* [PATCH] c++: C++20 DR 2237, disallow simple-template-id in cdtor.
@ 2020-04-04 23:30 Marek Polacek
2020-04-06 1:46 ` Jason Merrill
0 siblings, 1 reply; 5+ messages in thread
From: Marek Polacek @ 2020-04-04 23:30 UTC (permalink / raw)
To: Jason Merrill, GCC Patches
This patch implements DR 2237 which says that a simple-template-id is
no longer valid as the declarator-id of a constructor or destructor;
see <https://eel.is/c++draft/diff.cpp17.class#2>. It is not explicitly
stated but out-of-line destructors with a simple-template-id are also
meant to be ill-formed now. (Out-of-line constructors like that are
invalid since DR1435 I think.) This change only applies to C++20; it
is not a DR against C++17.
I'm not crazy about the diagnostic in constructors but ISTM that
cp_parser_constructor_declarator_p shouldn't print errors.
Does it seem reasonable to apply this now or should I defer to GCC 11?
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
2020-04-04 Marek Polacek <polacek@redhat.com>
DR 2237
* parser.c (cp_parser_unqualified_id): Reject simple-template-id as
the declarator-id of a destructor.
(cp_parser_constructor_declarator_p): Reject simple-template-id as
the declarator-id of a constructor.
* g++.dg/DRs/dr2237.C: New test.
* g++.dg/parse/constructor2.C: Add dg-error for C++20.
* g++.dg/parse/dtor12.C: Likewise.
* g++.dg/parse/dtor4.C: Likewise.
* g++.dg/template/dtor4.C: Adjust dg-error.
* g++.dg/template/error34.C: Likewise.
* g++.old-deja/g++.other/inline15.C: Only run for C++17 and lesses.
* g++.old-deja/g++.pt/ctor2.C: Add dg-error for C++20.
---
gcc/cp/parser.c | 16 ++++++++++++++++
gcc/testsuite/g++.dg/DRs/dr2237.C | 18 ++++++++++++++++++
gcc/testsuite/g++.dg/parse/constructor2.C | 4 ++--
gcc/testsuite/g++.dg/parse/dtor12.C | 2 +-
gcc/testsuite/g++.dg/parse/dtor4.C | 2 +-
gcc/testsuite/g++.dg/template/dtor4.C | 2 +-
gcc/testsuite/g++.dg/template/error34.C | 10 +++++-----
.../g++.old-deja/g++.other/inline15.C | 2 +-
gcc/testsuite/g++.old-deja/g++.pt/ctor2.C | 2 +-
9 files changed, 46 insertions(+), 12 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/DRs/dr2237.C
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 7e5921e039f..810edfa87a9 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -6114,6 +6114,16 @@ cp_parser_unqualified_id (cp_parser* parser,
return build_min_nt_loc (loc, BIT_NOT_EXPR, make_auto ());
}
+ /* DR 2237 (C++20 only): A simple-template-id is no longer valid as the
+ declarator-id of a constructor or destructor. */
+ if (token->type == CPP_TEMPLATE_ID && cxx_dialect >= cxx2a)
+ {
+ if (!cp_parser_uncommitted_to_tentative_parse_p (parser))
+ error_at (tilde_loc, "template-id not allowed for destructor");
+ cp_parser_simulate_error (parser);
+ return error_mark_node;
+ }
+
/* If there was an explicit qualification (S::~T), first look
in the scope given by the qualification (i.e., S).
@@ -28675,6 +28685,12 @@ cp_parser_constructor_declarator_p (cp_parser *parser, cp_parser_flags flags,
if (!constructor_name_p (id, nested_name_specifier))
constructor_p = false;
}
+ /* DR 2237 (C++20 only): A simple-template-id is no longer valid as the
+ declarator-id of a constructor or destructor. */
+ else if (constructor_p
+ && cxx_dialect >= cxx2a
+ && cp_lexer_next_token_is (parser->lexer, CPP_TEMPLATE_ID))
+ constructor_p = false;
/* If we still think that this might be a constructor-declarator,
look for a class-name. */
else if (constructor_p)
diff --git a/gcc/testsuite/g++.dg/DRs/dr2237.C b/gcc/testsuite/g++.dg/DRs/dr2237.C
new file mode 100644
index 00000000000..17abdf179c1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/DRs/dr2237.C
@@ -0,0 +1,18 @@
+// DR 2237 - Can a template-id name a constructor?
+
+template<class T>
+struct X {
+ X<T>(); // { dg-error "expected" "" { target c++2a } }
+ X(int); // OK, injected-class-name used
+ ~X<T>(); // { dg-error "template-id not allowed for destructor" "" { target c++2a } }
+};
+
+// ill-formed since DR1435
+template<typename T> X<T>::X<T>() {} // { dg-error "names the constructor|as no template constructors" }
+template<typename T> X<T>::~X<T>() {} // { dg-error "template-id not allowed for destructor" "" { target c++2a } }
+
+struct Q {
+ // ill-formed since DR1435
+ template<typename T> friend X<T>::X<T>(); // { dg-error "names the constructor|as no template constructors" }
+ template<typename T> friend X<T>::~X<T>(); // { dg-error "template-id not allowed for destructor" "" { target c++2a } }
+};
diff --git a/gcc/testsuite/g++.dg/parse/constructor2.C b/gcc/testsuite/g++.dg/parse/constructor2.C
index e514e9397e9..87007e9c715 100644
--- a/gcc/testsuite/g++.dg/parse/constructor2.C
+++ b/gcc/testsuite/g++.dg/parse/constructor2.C
@@ -5,7 +5,7 @@ class T
{
public:
T(short,short f=0) {}
- T<TClass>(int f) {}
- T<TClass>(int f=0,const char* b=0) {}
+ T<TClass>(int f) {} // { dg-error "expected" "" { target c++2a } }
+ T<TClass>(int f=0,const char* b=0) {} // { dg-error "expected" "" { target c++2a } }
};
diff --git a/gcc/testsuite/g++.dg/parse/dtor12.C b/gcc/testsuite/g++.dg/parse/dtor12.C
index 1acdfa36b69..d758d3e861d 100644
--- a/gcc/testsuite/g++.dg/parse/dtor12.C
+++ b/gcc/testsuite/g++.dg/parse/dtor12.C
@@ -2,5 +2,5 @@
template <class T> class a
{
- ~a<T>();
+ ~a<T>(); // { dg-error "template-id not allowed for destructor" "" { target c++2a } }
};
diff --git a/gcc/testsuite/g++.dg/parse/dtor4.C b/gcc/testsuite/g++.dg/parse/dtor4.C
index 729ee2fa130..1059c189eff 100644
--- a/gcc/testsuite/g++.dg/parse/dtor4.C
+++ b/gcc/testsuite/g++.dg/parse/dtor4.C
@@ -7,4 +7,4 @@ template <int N> struct X {
};
template <int N>
-X<N>::~X<N>(){}
+X<N>::~X<N>(){} // { dg-error "template-id not allowed for destructor" "" { target c++2a } }
diff --git a/gcc/testsuite/g++.dg/template/dtor4.C b/gcc/testsuite/g++.dg/template/dtor4.C
index 4f277b248bd..917681fc13e 100644
--- a/gcc/testsuite/g++.dg/template/dtor4.C
+++ b/gcc/testsuite/g++.dg/template/dtor4.C
@@ -5,5 +5,5 @@
template<int> struct A
{
- ~A<0>(); // { dg-error "parse error|declaration" }
+ ~A<0>(); // { dg-error "parse error|declaration|template-id" }
};
diff --git a/gcc/testsuite/g++.dg/template/error34.C b/gcc/testsuite/g++.dg/template/error34.C
index d0cbcaef28e..ab688d9ba8c 100644
--- a/gcc/testsuite/g++.dg/template/error34.C
+++ b/gcc/testsuite/g++.dg/template/error34.C
@@ -3,27 +3,27 @@
template<typename T> struct A
{
- A<__builtin_offsetof(T, x)>(); // { dg-error "type/value mismatch|offsetof\\(T, x\\)" }
+ A<__builtin_offsetof(T, x)>(); // { dg-error "type/value mismatch|offsetof\\(T, x\\)|expected" }
};
template<typename T> struct B
{
- B<__builtin_offsetof(T, x.y)>(); // { dg-error "type/value mismatch|offsetof\\(T, x.y\\)" }
+ B<__builtin_offsetof(T, x.y)>(); // { dg-error "type/value mismatch|offsetof\\(T, x.y\\)|expected" }
