https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91415
--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
On top of the above, I've tried:
--- gcc/c-family/c-common.c.jj 2019-08-12 09:45:54.463491950 +0200
+++ gcc/c-family/c-common.c 2019-08-12 12:01:32.783135654 +0200
@@ -1933,16 +1934,19 @@ verify_tree (tree x, struct tlist **pbef
tmp_before = tmp_nosp = tmp_list3 = 0;
verify_tree (TREE_OPERAND (x, 1), &tmp_before, &tmp_nosp, NULL_TREE);
verify_tree (TREE_OPERAND (x, 0), &tmp_list3, &tmp_list3, x);
- /* Expressions inside the LHS are not ordered wrt. the sequence points
- in the RHS. Example:
+ /* In C and C++ before 17 expressions inside the LHS are not ordered
+ wrt. the sequence points in the RHS. Example:
*a = (a++, 2)
Despite the fact that the modification of "a" is in the before_sp
list (tmp_before), it conflicts with the use of "a" in the LHS.
We can handle this by adding the contents of tmp_list3
to those of tmp_before, and redoing the collision warnings for that
list. */
- add_tlist (&tmp_before, tmp_list3, x, 1);
- warn_for_collisions (tmp_before);
+ if (cxx_dialect < cxx17)
+ {
+ add_tlist (&tmp_before, tmp_list3, x, 1);
+ warn_for_collisions (tmp_before);
+ }
/* Exclude the LHS itself here; we first have to merge it into the
tmp_nosp list. This is done to avoid warning for "a = a"; if we
didn't exclude the LHS, we'd get it twice, once as a read and once
--- gcc/testsuite/g++.dg/warn/sequence-pt-1.C.jj 2011-07-11
10:39:37.000000000 +0200
+++ gcc/testsuite/g++.dg/warn/sequence-pt-1.C 2019-08-12 12:22:42.033011124
+0200
@@ -35,7 +35,7 @@ foo (int a, int b, int n, int p, int *pt
*ptr++ = (size_t)ptr++; /* { dg-warning "undefined" "sequence point warning"
} */
sptr->a = sptr->a++; /* { dg-warning "undefined" "sequence point warning" }
*/
sptr->a = (size_t)(sptr++); /* { dg-warning "undefined" "sequence point
warning" } */
- *ptr++ = fn (*ptr); /* { dg-warning "undefined" "sequence point warning" }
*/
+ *ptr++ = fn (*ptr); /* { dg-warning "undefined" "sequence point warning" {
target c++14_down } } */
a = b = a++; /* { dg-warning "undefined" "sequence point warning" } */
b = a = --b; /* { dg-warning "undefined" "sequence point warning" } */
a = 1 + (a = 1); /* { dg-warning "undefined" "sequence point warning" } */
@@ -47,13 +47,13 @@ foo (int a, int b, int n, int p, int *pt
a = (*fnp[b++]) (b++); /* { dg-warning "undefined" "sequence point warning"
} */
a = (*fnp[b]) (b++); /* { dg-warning "undefined" "sequence point warning" }
*/
a = (*fnp[b++]) (b); /* { dg-warning "undefined" "sequence point warning" }
*/
- *ap = fnc (ap++); /* { dg-warning "undefined" "sequence point warning" } */
+ *ap = fnc (ap++); /* { dg-warning "undefined" "sequence point warning" {
target c++14_down } } */
(a += b) + (a += n); /* { dg-warning "undefined" "sequence point warning" }
*/
a = (b, b++) + (b++, b); /* { dg-warning "undefined" "sequence point
warning" } */
ap[a++] += a; /* { dg-warning "undefined" "sequence point warning" } */
ap[a+=1] += a; /* { dg-warning "undefined" "sequence point warning" } */
- ap[a++] += a++; /* { dg-warning "undefined" "sequence point warning" } */
- ap[a+=1] += a++; /* { dg-warning "undefined" "sequence point warning" } */
+ ap[a++] += a++; /* { dg-warning "undefined" "sequence point warning" {
target c++14_down } } */
+ ap[a+=1] += a++; /* { dg-warning "undefined" "sequence point warning" {
target c++14_down } } */
a = a++, b = a; /* { dg-warning "undefined" "sequence point warning" } */
b = a, a = a++; /* { dg-warning "undefined" "sequence point warning" } */
a = (b++ ? n : a) + b; /* { dg-warning "undefined" "sequence point warning"
} */
to handle the assignment operator, but while that handles some cases as shown
in the testsuite that IMHO are now well defined in C++17, it doesn't handle the
case from the testcase:
void
foo (int i, int y[10])
{
y[i++] = y[i++];
}
So I probably don't understand the code well enough :(. And the PMF case is
something to be resolved later too.
