From f50f603cbfd05653555e9856360c83108bbd1d8a Mon Sep 17 00:00:00 2001
From: Patrick Palka <ppalka@redhat.com>
Date: Fri, 11 Aug 2023 21:13:23 -0400
Subject: [PATCH] c++: bogus warning w/ deduction guide in anon ns [PR106604]
Here we're unintentionally issuing a "declared static but never defined"
warning from wrapup_namespace_globals for a deduction guide declared in
an anonymous namespace. This patch fixes this by giving deduction guides
a dummy DECL_INITIAL, which suppresses the warning and also allows us to
simplify redeclaration checking for them.
Co-authored-by: Jason Merrill <jason@redhat.com>
PR c++/106604
gcc/cp/ChangeLog:
* decl.cc (redeclaration_error_message): Remove special handling
for deduction guides.
(grokfndecl): Give deduction guides a dummy DECL_INITIAL.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1z/class-deduction74.C: Expect "defined" instead
of "declared" in the repeated deduction guide diagnostics.
* g++.dg/cpp1z/class-deduction116.C: New test.
---
gcc/cp/decl.cc | 14 ++++++--------
gcc/testsuite/g++.dg/cpp1z/class-deduction116.C | 8 ++++++++
gcc/testsuite/g++.dg/cpp1z/class-deduction74.C | 14 +++++++-------
3 files changed, 21 insertions(+), 15 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp1z/class-deduction116.C
diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index e21e015d5d8f..126c58180909 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -3297,10 +3297,6 @@ redeclaration_error_message (tree newdecl, tree olddecl)
}
}
- if (deduction_guide_p (olddecl)
- && deduction_guide_p (newdecl))
- return G_("deduction guide %q+D redeclared");
-
/* [class.compare.default]: A definition of a comparison operator as
defaulted that appears in a class shall be the first declaration of
that function. */
@@ -3355,10 +3351,6 @@ redeclaration_error_message (tree newdecl, tree olddecl)
}
}
- if (deduction_guide_p (olddecl)
- && deduction_guide_p (newdecl))
- return G_("deduction guide %q+D redeclared");
-
/* Core issue #226 (C++11):
If a friend function template declaration specifies a
@@ -10352,6 +10344,12 @@ grokfndecl (tree ctype,
DECL_CXX_DESTRUCTOR_P (decl) = 1;
DECL_NAME (decl) = dtor_identifier;
break;
+ case sfk_deduction_guide:
+ /* Give deduction guides a definition even though they don't really
+ have one: the restriction that you can't repeat a deduction guide
+ makes them more like a definition anyway. */
+ DECL_INITIAL (decl) = void_node;
+ break;
default:
break;
}
diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction116.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction116.C
new file mode 100644
index 000000000000..00f6d5fef419
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction116.C
@@ -0,0 +1,8 @@
+// PR c++/106604
+// { dg-do compile { target c++17 } }
+// { dg-additional-options "-Wunused-function" }
+
+namespace {
+ template<class T> struct A { A(...); };
+ A(bool) -> A<bool>; // { dg-bogus "never defined" }
+}
diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction74.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction74.C
index fe113819a956..7bab882da7d9 100644
--- a/gcc/testsuite/g++.dg/cpp1z/class-deduction74.C
+++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction74.C
@@ -7,20 +7,20 @@
template<typename> struct S { };
template<typename> struct X { };
-S() -> S<int>; // { dg-message "previously declared here|old declaration" }
-S() -> S<int>; // { dg-error "redeclared" }
+S() -> S<int>; // { dg-message "previously defined here|old declaration" }
+S() -> S<int>; // { dg-error "redefinition" }
X() -> X<int>;
S() -> S<float>; // { dg-error "ambiguating new declaration of" }
-S(bool) -> S<int>; // { dg-message "previously declared here" }
-explicit S(bool) -> S<int>; // { dg-error "redeclared" }
+S(bool) -> S<int>; // { dg-message "previously defined here" }
+explicit S(bool) -> S<int>; // { dg-error "redefinition" }
-explicit S(char) -> S<int>; // { dg-message "previously declared here" }
-S(char) -> S<int>; // { dg-error "redeclared" }
+explicit S(char) -> S<int>; // { dg-message "previously defined here" }
+S(char) -> S<int>; // { dg-error "redefinition" }
template<typename T> S(T, T) -> S<int>; // { dg-message "previously declared here" }
template<typename T> X(T, T) -> X<int>;
-template<typename T> S(T, T) -> S<int>; // { dg-error "redeclared" }
+template<typename T> S(T, T) -> S<int>; // { dg-error "redefinition" }
// OK: Use SFINAE.
template<typename T> S(T) -> S<typename T::foo>;
--
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