diff options
Diffstat (limited to 'src/libsyntax/parse/diagnostics.rs')
| -rw-r--r-- | src/libsyntax/parse/diagnostics.rs | 436 |
1 files changed, 429 insertions, 7 deletions
diff --git a/src/libsyntax/parse/diagnostics.rs b/src/libsyntax/parse/diagnostics.rs index 11f8eba033e..7df9b80c3c5 100644 --- a/src/libsyntax/parse/diagnostics.rs +++ b/src/libsyntax/parse/diagnostics.rs @@ -1,19 +1,104 @@ use crate::ast; use crate::ast::{ - BlockCheckMode, Expr, ExprKind, Item, ItemKind, Pat, PatKind, QSelf, Ty, TyKind, VariantData, + BlockCheckMode, BinOpKind, Expr, ExprKind, Item, ItemKind, Pat, PatKind, PathSegment, QSelf, + Ty, TyKind, VariantData, }; -use crate::parse::parser::{BlockMode, PathStyle, SemiColonMode, TokenType}; +use crate::parse::{SeqSep, token, PResult, Parser}; +use crate::parse::parser::{BlockMode, PathStyle, SemiColonMode, TokenType, TokenExpectType}; use crate::parse::token; -use crate::parse::PResult; -use crate::parse::Parser; use crate::print::pprust; use crate::ptr::P; use crate::source_map::Spanned; use crate::symbol::kw; use crate::ThinVec; -use errors::{Applicability, DiagnosticBuilder}; -use log::debug; -use syntax_pos::{Span, DUMMY_SP}; +use crate::tokenstream::TokenTree; +use crate::util::parser::AssocOp; +use errors::{Applicability, DiagnosticBuilder, DiagnosticId, FatalError}; +use syntax_pos::{Span, DUMMY_SP, MultiSpan}; +use log::{debug, trace}; +use std::slice; + +pub enum Error { + FileNotFoundForModule { + mod_name: String, + default_path: String, + secondary_path: String, + dir_path: String, + }, + DuplicatePaths { + mod_name: String, + default_path: String, + secondary_path: String, + }, + UselessDocComment, + InclusiveRangeWithNoEnd, +} + +impl Error { + fn span_err<S: Into<MultiSpan>>( + self, + sp: S, + handler: &errors::Handler, + ) -> DiagnosticBuilder<'_> { + match self { + Error::FileNotFoundForModule { + ref mod_name, + ref default_path, + ref secondary_path, + ref dir_path, + } => { + let mut err = struct_span_err!( + handler, + sp, + E0583, + "file not found for module `{}`", + mod_name, + ); + err.help(&format!( + "name the file either {} or {} inside the directory \"{}\"", + default_path, + secondary_path, + dir_path, + )); + err + } + Error::DuplicatePaths { ref mod_name, ref default_path, ref secondary_path } => { + let mut err = struct_span_err!( + handler, + sp, + E0584, + "file for module `{}` found at both {} and {}", + mod_name, + default_path, + secondary_path, + ); + err.help("delete or rename one of them to remove the ambiguity"); + err + } + Error::UselessDocComment => { + let mut err = struct_span_err!( + handler, + sp, + E0585, + "found a documentation comment that doesn't document anything", + ); + err.help("doc comments must come before what they document, maybe a comment was \ + intended with `//`?"); + err + } + Error::InclusiveRangeWithNoEnd => { + let mut err = struct_span_err!( + handler, + sp, + E0586, + "inclusive range with no end", + ); + err.help("inclusive ranges must be bounded at the end (`..=b` or `a..