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Re: C++ PATCH for c++/86499, non-local lambda with a capture-default


On Tue, Aug 14, 2018 at 6:50 AM, Marek Polacek <polacek@redhat.com> wrote:
> This PR complains about us accepting a lambda with a capture-default
> at file scope, which seems to be forbidden.  This patch disallows
> such a use.  clang gives an error, so I did the same, but maybe we
> only want a pedwarn.
>
> Bootstrapped/regtested on x86_64-linux, ok for trunk?
>
> 2018-08-13  Marek Polacek  <polacek@redhat.com>
>
>         PR c++/86499
>         * parser.c (cp_parser_lambda_introducer): Give error if a non-local
>         lambda has a capture-default.
>
>         * g++.dg/cpp0x/lambda/lambda-non-local.C: New test.
>         * g++.dg/cpp0x/lambda/lambda-this10.C: Adjust dg-error.
>
> diff --git gcc/cp/parser.c gcc/cp/parser.c
> index 8cfcd150705..6a760136f99 100644
> --- gcc/cp/parser.c
> +++ gcc/cp/parser.c
> @@ -10280,6 +10280,9 @@ cp_parser_lambda_introducer (cp_parser* parser, tree lambda_expr)
>      {
>        cp_lexer_consume_token (parser->lexer);
>        first = false;
> +
> +      if (!(at_function_scope_p () || at_class_scope_p ()))

I think we want parsing_nsdmi() instead of at_class_scope_p(); other
uses in a class are ill-formed.  OK with that change.

> +       error ("non-local lambda expression cannot have a capture-default");
>      }
>
>    while (cp_lexer_next_token_is_not (parser->lexer, CPP_CLOSE_SQUARE))
> diff --git gcc/testsuite/g++.dg/cpp0x/lambda/lambda-non-local.C gcc/testsuite/g++.dg/cpp0x/lambda/lambda-non-local.C
> index e69de29bb2d..005f8f3888b 100644
> --- gcc/testsuite/g++.dg/cpp0x/lambda/lambda-non-local.C
> +++ gcc/testsuite/g++.dg/cpp0x/lambda/lambda-non-local.C
> @@ -0,0 +1,10 @@
> +// PR c++/86499
> +// { dg-do compile { target c++11 } }
> +
> +auto l1 = [=]{}; // { dg-error "non-local lambda expression cannot have a capture-default" }
> +auto l2 = [&]{}; // { dg-error "non-local lambda expression cannot have a capture-default" }
> +
> +namespace {
> +  auto l3 = [=]{}; // { dg-error "non-local lambda expression cannot have a capture-default" }
> +  auto l4 = [&]{}; // { dg-error "non-local lambda expression cannot have a capture-default" }
> +}
> diff --git gcc/testsuite/g++.dg/cpp0x/lambda/lambda-this10.C gcc/testsuite/g++.dg/cpp0x/lambda/lambda-this10.C
> index b4b8e7201aa..e8e94771ef0 100644
> --- gcc/testsuite/g++.dg/cpp0x/lambda/lambda-this10.C
> +++ gcc/testsuite/g++.dg/cpp0x/lambda/lambda-this10.C
> @@ -1,4 +1,4 @@
>  // PR c++/54383
>  // { dg-do compile { target c++11 } }
>
> -auto foo = [&](int a) { return a > this->b; }; // { dg-error "this" }
> +auto foo = [&](int a) { return a > this->b; }; // { dg-error "non-local|this" }


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