};
template<typename T> struct C
{
- C<__builtin_offsetof(T, x[6])>(); // { dg-error "type/value mismatch|offsetof\\(T, x\\\[6\\\]\\)" }
+ C<__builtin_offsetof(T, x[6])>(); // { dg-error "type/value mismatch|offsetof\\(T, x\\\[6\\\]\\)|expected" }
};
template<typename T> struct D
{
- D<__builtin_offsetof(T, x.y[6].z)>(); // { dg-error "type/value mismatch|offsetof\\(T, x.y\\\[6\\\].z\\)" }
+ D<__builtin_offsetof(T, x.y[6].z)>(); // { dg-error "type/value mismatch|offsetof\\(T, x.y\\\[6\\\].z\\)|expected" }
};
struct E { int x; };
template<typename T> struct F
{
- F<__builtin_offsetof(E, x)>(); // { dg-error "type/value mismatch|offsetof\\(E, x\\)" }
+ F<__builtin_offsetof(E, x)>(); // { dg-error "type/value mismatch|offsetof\\(E, x\\)|expected" }
};
diff --git a/gcc/testsuite/g++.old-deja/g++.other/inline15.C b/gcc/testsuite/g++.old-deja/g++.other/inline15.C
index 43f7f5e3025..a31c60960a5 100644
--- a/gcc/testsuite/g++.old-deja/g++.other/inline15.C
+++ b/gcc/testsuite/g++.old-deja/g++.other/inline15.C
@@ -1,4 +1,4 @@
-// { dg-do assemble }
+// { dg-do assemble { target c++17_down } }
// { dg-options "-O1" }
// Origin: Jakub Jelinek <jakub@redhat.com>
diff --git a/gcc/testsuite/g++.old-deja/g++.pt/ctor2.C b/gcc/testsuite/g++.old-deja/g++.pt/ctor2.C
index a8be91ddbb9..4159c84ff56 100644
--- a/gcc/testsuite/g++.old-deja/g++.pt/ctor2.C
+++ b/gcc/testsuite/g++.old-deja/g++.pt/ctor2.C
@@ -4,7 +4,7 @@
template <class T>
struct A {
- A<T>();
+ A<T>(); // { dg-error "expected" "" { target c++2a } }
};
template <class T>
base-commit: 49a86fce1a879a206fb4b27f097910005d968fda
--
Marek Polacek • Red Hat, Inc. • 300 A St, Boston, MA
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] c++: C++20 DR 2237, disallow simple-template-id in cdtor.
2020-04-04 23:30 [PATCH] c++: C++20 DR 2237, disallow simple-template-id in cdtor Marek Polacek
@ 2020-04-06 1:46 ` Jason Merrill
2020-05-11 20:23 ` Marek Polacek
0 siblings, 1 reply; 5+ messages in thread
From: Jason Merrill @ 2020-04-06 1:46 UTC (permalink / raw)
To: Marek Polacek, GCC Patches
On 4/4/20 7:30 PM, Marek Polacek wrote:
> This patch implements DR 2237 which says that a simple-template-id is
> no longer valid as the declarator-id of a constructor or destructor;
> see <https://eel.is/c++draft/diff.cpp17.class#2>. It is not explicitly
> stated but out-of-line destructors with a simple-template-id are also
> meant to be ill-formed now. (Out-of-line constructors like that are
> invalid since DR1435 I think.) This change only applies to C++20; it
> is not a DR against C++17.
>
> I'm not crazy about the diagnostic in constructors but ISTM that
> cp_parser_constructor_declarator_p shouldn't print errors.
>
> Does it seem reasonable to apply this now or should I defer to GCC 11?
A new error should wait for GCC 11.
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
>
> 2020-04-04 Marek Polacek <polacek@redhat.com>
>
> DR 2237
> * parser.c (cp_parser_unqualified_id): Reject simple-template-id as
> the declarator-id of a destructor.
> (cp_parser_constructor_declarator_p): Reject simple-template-id as
> the declarator-id of a constructor.
>
> * g++.dg/DRs/dr2237.C: New test.
> * g++.dg/parse/constructor2.C: Add dg-error for C++20.
> * g++.dg/parse/dtor12.C: Likewise.
> * g++.dg/parse/dtor4.C: Likewise.
> * g++.dg/template/dtor4.C: Adjust dg-error.
> * g++.dg/template/error34.C: Likewise.
> * g++.old-deja/g++.other/inline15.C: Only run for C++17 and lesses.
> * g++.old-deja/g++.pt/ctor2.C: Add dg-error for C++20.
> ---
> gcc/cp/parser.c | 16 ++++++++++++++++
> gcc/testsuite/g++.dg/DRs/dr2237.C | 18 ++++++++++++++++++
> gcc/testsuite/g++.dg/parse/constructor2.C | 4 ++--
> gcc/testsuite/g++.dg/parse/dtor12.C | 2 +-
> gcc/testsuite/g++.dg/parse/dtor4.C | 2 +-
> gcc/testsuite/g++.dg/template/dtor4.C | 2 +-
> gcc/testsuite/g++.dg/template/error34.C | 10 +++++-----
> .../g++.old-deja/g++.other/inline15.C | 2 +-
> gcc/testsuite/g++.old-deja/g++.pt/ctor2.C | 2 +-
> 9 files changed, 46 insertions(+), 12 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/DRs/dr2237.C
>
> diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
> index 7e5921e039f..810edfa87a9 100644
> --- a/gcc/cp/parser.c
> +++ b/gcc/cp/parser.c
> @@ -6114,6 +6114,16 @@ cp_parser_unqualified_id (cp_parser* parser,
> return build_min_nt_loc (loc, BIT_NOT_EXPR, make_auto ());
> }
>
> + /* DR 2237 (C++20 only): A simple-template-id is no longer valid as the
> + declarator-id of a constructor or destructor. */
> + if (token->type == CPP_TEMPLATE_ID && cxx_dialect >= cxx2a)
> + {
> + if (!cp_parser_uncommitted_to_tentative_parse_p (parser))
> + error_at (tilde_loc, "template-id not allowed for destructor");
> + cp_parser_simulate_error (parser);
The usual pattern is
if (!cp_parser_simulate_error (parser))
error...
> + return error_mark_node;
> + }
> +
> /* If there was an explicit qualification (S::~T), first look
> in the scope given by the qualification (i.e., S).
>
> @@ -28675,6 +28685,12 @@ cp_parser_constructor_declarator_p (cp_parser *parser, cp_parser_flags flags,
> if (!constructor_name_p (id, nested_name_specifier))
> constructor_p = false;
> }
> + /* DR 2237 (C++20 only): A simple-template-id is no longer valid as the
> + declarator-id of a constructor or destructor. */
> + else if (constructor_p
> + && cxx_dialect >= cxx2a
> + && cp_lexer_next_token_is (parser->lexer, CPP_TEMPLATE_ID))
> + constructor_p = false;
> /* If we still think that this might be a constructor-declarator,
> look for a class-name. */
> else if (constructor_p)
Do you also want to exclude CPP_TEMPLATE_ID from the test at the top of
the function for C++20?
> if (next_token->type != CPP_NAME
> && next_token->type != CPP_SCOPE
> && next_token->type != CPP_NESTED_NAME_SPECIFIER
> && next_token->type != CPP_TEMPLATE_ID)
> return false;
Jason
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] c++: C++20 DR 2237, disallow simple-template-id in cdtor.
2020-04-06 1:46 ` Jason Merrill
@ 2020-05-11 20:23 ` Marek Polacek
2020-05-20 18:05 ` Marek Polacek
0 siblings, 1 reply; 5+ messages in thread
From: Marek Polacek @ 2020-05-11 20:23 UTC (permalink / raw)
To: Jason Merrill; +Cc: GCC Patches
On Sun, Apr 05, 2020 at 09:46:09PM -0400, Jason Merrill wrote:
> On 4/4/20 7:30 PM, Marek Polacek wrote:
> > This patch implements DR 2237 which says that a simple-template-id is
> > no longer valid as the declarator-id of a constructor or destructor;
> > see <https://eel.is/c++draft/diff.cpp17.class#2>. It is not explicitly
> > stated but out-of-line destructors with a simple-template-id are also
> > meant to be ill-formed now. (Out-of-line constructors like that are
> > invalid since DR1435 I think.) This change only applies to C++20; it
> > is not a DR against C++17.
