diff --git a/src/librustc_parse/parser/diagnostics.rs b/src/librustc_parse/parser/diagnostics.rs index 12b9b68268248..552f3d798ae8a 100644 --- a/src/librustc_parse/parser/diagnostics.rs +++ b/src/librustc_parse/parser/diagnostics.rs @@ -1054,6 +1054,39 @@ impl<'a> Parser<'a> { } } + pub(super) fn try_macro_suggestion(&mut self) -> PResult<'a, P> { + let is_try = self.token.is_keyword(kw::Try); + let is_questionmark = self.look_ahead(1, |t| t == &token::Not); //check for ! + let is_open = self.look_ahead(2, |t| t == &token::OpenDelim(token::Paren)); //check for ( + + if is_try && is_questionmark && is_open { + let lo = self.token.span; + self.bump(); //remove try + self.bump(); //remove ! + let try_span = lo.to(self.token.span); //we take the try!( span + self.bump(); //remove ( + let is_empty = self.token == token::CloseDelim(token::Paren); //check if the block is empty + self.consume_block(token::Paren, ConsumeClosingDelim::No); //eat the block + let hi = self.token.span; + self.bump(); //remove ) + let mut err = self.struct_span_err(lo.to(hi), "use of deprecated `try` macro"); + err.note("in the 2018 edition `try` is a reserved keyword, and the `try!()` macro is deprecated"); + let prefix = if is_empty { "" } else { "alternatively, " }; + if !is_empty { + err.multipart_suggestion( + "you can use the `?` operator instead", + vec![(try_span, "".to_owned()), (hi, "?".to_owned())], + Applicability::MachineApplicable, + ); + } + err.span_suggestion(lo.shrink_to_lo(), &format!("{}you can still access the deprecated `try!()` macro using the \"raw identifier\" syntax", prefix), "r#".to_string(), Applicability::MachineApplicable); + err.emit(); + Ok(self.mk_expr_err(lo.to(hi))) + } else { + Err(self.expected_expression_found()) // The user isn't trying to invoke the try! macro + } + } + /// Recovers a situation like `for ( $pat in $expr )` /// and suggest writing `for $pat in $expr` instead. /// diff --git a/src/librustc_parse/parser/expr.rs b/src/librustc_parse/parser/expr.rs index 4e3c5fa63de2c..986f5410e26c0 100644 --- a/src/librustc_parse/parser/expr.rs +++ b/src/librustc_parse/parser/expr.rs @@ -1006,7 +1006,7 @@ impl<'a> Parser<'a> { let expr = self.mk_expr(lo.to(self.prev_token.span), ExprKind::Lit(literal), attrs); self.maybe_recover_from_bad_qpath(expr, true) } - None => Err(self.expected_expression_found()), + None => self.try_macro_suggestion(), } } diff --git a/src/test/ui/try-macro-suggestion.rs b/src/test/ui/try-macro-suggestion.rs new file mode 100644 index 0000000000000..635ceac0b199e --- /dev/null +++ b/src/test/ui/try-macro-suggestion.rs @@ -0,0 +1,9 @@ +// compile-flags: --edition 2018 +fn foo() -> Result<(), ()> { + Ok(try!()); //~ ERROR use of deprecated `try` macro + Ok(try!(Ok(()))) //~ ERROR use of deprecated `try` macro +} + +fn main() { + let _ = foo(); +} diff --git a/src/test/ui/try-macro-suggestion.stderr b/src/test/ui/try-macro-suggestion.stderr new file mode 100644 index 0000000000000..9d833ef5ed9fb --- /dev/null +++ b/src/test/ui/try-macro-suggestion.stderr @@ -0,0 +1,30 @@ +error: use of deprecated `try` macro + --> $DIR/try-macro-suggestion.rs:3:8 + | +LL | Ok(try!()); + | ^^^^^^ + | + = note: in the 2018 edition `try` is a reserved keyword, and the `try!()` macro is deprecated +help: you can still access the deprecated `try!()` macro using the "raw identifier" syntax + | +LL | Ok(r#try!()); + | ^^ + +error: use of deprecated `try` macro + --> $DIR/try-macro-suggestion.rs:4:8 + | +LL | Ok(try!(Ok(()))) + | ^^^^^^^^^^^^ + | + = note: in the 2018 edition `try` is a reserved keyword, and the `try!()` macro is deprecated +help: you can use the `?` operator instead + | +LL | Ok(Ok(())?) + | -- ^ +help: alternatively, you can still access the deprecated `try!()` macro using the "raw identifier" syntax + | +LL | Ok(r#try!(Ok(()))) + | ^^ + +error: aborting due to 2 previous errors +