On 2/26/20 5:00 PM, Jason Merrill wrote:
On 2/25/20 4:09 PM, Nathan Sidwell wrote:
We consider all TYPE_ARGUMENT_PACKS distinct types, leading to
problems with redeclarations.
I'd think that the bug is that we're treating them as types in the first
place; they aren't types, so they shouldn't reach comptypes. I'd lean
toward adding an assert to that effect and fixing the caller to use e.g.
template_args_equal.
Thanks, this patch implements that approach.
That TYPE_ARGUMENT_PACKS are not types, suggests to me that
NONTYPE_ARGUMENT_PACKS are not expressions. Perhaps their
representation should be unified -- I keep encountering code handling
them essentially doing the same thing for both kinds. But that's a
GCC-11 thing at least.
nathan
--
Nathan Sidwell
2020-02-27 Nathan Sidwell <nat...@acm.org>
PR c++/93933
* pt.c (template_args_equal): Pass ARGUMENT_PACKS through to
cp_tree_equal.
* tree.c (cp_tree_equal): Compare ARGUMENT_PACKS here,
* typeck.c (comptypes): Assert we don't get any argument packs.
diff --git c/gcc/cp/pt.c w/gcc/cp/pt.c
index 6c9abb8f3d3..622c70b352f 100644
--- c/gcc/cp/pt.c
+++ w/gcc/cp/pt.c
@@ -8999,25 +8999,8 @@ template_args_equal (tree ot, tree nt, bool partial_order /* = false */)
PACK_EXPANSION_PATTERN (nt))
&& template_args_equal (PACK_EXPANSION_EXTRA_ARGS (ot),
PACK_EXPANSION_EXTRA_ARGS (nt)));
- else if (ARGUMENT_PACK_P (ot))
- {
- int i, len;
- tree opack, npack;
-
- if (!ARGUMENT_PACK_P (nt))
- return 0;
-
- opack = ARGUMENT_PACK_ARGS (ot);
- npack = ARGUMENT_PACK_ARGS (nt);
- len = TREE_VEC_LENGTH (opack);
- if (TREE_VEC_LENGTH (npack) != len)
- return 0;
- for (i = 0; i < len; ++i)
- if (!template_args_equal (TREE_VEC_ELT (opack, i),
- TREE_VEC_ELT (npack, i)))
- return 0;
- return 1;
- }
+ else if (ARGUMENT_PACK_P (ot) || ARGUMENT_PACK_P (nt))
+ return cp_tree_equal (ot, nt);
else if (ot && TREE_CODE (ot) == ARGUMENT_PACK_SELECT)
gcc_unreachable ();
else if (TYPE_P (nt))
diff --git c/gcc/cp/tree.c w/gcc/cp/tree.c
index 72b3a720ee8..3fc6287d566 100644
--- c/gcc/cp/tree.c
+++ w/gcc/cp/tree.c
@@ -3857,12 +3857,27 @@ cp_tree_equal (tree t1, tree t2)
DEFERRED_NOEXCEPT_PATTERN (t2))
&& comp_template_args (DEFERRED_NOEXCEPT_ARGS (t1),
DEFERRED_NOEXCEPT_ARGS (t2)));
- break;
case LAMBDA_EXPR:
/* Two lambda-expressions are never considered equivalent. */
return false;
+ case TYPE_ARGUMENT_PACK:
+ case NONTYPE_ARGUMENT_PACK:
+ {
+ tree p1 = ARGUMENT_PACK_ARGS (t1);
+ tree p2 = ARGUMENT_PACK_ARGS (t2);
+ int len = TREE_VEC_LENGTH (p1);
+ if (TREE_VEC_LENGTH (p2) != len)
+ return false;
+
+ for (int ix = 0; ix != len; ix++)
+ if (!template_args_equal (TREE_VEC_ELT (p1, ix),
+ TREE_VEC_ELT (p2, ix)))
+ return false;
+ return true;
+ }
+
default:
break;
}
diff --git c/gcc/cp/typeck.c w/gcc/cp/typeck.c
index 42d0b47cf1b..2a3243f3e81 100644
--- c/gcc/cp/typeck.c
+++ w/gcc/cp/typeck.c
@@ -1485,6 +1485,10 @@ comptypes (tree t1, tree t2, int strict)
{
gcc_checking_assert (t1 && t2);
+ /* TYPE_ARGUMENT_PACKS are not really types. */
+ gcc_checking_assert (TREE_CODE (t1) != TYPE_ARGUMENT_PACK
+ && TREE_CODE (t2) != TYPE_ARGUMENT_PACK);
+
if (strict == COMPARE_STRICT && comparing_specializations
&& (t1 != TYPE_CANONICAL (t1) || t2 != TYPE_CANONICAL (t2)))
/* If comparing_specializations, treat dependent aliases as distinct. */
diff --git c/gcc/testsuite/g++.dg/concepts/pr93933.C w/gcc/testsuite/g++.dg/concepts/pr93933.C
new file mode 100644
index 00000000000..b4f2c36374d
--- /dev/null
+++ w/gcc/testsuite/g++.dg/concepts/pr93933.C
@@ -0,0 +1,31 @@
+// { dg-do compile { target c++17 } }
+// { dg-options "-fconcepts" }
+
+// distilled from <concepts>, via header units
+
+template<typename _ArgTypes>
+struct is_invocable;
+
+template<typename... _Args>
+concept invocable = is_invocable<_Args...>::value;
+
+template<typename _Is>
+requires invocable<_Is>
+class BUG;
+
+template<typename _Is>
+requires invocable<_Is>
+class BUG {}; // { dg-bogus "different constraints" }
+
+template<int> struct is_invocable_NT;
+
+template<int... Ints>
+concept invocable_NT = is_invocable_NT<Ints...>::value;
+
+template<int _Is>
+requires invocable_NT<_Is>
+class BUG_NT;
+
+template<int _Is>
+requires invocable_NT<_Is>
+class BUG_NT {};
