1 files changed, 252 insertions, 0 deletions
diff --git a/gcc/testsuite/gcc.dg/Wstringop-overflow-34.c b/gcc/testsuite/gcc.dg/Wstringop-overflow-34.c
new file mode 100644
index 0000000..fd43f3a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Wstringop-overflow-34.c
@@ -0,0 +1,252 @@
+/* PR middle-end/95353 - spurious -Wstringop-overflow writing to a trailing
+   array plus offset
+   { dg-do compile }
+   { dg-options "-O2 -Wall" } */
+
+typedef __SIZE_TYPE__ size_t;
+
+struct S0 { char n, a[0]; };
+
+
+void s0_nowarn_cstidx (struct S0 *p)
+{
+  char *q = p->a;
+  q[1] = __LINE__;
+  q[9] = __LINE__;
+}
+
+void s0_nowarn_cstoff_cstidx (struct S0 *p)
+{
+  char *q = p->a + 1;
+  q[1] = __LINE__;
+  q[9] = __LINE__;
+}
+
+void s0_nowarn_varoff_cstdix (struct S0 *p, int i)
+{
+  char *q = p->a + i;
+  q[1] = __LINE__;            // { dg-bogus "\\\[-Wstringop-overflow" }
+  q[9] = __LINE__;            // { dg-bogus "\\\[-Wstringop-overflow" }
+}
+
+void s0_nowarn_cstoff_varidx (struct S0 *p, int i)
+{
+  char *q = p->a + 1;
+  q[i] = __LINE__;
+}
+
+void s0_nowarn_varoff_varidx (struct S0 *p, int i, int j)
+{
+  char *q = p->a + i;
+  q[j] = __LINE__;            // { dg-bogus "\\\[-Wstringop-overflow" }
+}
+
+
+/* Accesses past the end of a trailing array with one element is
+   discouraged but still reluctantly not diagnosed.  This should
+   change.  */
+
+struct S1 { char n, a[1]; };
+
+
+void s1_nowarn_cstidx (struct S1 *p)
+{
+  char *q = p->a;
+  q[1] = __LINE__;
+  q[9] = __LINE__;
+}
+
+void s1_nowarn_cstoff_cstidx (struct S1 *p)
+{
+  char *q = p->a + 1;
+  q[1] = __LINE__;
+  q[9] = __LINE__;
+}
+
+void s1_nowarn_varoff_cstdix (struct S1 *p, int i)
+{
+  char *q = p->a + i;
+  q[1] = __LINE__;            // { dg-bogus "\\\[-Wstringop-overflow" }
+  q[9] = __LINE__;            // { dg-bogus "\\\[-Wstringop-overflow" }
+}
+
+void s1_nowarn_cstoff_varidx (struct S1 *p, int i)
+{
+  char *q = p->a + 1;
+  q[i] = __LINE__;
+}
+
+void s1_nowarn_varoff_varidx (struct S1 *p, int i, int j)
+{
+  char *q = p->a + i;
+  q[j] = __LINE__;
+}
+
+
+/* Accesses past the end of a trailing array with more than one
+   element should be diagnosed but aren't yet because the MEM_REF
+   makes the out-of-bounds accesses indistinguishable from valid
+   ones to subsequent elements of the array pointed by P.  */
+
+struct S2 { char n, a[2]; };
+
+
+void s2_warn_cstidx (struct S2 *p)
+{
+  char *q = p->a;
+
+  /* The following invalid store is represented as
+       MEM[(char *)p_1(D) + 3B] = __LINE__;
+     which is indistinguishable from the valid
+       q = &p[1].n; q[0] = __LINE__;
+  */
+  q[2] = __LINE__;            // { dg-warning "\\\[-Wstringop-overflow" "pr?????" { xfail *-*-* } }
+}
+
+void s2_warn_cstoff_cstidx (struct S2 *p)
+{
+  char *q = p->a + 1;
+  q[1] = __LINE__;            // { dg-warning "\\\[-Wstringop-overflow" "pr?????" { xfail *-*-* }  }
+}
+
+void s2_warn_varoff_cstdix (struct S2 *p, int i)
+{
+  char *q = p->a + i;
+  q[2] = __LINE__;            // { dg-warning "\\\[-Wstringop-overflow" "pr?????" { xfail *-*-* }  }
+}
+
+void s2_warn_cstoff_varidx (struct S2 *p, int i)
+{
+  char *q = p->a + 1;
+  q[i] = __LINE__;            // { dg-warning "\\\[-Wstringop-overflow" "pr?????" { xfail *-*-* }  }
+}
+
+void s2_warn_varoff_varidx (struct S2 *p, int i, int j)