> >
> > I'm not crazy about the diagnostic in constructors but ISTM that
> > cp_parser_constructor_declarator_p shouldn't print errors.
> >
> > Does it seem reasonable to apply this now or should I defer to GCC 11?
>
> A new error should wait for GCC 11.
Coming back to this now that we're again in stage 1.
> > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> >
> > 2020-04-04 Marek Polacek <polacek@redhat.com>
> >
> > DR 2237
> > * parser.c (cp_parser_unqualified_id): Reject simple-template-id as
> > the declarator-id of a destructor.
> > (cp_parser_constructor_declarator_p): Reject simple-template-id as
> > the declarator-id of a constructor.
> >
> > * g++.dg/DRs/dr2237.C: New test.
> > * g++.dg/parse/constructor2.C: Add dg-error for C++20.
> > * g++.dg/parse/dtor12.C: Likewise.
> > * g++.dg/parse/dtor4.C: Likewise.
> > * g++.dg/template/dtor4.C: Adjust dg-error.
> > * g++.dg/template/error34.C: Likewise.
> > * g++.old-deja/g++.other/inline15.C: Only run for C++17 and lesses.
> > * g++.old-deja/g++.pt/ctor2.C: Add dg-error for C++20.
> > ---
> > gcc/cp/parser.c | 16 ++++++++++++++++
> > gcc/testsuite/g++.dg/DRs/dr2237.C | 18 ++++++++++++++++++
> > gcc/testsuite/g++.dg/parse/constructor2.C | 4 ++--
> > gcc/testsuite/g++.dg/parse/dtor12.C | 2 +-
> > gcc/testsuite/g++.dg/parse/dtor4.C | 2 +-
> > gcc/testsuite/g++.dg/template/dtor4.C | 2 +-
> > gcc/testsuite/g++.dg/template/error34.C | 10 +++++-----
> > .../g++.old-deja/g++.other/inline15.C | 2 +-
> > gcc/testsuite/g++.old-deja/g++.pt/ctor2.C | 2 +-
> > 9 files changed, 46 insertions(+), 12 deletions(-)
> > create mode 100644 gcc/testsuite/g++.dg/DRs/dr2237.C
> >
> > diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
> > index 7e5921e039f..810edfa87a9 100644
> > --- a/gcc/cp/parser.c
> > +++ b/gcc/cp/parser.c
> > @@ -6114,6 +6114,16 @@ cp_parser_unqualified_id (cp_parser* parser,
> > return build_min_nt_loc (loc, BIT_NOT_EXPR, make_auto ());
> > }
> > + /* DR 2237 (C++20 only): A simple-template-id is no longer valid as the
> > + declarator-id of a constructor or destructor. */
> > + if (token->type == CPP_TEMPLATE_ID && cxx_dialect >= cxx2a)
> > + {
> > + if (!cp_parser_uncommitted_to_tentative_parse_p (parser))
> > + error_at (tilde_loc, "template-id not allowed for destructor");
> > + cp_parser_simulate_error (parser);
>
> The usual pattern is
>
> if (!cp_parser_simulate_error (parser))
> error...
Fixed.
> > + return error_mark_node;
> > + }
> > +
> > /* If there was an explicit qualification (S::~T), first look
> > in the scope given by the qualification (i.e., S).
> > @@ -28675,6 +28685,12 @@ cp_parser_constructor_declarator_p (cp_parser *parser, cp_parser_flags flags,
> > if (!constructor_name_p (id, nested_name_specifier))
> > constructor_p = false;
> > }
> > + /* DR 2237 (C++20 only): A simple-template-id is no longer valid as the
> > + declarator-id of a constructor or destructor. */
> > + else if (constructor_p
> > + && cxx_dialect >= cxx2a
> > + && cp_lexer_next_token_is (parser->lexer, CPP_TEMPLATE_ID))
> > + constructor_p = false;
> > /* If we still think that this might be a constructor-declarator,
> > look for a class-name. */
> > else if (constructor_p)
>
> Do you also want to exclude CPP_TEMPLATE_ID from the test at the top of the
> function for C++20?
In fact we can get away with only excluding CPP_TEMPLATE_ID in C++20 there,
because for e.g. X<T>::X<T>(); we'll give the "names the constructor, not the
type" error, so we won't even get here.
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
-- >8 --
This patch implements DR 2237 which says that a simple-template-id is
no longer valid as the declarator-id of a constructor or destructor;
see [diff.cpp17.class]#2. It is not explicitly stated but out-of-line
destructors with a simple-template-id are also meant to be ill-formed
now. (Out-of-line constructors like that are invalid since DR1435 I
think.) This change only applies to C++20; it is not a DR against C++17.
I'm not crazy about the diagnostic in constructors but ISTM that
cp_parser_constructor_declarator_p shouldn't print errors.
DR 2237
* parser.c (cp_parser_unqualified_id): Reject simple-template-id as
the declarator-id of a destructor.
(cp_parser_constructor_declarator_p): Reject simple-template-id as
the declarator-id of a constructor.
* g++.dg/DRs/dr2237.C: New test.
* g++.dg/parse/constructor2.C: Add dg-error for C++20.
* g++.dg/parse/dtor12.C: Likewise.
* g++.dg/parse/dtor4.C: Likewise.
* g++.dg/template/dtor4.C: Adjust dg-error.
* g++.dg/template/error34.C: Likewise.
* g++.old-deja/g++.other/inline15.C: Only run for C++17 and lesses.
* g++.old-deja/g++.pt/ctor2.C: Add dg-error for C++20.
---
gcc/cp/parser.c | 13 ++++++++++++-
gcc/testsuite/g++.dg/DRs/dr2237.C | 18 ++++++++++++++++++
gcc/testsuite/g++.dg/parse/constructor2.C | 4 ++--
gcc/testsuite/g++.dg/parse/dtor12.C | 2 +-
gcc/testsuite/g++.dg/parse/dtor4.C | 2 +-
gcc/testsuite/g++.dg/template/dtor4.C | 2 +-
gcc/testsuite/g++.dg/template/error34.C | 10 +++++-----
.../g++.old-deja/g++.other/inline15.C | 2 +-
gcc/testsuite/g++.old-deja/g++.pt/ctor2.C | 2 +-
9 files changed, 42 insertions(+), 13 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/DRs/dr2237.C
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 591f44f4934..593c45b5888 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -6114,6 +6114,15 @@ cp_parser_unqualified_id (cp_parser* parser,
return build_min_nt_loc (loc, BIT_NOT_EXPR, make_auto ());
}
+ /* DR 2237 (C++20 only): A simple-template-id is no longer valid as the
+ declarator-id of a constructor or destructor. */
+ if (token->type == CPP_TEMPLATE_ID && cxx_dialect >= cxx2a)
+ {
+ if (!cp_parser_simulate_error (parser))
+ error_at (tilde_loc, "template-id not allowed for destructor");
+ return error_mark_node;
+ }
+
/* If there was an explicit qualification (S::~T), first look
in the scope given by the qualification (i.e., S).
@@ -28636,7 +28645,9 @@ cp_parser_constructor_declarator_p (cp_parser *parser, cp_parser_flags flags,
if (next_token->type != CPP_NAME
&& next_token->type != CPP_SCOPE
&& next_token->type != CPP_NESTED_NAME_SPECIFIER
- && next_token->type != CPP_TEMPLATE_ID)
+ /* DR 2237 (C++20 only): A simple-template-id is no longer valid as the
+ declarator-id of a constructor or destructor. */
+ && (next_token->type != CPP_TEMPLATE_ID || cxx_dialect >= cxx2a))
return false;
/* Parse tentatively; we are going to roll back all of the tokens
diff --git a/gcc/testsuite/g++.dg/DRs/dr2237.C b/gcc/testsuite/g++.dg/DRs/dr2237.C
new file mode 100644
index 00000000000..17abdf179c1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/DRs/dr2237.C
@@ -0,0 +1,18 @@
+// DR 2237 - Can a template-id name a constructor?
