c++: explicit inst w/ many constrained partial specs [PR104634]

Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK
for trunk and perhaps 13?

-- >8 --

Here we neglect to emit the definitions of A<double>::f2 and A<double*>::f4
despite the explicit instantiations ultimately because TREE_PUBLIC isn't
set on the corresponding partial specializations, the declarations of which
are created from maybe_new_partial_specialization which is responsible for
disambiguating them from the first and third partial specializations (which
have the same class-head but different constraints).  This makes grokfndecl
in turn clear TREE_PUBLIC for f2 and f4 as if they have internal linkage.

This patch fixes this by setting TREE_PUBLIC appropriately for such partial
specializations.

	PR c++/104634

gcc/cp/ChangeLog:

	* pt.cc (maybe_new_partial_specialization): Propagate TREE_PUBLIC
	to the newly created partial specialization.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp2a/concepts-explicit-inst6.C: New test.
---
 gcc/cp/pt.cc                                  |  1 +
 .../g++.dg/cpp2a/concepts-explicit-inst6.C    | 35 +++++++++++++++++++
 2 files changed, 36 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-explicit-inst6.C

On Wed, Jan 3, 2024 at 1:49 PM Patrick Palka <ppalka@redhat.com> wrote:
>
> Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK
> for trunk and perhaps 13?

Ping.

>
> -- >8 --
>
> Here we neglect to emit the definitions of A<double>::f2 and A<double*>::f4
> despite the explicit instantiations ultimately because TREE_PUBLIC isn't
> set on the corresponding partial specializations, the declarations of which
> are created from maybe_new_partial_specialization which is responsible for
> disambiguating them from the first and third partial specializations (which
> have the same class-head but different constraints).  This makes grokfndecl
> in turn clear TREE_PUBLIC for f2 and f4 as if they have internal linkage.
>
> This patch fixes this by setting TREE_PUBLIC appropriately for such partial
> specializations.
>
>         PR c++/104634
>
> gcc/cp/ChangeLog:
>
>         * pt.cc (maybe_new_partial_specialization): Propagate TREE_PUBLIC
>         to the newly created partial specialization.
>
> gcc/testsuite/ChangeLog:
>
>         * g++.dg/cpp2a/concepts-explicit-inst6.C: New test.
> ---
>  gcc/cp/pt.cc                                  |  1 +
>  .../g++.dg/cpp2a/concepts-explicit-inst6.C    | 35 +++++++++++++++++++
>  2 files changed, 36 insertions(+)
>  create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-explicit-inst6.C
>
> diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
> index e38e7a773f0..154ac76cb65 100644
> --- a/gcc/cp/pt.cc
> +++ b/gcc/cp/pt.cc
> @@ -980,6 +980,7 @@ maybe_new_partial_specialization (tree& type)
>        DECL_SOURCE_LOCATION (d) = input_location;
>        TREE_PRIVATE (d) = (current_access_specifier == access_private_node);
>        TREE_PROTECTED (d) = (current_access_specifier == access_protected_node);
> +      TREE_PUBLIC (d) = TREE_PUBLIC (DECL_TEMPLATE_RESULT (tmpl));
>
>        set_instantiating_module (d);
>        DECL_MODULE_EXPORT_P (d) = DECL_MODULE_EXPORT_P (tmpl);
> diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-explicit-inst6.C b/gcc/testsuite/g++.dg/cpp2a/concepts-explicit-inst6.C
> new file mode 100644
> index 00000000000..4ac0c65c490
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-explicit-inst6.C
> @@ -0,0 +1,35 @@
> +// PR c++/104634
> +// { dg-do compile { target c++20 } }
> +// { dg-final { scan-assembler "_ZN1AIiE2f1Ev" } }
> +// { dg-final { scan-assembler "_ZN1AIdE2f2Ev" } }
> +// { dg-final { scan-assembler "_ZN1AIPiE2f3Ev" } }
> +// { dg-final { scan-assembler "_ZN1AIPdE2f4Ev" } }
> +
> +template<typename T>
> +struct A { };
> +
> +template<class T> requires __is_same(T, int)
> +struct A<T> {
> +  void f1() { }
> +  static inline int m1;
> +};
> +
> +template<class T> requires __is_same(T, double)
> +struct A<T> {
> +  void f2() { }
> +};
> +
> +template<class T> requires __is_same(T, int)
> +struct A<T*> {
> +  void f3() { }
> +};
> +
> +template<class T> requires __is_same(T, double)
> +struct A<T*> {
> +  void f4() { }
> +};
> +
> +template struct A<int>;
> +template struct A<double>;
> +template struct A<int*>;
> +template struct A<double*>;
> --
> 2.43.0.254.ga26002b628
>

