Re: [PATCH 1/2] Better union support in the parser

[Philip Herron <philip.herron@embecosm.com>]

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On 23/07/2021 00:19, Mark Wielaard wrote:
> union is a weak keyword which means it isn't reserved and can be used
> as a generic identifier. When we see an identifier where a union could
> be declared we check whether the identifier is "union", but only when
> the next token is also an identifier. In parse_union we shouldn't skip
> the first identifier token, because it is already skipped when we call
> expect_token.
> ---
>  gcc/rust/parse/rust-parse-impl.h | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/gcc/rust/parse/rust-parse-impl.h b/gcc/rust/parse/rust-parse-impl.h
> index bdf1e09a029..3996ef21672 100644
> --- a/gcc/rust/parse/rust-parse-impl.h
> +++ b/gcc/rust/parse/rust-parse-impl.h
> @@ -1083,7 +1083,8 @@ Parser<ManagedTokenSource>::parse_item (bool called_from_statement)
>      // crappy hack to do union "keyword"
>      case IDENTIFIER:
>        // TODO: ensure std::string and literal comparison works
> -      if (t->get_str () == "union")
> +      if (t->get_str () == "union"
> +	  && lexer.peek_token (1)->get_id () == IDENTIFIER)
>  	{
>  	  return parse_vis_item (std::move (outer_attrs));
>  	  // or should this go straight to parsing union?
> @@ -1274,8 +1275,8 @@ Parser<ManagedTokenSource>::parse_vis_item (AST::AttrVec outer_attrs)
>      // TODO: implement union keyword but not really because of
>      // context-dependence case UNION: crappy hack to do union "keyword"
>      case IDENTIFIER:
> -      // TODO: ensure std::string and literal comparison works
> -      if (t->get_str () == "union")
> +      if (t->get_str () == "union"
> +	  && lexer.peek_token (1)->get_id () == IDENTIFIER)
>  	{
>  	  return parse_union (std::move (vis), std::move (outer_attrs));
>  	  // or should item switch go straight to parsing union?
> @@ -4524,7 +4525,6 @@ Parser<ManagedTokenSource>::parse_union (AST::Visibility vis,
>    const_TokenPtr union_keyword = expect_token (IDENTIFIER);
>    rust_assert (union_keyword->get_str () == "union");
>    Location locus = union_keyword->get_locus ();
> -  lexer.skip_token ();
>  
>    // parse actual union name
>    const_TokenPtr union_name_tok = expect_token (IDENTIFIER);
> @@ -6054,8 +6054,8 @@ Parser<ManagedTokenSource>::parse_stmt ()
>        break;
>      // crappy hack to do union "keyword"
>      case IDENTIFIER:
> -      // TODO: ensure std::string and literal comparison works
> -      if (t->get_str () == "union")
> +      if (t->get_str () == "union"
> +	  && lexer.peek_token (1)->get_id () == IDENTIFIER)
>  	{
>  	  return parse_vis_item (std::move (outer_attrs));
>  	  // or should this go straight to parsing union?
> @@ -11674,8 +11674,8 @@ Parser<ManagedTokenSource>::parse_stmt_or_expr_without_block ()
>        }
>      // crappy hack to do union "keyword"
>      case IDENTIFIER:
> -      // TODO: ensure std::string and literal comparison works
> -      if (t->get_str () == "union")
> +      if (t->get_str () == "union"
> +	  && lexer.peek_token (1)->get_id () == IDENTIFIER)
>  	{
>  	  std::unique_ptr<AST::VisItem> item (
>  	    parse_vis_item (std::move (outer_attrs)));

Looks great, I will merge this now.

--Phil



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