=b`)"); + err + } + } + } +} pub trait RecoverQPath: Sized + 'static { const PATH_STYLE: PathStyle = PathStyle::Expr; @@ -63,6 +148,253 @@ impl RecoverQPath for Expr { } impl<'a> Parser<'a> { + pub fn look_ahead<R, F>(&self, dist: usize, f: F) -> R where + F: FnOnce(&token::Token) -> R, + { + if dist == 0 { + return f(&self.token) + } + + f(&match self.token_cursor.frame.tree_cursor.look_ahead(dist - 1) { + Some(tree) => match tree { + TokenTree::Token(_, tok) => tok, + TokenTree::Delimited(_, delim, _) => token::OpenDelim(delim), + }, + None => token::CloseDelim(self.token_cursor.frame.delim), + }) + } + + crate fn look_ahead_span(&self, dist: usize) -> Span { + if dist == 0 { + return self.span + } + + match self.token_cursor.frame.tree_cursor.look_ahead(dist - 1) { + Some(TokenTree::Token(span, _)) => span, + Some(TokenTree::Delimited(span, ..)) => span.entire(), + None => self.look_ahead_span(dist - 1), + } + } + + pub fn fatal(&self, m: &str) -> DiagnosticBuilder<'a> { + self.sess.span_diagnostic.struct_span_fatal(self.span, m) + } + + pub fn span_fatal<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> DiagnosticBuilder<'a> { + self.sess.span_diagnostic.struct_span_fatal(sp, m) + } + + pub fn span_fatal_err<S: Into<MultiSpan>>(&self, sp: S, err: Error) -> DiagnosticBuilder<'a> { + err.span_err(sp, self.diagnostic()) + } + + pub fn bug(&self, m: &str) -> ! { + self.sess.span_diagnostic.span_bug(self.span, m) + } + + pub fn span_err<S: Into<MultiSpan>>(&self, sp: S, m: &str) { + self.sess.span_diagnostic.span_err(sp, m) + } + + crate fn struct_span_err<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> DiagnosticBuilder<'a> { + self.sess.span_diagnostic.struct_span_err(sp, m) + } + + crate fn span_bug<S: Into<MultiSpan>>(&self, sp: S, m: &str) -> ! { + self.sess.span_diagnostic.span_bug(sp, m) + } + + crate fn cancel(&self, err: &mut DiagnosticBuilder<'_>) { + self.sess.span_diagnostic.cancel(err) + } + + crate fn diagnostic(&self) -> &'a errors::Handler { + &self.sess.span_diagnostic + } + + crate fn expected_ident_found(&self) -> DiagnosticBuilder<'a> { + let mut err = self.struct_span_err( + self.span, + &format!("expected identifier, found {}", self.this_token_descr()), + ); + if let token::Ident(ident, false) = &self.token { + if ident.is_raw_guess() { + err.span_suggestion( + self.span, + "you can escape reserved keywords to use them as identifiers", + format!("r#{}", ident), + Applicability::MaybeIncorrect, + ); + } + } + if let Some(token_descr) = self.token_descr() { + err.span_label(self.span, format!("expected identifier, found {}", token_descr)); + } else { + err.span_label(self.span, "expected identifier"); + if self.token == token::Comma && self.look_ahead(1, |t| t.is_ident()) { + err.span_suggestion( + self.span, + "remove this comma", + String::new(), + Applicability::MachineApplicable, + ); + } + } + err + } + + /// Eats and discards tokens until one of `kets` is encountered. Respects token trees, + /// passes through any errors encountered. Used for error recovery. + crate fn eat_to_tokens(&mut self, kets: &[&token::Token]) { + let handler = self.diagnostic(); + + if let Err(ref mut err) = self.parse_seq_to_before_tokens( + kets, + SeqSep::none(), + TokenExpectType::Expect, + |p| Ok(p.parse_token_tree()), + ) { + handler.cancel(err); + } + } + + /// This function checks if there are trailing angle brackets and produces + /// a diagnostic to suggest removing them. + /// + /// ```ignore (diagnostic) + /// let _ = vec![1, 2, 3].into_iter().collect::<Vec<usize>>>>(); + /// ^^ help: remove extra angle brackets + /// ``` + crate fn check_trailing_angle_brackets(&mut self, segment: &PathSegment, end: token::Token) { + // This function is intended to be invoked after parsing a path segment where there are two + // cases: + // + // 1. A specific token is expected after the path segment. + // eg. `x.foo(`, `x.foo::<u32>(` (parenthesis - method call), + // `Foo::`, or `Foo::<Bar>::` (mod sep - continued path). + // 2. No specific token is expected after the path segment. + // eg. `x.foo` (field