On 1/3/24 13:49, Patrick Palka wrote:
> Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK
> for trunk and perhaps 13?

OK for both.

> -- >8 --
> 
> Here we neglect to emit the definitions of A<double>::f2 and A<double*>::f4
> despite the explicit instantiations ultimately because TREE_PUBLIC isn't
> set on the corresponding partial specializations, the declarations of which
> are created from maybe_new_partial_specialization which is responsible for
> disambiguating them from the first and third partial specializations (which
> have the same class-head but different constraints).  This makes grokfndecl
> in turn clear TREE_PUBLIC for f2 and f4 as if they have internal linkage.
> 
> This patch fixes this by setting TREE_PUBLIC appropriately for such partial
> specializations.
> 
> 	PR c++/104634
> 
> gcc/cp/ChangeLog:
> 
> 	* pt.cc (maybe_new_partial_specialization): Propagate TREE_PUBLIC
> 	to the newly created partial specialization.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/cpp2a/concepts-explicit-inst6.C: New test.
> ---
>   gcc/cp/pt.cc                                  |  1 +
>   .../g++.dg/cpp2a/concepts-explicit-inst6.C    | 35 +++++++++++++++++++
>   2 files changed, 36 insertions(+)
>   create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-explicit-inst6.C
> 
> diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
> index e38e7a773f0..154ac76cb65 100644
> --- a/gcc/cp/pt.cc
> +++ b/gcc/cp/pt.cc
> @@ -980,6 +980,7 @@ maybe_new_partial_specialization (tree& type)
>         DECL_SOURCE_LOCATION (d) = input_location;
>         TREE_PRIVATE (d) = (current_access_specifier == access_private_node);
>         TREE_PROTECTED (d) = (current_access_specifier == access_protected_node);
> +      TREE_PUBLIC (d) = TREE_PUBLIC (DECL_TEMPLATE_RESULT (tmpl));
>   
>         set_instantiating_module (d);
>         DECL_MODULE_EXPORT_P (d) = DECL_MODULE_EXPORT_P (tmpl);
> diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-explicit-inst6.C b/gcc/testsuite/g++.dg/cpp2a/concepts-explicit-inst6.C
> new file mode 100644
> index 00000000000..4ac0c65c490
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-explicit-inst6.C
> @@ -0,0 +1,35 @@
> +// PR c++/104634
> +// { dg-do compile { target c++20 } }
> +// { dg-final { scan-assembler "_ZN1AIiE2f1Ev" } }
> +// { dg-final { scan-assembler "_ZN1AIdE2f2Ev" } }
> +// { dg-final { scan-assembler "_ZN1AIPiE2f3Ev" } }
> +// { dg-final { scan-assembler "_ZN1AIPdE2f4Ev" } }
> +
> +template<typename T>
> +struct A { };
> +
> +template<class T> requires __is_same(T, int)
> +struct A<T> {
> +  void f1() { }
> +  static inline int m1;
> +};
> +
> +template<class T> requires __is_same(T, double)
> +struct A<T> {
> +  void f2() { }
> +};
> +
> +template<class T> requires __is_same(T, int)
> +struct A<T*> {
> +  void f3() { }
> +};
> +
> +template<class T> requires __is_same(T, double)
> +struct A<T*> {
> +  void f4() { }
> +};
> +
> +template struct A<int>;
> +template struct A<double>;
> +template struct A<int*>;
> +template struct A<double*>;