+{
+  char *q = p->a + i;
+  q[j] = __LINE__;            // { dg-warning "\\\[-Wstringop-overflow" "pr?????" { xfail *-*-* }  }
+}
+
+
+/* Verify that none of these triggers a bogus warning (not tested
+   elsewhere but triggered during bootstrap).  */
+
+void s2_nowarn_varidx_int (struct S2 *p, int i)
+{
+  extern struct S2 s2;
+  extern struct S2 s2a[];
+
+  s2.a[i - 1] = __LINE__;
+  s2.a[i] = __LINE__;
+  s2.a[i + 1] = __LINE__;
+
+  s2a[i].a[i - 1] = __LINE__;
+  s2a[i].a[i] = __LINE__;
+  s2a[i].a[i + 1] = __LINE__;
+
+  p[i].a[i - 1] = __LINE__;
+  p[i].a[i] = __LINE__;
+  p[i].a[i + 1] = __LINE__;
+
+  char *q = p->a;
+  q[i - 1] = __LINE__;
+  q[i] = __LINE__;
+  q[i + 1] = __LINE__;
+}
+
+/* Same as above but with a size_t index in range [1, SIZE_MAX].  */
+
+void* s2_nowarn_varidx_size (struct S2 *p, size_t i, size_t j)
+{
+  extern struct S2 s2;
+  extern struct S2 s2a[];
+  struct S2 *ps2 = __builtin_malloc (3 * sizeof *ps2);
+
+  s2.a[i - 1] = __LINE__;
+  s2.a[i] = __LINE__;
+  s2.a[i + 1] = __LINE__;
+
+  s2a[i].a[i - 1] = __LINE__;
+  s2a[i].a[i] = __LINE__;
+  s2a[i].a[i + 1] = __LINE__;
+
+  p[i].a[i - 1] = __LINE__;
+  p[i].a[i] = __LINE__;
+  p[i].a[i + 1] = __LINE__;
+
+  ps2->a[i - 1] = __LINE__;
+  ps2->a[i] = __LINE__;
+  ps2->a[i + 1] = __LINE__;
+
+  char *q = p->a;
+  q[i - 1] = __LINE__;
+  q[i] = __LINE__;
+  q[i + 1] = __LINE__;
+
+  if (j == 0)
+    return ps2;
+
+  s2.a[j - 1] = __LINE__;
+  s2.a[j] = __LINE__;
+  s2.a[j + 1] = __LINE__;
+
+  s2a[j].a[j - 1] = __LINE__;
+  s2a[j].a[j] = __LINE__;
+  s2a[j].a[j + 1] = __LINE__;
+
+  p[j].a[j - 1] = __LINE__;
+  p[j].a[j] = __LINE__;
+  p[j].a[j + 1] = __LINE__;
+
+  ps2->a[j - 1] = __LINE__;
+  ps2->a[j] = __LINE__;
+  ps2->a[j + 1] = __LINE__;
+
+  q = p->a;
+  q[j - 1] = __LINE__;
+  q[j] = __LINE__;
+  q[j + 1] = __LINE__;
+
+  return ps2;
+}
+
+/* Verify that accesses to an interior zero-length array are diagnosed.  */
+
+struct Si0 { char c, a[0], d; };
+
+void si0_warn_cstidx (struct Si0 *p)
+{
+  // These are indistinguishable from valid accesses to p->d:
+  //   MEM[(char *)p_1(D) + 1B] = 0;
+  char *q = p->a;
+  q[1] = __LINE__;            // { dg-warning "writing 1 byte into a region of size 0"  "pr?????" { xfail *-*-* } }
+  q[9] = __LINE__;            // { dg-warning "\\\[-Wstringop-overflow" "pr?????" { xfail *-*-* } }
+}
+
+void si0_warn_cstoff_cstidx (struct Si0 *p)
+{
+  // Like those above, these too are indistinguishable from valid accesses
+  // to p->d.
+  char *q = p->a + 1;
+  q[1] = __LINE__;            // { dg-warning "\\\[-Wstringop-overflow" "pr?????" { xfail *-*-* } }
+  q[9] = __LINE__;            // { dg-warning "\\\[-Wstringop-overflow" "pr?????" { xfail *-*-* } }
+}
+
+void si0_warn_varoff_cstdix (struct Si0 *p, int i)
+{
+  char *q = p->a + i;
+  q[1] = __LINE__;            // { dg-warning "\\\[-Wstringop-overflow" }
+  q[9] = __LINE__;            // { dg-warning "\\\[-Wstringop-overflow" }
+}
+
+void si0_warn_cstoff_varidx (struct Si0 *p, int i)
+{
+  char *q = p->a + 1;
+  q[i] = __LINE__;            // { dg-warning "\\\[-Wstringop-overflow" "pr?????" { xfail *-*-* } }
+}
+
+void si0_warn_varoff_varidx (struct Si0 *p, int i, int j)
+{
+  char *q = p->a + i;
+  q[j] = __LINE__;            // { dg-warning "\\\[-Wstringop-overflow" }
+}