From ca2676654736e6b0bd1ba88edf5694df43718cd9 Mon Sep 17 00:00:00 2001
From: Patrick Palka <ppalka@redhat.com>
Date: Fri, 11 Aug 2023 13:25:58 -0400
Subject: [PATCH] c++: recognize in-class var tmpl partial spec [PR71954]
This makes us recognize member variable template partial specializations
defined directly inside the class body. It seems we mainly just need to
call check_explicit_specialization when we see a static TEMPLATE_ID_EXPR
data member, which sets SET_DECL_TEMPLATE_SPECIALIZATION for us and which
we otherwise don't call (for the out-of-class case we call it from
grokvardecl).
We also need to make finish_member_template_decl return NULL_TREE for
such partial specializations, matching its behavior for class template
partial specializations, so that later we don't try to register it as a
separate member declaration.
PR c++/71954
gcc/cp/ChangeLog:
* decl.cc (grokdeclarator): Pass 'dname' instead of
'unqualified_id' as the name when building the VAR_DECL for a
static data member. Call check_explicit_specialization for a
TEMPLATE_ID_EXPR such member.
* pt.cc (finish_member_template_decl): Return NULL_TREE
instead of 'decl' when DECL_TEMPLATE_SPECIALIZATION is not
set.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1y/var-templ84.C: New test.
* g++.dg/cpp1y/var-templ84a.C: New test.
---
gcc/cp/decl.cc | 11 ++++++++++-
gcc/cp/pt.cc | 2 +-
gcc/testsuite/g++.dg/cpp1y/var-templ84.C | 12 ++++++++++++
gcc/testsuite/g++.dg/cpp1y/var-templ84a.C | 19 +++++++++++++++++++
4 files changed, 42 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp1y/var-templ84.C
create mode 100644 gcc/testsuite/g++.dg/cpp1y/var-templ84a.C
diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 792ab330dd05..e21e015d5d8f 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -14439,7 +14439,16 @@ grokdeclarator (const cp_declarator *declarator,
/* C++ allows static class members. All other work
for this is done by grokfield. */
decl = build_lang_decl_loc (id_loc, VAR_DECL,
- unqualified_id, type);
+ dname, type);
+ if (unqualified_id
+ && TREE_CODE (unqualified_id) == TEMPLATE_ID_EXPR)
+ {
+ decl = check_explicit_specialization (unqualified_id, decl,
+ template_count,
+ concept_p * 8);
+ if (decl == error_mark_node)
+ return error_mark_node;
+ }
set_linkage_for_static_data_member (decl);
if (concept_p)
error_at (declspecs->locations[ds_concept],
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 2706fa619bf8..a4809f034dce 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -314,7 +314,7 @@ finish_member_template_decl (tree decl)
return DECL_TI_TEMPLATE (decl);
}
else
- return decl;
+ return NULL_TREE;
}
else
error_at (DECL_SOURCE_LOCATION (decl),
diff --git a/gcc/testsuite/g++.dg/cpp1y/var-templ84.C b/gcc/testsuite/g++.dg/cpp1y/var-templ84.C
new file mode 100644
index 000000000000..39c2a0dc0cc9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/var-templ84.C
@@ -0,0 +1,12 @@
+// PR c++/71954
+// { dg-do compile { target c++14 } }
+
+struct A {
+ template<class T> static const int var = 0;
+ template<class T> static const int var<T*> = 1;
+ template<class T> static const int var<const T*> = 2;
+};
+
+static_assert(A::var<int> == 0, "");
+static_assert(A::var<int*> == 1, "");
+static_assert(A::var<const int*> == 2, "");
diff --git a/gcc/testsuite/g++.dg/cpp1y/var-templ84a.C b/gcc/testsuite/g++.dg/cpp1y/var-templ84a.C
new file mode 100644
index 000000000000..4aa3a2a7245e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/var-templ84a.C
@@ -0,0 +1,19 @@
+// PR c++/71954
+// A version of var-templ84.C where the partial specializations depend on
+// outer template parameters.
+// { dg-do compile { target c++14 } }
+
+template<class T>
+struct A {
+ template<class U, class V> static const int var = 0;
+ template<class U> static const int var<U*, T> = 1;
+ template<class U> static const int var<const U*, T> = 2;
+};
+
+static_assert(A<int>::var<int, int> == 0, "");
+static_assert(A<int>::var<int*, int> == 1, "");
+static_assert(A<int>::var<const int*, int> == 2, "");
+
+static_assert(A<int>::var<int, char> == 0, "");
+static_assert(A<int>::var<int*, char> == 0, "");
+static_assert(A<int>::var<const int*, char> == 0, "");
--
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