+
+template<class T>
+struct X {
+ X<T>(); // { dg-error "expected" "" { target c++2a } }
+ X(int); // OK, injected-class-name used
+ ~X<T>(); // { dg-error "template-id not allowed for destructor" "" { target c++2a } }
+};
+
+// ill-formed since DR1435
+template<typename T> X<T>::X<T>() {} // { dg-error "names the constructor|as no template constructors" }
+template<typename T> X<T>::~X<T>() {} // { dg-error "template-id not allowed for destructor" "" { target c++2a } }
+
+struct Q {
+ // ill-formed since DR1435
+ template<typename T> friend X<T>::X<T>(); // { dg-error "names the constructor|as no template constructors" }
+ template<typename T> friend X<T>::~X<T>(); // { dg-error "template-id not allowed for destructor" "" { target c++2a } }
+};
diff --git a/gcc/testsuite/g++.dg/parse/constructor2.C b/gcc/testsuite/g++.dg/parse/constructor2.C
index e514e9397e9..87007e9c715 100644
--- a/gcc/testsuite/g++.dg/parse/constructor2.C
+++ b/gcc/testsuite/g++.dg/parse/constructor2.C
@@ -5,7 +5,7 @@ class T
{
public:
T(short,short f=0) {}
- T<TClass>(int f) {}
- T<TClass>(int f=0,const char* b=0) {}
+ T<TClass>(int f) {} // { dg-error "expected" "" { target c++2a } }
+ T<TClass>(int f=0,const char* b=0) {} // { dg-error "expected" "" { target c++2a } }
};
diff --git a/gcc/testsuite/g++.dg/parse/dtor12.C b/gcc/testsuite/g++.dg/parse/dtor12.C
index 1acdfa36b69..d758d3e861d 100644
--- a/gcc/testsuite/g++.dg/parse/dtor12.C
+++ b/gcc/testsuite/g++.dg/parse/dtor12.C
@@ -2,5 +2,5 @@
template <class T> class a
{
- ~a<T>();
+ ~a<T>(); // { dg-error "template-id not allowed for destructor" "" { target c++2a } }
};
diff --git a/gcc/testsuite/g++.dg/parse/dtor4.C b/gcc/testsuite/g++.dg/parse/dtor4.C
index 729ee2fa130..1059c189eff 100644
--- a/gcc/testsuite/g++.dg/parse/dtor4.C
+++ b/gcc/testsuite/g++.dg/parse/dtor4.C
@@ -7,4 +7,4 @@ template <int N> struct X {
};
template <int N>
-X<N>::~X<N>(){}
+X<N>::~X<N>(){} // { dg-error "template-id not allowed for destructor" "" { target c++2a } }
diff --git a/gcc/testsuite/g++.dg/template/dtor4.C b/gcc/testsuite/g++.dg/template/dtor4.C
index 4f277b248bd..917681fc13e 100644
--- a/gcc/testsuite/g++.dg/template/dtor4.C
+++ b/gcc/testsuite/g++.dg/template/dtor4.C
@@ -5,5 +5,5 @@
template<int> struct A
{
- ~A<0>(); // { dg-error "parse error|declaration" }
+ ~A<0>(); // { dg-error "parse error|declaration|template-id" }
};
diff --git a/gcc/testsuite/g++.dg/template/error34.C b/gcc/testsuite/g++.dg/template/error34.C
index d0cbcaef28e..ab688d9ba8c 100644
--- a/gcc/testsuite/g++.dg/template/error34.C
+++ b/gcc/testsuite/g++.dg/template/error34.C
@@ -3,27 +3,27 @@
template<typename T> struct A
{
- A<__builtin_offsetof(T, x)>(); // { dg-error "type/value mismatch|offsetof\\(T, x\\)" }
+ A<__builtin_offsetof(T, x)>(); // { dg-error "type/value mismatch|offsetof\\(T, x\\)|expected" }
};
template<typename T> struct B
{
- B<__builtin_offsetof(T, x.y)>(); // { dg-error "type/value mismatch|offsetof\\(T, x.y\\)" }
+ B<__builtin_offsetof(T, x.y)>(); // { dg-error "type/value mismatch|offsetof\\(T, x.y\\)|expected" }
};
template<typename T> struct C
{
- C<__builtin_offsetof(T, x[6])>(); // { dg-error "type/value mismatch|offsetof\\(T, x\\\[6\\\]\\)" }
+ C<__builtin_offsetof(T, x[6])>(); // { dg-error "type/value mismatch|offsetof\\(T, x\\\[6\\\]\\)|expected" }
};
template<typename T> struct D
{
- D<__builtin_offsetof(T, x.y[6].z)>(); // { dg-error "type/value mismatch|offsetof\\(T, x.y\\\[6\\\].z\\)" }
+ D<__builtin_offsetof(T, x.y[6].z)>(); // { dg-error "type/value mismatch|offsetof\\(T, x.y\\\[6\\\].z\\)|expected" }
};
struct E { int x; };
template<typename T> struct F
{
- F<__builtin_offsetof(E, x)>(); // { dg-error "type/value mismatch|offsetof\\(E, x\\)" }
+ F<__builtin_offsetof(E, x)>(); // { dg-error "type/value mismatch|offsetof\\(E, x\\)|expected" }
};
diff --git a/gcc/testsuite/g++.old-deja/g++.other/inline15.C b/gcc/testsuite/g++.old-deja/g++.other/inline15.C
index 43f7f5e3025..a31c60960a5 100644
--- a/gcc/testsuite/g++.old-deja/g++.other/inline15.C
+++ b/gcc/testsuite/g++.old-deja/g++.other/inline15.C
@@ -1,4 +1,4 @@
-// { dg-do assemble }
+// { dg-do assemble { target c++17_down } }
// { dg-options "-O1" }
// Origin: Jakub Jelinek <jakub@redhat.com>
diff --git a/gcc/testsuite/g++.old-deja/g++.pt/ctor2.C b/gcc/testsuite/g++.old-deja/g++.pt/ctor2.C
index a8be91ddbb9..4159c84ff56 100644
--- a/gcc/testsuite/g++.old-deja/g++.pt/ctor2.C
+++ b/gcc/testsuite/g++.old-deja/g++.pt/ctor2.C
@@ -4,7 +4,7 @@
template <class T>
struct A {
- A<T>();
+ A<T>(); // { dg-error "expected" "" { target c++2a } }
};
template <class T>
base-commit: 2b2d298ff845ab7a07ffbd51da79473736da3324
--
Marek Polacek • Red Hat, Inc. • 300 A St, Boston, MA
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] c++: C++20 DR 2237, disallow simple-template-id in cdtor.
2020-05-11 20:23 ` Marek Polacek
@ 2020-05-20 18:05 ` Marek Polacek
2020-05-20 20:45 ` Jason Merrill
0 siblings, 1 reply; 5+ messages in thread
From: Marek Polacek @ 2020-05-20 18:05 UTC (permalink / raw)
To: Jason Merrill, GCC Patches
Ping.
On Mon, May 11, 2020 at 04:23:17PM -0400, Marek Polacek via Gcc-patches wrote:
> On Sun, Apr 05, 2020 at 09:46:09PM -0400, Jason Merrill wrote:
> > On 4/4/20 7:30 PM, Marek Polacek wrote:
> > > This patch implements DR 2237 which says that a simple-template-id is
> > > no longer valid as the declarator-id of a constructor or destructor;
> > > see <https://eel.is/c++draft/diff.cpp17.class#2>. It is not explicitly
> > > stated but out-of-line destructors with a simple-template-id are also
> > > meant to be ill-formed now. (Out-of-line constructors like that are
> > > invalid since DR1435 I think.) This change only applies to C++20; it
> > > is not a DR against C++17.
> > >
> > > I'm not crazy about the diagnostic in constructors but ISTM that
> > > cp_parser_constructor_declarator_p shouldn't print errors.
> > >
> > > Does it seem reasonable to apply this now or should I defer to GCC 11?
> >
> > A new error should wait for GCC 11.
>
> Coming back to this now that we're again in stage 1.
