Re: [PATCH] c++: Allow template lambdas without lambda-declarator [PR97839]
On 11/18/20 1:16 PM, Marek Polacek wrote:
On Tue, Nov 17, 2020 at 01:05:20PM -0500, Marek Polacek via Gcc-patches wrote:
Our implementation of template lambdas incorrectly requires the optional
lambda-declarator. This was probably required by an early draft of
generic lambdas, but now the production is [expr.prim.lambda.general]:
lambda-expression:
lambda-introducer lambda-declarator [opt] compound-statement
lambda-introducer < template-parameter-list > requires-clause [opt]
lambda-declarator [opt] compound-statement
Therefore, we should accept the following test.
Incidentally, I noticed we give a terrible diagnostic when the user uses
'mutable', but forgets to type '()' before it, which sounds like a common
mistake. So it seems to me we should handle that specifically, rather
than to emit this:
This might be necessary to handle anyway.
Agreed.
lambda-generic8.C: In lambda function:
lambda-generic8.C:8:18: error: expected '{' before 'mutable'
8 | [] mutable {}.operator()();
| ^~~
lambda-generic8.C: In function 'int main()':
lambda-generic8.C:8:17: error: expected ';' before 'mutable'
8 | [] mutable {}.operator()();
| ^~~~
| ;
lambda-generic8.C:8:28: error: expected primary-expression before '.' token
8 | [] mutable {}.operator()();
|^
lambda-generic8.C:8:40: error: expected primary-expression before 'int'
8 | [] mutable {}.operator()();
|^~~
Is it okay to fix this in stage3?
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
gcc/cp/ChangeLog:
PR c++/97839
* parser.c (cp_parser_lambda_declarator_opt): Don't require ().
gcc/testsuite/ChangeLog:
PR c++/97839
* g++.dg/cpp2a/lambda-generic8.C: New test.
---
gcc/cp/parser.c | 14 ++
gcc/testsuite/g++.dg/cpp2a/lambda-generic8.C | 9 +
2 files changed, 15 insertions(+), 8 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp2a/lambda-generic8.C
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 42f705266bb..9f09c778c29 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -10604,6 +10604,8 @@ cp_parser_trait_expr (cp_parser* parser, enum rid
keyword)
lambda-expression:
lambda-introducer lambda-declarator [opt] compound-statement
+ lambda-introducer < template-parameter-list > requires-clause [opt]
+ lambda-declarator [opt] compound-statement
Returns a representation of the expression. */
@@ -11061,13 +11063,11 @@ cp_parser_lambda_introducer (cp_parser* parser, tree lambda_expr)
/* Parse the (optional) middle of a lambda expression.
lambda-declarator:
- < template-parameter-list [opt] >
- requires-clause [opt]
- ( parameter-declaration-clause [opt] )
- attribute-specifier [opt]
+ ( parameter-declaration-clause )
decl-specifier-seq [opt]
- exception-specification [opt]
- lambda-return-type-clause [opt]
+ noexcept-specifier [opt]
+ attribute-specifier-seq [opt]
+ trailing-return-type [opt]
requires-clause [opt]
LAMBDA_EXPR is the current representation of the lambda expression. */
@@ -11217,8 +11217,6 @@ cp_parser_lambda_declarator_opt (cp_parser* parser,
tree lambda_expr)
trailing-return-type in case of decltype. */
pop_bindings_and_leave_scope ();
}
- else if (template_param_list != NULL_TREE) // generate diagnostic
-cp_parser_require (parser, CPP_OPEN_PAREN, RT_OPEN_PAREN);
/* Create the function call operator.
diff --git a/gcc/testsuite/g++.dg/cpp2a/lambda-generic8.C b/gcc/testsuite/g++.dg/cpp2a/lambda-generic8.C
new file mode 100644
index 000..f3c3809b36d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/lambda-generic8.C
@@ -0,0 +1,9 @@
+// PR c++/97839
+// { dg-do compile { target c++20 } }
+// Test that a lambda with doesn't require
+// a lambda-declarator.
