* [PATCH] c++: abbreviated function template friend matching [PR96106]
@ 2020-07-20 20:18 Patrick Palka
2020-07-29 21:57 ` Jason Merrill
0 siblings, 1 reply; 2+ messages in thread
From: Patrick Palka @ 2020-07-20 20:18 UTC (permalink / raw)
To: gcc-patches
In the below testcase, duplicate_decls wasn't merging the tsubsted
friend declaration for 'void add(auto)' with its definition, because
reduce_template_parm_level (during tsubst_friend_function) lost the
DECL_VIRTUAL_P flag on the invented 'auto' template parameter, which
made template_heads_equivalent_p deem the two template heads as not
equivalent in C++20 mode.
This patch makes reduce_template_parm_level carry over the
DECL_VIRTUAL_P from the original TEMPLATE_PARM_DECL.
Passes 'make check-c++' and the cmcstl2 testsuite. Does this look OK
for trunk after a full bootstrap and regtest?
gcc/cp/ChangeLog:
PR c++/96106
* pt.c (reduce_template_parm_level): Carry over DECL_VIRTUAL_P
from the original TEMPLATE_PARM_DECL.
gcc/testsuite/ChangeLog:
PR c++/96106
* g++.dg/concepts/abbrev7.C: New test.
---
gcc/cp/pt.c | 1 +
gcc/testsuite/g++.dg/concepts/abbrev7.C | 14 ++++++++++++++
2 files changed, 15 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/concepts/abbrev7.C
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index defc2a9abd8..3f7b89141b6 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -4453,6 +4453,7 @@ reduce_template_parm_level (tree index, tree type, int levels, tree args,
type);
TREE_CONSTANT (decl) = TREE_CONSTANT (orig_decl);
TREE_READONLY (decl) = TREE_READONLY (orig_decl);
+ DECL_VIRTUAL_P (decl) = DECL_VIRTUAL_P (orig_decl);
DECL_ARTIFICIAL (decl) = 1;
SET_DECL_TEMPLATE_PARM_P (decl);
diff --git a/gcc/testsuite/g++.dg/concepts/abbrev7.C b/gcc/testsuite/g++.dg/concepts/abbrev7.C
new file mode 100644
index 00000000000..443c1b7871b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/concepts/abbrev7.C
@@ -0,0 +1,14 @@
+// PR c++/96106
+// { dg-do compile { target concepts } }
+
+template<typename>
+struct number {
+ friend void add(auto);
+};
+
+void add(auto) { }
+
+void foo() {
+ number<int> n;
+ add(n); // { dg-bogus "ambiguous" }
+}
--
2.28.0.rc1
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] c++: abbreviated function template friend matching [PR96106]
2020-07-20 20:18 [PATCH] c++: abbreviated function template friend matching [PR96106] Patrick Palka
@ 2020-07-29 21:57 ` Jason Merrill
0 siblings, 0 replies; 2+ messages in thread
From: Jason Merrill @ 2020-07-29 21:57 UTC (permalink / raw)
To: Patrick Palka, gcc-patches
On 7/20/20 4:18 PM, Patrick Palka wrote:
> In the below testcase, duplicate_decls wasn't merging the tsubsted
> friend declaration for 'void add(auto)' with its definition, because
> reduce_template_parm_level (during tsubst_friend_function) lost the
> DECL_VIRTUAL_P flag on the invented 'auto' template parameter, which
> made template_heads_equivalent_p deem the two template heads as not
> equivalent in C++20 mode.
>
> This patch makes reduce_template_parm_level carry over the
> DECL_VIRTUAL_P from the original TEMPLATE_PARM_DECL.
>
> Passes 'make check-c++' and the cmcstl2 testsuite. Does this look OK
> for trunk after a full bootstrap and regtest?
OK.
> gcc/cp/ChangeLog:
>
> PR c++/96106
> * pt.c (reduce_template_parm_level): Carry over DECL_VIRTUAL_P
> from the original TEMPLATE_PARM_DECL.
>
> gcc/testsuite/ChangeLog:
>
> PR c++/96106
> * g++.dg/concepts/abbrev7.C: New test.
> ---
> gcc/cp/pt.c | 1 +
> gcc/testsuite/g++.dg/concepts/abbrev7.C | 14 ++++++++++++++
> 2 files changed, 15 insertions(+)
> create mode 100644 gcc/testsuite/g++.dg/concepts/abbrev7.C
>
> diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
> index defc2a9abd8..3f7b89141b6 100644
> --- a/gcc/cp/pt.c
> +++ b/gcc/cp/pt.c
> @@ -4453,6 +4453,7 @@ reduce_template_parm_level (tree index, tree type, int levels, tree args,
> type);
> TREE_CONSTANT (decl) = TREE_CONSTANT (orig_decl);
> TREE_READONLY (decl) = TREE_READONLY (orig_decl);
> + DECL_VIRTUAL_P (decl) = DECL_VIRTUAL_P (orig_decl);
> DECL_ARTIFICIAL (decl) = 1;
> SET_DECL_TEMPLATE_PARM_P (decl);
>
> diff --git a/gcc/testsuite/g++.dg/concepts/abbrev7.C b/gcc/testsuite/g++.dg/concepts/abbrev7.C
> new file mode 100644
> index 00000000000..443c1b7871b
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/concepts/abbrev7.C
> @@ -0,0 +1,14 @@
> +// PR c++/96106
> +// { dg-do compile { target concepts } }
> +
> +template<typename>
> +struct number {
> + friend void add(auto);
> +};
> +
> +void add(auto) { }
> +
> +void foo() {
> + number<int> n;
> + add(n); // { dg-bogus "ambiguous" }
> +}
>
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