diff options
Diffstat (limited to 'compiler/rustc_parse/src')
| -rw-r--r-- | compiler/rustc_parse/src/errors.rs | 8 | ||||
| -rw-r--r-- | compiler/rustc_parse/src/parser/diagnostics.rs | 87 | ||||
| -rw-r--r-- | compiler/rustc_parse/src/parser/expr.rs | 24 | ||||
| -rw-r--r-- | compiler/rustc_parse/src/parser/item.rs | 46 | ||||
| -rw-r--r-- | compiler/rustc_parse/src/parser/mod.rs | 6 | ||||
| -rw-r--r-- | compiler/rustc_parse/src/parser/pat.rs | 18 | ||||
| -rw-r--r-- | compiler/rustc_parse/src/parser/stmt.rs | 10 | ||||
| -rw-r--r-- | compiler/rustc_parse/src/parser/ty.rs | 162 |
8 files changed, 322 insertions, 39 deletions
diff --git a/compiler/rustc_parse/src/errors.rs b/compiler/rustc_parse/src/errors.rs index 18a0bee9c2e..574591529f3 100644 --- a/compiler/rustc_parse/src/errors.rs +++ b/compiler/rustc_parse/src/errors.rs @@ -1229,3 +1229,11 @@ pub(crate) struct FnTypoWithImpl { #[suggestion(applicability = "maybe-incorrect", code = "impl", style = "verbose")] pub fn_span: Span, } + +#[derive(Diagnostic)] +#[diag(parse_expected_fn_path_found_fn_keyword)] +pub(crate) struct ExpectedFnPathFoundFnKeyword { + #[primary_span] + #[suggestion(applicability = "machine-applicable", code = "Fn", style = "verbose")] + pub fn_token_span: Span, +} diff --git a/compiler/rustc_parse/src/parser/diagnostics.rs b/compiler/rustc_parse/src/parser/diagnostics.rs index 0191ab730c8..d9fa3e31db9 100644 --- a/compiler/rustc_parse/src/parser/diagnostics.rs +++ b/compiler/rustc_parse/src/parser/diagnostics.rs @@ -31,7 +31,8 @@ use rustc_ast::{ use rustc_ast_pretty::pprust; use rustc_data_structures::fx::FxHashSet; use rustc_errors::{ - fluent, Applicability, DiagnosticBuilder, DiagnosticMessage, Handler, MultiSpan, PResult, + fluent, Applicability, DiagnosticBuilder, DiagnosticMessage, FatalError, Handler, MultiSpan, + PResult, }; use rustc_errors::{pluralize, Diagnostic, ErrorGuaranteed, IntoDiagnostic}; use rustc_session::errors::ExprParenthesesNeeded; @@ -41,7 +42,6 @@ use rustc_span::{Span, SpanSnippetError, DUMMY_SP}; use std::mem::take; use std::ops::{Deref, DerefMut}; use thin_vec::{thin_vec, ThinVec}; -use tracing::{debug, trace}; /// Creates a placeholder argument. pub(super) fn dummy_arg(ident: Ident) -> Param { @@ -1104,7 +1104,11 @@ impl<'a> Parser<'a> { return if token::ModSep == self.token.kind { // We have some certainty that this was a bad turbofish at this point. // `foo< bar >::` - err.suggest_turbofish = Some(op.span.shrink_to_lo()); + if let ExprKind::Binary(o, ..) = inner_op.kind && o.node == BinOpKind::Lt { + err.suggest_turbofish = Some(op.span.shrink_to_lo()); + } else { + err.help_turbofish = Some(()); + } let snapshot = self.create_snapshot_for_diagnostic(); self.bump(); // `::` @@ -1130,7 +1134,11 @@ impl<'a> Parser<'a> { } else if token::OpenDelim(Delimiter::Parenthesis) == self.token.kind { // We have high certainty that this was a bad turbofish at this point. // `foo< bar >(` - err.suggest_turbofish = Some(op.span.shrink_to_lo()); + if let ExprKind::Binary(o, ..) = inner_op.kind && o.node == BinOpKind::Lt { + err.suggest_turbofish = Some(op.span.shrink_to_lo()); + } else { + err.help_turbofish = Some(()); + } // Consume the