>
> > > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> > >
> > > 2020-04-04 Marek Polacek <polacek@redhat.com>
> > >
> > > DR 2237
> > > * parser.c (cp_parser_unqualified_id): Reject simple-template-id as
> > > the declarator-id of a destructor.
> > > (cp_parser_constructor_declarator_p): Reject simple-template-id as
> > > the declarator-id of a constructor.
> > >
> > > * g++.dg/DRs/dr2237.C: New test.
> > > * g++.dg/parse/constructor2.C: Add dg-error for C++20.
> > > * g++.dg/parse/dtor12.C: Likewise.
> > > * g++.dg/parse/dtor4.C: Likewise.
> > > * g++.dg/template/dtor4.C: Adjust dg-error.
> > > * g++.dg/template/error34.C: Likewise.
> > > * g++.old-deja/g++.other/inline15.C: Only run for C++17 and lesses.
> > > * g++.old-deja/g++.pt/ctor2.C: Add dg-error for C++20.
> > > ---
> > > gcc/cp/parser.c | 16 ++++++++++++++++
> > > gcc/testsuite/g++.dg/DRs/dr2237.C | 18 ++++++++++++++++++
> > > gcc/testsuite/g++.dg/parse/constructor2.C | 4 ++--
> > > gcc/testsuite/g++.dg/parse/dtor12.C | 2 +-
> > > gcc/testsuite/g++.dg/parse/dtor4.C | 2 +-
> > > gcc/testsuite/g++.dg/template/dtor4.C | 2 +-
> > > gcc/testsuite/g++.dg/template/error34.C | 10 +++++-----
> > > .../g++.old-deja/g++.other/inline15.C | 2 +-
> > > gcc/testsuite/g++.old-deja/g++.pt/ctor2.C | 2 +-
> > > 9 files changed, 46 insertions(+), 12 deletions(-)
> > > create mode 100644 gcc/testsuite/g++.dg/DRs/dr2237.C
> > >
> > > diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
> > > index 7e5921e039f..810edfa87a9 100644
> > > --- a/gcc/cp/parser.c
> > > +++ b/gcc/cp/parser.c
> > > @@ -6114,6 +6114,16 @@ cp_parser_unqualified_id (cp_parser* parser,
> > > return build_min_nt_loc (loc, BIT_NOT_EXPR, make_auto ());
> > > }
> > > + /* DR 2237 (C++20 only): A simple-template-id is no longer valid as the
> > > + declarator-id of a constructor or destructor. */
> > > + if (token->type == CPP_TEMPLATE_ID && cxx_dialect >= cxx2a)
> > > + {
> > > + if (!cp_parser_uncommitted_to_tentative_parse_p (parser))
> > > + error_at (tilde_loc, "template-id not allowed for destructor");
> > > + cp_parser_simulate_error (parser);
> >
> > The usual pattern is
> >
> > if (!cp_parser_simulate_error (parser))
> > error...
>
> Fixed.
>
> > > + return error_mark_node;
> > > + }
> > > +
> > > /* If there was an explicit qualification (S::~T), first look
> > > in the scope given by the qualification (i.e., S).
> > > @@ -28675,6 +28685,12 @@ cp_parser_constructor_declarator_p (cp_parser *parser, cp_parser_flags flags,
> > > if (!constructor_name_p (id, nested_name_specifier))
> > > constructor_p = false;
> > > }
> > > + /* DR 2237 (C++20 only): A simple-template-id is no longer valid as the
> > > + declarator-id of a constructor or destructor. */
> > > + else if (constructor_p
> > > + && cxx_dialect >= cxx2a
> > > + && cp_lexer_next_token_is (parser->lexer, CPP_TEMPLATE_ID))
> > > + constructor_p = false;
> > > /* If we still think that this might be a constructor-declarator,
> > > look for a class-name. */
> > > else if (constructor_p)
> >
> > Do you also want to exclude CPP_TEMPLATE_ID from the test at the top of the
> > function for C++20?
>
> In fact we can get away with only excluding CPP_TEMPLATE_ID in C++20 there,
> because for e.g. X<T>::X<T>(); we'll give the "names the constructor, not the
> type" error, so we won't even get here.
>
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
>
> -- >8 --
> This patch implements DR 2237 which says that a simple-template-id is
> no longer valid as the declarator-id of a constructor or destructor;
> see [diff.cpp17.class]#2. It is not explicitly stated but out-of-line
> destructors with a simple-template-id are also meant to be ill-formed
> now. (Out-of-line constructors like that are invalid since DR1435 I
> think.) This change only applies to C++20; it is not a DR against C++17.
>
> I'm not crazy about the diagnostic in constructors but ISTM that
> cp_parser_constructor_declarator_p shouldn't print errors.
>
> DR 2237
> * parser.c (cp_parser_unqualified_id): Reject simple-template-id as
> the declarator-id of a destructor.
> (cp_parser_constructor_declarator_p): Reject simple-template-id as
> the declarator-id of a constructor.
>
> * g++.dg/DRs/dr2237.C: New test.
> * g++.dg/parse/constructor2.C: Add dg-error for C++20.
> * g++.dg/parse/dtor12.C: Likewise.
> * g++.dg/parse/dtor4.C: Likewise.
> * g++.dg/template/dtor4.C: Adjust dg-error.
> * g++.dg/template/error34.C: Likewise.
> * g++.old-deja/g++.other/inline15.C: Only run for C++17 and lesses.
> * g++.old-deja/g++.pt/ctor2.C: Add dg-error for C++20.
> ---
> gcc/cp/parser.c | 13 ++++++++++++-
> gcc/testsuite/g++.dg/DRs/dr2237.C | 18 ++++++++++++++++++
> gcc/testsuite/g++.dg/parse/constructor2.C | 4 ++--
> gcc/testsuite/g++.dg/parse/dtor12.C | 2 +-
> gcc/testsuite/g++.dg/parse/dtor4.C | 2 +-
> gcc/testsuite/g++.dg/template/dtor4.C | 2 +-
> gcc/testsuite/g++.dg/template/error34.C | 10 +++++-----
> .../g++.old-deja/g++.other/inline15.C | 2 +-
> gcc/testsuite/g++.old-deja/g++.pt/ctor2.C | 2 +-
> 9 files changed, 42 insertions(+), 13 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/DRs/dr2237.C
>
> diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
> index 591f44f4934..593c45b5888 100644
> --- a/gcc/cp/parser.c
> +++ b/gcc/cp/parser.c
> @@ -6114,6 +6114,15 @@ cp_parser_unqualified_id (cp_parser* parser,
> return build_min_nt_loc (loc, BIT_NOT_EXPR, make_auto ());
> }
>
> + /* DR 2237 (C++20 only): A simple-template-id is no longer valid as the
> + declarator-id of a constructor or destructor. */
> + if (token->type == CPP_TEMPLATE_ID && cxx_dialect >= cxx2a)
> + {
> + if (!cp_parser_simulate_error (parser))
> + error_at (tilde_loc, "template-id not allowed for destructor");
> + return error_mark_node;
> + }
> +
> /* If there was an explicit qualification (S::~T), first look
> in the scope given by the qualification (i.e., S).
>
> @@ -28636,7 +28645,9 @@ cp_parser_constructor_declarator_p (cp_parser *parser, cp_parser_flags flags,
> if (next_token->type != CPP_NAME
> && next_token->type != CPP_SCOPE
> && next_token->type != CPP_NESTED_NAME_SPECIFIER
> - && next_token->type != CPP_TEMPLATE_ID)
> + /* DR 2237 (C++20 only): A simple-template-id is no longer valid as the
> + declarator-id of a constructor or destructor. */
> + && (next_token->type != CPP_TEMPLATE_ID || cxx_dialect >= cxx2a))
> return false;
>
> /* Parse tentatively; we are going to roll back all of the tokens
> diff --git a/gcc/testsuite/g++.dg/DRs/dr2237.C b/gcc/testsuite/g++.dg/DRs/dr2237.C
> new file mode 100644
> index 00000000000..17abdf179c1
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/DRs/dr2237.C
> @@ -0,0 +1,18 @@
> +// DR 2237 - Can a template-id name a constructor?
