https://gcc.gnu.org/g:1301e18f69ced6a14a7648a24d1eb3addd836b6c
commit r15-7921-g1301e18f69ced6a14a7648a24d1eb3addd836b6c
Author: Jakub Jelinek <ja...@redhat.com>
Date: Mon Mar 10 09:31:41 2025 +0100
gimple-ssa-warn-access: Adjust maybe_warn_nonstring_arg for nonstring
multidimensional arrays [PR117178]
The following patch fixes 4 xfails in attr-nonstring-11.c (and results in 2
false positive warnings in attr-nonstring-12.c not being produced either).
The thing is that maybe_warn_nonstring_arg simply assumed that nonstring
arrays must be single-dimensional, so when it sees a nonstring decl with
ARRAY_TYPE, it just used its dimension. With multi-dimensional arrays
that is not the right dimension to use though, it can be dimension of
some outer dimension, e.g. if we have
char a[5][6][7] __attribute__((nonstring)) if decl is
a[5] it would assume maximum non-NUL terminated string length of 5 rather
than
7, if a[5][6] it would assume 6 and only for a[5][6][0] it would assume the
correct 7. So, the following patch looks through all the outer dimensions
to reach the innermost one (which for attribute nonstring is guaranteed to
have char/unsigned char/signed char element type).
2025-03-10 Jakub Jelinek <ja...@redhat.com>
PR c/117178
* gimple-ssa-warn-access.cc (maybe_warn_nonstring_arg): Look through
multi-dimensional array types, stop at the innermost ARRAY_TYPE.
* c-c++-common/attr-nonstring-11.c: Remove xfails.
* c-c++-common/attr-nonstring-12.c (warn_strcmp_cst_1,
warn_strcmp_cst_2): Don't expect any warnings here.
(warn_strcmp_cst_3, warn_strcmp_cst_4): New functions with expected
warnings.
Diff:
---
gcc/gimple-ssa-warn-access.cc | 4 ++++
gcc/testsuite/c-c++-common/attr-nonstring-11.c | 8 ++++----
gcc/testsuite/c-c++-common/attr-nonstring-12.c | 14 ++++++++++++--
3 files changed, 20 insertions(+), 6 deletions(-)
diff --git a/gcc/gimple-ssa-warn-access.cc b/gcc/gimple-ssa-warn-access.cc
index 351f48765101..305b63567fea 100644
--- a/gcc/gimple-ssa-warn-access.cc
+++ b/gcc/gimple-ssa-warn-access.cc
@@ -602,6 +602,10 @@ maybe_warn_nonstring_arg (tree fndecl, GimpleOrTree exp)
bool known_size = false;
tree type = TREE_TYPE (decl);
+ while (TREE_CODE (type) == ARRAY_TYPE
+ && TREE_CODE (TREE_TYPE (type)) == ARRAY_TYPE)
+ type = TREE_TYPE (type);
+
/* Determine the array size. For arrays of unknown bound and
pointers reset BOUND to trigger the appropriate warning. */
if (TREE_CODE (type) == ARRAY_TYPE)
diff --git a/gcc/testsuite/c-c++-common/attr-nonstring-11.c
b/gcc/testsuite/c-c++-common/attr-nonstring-11.c
index 12fbc9005e33..745e99382fe3 100644
--- a/gcc/testsuite/c-c++-common/attr-nonstring-11.c
+++ b/gcc/testsuite/c-c++-common/attr-nonstring-11.c
@@ -165,8 +165,8 @@ void test_strcmp (struct MemArrays *p)
void test_strncmp_warn (struct MemArrays *p)
{
enum { N = sizeof arr[2] };
- T (strncmp (str[2], arr[2], N)); /* { dg-bogus "argument 2 declared
attribute 'nonstring' is smaller than the specified bound 4" "" { xfail *-*-* }
} */
- T (strncmp (arr[2], str[2], N)); /* { dg-bogus "argument 1 declared
attribute 'nonstring' is smaller than the specified bound 4" "" { xfail *-*-* }
} */
+ T (strncmp (str[2], arr[2], N));
+ T (strncmp (arr[2], str[2], N));
T (strncmp (str[2], arr[2], N + 1)); /* { dg-warning "argument 2 declared
attribute .nonstring. is smaller than the specified bound 5" } */
T (strncmp (arr[2], str[2], N + 1)); /* { dg-warning "argument 1 declared
attribute .nonstring. is smaller than the specified bound 5" } */
@@ -237,7 +237,7 @@ void test_stpncpy_warn (struct MemArrays *p, unsigned n)
enum { N = sizeof arr[2] };
T (stpncpy (str[2], str[2], N));
- T (stpncpy (str[2], arr[2], N)); /* { dg-bogus "argument 2 declared
attribute 'nonstring' is smaller than the specified bound 4" "" { xfail *-*-* }
} */
+ T (stpncpy (str[2], arr[2], N));
T (stpncpy (arr[2], str[2], N));
T (stpncpy (str[2], *ptr, N));
@@ -370,7 +370,7 @@ void test_stnrdup_warn (struct MemArrays *p)
enum { N = sizeof arr[2] };
T (strndup (str[2], N));
- T (strndup (arr[2], N)); /* { dg-bogus "argument 1 declared attribute
'nonstring' is smaller than the specified bound 4" "" { xfail *-*-* } } */
+ T (strndup (arr[2], N));
T (strndup (*ptr, N));
T (strndup (*parr, N));
diff --git a/gcc/testsuite/c-c++-common/attr-nonstring-12.c
b/gcc/testsuite/c-c++-common/attr-nonstring-12.c
index 75787e898be9..739e336c0b56 100644
--- a/gcc/testsuite/c-c++-common/attr-nonstring-12.c
+++ b/gcc/testsuite/c-c++-common/attr-nonstring-12.c
@@ -26,12 +26,22 @@ enum { X = sizeof ar5[2] + 1 };
int warn_strcmp_cst_1 (void)
{
- return strcmp ("bar", arx[3]); /* { dg-warning "argument 2 declared
attribute .nonstring." } */
+ return strcmp ("bar", arx[3]);
}
int warn_strcmp_cst_2 (void)
{
- return strcmp (arx[3], "foo"); /* { dg-warning "argument 1 declared
attribute .nonstring." } */
+ return strcmp (arx[3], "foo");
+}
+
+int warn_strcmp_cst_3 (void)
+{
+ return strcmp ("barfoobazquxcorge1", arx[3]); /* { dg-warning
"argument 2 declared attribute .nonstring." } */
+}
+
+int warn_strcmp_cst_4 (void)
+{
+ return strcmp (arx[3], "foobarbazquxcorge1"); /* { dg-warning
"argument 1 declared attribute .nonstring." } */
}