fn call arguments. match self.consume_fn_args() { Err(()) => Err(err.into_diagnostic(&self.sess.span_diagnostic)), @@ -1230,7 +1238,7 @@ impl<'a> Parser<'a> { let sum_span = ty.span.to(self.prev_token.span); let sub = match &ty.kind { - TyKind::Rptr(lifetime, mut_ty) => { + TyKind::Ref(lifetime, mut_ty) => { let sum_with_parens = pprust::to_string(|s| { s.s.word("&"); s.print_opt_lifetime(lifetime); @@ -2557,6 +2565,75 @@ impl<'a> Parser<'a> { Ok(()) } + pub fn is_diff_marker(&mut self, long_kind: &TokenKind, short_kind: &TokenKind) -> bool { + (0..3).all(|i| self.look_ahead(i, |tok| tok == long_kind)) + && self.look_ahead(3, |tok| tok == short_kind) + } + + fn diff_marker(&mut self, long_kind: &TokenKind, short_kind: &TokenKind) -> Option<Span> { + if self.is_diff_marker(long_kind, short_kind) { + let lo = self.token.span; + for _ in 0..4 { + self.bump(); + } + return Some(lo.to(self.prev_token.span)); + } + None + } + + pub fn recover_diff_marker(&mut self) { + let Some(start) = self.diff_marker(&TokenKind::BinOp(token::Shl), &TokenKind::Lt) else { + return; + }; + let mut spans = Vec::with_capacity(3); + spans.push(start); + let mut middlediff3 = None; + let mut middle = None; + let mut end = None; + loop { + if self.token.kind == TokenKind::Eof { + break; + } + if let Some(span) = self.diff_marker(&TokenKind::OrOr, &TokenKind::BinOp(token::Or)) { + middlediff3 = Some(span); + } + if let Some(span) = self.diff_marker(&TokenKind::EqEq, &TokenKind::Eq) { + middle = Some(span); + } + if let Some(span) = self.diff_marker(&TokenKind::BinOp(token::Shr), &TokenKind::Gt) { + spans.push(span); + end = Some(span); + break; + } + self.bump(); + } + let mut err = self.struct_span_err(spans, "encountered diff marker"); + err.span_label(start, "after this is the code before the merge"); + if let Some(middle) = middlediff3 { + err.span_label(middle, ""); + } + if let Some(middle) = middle { + err.span_label(middle, ""); + } + if let Some(end) = end { + err.span_label(end, "above this are the incoming code changes"); + } + err.help( + "if you're having merge conflicts after pulling new code, the top section is the code \ + you already had and the bottom section is the remote code", + ); + err.help( + "if you're in the middle of a rebase, the top section is the code being rebased onto \ + and the bottom section is the code coming from the current commit being rebased", + ); + err.note( + "for an explanation on these markers from the `git` documentation, visit \ + <https://git-scm.com/book/en/v2/Git-Tools-Advanced-Merging#_checking_out_conflicts>", + ); + err.emit(); + FatalError.raise() + } + /// Parse and throw away a parenthesized comma separated /// sequence of patterns until `)` is reached. fn skip_pat_list(&mut self) -> PResult<'a, ()> { diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs index c0ed450b985..9f436783ced 100644 --- a/compiler/rustc_parse/src/parser/expr.rs +++ b/compiler/rustc_parse/src/parser/expr.rs @@ -182,7 +182,7 @@ impl<'a> Parser<'a> { LhsExpr::AttributesParsed(attrs) => Some(attrs), _ => None, }; - if [token::DotDot, token::DotDotDot, token::DotDotEq].contains(&self.token.kind) { + if self.token.is_range_separator() { return self.parse_prefix_range_expr(attrs); } else { self.parse_prefix_expr(attrs)? @@ -514,7 +514,7 @@ impl<'a> Parser<'a> { } debug_assert!