> +
> +template<class T>
> +struct X {
> + X<T>(); // { dg-error "expected" "" { target c++2a } }
> + X(int); // OK, injected-class-name used
> + ~X<T>(); // { dg-error "template-id not allowed for destructor" "" { target c++2a } }
> +};
> +
> +// ill-formed since DR1435
> +template<typename T> X<T>::X<T>() {} // { dg-error "names the constructor|as no template constructors" }
> +template<typename T> X<T>::~X<T>() {} // { dg-error "template-id not allowed for destructor" "" { target c++2a } }
> +
> +struct Q {
> + // ill-formed since DR1435
> + template<typename T> friend X<T>::X<T>(); // { dg-error "names the constructor|as no template constructors" }
> + template<typename T> friend X<T>::~X<T>(); // { dg-error "template-id not allowed for destructor" "" { target c++2a } }
> +};
> diff --git a/gcc/testsuite/g++.dg/parse/constructor2.C b/gcc/testsuite/g++.dg/parse/constructor2.C
> index e514e9397e9..87007e9c715 100644
> --- a/gcc/testsuite/g++.dg/parse/constructor2.C
> +++ b/gcc/testsuite/g++.dg/parse/constructor2.C
> @@ -5,7 +5,7 @@ class T
> {
> public:
> T(short,short f=0) {}
> - T<TClass>(int f) {}
> - T<TClass>(int f=0,const char* b=0) {}
> + T<TClass>(int f) {} // { dg-error "expected" "" { target c++2a } }
> + T<TClass>(int f=0,const char* b=0) {} // { dg-error "expected" "" { target c++2a } }
> };
>
> diff --git a/gcc/testsuite/g++.dg/parse/dtor12.C b/gcc/testsuite/g++.dg/parse/dtor12.C
> index 1acdfa36b69..d758d3e861d 100644
> --- a/gcc/testsuite/g++.dg/parse/dtor12.C
> +++ b/gcc/testsuite/g++.dg/parse/dtor12.C
> @@ -2,5 +2,5 @@
>
> template <class T> class a
> {
> - ~a<T>();
> + ~a<T>(); // { dg-error "template-id not allowed for destructor" "" { target c++2a } }
> };
> diff --git a/gcc/testsuite/g++.dg/parse/dtor4.C b/gcc/testsuite/g++.dg/parse/dtor4.C
> index 729ee2fa130..1059c189eff 100644
> --- a/gcc/testsuite/g++.dg/parse/dtor4.C
> +++ b/gcc/testsuite/g++.dg/parse/dtor4.C
> @@ -7,4 +7,4 @@ template <int N> struct X {
> };
>
> template <int N>
> -X<N>::~X<N>(){}
> +X<N>::~X<N>(){} // { dg-error "template-id not allowed for destructor" "" { target c++2a } }
> diff --git a/gcc/testsuite/g++.dg/template/dtor4.C b/gcc/testsuite/g++.dg/template/dtor4.C
> index 4f277b248bd..917681fc13e 100644
> --- a/gcc/testsuite/g++.dg/template/dtor4.C
> +++ b/gcc/testsuite/g++.dg/template/dtor4.C
> @@ -5,5 +5,5 @@
>
> template<int> struct A
> {
> - ~A<0>(); // { dg-error "parse error|declaration" }
> + ~A<0>(); // { dg-error "parse error|declaration|template-id" }
> };
> diff --git a/gcc/testsuite/g++.dg/template/error34.C b/gcc/testsuite/g++.dg/template/error34.C
> index d0cbcaef28e..ab688d9ba8c 100644
> --- a/gcc/testsuite/g++.dg/template/error34.C
> +++ b/gcc/testsuite/g++.dg/template/error34.C
> @@ -3,27 +3,27 @@
>
> template<typename T> struct A
> {
> - A<__builtin_offsetof(T, x)>(); // { dg-error "type/value mismatch|offsetof\\(T, x\\)" }
> + A<__builtin_offsetof(T, x)>(); // { dg-error "type/value mismatch|offsetof\\(T, x\\)|expected" }
> };
>
> template<typename T> struct B
> {
> - B<__builtin_offsetof(T, x.y)>(); // { dg-error "type/value mismatch|offsetof\\(T, x.y\\)" }
> + B<__builtin_offsetof(T, x.y)>(); // { dg-error "type/value mismatch|offsetof\\(T, x.y\\)|expected" }
> };
>
> template<typename T> struct C
> {
> - C<__builtin_offsetof(T, x[6])>(); // { dg-error "type/value mismatch|offsetof\\(T, x\\\[6\\\]\\)" }
> + C<__builtin_offsetof(T, x[6])>(); // { dg-error "type/value mismatch|offsetof\\(T, x\\\[6\\\]\\)|expected" }
> };
>
> template<typename T> struct D
> {
> - D<__builtin_offsetof(T, x.y[6].z)>(); // { dg-error "type/value mismatch|offsetof\\(T, x.y\\\[6\\\].z\\)" }
> + D<__builtin_offsetof(T, x.y[6].z)>(); // { dg-error "type/value mismatch|offsetof\\(T, x.y\\\[6\\\].z\\)|expected" }
> };
>
> struct E { int x; };
>
> template<typename T> struct F
> {
> - F<__builtin_offsetof(E, x)>(); // { dg-error "type/value mismatch|offsetof\\(E, x\\)" }
> + F<__builtin_offsetof(E, x)>(); // { dg-error "type/value mismatch|offsetof\\(E, x\\)|expected" }
> };
> diff --git a/gcc/testsuite/g++.old-deja/g++.other/inline15.C b/gcc/testsuite/g++.old-deja/g++.other/inline15.C
> index 43f7f5e3025..a31c60960a5 100644
> --- a/gcc/testsuite/g++.old-deja/g++.other/inline15.C
> +++ b/gcc/testsuite/g++.old-deja/g++.other/inline15.C
> @@ -1,4 +1,4 @@
> -// { dg-do assemble }
> +// { dg-do assemble { target c++17_down } }
> // { dg-options "-O1" }
> // Origin: Jakub Jelinek <jakub@redhat.com>
>
> diff --git a/gcc/testsuite/g++.old-deja/g++.pt/ctor2.C b/gcc/testsuite/g++.old-deja/g++.pt/ctor2.C
> index a8be91ddbb9..4159c84ff56 100644
> --- a/gcc/testsuite/g++.old-deja/g++.pt/ctor2.C
> +++ b/gcc/testsuite/g++.old-deja/g++.pt/ctor2.C
> @@ -4,7 +4,7 @@
>
> template <class T>
> struct A {
> - A<T>();
> + A<T>(); // { dg-error "expected" "" { target c++2a } }
> };
>
> template <class T>
>
> base-commit: 2b2d298ff845ab7a07ffbd51da79473736da3324
> --
> Marek Polacek • Red Hat, Inc. • 300 A St, Boston, MA
>
Marek
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] c++: C++20 DR 2237, disallow simple-template-id in cdtor.
2020-05-20 18:05 ` Marek Polacek
@ 2020-05-20 20:45 ` Jason Merrill
0 siblings, 0 replies; 5+ messages in thread
From: Jason Merrill @ 2020-05-20 20:45 UTC (permalink / raw)
To: Marek Polacek, GCC Patches
On 5/20/20 2:05 PM, Marek Polacek wrote:
> Ping.
OK (with 2a->20, of course).
Jason
> On Mon, May 11, 2020 at 04:23:17PM -0400, Marek Polacek via Gcc-patches wrote:
>> On Sun, Apr 05, 2020 at 09:46:09PM -0400, Jason Merrill wrote:
>>> On 4/4/20 7:30 PM, Marek Polacek wrote:
>>>> This patch implements DR 2237 which says that a simple-template-id is
>>>> no longer valid as the declarator-id of a constructor or destructor;
>>>> see <https://eel.is/c++draft/diff.cpp17.class#2>. It is not explicitly
>>>> stated but out-of-line destructors with a simple-template-id are also
>>>> meant to be ill-formed now. (Out-of-line constructors like that are
>>>> invalid since DR1435 I think.) This change only applies to C++20; it
>>>> is not a DR against C++17.
>>>>
>>>> I'm not crazy about the diagnostic in constructors but ISTM that
>>>> cp_parser_constructor_declarator_p shouldn't print errors.
