* [PATCH] c++: bogus warning w/ deduction guide in anon ns [PR106604]
@ 2023-08-10 16:09 Patrick Palka
2023-08-10 17:22 ` Jason Merrill
0 siblings, 1 reply; 6+ messages in thread
From: Patrick Palka @ 2023-08-10 16:09 UTC (permalink / raw)
To: gcc-patches; +Cc: jason, Patrick Palka
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.
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" }
+}
--
2.42.0.rc0.25.ga82fb66fed
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] c++: bogus warning w/ deduction guide in anon ns [PR106604]
2023-08-10 16:09 [PATCH] c++: bogus warning w/ deduction guide in anon ns [PR106604] Patrick Palka
@ 2023-08-10 17:22 ` Jason Merrill
2023-08-10 20:40 ` Patrick Palka
0 siblings, 1 reply; 6+ messages in thread
From: Jason Merrill @ 2023-08-10 17:22 UTC (permalink / raw)
To: Patrick Palka, gcc-patches
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?
> 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" }
> +}
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] c++: bogus warning w/ deduction guide in anon ns [PR106604]
2023-08-10 17:22 ` Jason Merrill
@ 2023-08-10 20:40 ` Patrick Palka
2023-08-10 21:11 ` Jason Merrill
0 siblings, 1 reply; 6+ messages in thread
From: Patrick Palka @ 2023-08-10 20:40 UTC (permalink / raw)
To: Jason Merrill; +Cc: Patrick Palka, gcc-patches
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" }
> > +}
>
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] c++: bogus warning w/ deduction guide in anon ns [PR106604]
2023-08-10 20:40 ` Patrick Palka
@ 2023-08-10 21:11 ` Jason Merrill
2023-08-11 13:54 ` Patrick Palka
0 siblings, 1 reply; 6+ messages in thread
From: Jason Merrill @ 2023-08-10 21:11 UTC (permalink / raw)
To: Patrick Palka; +Cc: gcc-patches
On 8/10/23 16:40, Patrick Palka wrote:
> 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?
I'm not sure it matters which we say; the restriction that you can't
repeat a deduction guide makes it more like a definition anyway (even if
[basic.def] disagrees). Is the diagnostic worse apart from that word?
Jason
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] c++: bogus warning w/ deduction guide in anon ns [PR106604]
2023-08-10 21:11 ` Jason Merrill
@ 2023-08-11 13:54 ` Patrick Palka
2023-08-11 14:00 ` Jason Merrill
0 siblings, 1 reply; 6+ messages in thread
From: Patrick Palka @ 2023-08-11 13:54 UTC (permalink / raw)
To: Jason Merrill; +Cc: Patrick Palka, gcc-patches
[-- Attachment #1: Type: text/plain, Size: 6656 bytes --]
On Thu, 10 Aug 2023, Jason Merrill wrote:
> On 8/10/23 16:40, Patrick Palka wrote:
> > 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?
>
> I'm not sure it matters which we say; the restriction that you can't repeat a
> deduction guide makes it more like a definition anyway (even if [basic.def]
> disagrees). Is the diagnostic worse apart from that word?
Ah, makes sense. So we can also remove the special case for them in the
redeclaration checking code after we give them a dummy DECL_INITIAL.
Like so?
Here's a before/after for the diagnostic with the below patch:
Before
src/gcc/testsuite/g++.dg/cpp1z/class-deduction74.C:11:1: error: deduction guide ‘S()-> S<int>’ redeclared
11 | S() -> S<int>; // { dg-error "redefinition" }
| ^
src/gcc/testsuite/g++.dg/cpp1z/class-deduction74.C:10:1: note: ‘S()-> S<int>’ previously declared here
10 | S() -> S<int>; // { dg-message "previously defined here|old declaration" }
| ^
After
src/gcc/testsuite/g++.dg/cpp1z/class-deduction74.C:11:1: error: redefinition of ‘S()-> S<int>’
11 | S() -> S<int>; // { dg-error "redefinition" }
| ^
src/gcc/testsuite/g++.dg/cpp1z/class-deduction74.C:10:1: note: ‘S()-> S<int>’ previously defined here
10 | S() -> S<int>; // { dg-message "previously defined here|old declaration" }
| ^
-- >8 --
Subject: [PATCH] c++: bogus warning w/ deduction guide in anon ns [PR106604]
Here we're unintentionally issuing a "declared static but never defined"
warning 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 diagnostics for a repeated deduction guide.
* 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 792ab330dd0..3ada5516c58 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 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" }
+}
diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction74.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction74.C
index fe113819a95..7bab882da7d 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>;
--
2.42.0.rc1
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] c++: bogus warning w/ deduction guide in anon ns [PR106604]
2023-08-11 13:54 ` Patrick Palka
@ 2023-08-11 14:00 ` Jason Merrill
0 siblings, 0 replies; 6+ messages in thread
From: Jason Merrill @ 2023-08-11 14:00 UTC (permalink / raw)
To: Patrick Palka; +Cc: gcc-patches
On 8/11/23 09:54, Patrick Palka wrote:
> On Thu, 10 Aug 2023, Jason Merrill wrote:
>
>> On 8/10/23 16:40, Patrick Palka wrote:
>>> 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?
>>
>> I'm not sure it matters which we say; the restriction that you can't repeat a
>> deduction guide makes it more like a definition anyway (even if [basic.def]
>> disagrees). Is the diagnostic worse apart from that word?
>
> Ah, makes sense. So we can also remove the special case for them in the
> redeclaration checking code after we give them a dummy DECL_INITIAL.
> Like so?
OK, thanks.
> Here's a before/after for the diagnostic with the below patch:
>
> Before
>
> src/gcc/testsuite/g++.dg/cpp1z/class-deduction74.C:11:1: error: deduction guide ‘S()-> S<int>’ redeclared
> 11 | S() -> S<int>; // { dg-error "redefinition" }
> | ^
> src/gcc/testsuite/g++.dg/cpp1z/class-deduction74.C:10:1: note: ‘S()-> S<int>’ previously declared here
> 10 | S() -> S<int>; // { dg-message "previously defined here|old declaration" }
> | ^
>
> After
>
> src/gcc/testsuite/g++.dg/cpp1z/class-deduction74.C:11:1: error: redefinition of ‘S()-> S<int>’
> 11 | S() -> S<int>; // { dg-error "redefinition" }
> | ^
> src/gcc/testsuite/g++.dg/cpp1z/class-deduction74.C:10:1: note: ‘S()-> S<int>’ previously defined here
> 10 | S() -> S<int>; // { dg-message "previously defined here|old declaration" }
> | ^
>
> -- >8 --
>
> Subject: [PATCH] c++: bogus warning w/ deduction guide in anon ns [PR106604]
>
> Here we're unintentionally issuing a "declared static but never defined"
> warning 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 diagnostics for a repeated deduction guide.
> * 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 792ab330dd0..3ada5516c58 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 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" }
> +}
> diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction74.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction74.C
> index fe113819a95..7bab882da7d 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>;
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2023-08-11 14:00 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-08-10 16:09 [PATCH] c++: bogus warning w/ deduction guide in anon ns [PR106604] Patrick Palka
2023-08-10 17:22 ` Jason Merrill
2023-08-10 20:40 ` Patrick Palka
2023-08-10 21:11 ` Jason Merrill
2023-08-11 13:54 ` Patrick Palka
2023-08-11 14:00 ` Jason Merrill
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