( - [token::DotDot, token::DotDotDot, token::DotDotEq].contains(&self.token.kind), + self.token.is_range_separator(), "parse_prefix_range_expr: token {:?} is not DotDot/DotDotEq", self.token ); @@ -899,7 +899,11 @@ impl<'a> Parser<'a> { let has_lifetime = self.token.is_lifetime() && self.look_ahead(1, |t| t != &token::Colon); let lifetime = has_lifetime.then(|| self.expect_lifetime()); // For recovery, see below. let (borrow_kind, mutbl) = self.parse_borrow_modifiers(lo); - let expr = self.parse_prefix_expr(None); + let expr = if self.token.is_range_separator() { + self.parse_prefix_range_expr(None) + } else { + self.parse_prefix_expr(None) + }; let (hi, expr) = self.interpolated_or_expr_span(expr)?; let span = lo.to(hi); if let Some(lt) = lifetime { @@ -1499,12 +1503,13 @@ impl<'a> Parser<'a> { prior_type_ascription: self.last_type_ascription, }); (lo.to(self.prev_token.span), ExprKind::MacCall(mac)) - } else if self.check(&token::OpenDelim(Delimiter::Brace)) && - let Some(expr) = self.maybe_parse_struct_expr(&qself, &path) { - if qself.is_some() { - self.sess.gated_spans.gate(sym::more_qualified_paths, path.span); - } - return expr; + } else if self.check(&token::OpenDelim(Delimiter::Brace)) + && let Some(expr) = self.maybe_parse_struct_expr(&qself, &path) + { + if qself.is_some() { + self.sess.gated_spans.gate(sym::more_qualified_paths, path.span); + } + return expr; } else { (path.span, ExprKind::Path(qself, path)) }; @@ -3035,6 +3040,7 @@ impl<'a> Parser<'a> { /// Parses `ident (COLON expr)?`. fn parse_expr_field(&mut self) -> PResult<'a, ExprField> { let attrs = self.parse_outer_attributes()?; + self.recover_diff_marker(); self.collect_tokens_trailing_token(attrs, ForceCollect::No, |this, attrs| { let lo = this.token.span; diff --git a/compiler/rustc_parse/src/parser/item.rs b/compiler/rustc_parse/src/parser/item.rs index 7c2d01509de..a958c294930 100644 --- a/compiler/rustc_parse/src/parser/item.rs +++ b/compiler/rustc_parse/src/parser/item.rs @@ -24,7 +24,6 @@ use rustc_span::symbol::{kw, sym, Ident, Symbol}; use rustc_span::DUMMY_SP; use std::mem; use thin_vec::ThinVec; -use tracing::debug; impl<'a> Parser<'a> { /// Parses a source module as a crate. This is the main entry point for the parser. @@ -99,7 +98,9 @@ impl<'a> Parser<'a> { fn_parse_mode: FnParseMode, force_collect: ForceCollect, ) -> PResult<'a, Option<Item>> { + self.recover_diff_marker(); let attrs = self.parse_outer_attributes()?; + self.recover_diff_marker(); self.parse_item_common(attrs, true, false, fn_parse_mode, force_collect) } @@ -705,6 +706,7 @@ impl<'a> Parser<'a> { if self.recover_doc_comment_before_brace() { continue; } + self.recover_diff_marker(); match parse_item(self) { Ok(None) => { let mut is_unnecessary_semicolon = !items.is_empty() @@ -1040,8 +1042,11 @@ impl<'a> Parser<'a> { /// USE_TREE_LIST = Ø | (USE_TREE `,`)* USE_TREE [`,`] /// ``` fn parse_use_tree_list(&mut