diff options
Diffstat (limited to 'src/libsyntax/parse/parser.rs')
| -rw-r--r-- | src/libsyntax/parse/parser.rs | 80 |
1 files changed, 66 insertions, 14 deletions
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs index f3eac71ee77..d97d1e2f0f4 100644 --- a/src/libsyntax/parse/parser.rs +++ b/src/libsyntax/parse/parser.rs @@ -50,7 +50,10 @@ use crate::symbol::{Symbol, keywords}; use errors::{Applicability, DiagnosticBuilder, DiagnosticId, FatalError}; use rustc_target::spec::abi::{self, Abi}; -use syntax_pos::{Span, MultiSpan, BytePos, FileName}; +use syntax_pos::{ + Span, MultiSpan, BytePos, FileName, + hygiene::CompilerDesugaringKind, +}; use log::{debug, trace}; use std::borrow::Cow; @@ -186,6 +189,7 @@ enum PrevTokenKind { Interpolated, Eof, Ident, + BitOr, Other, } @@ -1375,6 +1379,7 @@ impl<'a> Parser<'a> { token::DocComment(..) => PrevTokenKind::DocComment, token::Comma => PrevTokenKind::Comma, token::BinOp(token::Plus) => PrevTokenKind::Plus, + token::BinOp(token::Or) => PrevTokenKind::BitOr, token::Interpolated(..) => PrevTokenKind::Interpolated, token::Eof => PrevTokenKind::Eof, token::Ident(..) => PrevTokenKind::Ident, @@ -2806,6 +2811,12 @@ impl<'a> Parser<'a> { let msg = format!("expected expression, found {}", self.this_token_descr()); let mut err = self.fatal(&msg); + let sp = self.sess.source_map().start_point(self.span); + if let Some(sp) = self.sess.ambiguous_block_expr_parse.borrow() + .get(&sp) + { + self.sess.expr_parentheses_needed(&mut err, *sp, None); + } err.span_label(self.span, "expected expression"); return Err(err); } @@ -2845,7 +2856,7 @@ impl<'a> Parser<'a> { "struct literals are not allowed here", ); err.multipart_suggestion( - "surround the struct literal with parenthesis", + "surround the struct literal with parentheses", vec![ (lo.shrink_to_lo(), "(".to_string()), (expr.span.shrink_to_hi(), ")".to_string()), @@ -3506,9 +3517,42 @@ impl<'a> Parser<'a> { } }; - if self.expr_is_complete(&lhs) { - // Semi-statement forms are odd. See https://github.com/rust-lang/rust/issues/29071 - return Ok(lhs); + match (self.expr_is_complete(&lhs), AssocOp::from_token(&self.token)) { + (true, None) => { + // Semi-statement forms are odd. See https://github.com/rust-lang/rust/issues/29071 + return Ok(lhs); + } + (false, _) => {} // continue parsing the expression + // An exhaustive check is done in the following block, but these are checked first + // because they *are* ambiguous but also reasonable looking incorrect syntax, so we + // want to keep their span info to improve diagnostics in these cases in a later stage. + (true, Some(AssocOp::Multiply)) | // `{ 42 } *foo = bar;` or `{ 42 } * 3` + (true, Some(AssocOp::Subtract)) | // `{ 42 } -5` + (true, Some(AssocOp::Add)) => { // `{ 42 } + 42 + // These cases are ambiguous and can't be identified in the parser alone + let sp = self.sess.source_map().start_point(self.span); + self.sess.ambiguous_block_expr_parse.borrow_mut().insert(sp, lhs.span); + return Ok(lhs); + } + (true, Some(ref op)) if !op.can_continue_expr_unambiguously() => { + return Ok(lhs); + } + (true, Some(_)) => { + // We've found an expression that would be parsed as a statement, but the next + // token implies this should be parsed as an expression. + // For example: `if let Some(x) = x { x } else { 0 } / 2` + let mut err = self.sess.span_diagnostic.struct_span_err(self.span, &format!( + "expected expression, found `{}`", + pprust::token_to_string(&self.token), + )); + err.span_label(self.span, "expected expression"); + self.sess.expr_parentheses_needed( + &mut err, + lhs.span, + Some(pprust::expr_to_string(&lhs), + )); + err.emit(); + } } self.expected_tokens.push(TokenType::Operator); while let Some(op) = AssocOp::from_token(&self.token) { @@ -4819,6 +4863,10 @@ impl<'a> Parser<'a> { ); let mut err = self.fatal(&msg); err.span_label(self.span, format!("expected {}", expected)); + let sp = self.sess.source_map().start_point(self.span); + if let Some(sp) = self.sess.ambiguous_block_expr_parse.borrow().get(&sp) { + self.sess.expr_parentheses_needed(&mut err, *sp, None); + } return Err(err); } } @@ -8727,6 +8775,10 @@ impl<'a> Parser<'a> { /// The arguments of the function are replaced in HIR lowering with the arguments created by /// this function and the statements created here are inserted at the top of the closure body. fn construct_async_arguments(&mut self, asyncness: &mut Spanned<IsAsync>, decl: &mut FnDecl) { + // FIXME(davidtwco): This function should really live in the HIR lowering but because + // the types constructed here need to be used in parts of resolve so that the correct + // locals are considered upvars, it is currently easier for it to live here in the parser, + // where it can be constructed once. if let IsAsync::Async { ref mut arguments, .. } = asyncness.node { for (index, input) in decl.inputs.iter_mut().enumerate() { let id = ast::DUMMY_NODE_ID; @@ -8741,6 +8793,15 @@ impl<'a> Parser<'a> { // statement. let (binding_mode, ident, is_simple_pattern) = match input.pat.node { PatKind::Ident(binding_mode @ BindingMode::ByValue(_), ident, _) => { + // Simple patterns like this don't have a generated argument, but they are + // moved into the closure with a statement, so any `mut` bindings on the + // argument will be unused. This binding mode can't be removed, because + // this would affect the input to procedural macros, but they can have + // their span marked as being the result of a compiler desugaring so + // that they aren't linted against. + input.pat.span = self.sess.source_map().mark_span_with_reason( + CompilerDesugaringKind::Async, span, None); + (binding_mode, ident, true) } _ => (BindingMode::ByValue(Mutability::Mutable), ident, false), @@ -8810,15 +8871,6 @@ impl<'a> Parser<'a> { }) }; - // Remove mutability from arguments. If this is not a simple pattern, - // those arguments are replaced by `__argN`, so there is no need to do this. - if let PatKind::Ident(BindingMode::ByValue(mutability @ Mutability::Mutable), ..) = - &mut input.pat.node - { - assert!(is_simple_pattern); - *mutability = Mutability::Immutable; - } - let move_stmt = Stmt { id, node: StmtKind::Local(P(move_local)), span }; arguments.push(AsyncArgument { ident, arg, pat_stmt, move_stmt }); } |