access) + // + // This function is called after parsing `.foo` and before parsing the token `end` (if + // present). This includes any angle bracket arguments, such as `.foo::<u32>` or + // `Foo::<Bar>`. + + // We only care about trailing angle brackets if we previously parsed angle bracket + // arguments. This helps stop us incorrectly suggesting that extra angle brackets be + // removed in this case: + // + // `x.foo >> (3)` (where `x.foo` is a `u32` for example) + // + // This case is particularly tricky as we won't notice it just looking at the tokens - + // it will appear the same (in terms of upcoming tokens) as below (since the `::<u32>` will + // have already been parsed): + // + // `x.foo::<u32>>>(3)` + let parsed_angle_bracket_args = segment.args + .as_ref() + .map(|args| args.is_angle_bracketed()) + .unwrap_or(false); + + debug!( + "check_trailing_angle_brackets: parsed_angle_bracket_args={:?}", + parsed_angle_bracket_args, + ); + if !parsed_angle_bracket_args { + return; + } + + // Keep the span at the start so we can highlight the sequence of `>` characters to be + // removed. + let lo = self.span; + + // We need to look-ahead to see if we have `>` characters without moving the cursor forward + // (since we might have the field access case and the characters we're eating are + // actual operators and not trailing characters - ie `x.foo >> 3`). + let mut position = 0; + + // We can encounter `>` or `>>` tokens in any order, so we need to keep track of how + // many of each (so we can correctly pluralize our error messages) and continue to + // advance. + let mut number_of_shr = 0; + let mut number_of_gt = 0; + while self.look_ahead(position, |t| { + trace!("check_trailing_angle_brackets: t={:?}", t); + if *t == token::BinOp(token::BinOpToken::Shr) { + number_of_shr += 1; + true + } else if *t == token::Gt { + number_of_gt += 1; + true + } else { + false + } + }) { + position += 1; + } + + // If we didn't find any trailing `>` characters, then we have nothing to error about. + debug!( + "check_trailing_angle_brackets: number_of_gt={:?} number_of_shr={:?}", + number_of_gt, number_of_shr, + ); + if number_of_gt < 1 && number_of_shr < 1 { + return; + } + + // Finally, double check that we have our end token as otherwise this is the + // second case. + if self.look_ahead(position, |t| { + trace!("check_trailing_angle_brackets: t={:?}", t); + *t == end + }) { + // Eat from where we started until the end token so that parsing can continue + // as if we didn't have those extra angle brackets. + self.eat_to_tokens(&[&end]); + let span = lo.until(self.span); + + let plural = number_of_gt > 1 || number_of_shr >= 1; + self.diagnostic() + .struct_span_err( + span, + &format!("unmatched angle bracket{}", if plural { "s" } else { "" }), + ) + .span_suggestion( + span, + &format!("remove extra angle bracket{}", if plural { "s" } else { "" }), + String::new(), + Applicability::MachineApplicable, + ) + .emit(); + } + } + + /// Produce an error if comparison operators are chained (RFC #558). + /// We only need to check lhs, not rhs, because all comparison ops + /// have same precedence and are left-associative + crate fn check_no_chained_comparison(&self, lhs: &Expr, outer_op: &AssocOp) { + debug_assert!(outer_op.is_comparison(), + "check_no_chained_comparison: {:?