self) -> PResult<'a, Vec<(UseTree, ast::NodeId)>> { - self.parse_delim_comma_seq(Delimiter::Brace, |p| Ok((p.parse_use_tree()?, DUMMY_NODE_ID))) - .map(|(r, _)| r) + self.parse_delim_comma_seq(Delimiter::Brace, |p| { + p.recover_diff_marker(); + Ok((p.parse_use_tree()?, DUMMY_NODE_ID)) + }) + .map(|(r, _)| r) } fn parse_rename(&mut self) -> PResult<'a, Option<Ident>> { @@ -1380,7 +1385,9 @@ impl<'a> Parser<'a> { } fn parse_enum_variant(&mut self) -> PResult<'a, Option<Variant>> { + self.recover_diff_marker(); let variant_attrs = self.parse_outer_attributes()?; + self.recover_diff_marker(); self.collect_tokens_trailing_token( variant_attrs, ForceCollect::No, @@ -1574,9 +1581,32 @@ impl<'a> Parser<'a> { self.parse_paren_comma_seq(|p| { let attrs = p.parse_outer_attributes()?; p.collect_tokens_trailing_token(attrs, ForceCollect::No, |p, attrs| { + let mut snapshot = None; + if p.is_diff_marker(&TokenKind::BinOp(token::Shl), &TokenKind::Lt) { + // Account for `<<<<<<<` diff markers. We can't proactively error here because + // that can be a valid type start, so we snapshot and reparse only we've + // encountered another parse error. + snapshot = Some(p.create_snapshot_for_diagnostic()); + } let lo = p.token.span; - let vis = p.parse_visibility(FollowedByType::Yes)?; - let ty = p.parse_ty()?; + let vis = match p.parse_visibility(FollowedByType::Yes) { + Ok(vis) => vis, + Err(err) => { + if let Some(ref mut snapshot) = snapshot { + snapshot.recover_diff_marker(); + } + return Err(err); + } + }; + let ty = match p.parse_ty() { + Ok(ty) => ty, + Err(err) => { + if let Some(ref mut snapshot) = snapshot { + snapshot.recover_diff_marker(); + } + return Err(err); + } + }; Ok(( FieldDef { @@ -1597,7 +1627,9 @@ impl<'a> Parser<'a> { /// Parses an element of a struct declaration. fn parse_field_def(&mut self, adt_ty: &str) -> PResult<'a, FieldDef> { + self.recover_diff_marker(); let attrs = self.parse_outer_attributes()?; + self.recover_diff_marker(); self.collect_tokens_trailing_token(attrs, ForceCollect::No, |this, attrs| { let lo = this.token.span; let vis = this.parse_visibility(FollowedByType::No)?; @@ -2424,10 +2456,11 @@ impl<'a> Parser<'a> { } /// Parses the parameter list of a function, including the `(` and `)` delimiters. - fn parse_fn_params(&mut self, req_name: ReqName) -> PResult<'a, Vec<Param>> { + pub(super) fn parse_fn_params(&mut self, req_name: ReqName) -> PResult<'a, Vec<Param>> { let mut first_param = true; // Parse the arguments, starting out with `self` being allowed... let (mut params, _) = self.parse_paren_comma_seq(|p| { + p.recover_diff_marker(); let param = p.parse_param_general(req_name, first_param).or_else(|mut e| { e.emit(); let lo = p.prev_token.span; @@ -2465,7 +2498,6 @@ impl<'a> Parser<'a> { }; let (pat, ty) = if is_name_required || this.is_named_param() { debug!("parse_param_general parse_pat (is_name_required:{})", is_name_required); - let (pat, colon) = this.parse_fn_param_pat_colon()?; if !colon { let mut err = this.unexpected::<()>().unwrap_err(); diff --git a/compiler/rustc_parse/src/parser/mod.rs b/compiler/rustc_parse/src/parser/mod.rs index 40b88788caa..49d31981539 100644 --- a/compiler/rustc_parse/src/parser/mod.rs +++ b/compiler/rustc_parse/src/parser/mod.rs @@ -317,7 +317,7 @@ impl TokenCursor { // required to wrap the text. E.g. // - `abc