[PATCH] c++: alias template of non-template class [PR112633]

[PATCH] c++: alias template of non-template class [PR112633]

[Patrick Palka]

Bootstrapped and regtested on x86-64-pc-linux-gnu, does this look OK for
trunk/13?

-- >8 --

The entering_scope adjustment in tsubst_aggr_type assumes if an alias is
dependent, then so is the aliased type (and therefore it has template info)
but that's not true for the dependent alias template specialization ty1<T>
below which aliases the non-template class A.

	PR c++/112633

gcc/cp/ChangeLog:

	* pt.cc (tsubst_aggr_type): Handle empty TYPE_TEMPLATE_INFO
	in the entering_scope adjustment.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/alias-decl-75.C: New test.
---
 gcc/cp/pt.cc                               |  1 +
 gcc/testsuite/g++.dg/cpp0x/alias-decl-75.C | 13 +++++++++++++
 2 files changed, 14 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/cpp0x/alias-decl-75.C

diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index ed681afb5d4..68ce4a87372 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -13976,6 +13976,7 @@ tsubst_aggr_type (tree t,
       if (entering_scope
 	  && CLASS_TYPE_P (t)
 	  && dependent_type_p (t)
+	  && TYPE_TEMPLATE_INFO (t)
 	  && TYPE_CANONICAL (t) == TREE_TYPE (TYPE_TI_TEMPLATE (t)))
 	t = TYPE_CANONICAL (t);
 
diff --git a/gcc/testsuite/g++.dg/cpp0x/alias-decl-75.C b/gcc/testsuite/g++.dg/cpp0x/alias-decl-75.C
new file mode 100644
index 00000000000..1a73a99856e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/alias-decl-75.C
@@ -0,0 +1,13 @@
+// PR c++/112633
+// { dg-do compile { target c++11 } }
+
+struct A { using type = void; };
+
+template<class>
+using ty1 = A;
+
+template<class T>
+using ty2 = typename ty1<T>::type;
+
+template<class T>
+ty2<T> f();
-- 
2.43.0.rc1

Re: [PATCH] c++: alias template of non-template class [PR112633]

[Jason Merrill]

On 11/22/23 12:26, Patrick Palka wrote:
> Bootstrapped and regtested on x86-64-pc-linux-gnu, does this look OK for
> trunk/13?

OK.

> -- >8 --
> 
> The entering_scope adjustment in tsubst_aggr_type assumes if an alias is
> dependent, then so is the aliased type (and therefore it has template info)
> but that's not true for the dependent alias template specialization ty1<T>
> below which aliases the non-template class A.
> 
> 	PR c++/112633
> 
> gcc/cp/ChangeLog:
> 
> 	* pt.cc (tsubst_aggr_type): Handle empty TYPE_TEMPLATE_INFO
> 	in the entering_scope adjustment.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/cpp0x/alias-decl-75.C: New test.
> ---
>   gcc/cp/pt.cc                               |  1 +
>   gcc/testsuite/g++.dg/cpp0x/alias-decl-75.C | 13 +++++++++++++
>   2 files changed, 14 insertions(+)
>   create mode 100644 gcc/testsuite/g++.dg/cpp0x/alias-decl-75.C
> 
> diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
> index ed681afb5d4..68ce4a87372 100644
> --- a/gcc/cp/pt.cc
> +++ b/gcc/cp/pt.cc
> @@ -13976,6 +13976,7 @@ tsubst_aggr_type (tree t,
>         if (entering_scope
>   	  && CLASS_TYPE_P (t)
>   	  && dependent_type_p (t)
> +	  && TYPE_TEMPLATE_INFO (t)
>   	  && TYPE_CANONICAL (t) == TREE_TYPE (TYPE_TI_TEMPLATE (t)))
>   	t = TYPE_CANONICAL (t);
>   
> diff --git a/gcc/testsuite/g++.dg/cpp0x/alias-decl-75.C b/gcc/testsuite/g++.dg/cpp0x/alias-decl-75.C
> new file mode 100644
> index 00000000000..1a73a99856e
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp0x/alias-decl-75.C
> @@ -0,0 +1,13 @@
> +// PR c++/112633
> +// { dg-do compile { target c++11 } }
> +
> +struct A { using type = void; };
> +
> +template<class>
> +using ty1 = A;
> +
> +template<class T>
> +using ty2 = typename ty1<T>::type;
> +
> +template<class T>
> +ty2<T> f();