>>>>
>>>> Does it seem reasonable to apply this now or should I defer to GCC 11?
>>>
>>> A new error should wait for GCC 11.
>>
>> Coming back to this now that we're again in stage 1.
>>
>>>> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
>>>>
>>>> 2020-04-04 Marek Polacek <polacek@redhat.com>
>>>>
>>>> DR 2237
>>>> * parser.c (cp_parser_unqualified_id): Reject simple-template-id as
>>>> the declarator-id of a destructor.
>>>> (cp_parser_constructor_declarator_p): Reject simple-template-id as
>>>> the declarator-id of a constructor.
>>>>
>>>> * g++.dg/DRs/dr2237.C: New test.
>>>> * g++.dg/parse/constructor2.C: Add dg-error for C++20.
>>>> * g++.dg/parse/dtor12.C: Likewise.
>>>> * g++.dg/parse/dtor4.C: Likewise.
>>>> * g++.dg/template/dtor4.C: Adjust dg-error.
>>>> * g++.dg/template/error34.C: Likewise.
>>>> * g++.old-deja/g++.other/inline15.C: Only run for C++17 and lesses.
>>>> * g++.old-deja/g++.pt/ctor2.C: Add dg-error for C++20.
>>>> ---
>>>> gcc/cp/parser.c | 16 ++++++++++++++++
>>>> gcc/testsuite/g++.dg/DRs/dr2237.C | 18 ++++++++++++++++++
>>>> gcc/testsuite/g++.dg/parse/constructor2.C | 4 ++--
>>>> gcc/testsuite/g++.dg/parse/dtor12.C | 2 +-
>>>> gcc/testsuite/g++.dg/parse/dtor4.C | 2 +-
>>>> gcc/testsuite/g++.dg/template/dtor4.C | 2 +-
>>>> gcc/testsuite/g++.dg/template/error34.C | 10 +++++-----
>>>> .../g++.old-deja/g++.other/inline15.C | 2 +-
>>>> gcc/testsuite/g++.old-deja/g++.pt/ctor2.C | 2 +-
>>>> 9 files changed, 46 insertions(+), 12 deletions(-)
>>>> create mode 100644 gcc/testsuite/g++.dg/DRs/dr2237.C
>>>>
>>>> diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
>>>> index 7e5921e039f..810edfa87a9 100644
>>>> --- a/gcc/cp/parser.c
>>>> +++ b/gcc/cp/parser.c
>>>> @@ -6114,6 +6114,16 @@ cp_parser_unqualified_id (cp_parser* parser,
>>>> return build_min_nt_loc (loc, BIT_NOT_EXPR, make_auto ());
>>>> }
>>>> + /* DR 2237 (C++20 only): A simple-template-id is no longer valid as the
>>>> + declarator-id of a constructor or destructor. */
>>>> + if (token->type == CPP_TEMPLATE_ID && cxx_dialect >= cxx2a)
>>>> + {
>>>> + if (!cp_parser_uncommitted_to_tentative_parse_p (parser))
>>>> + error_at (tilde_loc, "template-id not allowed for destructor");
>>>> + cp_parser_simulate_error (parser);
>>>
>>> The usual pattern is
>>>
>>> if (!cp_parser_simulate_error (parser))
>>> error...
>>
>> Fixed.
>>
>>>> + return error_mark_node;
>>>> + }
>>>> +
>>>> /* If there was an explicit qualification (S::~T), first look
>>>> in the scope given by the qualification (i.e., S).
>>>> @@ -28675,6 +28685,12 @@ cp_parser_constructor_declarator_p (cp_parser *parser, cp_parser_flags flags,
>>>> if (!constructor_name_p (id, nested_name_specifier))
>>>> constructor_p = false;
>>>> }
>>>> + /* DR 2237 (C++20 only): A simple-template-id is no longer valid as the
>>>> + declarator-id of a constructor or destructor. */
>>>> + else if (constructor_p
>>>> + && cxx_dialect >= cxx2a
>>>> + && cp_lexer_next_token_is (parser->lexer, CPP_TEMPLATE_ID))
>>>> + constructor_p = false;
>>>> /* If we still think that this might be a constructor-declarator,
>>>> look for a class-name. */
>>>> else if (constructor_p)
>>>
>>> Do you also want to exclude CPP_TEMPLATE_ID from the test at the top of the
>>> function for C++20?
>>
>> In fact we can get away with only excluding CPP_TEMPLATE_ID in C++20 there,
>> because for e.g. X<T>::X<T>(); we'll give the "names the constructor, not the
>> type" error, so we won't even get here.
>>
>> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
>>
>> -- >8 --
>> This patch implements DR 2237 which says that a simple-template-id is
>> no longer valid as the declarator-id of a constructor or destructor;
>> see [diff.cpp17.class]#2. It is not explicitly stated but out-of-line
>> destructors with a simple-template-id are also meant to be ill-formed
>> now. (Out-of-line constructors like that are invalid since DR1435 I
>> think.) This change only applies to C++20; it is not a DR against C++17.
>>
>> I'm not crazy about the diagnostic in constructors but ISTM that
>> cp_parser_constructor_declarator_p shouldn't print errors.
>>
>> DR 2237
>> * parser.c (cp_parser_unqualified_id): Reject simple-template-id as
>> the declarator-id of a destructor.
>> (cp_parser_constructor_declarator_p): Reject simple-template-id as
>> the declarator-id of a constructor.
>>
>> * g++.dg/DRs/dr2237.C: New test.
>> * g++.dg/parse/constructor2.C: Add dg-error for C++20.
>> * g++.dg/parse/dtor12.C: Likewise.
>> * g++.dg/parse/dtor4.C: Likewise.
>> * g++.dg/template/dtor4.C: Adjust dg-error.
>> * g++.dg/template/error34.C: Likewise.
>> * g++.old-deja/g++.other/inline15.C: Only run for C++17 and lesses.
>> * g++.old-deja/g++.pt/ctor2.C: Add dg-error for C++20.
>> ---
>> gcc/cp/parser.c | 13 ++++++++++++-
>> gcc/testsuite/g++.dg/DRs/dr2237.C | 18 ++++++++++++++++++
>> gcc/testsuite/g++.dg/parse/constructor2.C | 4 ++--
>> gcc/testsuite/g++.dg/parse/dtor12.C | 2 +-
>> gcc/testsuite/g++.dg/parse/dtor4.C | 2 +-
>> gcc/testsuite/g++.dg/template/dtor4.C | 2 +-
>> gcc/testsuite/g++.dg/template/error34.C | 10 +++++-----
>> .../g++.old-deja/g++.other/inline15.C | 2 +-
>> gcc/testsuite/g++.old-deja/g++.pt/ctor2.C | 2 +-
>> 9 files changed, 42 insertions(+), 13 deletions(-)
>> create mode 100644 gcc/testsuite/g++.dg/DRs/dr2237.C
>>
>> diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
>> index 591f44f4934..593c45b5888 100644
>> --- a/gcc/cp/parser.c
>> +++ b/gcc/cp/parser.c
>> @@ -6114,6 +6114,15 @@ cp_parser_unqualified_id (cp_parser* parser,
>> return build_min_nt_loc (loc, BIT_NOT_EXPR, make_auto ());
>> }
>>
>> + /* DR 2237 (C++20 only): A simple-template-id is no longer valid as the
>> + declarator-id of a constructor or destructor. */
>> + if (token->type == CPP_TEMPLATE_ID && cxx_dialect >= cxx2a)
>> + {
>> + if (!cp_parser_simulate_error (parser))
>> + error_at (tilde_loc, "template-id not allowed for destructor");
>> + return error_mark_node;
>> + }
>> +
>> /* If there was an explicit qualification (S::~T), first look
>> in the scope given by the qualification (i.e., S).