d` is wrapped as `r"abc d"` (num_of_hashes = 0) // - `abc "d"` is wrapped as `r#"abc "d""#` (num_of_hashes = 1) - // - `abc "##d##"` is wrapped as `r###"abc "d""###` (num_of_hashes = 3) + // - `abc "##d##"` is wrapped as `r###"abc ##"d"##"###` (num_of_hashes = 3) let mut num_of_hashes = 0; let mut count = 0; for ch in data.as_str().chars() { @@ -1499,6 +1499,10 @@ impl<'a> Parser<'a> { pub fn clear_expected_tokens(&mut self) { self.expected_tokens.clear(); } + + pub fn approx_token_stream_pos(&self) -> usize { + self.token_cursor.num_next_calls + } } pub(crate) fn make_unclosed_delims_error( diff --git a/compiler/rustc_parse/src/parser/pat.rs b/compiler/rustc_parse/src/parser/pat.rs index a1981e11477..0b057f2f577 100644 --- a/compiler/rustc_parse/src/parser/pat.rs +++ b/compiler/rustc_parse/src/parser/pat.rs @@ -491,17 +491,6 @@ impl<'a> Parser<'a> { if let PatKind::Ident(_, _, sub @ None) = &mut rhs.kind { // The user inverted the order, so help them fix that. - let mut applicability = Applicability::MachineApplicable; - // FIXME(bindings_after_at): Remove this code when stabilizing the feature. - lhs.walk(&mut |p| match p.kind { - // `check_match` is unhappy if the subpattern has a binding anywhere. - PatKind::Ident(..) => { - applicability = Applicability::MaybeIncorrect; - false // Short-circuit. - } - _ => true, - }); - let lhs_span = lhs.span; // Move the LHS into the RHS as a subpattern. // The RHS is now the full pattern. @@ -510,7 +499,12 @@ impl<'a> Parser<'a> { self.struct_span_err(sp, "pattern on wrong side of `@`") .span_label(lhs_span, "pattern on the left, should be on the right") .span_label(rhs.span, "binding on the right, should be on the left") - .span_suggestion(sp, "switch the order", pprust::pat_to_string(&rhs), applicability) + .span_suggestion( + sp, + "switch the order", + pprust::pat_to_string(&rhs), + Applicability::MachineApplicable, + ) .emit(); } else { // The special case above doesn't apply so we may have e.g. `A(x) @ B(y)`. diff --git a/compiler/rustc_parse/src/parser/stmt.rs b/compiler/rustc_parse/src/parser/stmt.rs index bae7f2670cb..0daae457d30 100644 --- a/compiler/rustc_parse/src/parser/stmt.rs +++ b/compiler/rustc_parse/src/parser/stmt.rs @@ -531,13 +531,23 @@ impl<'a> Parser<'a> { recover: AttemptLocalParseRecovery, ) -> PResult<'a, P<Block>> { let mut stmts = vec![]; + let mut snapshot = None; while !self.eat(&token::CloseDelim(Delimiter::Brace)) { if self.token == token::Eof { break; } + if self.is_diff_marker(&TokenKind::BinOp(token::Shl), &TokenKind::Lt) { + // Account for `<<<<<<<` diff markers. We can't proactively error here because + // that can be a valid path start, so we snapshot and reparse only we've + // encountered another parse error. + snapshot = Some(self.create_snapshot_for_diagnostic()); + } let stmt = match self.parse_full_stmt(recover) { Err(mut err) if recover.yes() => { self.maybe_annotate_with_ascription(&mut err, false); + if let Some(ref mut snapshot) = snapshot { + snapshot.recover_diff_marker(); + } err.emit(); self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore); Some(self.mk_stmt_err(self.token.span)) diff --git a/compiler/rustc_parse/src/parser/ty.rs