On Thu, 10 Aug 2023, Jason Merrill wrote:
> On 8/10/23 12:09, Patrick Palka wrote:
> > Booststrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
> > trunk and perhaps 13?
> >
> > -- >8 --
> >
> > We shouldn't issue a "declared static but never defined" warning
> > for a deduction guide (declared in an anonymous namespace).
> >
> > PR c++/106604
> >
> > gcc/cp/ChangeLog:
> >
> > * decl.cc (wrapup_namespace_globals): Don't issue a
> > -Wunused-function warning for a deduction guide.
>
> Maybe instead of special casing this here we could set DECL_INITIAL on
> deduction guides so they look defined?
That seems to work, but it requires some tweaks in duplicate_decls to keep
saying "declared" instead of "defined" when diagnosing a deduction guide
redeclaration. I'm not sure which approach is preferable?
-- >8 --
gcc/cp/ChangeLog:
* decl.cc (duplicate_decls): When diagnosing a redeclared
deduction guide, ensure we say "declared" instead of "defined".
(redeclaration_error_message): Move up deduction guide tests.
(grokfndecl): Set DECL_INITIAL to void_node for a deduction
guide.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1z/class-deduction116.C: New test.
---
gcc/cp/decl.cc | 23 +++++++++++--------
.../g++.dg/cpp1z/class-deduction116.C | 5 ++++
2 files changed, 19 insertions(+), 9 deletions(-)
diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 2b3fb313166..70dcff7aa8c 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -2025,7 +2025,9 @@ duplicate_decls (tree newdecl, tree olddecl, bool hiding,
bool was_hidden)
error_at (newdecl_loc, errmsg, newdecl);
if (DECL_NAME (olddecl) != NULL_TREE)
inform (olddecl_loc,
- (DECL_INITIAL (olddecl) && namespace_bindings_p ())
+ (DECL_INITIAL (olddecl)
+ && !deduction_guide_p (olddecl)
+ && namespace_bindings_p ())
? G_("%q#D previously defined here")
: G_("%q#D previously declared here"), olddecl);
return error_mark_node;
@@ -3271,6 +3273,10 @@ redeclaration_error_message (tree newdecl, tree olddecl)
/* We'll complain about linkage mismatches in
warn_extern_redeclared_static. */
+ if (deduction_guide_p (olddecl)
+ && deduction_guide_p (newdecl))
+ return G_("deduction guide %q+D redeclared");
+
/* Defining the same name twice is no good. */
if (decl_defined_p (olddecl)
&& decl_defined_p (newdecl))
@@ -3298,10 +3304,6 @@ 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. */
@@ -3330,6 +3332,10 @@ redeclaration_error_message (tree newdecl, tree olddecl)
if (DECL_TEMPLATE_RESULT (newdecl) == DECL_TEMPLATE_RESULT (olddecl))
return NULL;
+ if (deduction_guide_p (olddecl)
+ && deduction_guide_p (newdecl))
+ return G_("deduction guide %q+D redeclared");
+
nt = DECL_TEMPLATE_RESULT (newdecl);
if (DECL_TEMPLATE_INFO (nt))
nt = DECL_TEMPLATE_RESULT (template_for_substitution (nt));
@@ -3356,10 +3362,6 @@ 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
@@ -10353,6 +10355,9 @@ grokfndecl (tree ctype,
DECL_CXX_DESTRUCTOR_P (decl) = 1;
DECL_NAME (decl) = dtor_identifier;
break;
+ case sfk_deduction_guide:
+ 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 00000000000..00f6d5fef41
--- /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" }
+}
--
2.42.0.rc1
>
> > gcc/testsuite/ChangeLog:
> >
> > * g++.dg/cpp1z/class-deduction116.C: New test.
> > ---
> > gcc/cp/decl.cc | 1 +
> > gcc/testsuite/g++.dg/cpp1z/class-deduction116.C | 8 ++++++++
> > 2 files changed, 9 insertions(+)
> > create mode 100644 gcc/testsuite/g++.dg/cpp1z/class-deduction116.C
> >
> > diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
> > index 792ab330dd0..9fe3a0b98fd 100644
> > --- a/gcc/cp/decl.cc
> > +++ b/gcc/cp/decl.cc
> > @@ -856,6 +856,7 @@ wrapup_namespace_globals ()
> > && !TREE_PUBLIC (decl)
> > && !DECL_ARTIFICIAL (decl)
> > && !DECL_FRIEND_PSEUDO_TEMPLATE_INSTANTIATION (decl)
> > + && !deduction_guide_p (decl)
> > && !warning_suppressed_p (decl, OPT_Wunused_function))
> > warning_at (DECL_SOURCE_LOCATION (decl),
> > OPT_Wunused_function,
> > 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 00000000000..00f6d5fef41
> > --- /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" }
> > +}
>
>
