsuite/gcc.dg/strlenopt-49.c 2018-07-30 13:02:34.735478726 +0200
+++ gcc/testsuite/gcc.dg/strlenopt-49.c 2018-07-30 13:08:21.074859303 +0200
@@ -11,9 +11,6 @@ const char a3[3] = "12\0";
const char a8[8] = "1234567\0";
const char a9[9] = "12345678\0";
-const char ax[9] = "12345678\0\0\0\0"; /* { dg-warning "initializer-string for array of chars is too long" } */
-const char ay[9] = "\00012345678\0\0\0\0"; /* { dg-warning "initializer-string for array of chars is too long" } */
-
int len1 (void)
{
@@ -27,27 +24,13 @@ int len (void)
return len;
}
-int lenx (void)
-{
- size_t lenx = strlen (ax);
- return lenx;
-}
-
-int leny (void)
-{
- size_t leny = strlen (ay);
- return leny;
-}
-
int cmp88 (void)
{
int cmp88 = memcmp (a8, "1234567\0", sizeof a8);
return cmp88;
}
-/* { dg-final { scan-tree-dump-times "strlen" 0 "gimple" { xfail *-*-* } } }
- { dg-final { scan-tree-dump-times "len0 = 0;" 1 "gimple" { xfail *-*-* } } }
- { dg-final { scan-tree-dump-times "len = 18;" 1 "gimple" { xfail *-*-* } } }
- { dg-final { scan-tree-dump-times "lenx = 8;" 1 "gimple" { xfail *-*-* } } }
- { dg-final { scan-tree-dump-times "leny = 0;" 1 "gimple" { xfail *-*-* } } }
- { dg-final { scan-tree-dump-times "cmp88 = 0;" 1 "gimple" { xfail *-*-* } } } */
+/* { dg-final { scan-tree-dump-times "strlen" 0 "gimple" } }
+ { dg-final { scan-tree-dump-times "len0 = 0;" 1 "gimple" } }
+ { dg-final { scan-tree-dump-times "len = 18;" 1 "gimple" } }
+ { dg-final { scan-tree-dump-times "cmp88 = 0;" 1 "gimple" } } */