+
+int main()
+{
+ []{}.operator()();
+}
base-commit: 8661f4faa875f361cd22a197774c1fa04cd0580b
--
2.28.0
Marek
Re: [PATCH] c++: Allow template lambdas without lambda-declarator [PR97839]
On 11/17/20 1:05 PM, Marek Polacek wrote:
Our implementation of template lambdas incorrectly requires the optional
lambda-declarator. This was probably required by an early draft of
generic lambdas, but now the production is [expr.prim.lambda.general]:
lambda-expression:
lambda-introducer lambda-declarator [opt] compound-statement
lambda-introducer < template-parameter-list > requires-clause [opt]
lambda-declarator [opt] compound-statement
Therefore, we should accept the following test.
Incidentally, I noticed we give a terrible diagnostic when the user uses
'mutable', but forgets to type '()' before it, which sounds like a common
mistake. So it seems to me we should handle that specifically, rather
than to emit this:
lambda-generic8.C: In lambda function:
lambda-generic8.C:8:18: error: expected '{' before 'mutable'
8 | [] mutable {}.operator()();
| ^~~
lambda-generic8.C: In function 'int main()':
lambda-generic8.C:8:17: error: expected ';' before 'mutable'
8 | [] mutable {}.operator()();
| ^~~~
| ;
lambda-generic8.C:8:28: error: expected primary-expression before '.' token
8 | [] mutable {}.operator()();
|^
lambda-generic8.C:8:40: error: expected primary-expression before 'int'
8 | [] mutable {}.operator()();
|^~~
Is it okay to fix this in stage3?
Yes: this is a bugfix, not new functionality.
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
OK.
gcc/cp/ChangeLog:
PR c++/97839
* parser.c (cp_parser_lambda_declarator_opt): Don't require ().
gcc/testsuite/ChangeLog:
PR c++/97839
* g++.dg/cpp2a/lambda-generic8.C: New test.
---
gcc/cp/parser.c | 14 ++
gcc/testsuite/g++.dg/cpp2a/lambda-generic8.C | 9 +
2 files changed, 15 insertions(+), 8 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp2a/lambda-generic8.C
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 42f705266bb..9f09c778c29 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -10604,6 +10604,8 @@ cp_parser_trait_expr (cp_parser* parser, enum rid
keyword)
lambda-expression:
lambda-introducer lambda-declarator [opt] compound-statement
+ lambda-introducer < template-parameter-list > requires-clause [opt]
+ lambda-declarator [opt] compound-statement
Returns a representation of the expression. */
@@ -11061,13 +11063,11 @@ cp_parser_lambda_introducer (cp_parser* parser, tree lambda_expr)
/* Parse the (optional) middle of a lambda expression.
lambda-declarator:
- < template-parameter-list [opt] >
- requires-clause [opt]
- ( parameter-declaration-clause [opt] )
- attribute-specifier [opt]
+ ( parameter-declaration-clause )
decl-specifier-seq [opt]
- exception-specification [opt]
- lambda-return-type-clause [opt]
+ noexcept-specifier [opt]
+ attribute-specifier-seq [opt]
+ trailing-return-type [opt]
requires-clause [opt]
LAMBDA_EXPR is the current representation of the lambda expression. */
@@ -11217,8 +11217,6 @@ cp_parser_lambda_declarator_opt (cp_parser* parser,
tree lambda_expr)
trailing-return-type in case of decltype. */
pop_bindings_and_leave_scope ();
}
- else if (template_param_list != NULL_TREE) // generate diagnostic
-cp_parser_require (parser, CPP_OPEN_PAREN, RT_OPEN_PAREN);
/* Create the function call operator.
diff --git a/gcc/testsuite/g++.dg/cpp2a/lambda-generic8.C b/gcc/testsuite/g++.dg/cpp2a/lambda-generic8.C
new file mode 100644
index 000..f3c3809b36d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/lambda-generic8.C
@@ -0,0 +1,9 @@
+// PR c++/97839
+// { dg-do compile { target c++20 } }
+// Test that a lambda with doesn't require
+// a lambda-declarator.