b/compiler/rustc_parse/src/parser/ty.rs index b7206b57642..a6f702e5428 100644 --- a/compiler/rustc_parse/src/parser/ty.rs +++ b/compiler/rustc_parse/src/parser/ty.rs @@ -1,8 +1,9 @@ use super::{Parser, PathStyle, TokenType}; -use crate::errors::{FnPtrWithGenerics, FnPtrWithGenericsSugg}; +use crate::errors::{ExpectedFnPathFoundFnKeyword, FnPtrWithGenerics, FnPtrWithGenericsSugg}; use crate::{maybe_recover_from_interpolated_ty_qpath, maybe_whole}; +use ast::DUMMY_NODE_ID; use rustc_ast::ptr::P; use rustc_ast::token::{self, Delimiter, Token, TokenKind}; use rustc_ast::util::case::Case; @@ -12,7 +13,9 @@ use rustc_ast::{ }; use rustc_errors::{pluralize, struct_span_err, Applicability, PResult}; use rustc_span::source_map::Span; -use rustc_span::symbol::{kw, sym}; +use rustc_span::symbol::{kw, sym, Ident}; +use rustc_span::Symbol; +use thin_vec::thin_vec; /// Any `?` or `~const` modifiers that appear at the start of a bound. struct BoundModifiers { @@ -501,7 +504,7 @@ impl<'a> Parser<'a> { self.bump_with((dyn_tok, dyn_tok_sp)); } let ty = self.parse_ty_no_plus()?; - Ok(TyKind::Rptr(opt_lifetime, MutTy { ty, mutbl })) + Ok(TyKind::Ref(opt_lifetime, MutTy { ty, mutbl })) } // Parses the `typeof(EXPR)`. @@ -613,6 +616,25 @@ impl<'a> Parser<'a> { /// Parses an `impl B0 + ... + Bn` type. fn parse_impl_ty(&mut self, impl_dyn_multi: &mut bool) -> PResult<'a, TyKind> { // Always parse bounds greedily for better error recovery. + if self.token.is_lifetime() { + self.look_ahead(1, |t| { + if let token::Ident(symname, _) = t.kind { + // parse pattern with "'a Sized" we're supposed to give suggestion like + // "'a + Sized" + self.struct_span_err( + self.token.span, + &format!("expected `+` between lifetime and {}", symname), + ) + .span_suggestion_verbose( + self.token.span.shrink_to_hi(), + "add `+`", + " +", + Applicability::MaybeIncorrect, + ) + .emit(); + } + }) + } let bounds = self.parse_generic_bounds(None)?; *impl_dyn_multi = bounds.len() > 1 || self.prev_token.kind == TokenKind::BinOp(token::Plus); Ok(TyKind::ImplTrait(ast::DUMMY_NODE_ID, bounds)) @@ -911,8 +933,20 @@ impl<'a> Parser<'a> { has_parens: bool, modifiers: BoundModifiers, ) -> PResult<'a, GenericBound> { - let lifetime_defs = self.parse_late_bound_lifetime_defs()?; - let path = self.parse_path(PathStyle::Type)?; + let mut lifetime_defs = self.parse_late_bound_lifetime_defs()?; + let mut path = if self.token.is_keyword(kw::Fn) + && self.look_ahead(1, |tok| tok.kind == TokenKind::OpenDelim(Delimiter::Parenthesis)) + && let Some(path) = self.recover_path_from_fn() + { + path + } else { + self.parse_path(PathStyle::Type)? + }; + + if self.may_recover() && self.token == TokenKind::OpenDelim(Delimiter::Parenthesis) { + self.recover_fn_trait_with_lifetime_params(&mut path, &mut lifetime_defs)?; + } + if has_parens { if self.token.is_like_plus() { // Someone has written something like `&dyn (Trait + Other)`. The correct code @@ -941,6 +975,38 @@ impl<'a> Parser<'a> { Ok(GenericBound::Trait(poly_trait, modifier)) } + // recovers a `Fn(..)` parenthesized-style path from `fn(..)