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 no longer valid as the declarator-id of a constructor or destructor;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 <pola...@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 <ja...@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