+
+int main()
+{
+ []{}.operator()();
+}
base-commit: 8661f4faa875f361cd22a197774c1fa04cd0580b
Re: [PATCH] c++: Allow template lambdas without lambda-declarator [PR97839]
On Tue, Nov 17, 2020 at 01:05:20PM -0500, Marek Polacek via Gcc-patches wrote:
> Our implementation of template lambdas incorrectly requires the optional
> lambda-declarator. This was probably required by an early draft of
> generic lambdas, but now the production is [expr.prim.lambda.general]:
>
> lambda-expression:
> lambda-introducer lambda-declarator [opt] compound-statement
> lambda-introducer < template-parameter-list > requires-clause [opt]
> lambda-declarator [opt] compound-statement
>
> Therefore, we should accept the following test.
>
> Incidentally, I noticed we give a terrible diagnostic when the user uses
> 'mutable', but forgets to type '()' before it, which sounds like a common
> mistake. So it seems to me we should handle that specifically, rather
> than to emit this:
This might be necessary to handle anyway.
> lambda-generic8.C: In lambda function:
> lambda-generic8.C:8:18: error: expected '{' before 'mutable'
> 8 | [] mutable {}.operator()();
> | ^~~
> lambda-generic8.C: In function 'int main()':
> lambda-generic8.C:8:17: error: expected ';' before 'mutable'
> 8 | [] mutable {}.operator()();
> | ^~~~
> | ;
> lambda-generic8.C:8:28: error: expected primary-expression before '.' token
> 8 | [] mutable {}.operator()();
> |^
> lambda-generic8.C:8:40: error: expected primary-expression before 'int'
> 8 | [] mutable {}.operator()();
> |^~~
>
> Is it okay to fix this in stage3?
>
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
>
> gcc/cp/ChangeLog:
>
> PR c++/97839
> * parser.c (cp_parser_lambda_declarator_opt): Don't require ().
>
> gcc/testsuite/ChangeLog:
>
> PR c++/97839
> * g++.dg/cpp2a/lambda-generic8.C: New test.
> ---
> gcc/cp/parser.c | 14 ++
> gcc/testsuite/g++.dg/cpp2a/lambda-generic8.C | 9 +
> 2 files changed, 15 insertions(+), 8 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/cpp2a/lambda-generic8.C
>
> diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
> index 42f705266bb..9f09c778c29 100644
> --- a/gcc/cp/parser.c
> +++ b/gcc/cp/parser.c
> @@ -10604,6 +10604,8 @@ cp_parser_trait_expr (cp_parser* parser, enum rid
> keyword)
>
> lambda-expression:
> lambda-introducer lambda-declarator [opt] compound-statement
> + lambda-introducer < template-parameter-list > requires-clause [opt]
> + lambda-declarator [opt] compound-statement
>
> Returns a representation of the expression. */
>
> @@ -11061,13 +11063,11 @@ cp_parser_lambda_introducer (cp_parser* parser,
> tree lambda_expr)
> /* Parse the (optional) middle of a lambda expression.
>
> lambda-declarator:
> - < template-parameter-list [opt] >
> - requires-clause [opt]
> - ( parameter-declaration-clause [opt] )
> - attribute-specifier [opt]
> + ( parameter-declaration-clause )
> decl-specifier-seq [opt]
> - exception-specification [opt]
> - lambda-return-type-clause [opt]
> + noexcept-specifier [opt]
> + attribute-specifier-seq [opt]
> + trailing-return-type [opt]
> requires-clause [opt]
>
> LAMBDA_EXPR is the current representation of the lambda expression. */
> @@ -11217,8 +11217,6 @@ cp_parser_lambda_declarator_opt (cp_parser* parser,
> tree lambda_expr)
> trailing-return-type in case of decltype. */
>pop_bindings_and_leave_scope ();
> }
> - else if (template_param_list != NULL_TREE) // generate diagnostic
> -cp_parser_require (parser, CPP_OPEN_PAREN, RT_OPEN_PAREN);
>
>/* Create the function call operator.
>
> diff --git a/gcc/testsuite/g++.dg/cpp2a/lambda-generic8.C
> b/gcc/testsuite/g++.dg/cpp2a/lambda-generic8.C
> new file mode 100644
> index 000..f3c3809b36d
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp2a/lambda-generic8.C
> @@ -0,0 +1,9 @@
> +// PR c++/97839
> +// { dg-do compile { target c++20 } }
> +// Test that a lambda with doesn't require
> +// a lambda-declarator.
