We represent deduction guides with FUNCTION_DECLs, but they are built
without DECL_CONTEXT, leading to an ICE in type_dependent_expression_p
on the assert that the type of a function template with no dependent
(innermost!) template arguments must be non-dependent. Consider the
attached class-deduction79.C: we create a deduction guide:
template<class T> G(T)-> E<Z>::G<T>
we deduce T and create a partial instantiation:
G(T) -> E<Z>::G<T> [with T = int]
And then do_class_deduction wants to create a CALL_EXPR from the above
using build_new_function_call -> build_over_call which calls mark_used
-> maybe_instantiate_noexcept -> type_dependent_expression_p.
There, the innermost template arguments are non-dependent (<int>), but
the fntype is dependent -- the return type is a TYPENAME_TYPE, and
since we have no DECL_CONTEXT, this check holds:
/* Otherwise, if the function decl isn't from a dependent scope, it can't be
type-dependent. Checking this is important for functions with auto return
type, which looks like a dependent type. */
if (TREE_CODE (expression) == FUNCTION_DECL
&& !(DECL_CLASS_SCOPE_P (expression)
&& dependent_type_p (DECL_CONTEXT (expression)))
whereupon we ICE.
Experiments with setting DECL_CONTEXT didn't pan out. So perhaps we
just want to skip the assert for deduction guides, because they are
a little special. Better ideas solicited.
Bootstrapped/regtested on x86_64-pc-linux-gnu.
gcc/cp/ChangeLog:
PR c++/97034
PR c++/99009
* pt.c (type_dependent_expression_p): Don't assert that the type
of a deduction guide must non-dependent.
gcc/testsuite/ChangeLog:
PR c++/97034
PR c++/99009
* g++.dg/cpp1z/class-deduction79.C: New test.
* g++.dg/cpp1z/class-deduction80.C: New test.
* g++.dg/cpp2a/class-deduction-aggr8.C: New test.
* g++.dg/cpp2a/class-deduction-aggr9.C: New test.
---
gcc/cp/pt.c | 5 ++++-
.../g++.dg/cpp1z/class-deduction79.C | 20 +++++++++++++++++++
.../g++.dg/cpp1z/class-deduction80.C | 12 +++++++++++
.../g++.dg/cpp2a/class-deduction-aggr8.C | 19 ++++++++++++++++++
.../g++.dg/cpp2a/class-deduction-aggr9.C | 18 +++++++++++++++++
5 files changed, 73 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/cpp1z/class-deduction79.C
create mode 100644 gcc/testsuite/g++.dg/cpp1z/class-deduction80.C
create mode 100644 gcc/testsuite/g++.dg/cpp2a/class-deduction-aggr8.C
create mode 100644 gcc/testsuite/g++.dg/cpp2a/class-deduction-aggr9.C
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 60de8e93ff7..3e6f3407d40 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -27282,7 +27282,10 @@ type_dependent_expression_p (tree expression)
&& DECL_UNIQUE_FRIEND_P (expression)
&& (!DECL_FRIEND_CONTEXT (expression)
|| dependent_type_p (DECL_FRIEND_CONTEXT (expression))))
- && !DECL_LOCAL_DECL_P (expression))
+ && !DECL_LOCAL_DECL_P (expression)
+ /* We build deduction guides without any DECL_CONTEXT, but they can
+ be type-dependent. */
+ && !deduction_guide_p (expression))
{
gcc_assert (!dependent_type_p (TREE_TYPE (expression))
|| undeduced_auto_decl (expression));
diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction79.C
b/gcc/testsuite/g++.dg/cpp1z/class-deduction79.C
new file mode 100644
index 00000000000..86a68248157
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction79.C
@@ -0,0 +1,20 @@
+// PR c++/97034
+// { dg-do compile { target c++17 } }
+
+template <typename Z>
+struct E {
+ template <typename T>
+ struct G {
+ T t;
+ G(T) { }
+ };
+
+ void fn() { G{1}; }
+};
+
+void
+g ()
+{
+ E<int> e;
+ e.fn ();
+}
diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction80.C
b/gcc/testsuite/g++.dg/cpp1z/class-deduction80.C
new file mode 100644
index 00000000000..238024c508f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction80.C
@@ -0,0 +1,12 @@
+// PR c++/99009
+// { dg-do compile { target c++17 } }
+
+template<typename> struct B {
+ B(int = A()) {}
+ template <typename ...> struct A;
+};
+
+template<typename T> struct X {
+ template <T...> struct Y;
+ X() { Y y; };
+};
diff --git a/gcc/testsuite/g++.dg/cpp2a/class-deduction-aggr8.C
b/gcc/testsuite/g++.dg/cpp2a/class-deduction-aggr8.C
new file mode 100644
index 00000000000..399061100ae
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/class-deduction-aggr8.C
@@ -0,0 +1,19 @@
+// PR c++/97034
+// { dg-do compile { target c++20 } }
+
+namespace N {
+template <typename, typename> struct S {
+ template <typename T, typename U> S(T, U);
+};
+} // namespace N
+template <int> struct E {
+ template <typename T> struct G { T t; };
+ void fn() { G{N::S<char, int>{'a', 1}}; }
+};
+
+void
+g ()
+{
+ E<1> e;
+ e.fn ();
+}
diff --git a/gcc/testsuite/g++.dg/cpp2a/class-deduction-aggr9.C
b/gcc/testsuite/g++.dg/cpp2a/class-deduction-aggr9.C
new file mode 100644
index 00000000000..245a04cd5f9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/class-deduction-aggr9.C
@@ -0,0 +1,18 @@
+// PR c++/97034
+// { dg-do compile { target c++20 } }
+
+template<typename>
+struct E {
+ template <typename T>
+ struct G {
+ T t;
+ };
+
+ void fn() { G{1}; }
+};
+
+void
+g () {
+ E<int> e;
+ e.fn ();
+}
base-commit: eb64b0b285b4fda9e8eeda4c2f370e636b1ab2ae
--
2.29.2