>>
>> @@ -28636,7 +28645,9 @@ cp_parser_constructor_declarator_p (cp_parser *parser, cp_parser_flags flags,
>> if (next_token->type != CPP_NAME
>> && next_token->type != CPP_SCOPE
>> && next_token->type != CPP_NESTED_NAME_SPECIFIER
>> - && next_token->type != CPP_TEMPLATE_ID)
>> + /* DR 2237 (C++20 only): A simple-template-id is no longer valid as the
>> + declarator-id of a constructor or destructor. */
>> + && (next_token->type != CPP_TEMPLATE_ID || cxx_dialect >= cxx2a))
>> return false;
>>
>> /* Parse tentatively; we are going to roll back all of the tokens
>> diff --git a/gcc/testsuite/g++.dg/DRs/dr2237.C b/gcc/testsuite/g++.dg/DRs/dr2237.C
>> new file mode 100644
>> index 00000000000..17abdf179c1
>> --- /dev/null
>> +++ b/gcc/testsuite/g++.dg/DRs/dr2237.C
>> @@ -0,0 +1,18 @@
>> +// DR 2237 - Can a template-id name a constructor?
>> +
>> +template<class T>
>> +struct X {
>> + X<T>(); // { dg-error "expected" "" { target c++2a } }
>> + X(int); // OK, injected-class-name used
>> + ~X<T>(); // { dg-error "template-id not allowed for destructor" "" { target c++2a } }
>> +};
>> +
>> +// ill-formed since DR1435
>> +template<typename T> X<T>::X<T>() {} // { dg-error "names the constructor|as no template constructors" }
>> +template<typename T> X<T>::~X<T>() {} // { dg-error "template-id not allowed for destructor" "" { target c++2a } }
>> +
>> +struct Q {
>> + // ill-formed since DR1435
>> + template<typename T> friend X<T>::X<T>(); // { dg-error "names the constructor|as no template constructors" }
>> + template<typename T> friend X<T>::~X<T>(); // { dg-error "template-id not allowed for destructor" "" { target c++2a } }
>> +};
>> diff --git a/gcc/testsuite/g++.dg/parse/constructor2.C b/gcc/testsuite/g++.dg/parse/constructor2.C
>> index e514e9397e9..87007e9c715 100644
>> --- a/gcc/testsuite/g++.dg/parse/constructor2.C
>> +++ b/gcc/testsuite/g++.dg/parse/constructor2.C
>> @@ -5,7 +5,7 @@ class T
>> {
>> public:
>> T(short,short f=0) {}
>> - T<TClass>(int f) {}
>> - T<TClass>(int f=0,const char* b=0) {}
>> + T<TClass>(int f) {} // { dg-error "expected" "" { target c++2a } }
>> + T<TClass>(int f=0,const char* b=0) {} // { dg-error "expected" "" { target c++2a } }
>> };
>>
>> diff --git a/gcc/testsuite/g++.dg/parse/dtor12.C b/gcc/testsuite/g++.dg/parse/dtor12.C
>> index 1acdfa36b69..d758d3e861d 100644
>> --- a/gcc/testsuite/g++.dg/parse/dtor12.C
>> +++ b/gcc/testsuite/g++.dg/parse/dtor12.C
>> @@ -2,5 +2,5 @@
>>
>> template <class T> class a
>> {
>> - ~a<T>();
>> + ~a<T>(); // { dg-error "template-id not allowed for destructor" "" { target c++2a } }
>> };
>> diff --git a/gcc/testsuite/g++.dg/parse/dtor4.C b/gcc/testsuite/g++.dg/parse/dtor4.C
>> index 729ee2fa130..1059c189eff 100644
>> --- a/gcc/testsuite/g++.dg/parse/dtor4.C
>> +++ b/gcc/testsuite/g++.dg/parse/dtor4.C
>> @@ -7,4 +7,4 @@ template <int N> struct X {
>> };
>>
>> template <int N>
>> -X<N>::~X<N>(){}
>> +X<N>::~X<N>(){} // { dg-error "template-id not allowed for destructor" "" { target c++2a } }
>> diff --git a/gcc/testsuite/g++.dg/template/dtor4.C b/gcc/testsuite/g++.dg/template/dtor4.C
>> index 4f277b248bd..917681fc13e 100644
>> --- a/gcc/testsuite/g++.dg/template/dtor4.C
>> +++ b/gcc/testsuite/g++.dg/template/dtor4.C
>> @@ -5,5 +5,5 @@
>>
>> template<int> struct A
>> {
>> - ~A<0>(); // { dg-error "parse error|declaration" }
>> + ~A<0>(); // { dg-error "parse error|declaration|template-id" }
>> };
>> diff --git a/gcc/testsuite/g++.dg/template/error34.C b/gcc/testsuite/g++.dg/template/error34.C
>> index d0cbcaef28e..ab688d9ba8c 100644
>> --- a/gcc/testsuite/g++.dg/template/error34.C
>> +++ b/gcc/testsuite/g++.dg/template/error34.C
>> @@ -3,27 +3,27 @@
>>
>> template<typename T> struct A
>> {
>> - A<__builtin_offsetof(T, x)>(); // { dg-error "type/value mismatch|offsetof\\(T, x\\)" }
>> + A<__builtin_offsetof(T, x)>(); // { dg-error "type/value mismatch|offsetof\\(T, x\\)|expected" }
>> };
>>
>> template<typename T> struct B
>> {
>> - B<__builtin_offsetof(T, x.y)>(); // { dg-error "type/value mismatch|offsetof\\(T, x.y\\)" }
>> + B<__builtin_offsetof(T, x.y)>(); // { dg-error "type/value mismatch|offsetof\\(T, x.y\\)|expected" }
>> };
>>
>> template<typename T> struct C
>> {
>> - C<__builtin_offsetof(T, x[6])>(); // { dg-error "type/value mismatch|offsetof\\(T, x\\\[6\\\]\\)" }
>> + C<__builtin_offsetof(T, x[6])>(); // { dg-error "type/value mismatch|offsetof\\(T, x\\\[6\\\]\\)|expected" }
>> };
>>
>> template<typename T> struct D
>> {
>> - D<__builtin_offsetof(T, x.y[6].z)>(); // { dg-error "type/value mismatch|offsetof\\(T, x.y\\\[6\\\].z\\)" }
>> + D<__builtin_offsetof(T, x.y[6].z)>(); // { dg-error "type/value mismatch|offsetof\\(T, x.y\\\[6\\\].z\\)|expected" }
>> };
>>
>> struct E { int x; };
>>
>> template<typename T> struct F
>> {
>> - F<__builtin_offsetof(E, x)>(); // { dg-error "type/value mismatch|offsetof\\(E, x\\)" }
>> + F<__builtin_offsetof(E, x)>(); // { dg-error "type/value mismatch|offsetof\\(E, x\\)|expected" }
>> };
>> diff --git a/gcc/testsuite/g++.old-deja/g++.other/inline15.C b/gcc/testsuite/g++.old-deja/g++.other/inline15.C
>> index 43f7f5e3025..a31c60960a5 100644
>> --- a/gcc/testsuite/g++.old-deja/g++.other/inline15.C
>> +++ b/gcc/testsuite/g++.old-deja/g++.other/inline15.C
>> @@ -1,4 +1,4 @@
>> -// { dg-do assemble }
>> +// { dg-do assemble { target c++17_down } }
>> // { dg-options "-O1" }
>> // Origin: Jakub Jelinek <jakub@redhat.com>
>>
>> diff --git a/gcc/testsuite/g++.old-deja/g++.pt/ctor2.C b/gcc/testsuite/g++.old-deja/g++.pt/ctor2.C
>> index a8be91ddbb9..4159c84ff56 100644
>> --- a/gcc/testsuite/g++.old-deja/g++.pt/ctor2.C
>> +++ b/gcc/testsuite/g++.old-deja/g++.pt/ctor2.C
>> @@ -4,7 +4,7 @@
>>
>> template <class T>
>> struct A {
>> - A<T>();
>> + A<T>(); // { dg-error "expected" "" { target c++2a } }
>> };
>>
>> template <class T>
>>
>> base-commit: 2b2d298ff845ab7a07ffbd51da79473736da3324
>> --
>> Marek Polacek • Red Hat, Inc. • 300 A St, Boston, MA
>>
>
> Marek
>
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2020-04-04 23:30 [PATCH] c++: C++20 DR 2237, disallow simple-template-id in cdtor Marek Polacek
2020-04-06 1:46 ` Jason Merrill
2020-05-11 20:23 ` Marek Polacek
2020-05-20 18:05 ` Marek Polacek
2020-05-20 20:45 ` Jason Merrill
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