> +
> +int main()
> +{
> + []{}.operator()();
> +}
>
> base-commit: 8661f4faa875f361cd22a197774c1fa04cd0580b
> --
> 2.28.0
>
Marek
[PATCH] c++: Allow template lambdas without lambda-declarator [PR97839]
Our implementation of template lambdas incorrectly requires the optional
lambda-declarator. This was probably required by an early draft of
generic lambdas, but now the production is [expr.prim.lambda.general]:
lambda-expression:
lambda-introducer lambda-declarator [opt] compound-statement
lambda-introducer < template-parameter-list > requires-clause [opt]
lambda-declarator [opt] compound-statement
Therefore, we should accept the following test.
Incidentally, I noticed we give a terrible diagnostic when the user uses
'mutable', but forgets to type '()' before it, which sounds like a common
mistake. So it seems to me we should handle that specifically, rather
than to emit this:
lambda-generic8.C: In lambda function:
lambda-generic8.C:8:18: error: expected '{' before 'mutable'
8 | [] mutable {}.operator()();
| ^~~
lambda-generic8.C: In function 'int main()':
lambda-generic8.C:8:17: error: expected ';' before 'mutable'
8 | [] mutable {}.operator()();
| ^~~~
| ;
lambda-generic8.C:8:28: error: expected primary-expression before '.' token
8 | [] mutable {}.operator()();
|^
lambda-generic8.C:8:40: error: expected primary-expression before 'int'
8 | [] mutable {}.operator()();
|^~~
Is it okay to fix this in stage3?
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
gcc/cp/ChangeLog:
PR c++/97839
* parser.c (cp_parser_lambda_declarator_opt): Don't require ().
gcc/testsuite/ChangeLog:
PR c++/97839
* g++.dg/cpp2a/lambda-generic8.C: New test.
---
gcc/cp/parser.c | 14 ++
gcc/testsuite/g++.dg/cpp2a/lambda-generic8.C | 9 +
2 files changed, 15 insertions(+), 8 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp2a/lambda-generic8.C
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 42f705266bb..9f09c778c29 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -10604,6 +10604,8 @@ cp_parser_trait_expr (cp_parser* parser, enum rid
keyword)
lambda-expression:
lambda-introducer lambda-declarator [opt] compound-statement
+ lambda-introducer < template-parameter-list > requires-clause [opt]
+ lambda-declarator [opt] compound-statement
Returns a representation of the expression. */
@@ -11061,13 +11063,11 @@ cp_parser_lambda_introducer (cp_parser* parser, tree
lambda_expr)
/* Parse the (optional) middle of a lambda expression.
lambda-declarator:
- < template-parameter-list [opt] >
- requires-clause [opt]
- ( parameter-declaration-clause [opt] )
- attribute-specifier [opt]
+ ( parameter-declaration-clause )
decl-specifier-seq [opt]
- exception-specification [opt]
- lambda-return-type-clause [opt]
+ noexcept-specifier [opt]
+ attribute-specifier-seq [opt]
+ trailing-return-type [opt]
requires-clause [opt]
LAMBDA_EXPR is the current representation of the lambda expression. */
@@ -11217,8 +11217,6 @@ cp_parser_lambda_declarator_opt (cp_parser* parser,
tree lambda_expr)
trailing-return-type in case of decltype. */
pop_bindings_and_leave_scope ();
}
- else if (template_param_list != NULL_TREE) // generate diagnostic
-cp_parser_require (parser, CPP_OPEN_PAREN, RT_OPEN_PAREN);
/* Create the function call operator.
diff --git a/gcc/testsuite/g++.dg/cpp2a/lambda-generic8.C
b/gcc/testsuite/g++.dg/cpp2a/lambda-generic8.C
new file mode 100644
index 000..f3c3809b36d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/lambda-generic8.C
@@ -0,0 +1,9 @@
+// PR c++/97839
+// { dg-do compile { target c++20 } }
+// Test that a lambda with doesn't require
+// a lambda-declarator.
+
+int main()
+{
+ []{}.operator()();
+}
base-commit: 8661f4faa875f361cd22a197774c1fa04cd0580b
--
2.28.0
