From b83352e44c36e81db7f00eb60e78ff3828c51c9e Mon Sep 17 00:00:00 2001 From: Esteban Küber Date: Tue, 28 Mar 2017 18:56:29 -0700 Subject: Introduce `TyErr` independent from `TyInfer` Add a `TyErr` type to represent unknown types in places where parse errors have happened, while still able to build the AST. Initially only used to represent incorrectly written fn arguments and avoid "expected X parameters, found Y" errors when called with the appropriate amount of parameters. We cannot use `TyInfer` for this as `_` is not allowed as a valid argument type. Example output: ```rust error: expected one of `:` or `@`, found `,` --> file.rs:12:9 | 12 | fn bar(x, y: usize) {} | ^ error[E0061]: this function takes 2 parameters but 3 parameters were supplied --> file.rs:19:9 | 12 | fn bar(x, y) {} | --------------- defined here ... 19 | bar(1, 2, 3); | ^^^^^^^ expected 2 parameters ``` --- src/libsyntax/parse/parser.rs | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-) (limited to 'src/libsyntax/parse') diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs index c2c3e5a6855..23fc1351426 100644 --- a/src/libsyntax/parse/parser.rs +++ b/src/libsyntax/parse/parser.rs @@ -407,6 +407,25 @@ impl From> for LhsExpr { } } +/// Create a placeholder argument. +fn dummy_arg(span: Span) -> Arg { + let spanned = Spanned { + span: span, + node: keywords::Invalid.ident() + }; + let pat = P(Pat { + id: ast::DUMMY_NODE_ID, + node: PatKind::Ident(BindingMode::ByValue(Mutability::Immutable), spanned, None), + span: span + }); + let ty = Ty { + node: TyKind::Err, + span: span, + id: ast::DUMMY_NODE_ID + }; + Arg { ty: P(ty), pat: pat, id: ast::DUMMY_NODE_ID } +} + impl<'a> Parser<'a> { pub fn new(sess: &'a ParseSess, tokens: TokenStream, @@ -4343,8 +4362,12 @@ impl<'a> Parser<'a> { Ok(arg) => Ok(Some(arg)), Err(mut e) => { e.emit(); + let lo = p.prev_span; + // Skip every token until next possible arg or end. p.eat_to_tokens(&[&token::Comma, &token::CloseDelim(token::Paren)]); - Ok(None) + // Create a placeholder argument for proper arg count (#34264). + let span = lo.to(p.prev_span); + Ok(Some(dummy_arg(span))) } } } -- cgit 1.4.1-3-g733a5