} is not comparison", + outer_op); + match lhs.node { + ExprKind::Binary(op, _, _) if op.node.is_comparison() => { + // respan to include both operators + let op_span = op.span.to(self.span); + let mut err = self.diagnostic().struct_span_err(op_span, + "chained comparison operators require parentheses"); + if op.node == BinOpKind::Lt && + *outer_op == AssocOp::Less || // Include `<` to provide this recommendation + *outer_op == AssocOp::Greater // even in a case like the following: + { // Foo<Bar<Baz<Qux, ()>>> + err.help( + "use `::<...>` instead of `<...>` if you meant to specify type arguments"); + err.help("or use `(...)` if you meant to specify fn arguments"); + } + err.emit(); + } + _ => {} + } + } + crate fn maybe_report_ambiguous_plus( &mut self, allow_plus: bool, @@ -594,6 +926,96 @@ impl<'a> Parser<'a> { } } + crate fn check_for_for_in_in_typo(&mut self, in_span: Span) { + if self.eat_keyword(kw::In) { + // a common typo: `for _ in in bar {}` + let mut err = self.sess.span_diagnostic.struct_span_err( + self.prev_span, + "expected iterable, found keyword `in`", + ); + err.span_suggestion_short( + in_span.until(self.prev_span), + "remove the duplicated `in`", + String::new(), + Applicability::MachineApplicable, + ); + err.note("if you meant to use emplacement syntax, it is obsolete (for now, anyway)"); + err.note("for more information on the status of emplacement syntax, see <\ + https://github.com/rust-lang/rust/issues/27779#issuecomment-378416911>"); + err.emit(); + } + } + + crate fn expected_semi_or_open_brace(&mut self) -> PResult<'a, ast::TraitItem> { + let token_str = self.this_token_descr(); + let mut err = self.fatal(&format!("expected `;` or `{{`, found {}", token_str)); + err.span_label(self.span, "expected `;` or `{`"); + Err(err) + } + + crate fn eat_incorrect_doc_comment(&mut self, applied_to: &str) { + if let token::DocComment(_) = self.token { + let mut err = self.diagnostic().struct_span_err( + self.span, + &format!("documentation comments cannot be applied to {}", applied_to), + ); + err.span_label(self.span, "doc comments are not allowed here"); + err.emit(); + self.bump(); + } else if self.token == token::Pound && self.look_ahead(1, |t| { + *t == token::OpenDelim(token::Bracket) + }) { + let lo = self.span; + // Skip every token until next possible arg. + while self.token != token::CloseDelim(token::Bracket) { + self.bump(); + } + let sp = lo.to(self.span); + self.bump(); + let mut err = self.diagnostic().struct_span_err( + sp, + &format!("attributes cannot be applied to {}", applied_to), + ); + err.span_label(sp, "attributes are not allowed here"); + err.emit(); + } + } + + crate fn argument_without_type( + &mut self, + err: &mut DiagnosticBuilder<'_>, + pat: P<ast::Pat>, + require_name: bool, + is_trait_item: bool, + ) { + // If we find a pattern followed by an identifier, it could be an (incorrect) + // C-style parameter declaration. + if self.check_ident() && self.look_ahead(1, |t| { + *t == token::Comma || *t == token::CloseDelim(token::Paren) + }) { + let ident = self.parse_ident().unwrap(); + let span = pat.span.with_hi(ident.span.hi()); + + err.span_suggestion( + span, + "declare the type after the parameter binding", + String::from("<identifier>: <type>"), + Applicability::HasPlaceholders, + ); + } else if require_name && is_trait_item { + if let PatKind::Ident(_, ident, _) = pat.node { + err.span_suggestion( + pat.span, + "explicitly ignore parameter", + format!("_: {}", ident), + Applicability::MachineApplicable, + ); + } + + err.note("anonymous parameters are removed in the 2018 edition (see RFC 1685)"); + } + } + crate fn recover_arg_parse(&mut self) -> PResult<'a, (P<ast::Pat>, P<ast::Ty>)> { let pat = self.parse_pat(Some("argument name"))?; self.expect(&token::Colon)?; |