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* [gcc r13-3417] c++: constraint matching, TEMPLATE_ID_EXPR, current inst
@ 2022-10-20 18:13 Patrick Palka
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From: Patrick Palka @ 2022-10-20 18:13 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:14272aec22dcacbb3b937d6c5b86794faaa24620
commit r13-3417-g14272aec22dcacbb3b937d6c5b86794faaa24620
Author: Patrick Palka <ppalka@redhat.com>
Date: Thu Oct 20 14:13:10 2022 -0400
c++: constraint matching, TEMPLATE_ID_EXPR, current inst
Here we're crashing during constraint matching for the instantiated
hidden friends due to two issues with dependent substitution into a
TEMPLATE_ID_EXPR that names a template from the current instantiation
(as for C<1> with T=T from maybe_substitute_reqs_for):
* tsubst_copy substitutes into such a TEMPLATE_DECL by looking it up
from the substituted class scope. But for this lookup to work when
the args are dependent, we need to substitute the class scope with
entering_scope=true so that we obtain the primary template type
A<T> (which has TYPE_BINFO) instead of the implicit instantiation
A<T> (which doesn't).
* lookup_and_finish_template_variable shouldn't instantiate a
TEMPLATE_ID_EXPR that names a TEMPLATE_DECL which has more than
one level of (unsubstituted) parameters (such as A<T>::C).
gcc/cp/ChangeLog:
* pt.cc (lookup_and_finish_template_variable): Don't
instantiate if the template's scope is dependent.
(tsubst_copy) <case TEMPLATE_DECL>: Pass entering_scope=true
when substituting the class scope.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/concepts-friend10.C: New test.
Diff:
---
gcc/cp/pt.cc | 14 ++++++++------
gcc/testsuite/g++.dg/cpp2a/concepts-friend10.C | 24 ++++++++++++++++++++++++
2 files changed, 32 insertions(+), 6 deletions(-)
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 5eddad900ea..1289aabec75 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -10398,14 +10398,15 @@ tree
lookup_and_finish_template_variable (tree templ, tree targs,
tsubst_flags_t complain)
{
- templ = lookup_template_variable (templ, targs);
- if (!any_dependent_template_arguments_p (targs))
+ tree var = lookup_template_variable (templ, targs);
+ if (TMPL_PARMS_DEPTH (DECL_TEMPLATE_PARMS (templ)) == 1
+ && !any_dependent_template_arguments_p (targs))
{
- templ = finish_template_variable (templ, complain);
- mark_used (templ);
+ var = finish_template_variable (var, complain);
+ mark_used (var);
}
- return convert_from_reference (templ);
+ return convert_from_reference (var);
}
/* If the set of template parameters PARMS contains a template parameter
@@ -17229,7 +17230,8 @@ tsubst_copy (tree t, tree args, tsubst_flags_t complain, tree in_decl)
TEMPLATE_DECL with `D<T>' as its DECL_CONTEXT. Now we
have to substitute this with one having context `D<int>'. */
- tree context = tsubst (DECL_CONTEXT (t), args, complain, in_decl);
+ tree context = tsubst_aggr_type (DECL_CONTEXT (t), args, complain,
+ in_decl, /*entering_scope=*/true);
return lookup_field (context, DECL_NAME(t), 0, false);
}
else
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-friend10.C b/gcc/testsuite/g++.dg/cpp2a/concepts-friend10.C
new file mode 100644
index 00000000000..fc07120e112
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-friend10.C
@@ -0,0 +1,24 @@
+// Verify we don't crash when matching constraints containing a
+// TEMPLATE_ID_EXPR that names a template from the current instantiation.
+// { dg-do compile { target c++20 } }
+
+template<class T> static constexpr bool False = false;
+
+template<class T>
+struct A {
+ template<int N> static constexpr bool C = sizeof(T) > N;
+ friend constexpr void f(A) requires C<1> { }
+ friend constexpr void f(A) requires C<1> && False<T> { }
+};
+
+template<class T>
+struct A<T*> {
+ template<int N> static constexpr bool D = sizeof(T) > N;
+ friend constexpr void g(A) requires D<1> { }
+ friend constexpr void g(A) requires D<1> && False<T> { }
+};
+
+int main() {
+ f(A<int>{});
+ g(A<int*>{});
+}
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