` + fn recover_path_from_fn(&mut self) -> Option<ast::Path> { + let fn_token_span = self.token.span; + self.bump(); + let args_lo = self.token.span; + let snapshot = self.create_snapshot_for_diagnostic(); + match self.parse_fn_decl(|_| false, AllowPlus::No, RecoverReturnSign::OnlyFatArrow) { + Ok(decl) => { + self.sess.emit_err(ExpectedFnPathFoundFnKeyword { fn_token_span }); + Some(ast::Path { + span: fn_token_span.to(self.prev_token.span), + segments: thin_vec![ast::PathSegment { + ident: Ident::new(Symbol::intern("Fn"), fn_token_span), + id: DUMMY_NODE_ID, + args: Some(P(ast::GenericArgs::Parenthesized(ast::ParenthesizedArgs { + span: args_lo.to(self.prev_token.span), + inputs: decl.inputs.iter().map(|a| a.ty.clone()).collect(), + inputs_span: args_lo.until(decl.output.span()), + output: decl.output.clone(), + }))), + }], + tokens: None, + }) + } + Err(diag) => { + diag.cancel(); + self.restore_snapshot(snapshot); + None + } + } + } + /// Optionally parses `for<$generic_params>`. pub(super) fn parse_late_bound_lifetime_defs(&mut self) -> PResult<'a, Vec<GenericParam>> { if self.eat_keyword(kw::For) { @@ -955,6 +1021,92 @@ impl<'a> Parser<'a> { } } + /// Recover from `Fn`-family traits (Fn, FnMut, FnOnce) with lifetime arguments + /// (e.g. `FnOnce<'a>(&'a str) -> bool`). Up to generic arguments have already + /// been eaten. + fn recover_fn_trait_with_lifetime_params( + &mut self, + fn_path: &mut ast::Path, + lifetime_defs: &mut Vec<GenericParam>, + ) -> PResult<'a, ()> { + let fn_path_segment = fn_path.segments.last_mut().unwrap(); + let generic_args = if let Some(p_args) = &fn_path_segment.args { + p_args.clone().into_inner() + } else { + // Normally it wouldn't come here because the upstream should have parsed + // generic parameters (otherwise it's impossible to call this function). + return Ok(()); + }; + let lifetimes = + if let ast::GenericArgs::AngleBracketed(ast::AngleBracketedArgs { span: _, args }) = + &generic_args + { + args.into_iter() + .filter_map(|arg| { + if let ast::AngleBracketedArg::Arg(generic_arg) = arg + && let ast::GenericArg::Lifetime(lifetime) = generic_arg { + Some(lifetime) + } else { + None + } + }) + .collect() + } else { + Vec::new() + }; + // Only try to recover if the trait has lifetime params. + if lifetimes.is_empty() { + return Ok(()); + } + + // Parse `(T, U) -> R`. + let inputs_lo = self.token.span; + let inputs: Vec<_> = + self.parse_fn_params(|_| false)?.into_iter().map(|input| input.ty).collect(); + let inputs_span = inputs_lo.to(self.prev_token.span); + let output = self.parse_ret_ty(AllowPlus::No, RecoverQPath::No, RecoverReturnSign::No)?; + let args = ast::ParenthesizedArgs { + span: fn_path_segment.span().to(self.prev_token.span), + inputs, + inputs_span, + output, + } + .into(); + *fn_path_segment = + ast::PathSegment { ident: fn_path_segment.ident, args, id: ast::DUMMY_NODE_ID }; + + // Convert parsed `<'a>` in `Fn<'a>` into `for<'a>`. + let mut generic_params = lifetimes + .iter() + .map(|lt| GenericParam { + id: lt.id, + ident: lt.ident, + attrs: ast::AttrVec::new(), + bounds: Vec::new(), + is_placeholder: false, + kind: ast::GenericParamKind::Lifetime, + colon_span: None, + }) + .collect::<Vec<GenericParam>>(); + lifetime_defs.append(&mut generic_params); + + let generic_args_span = generic_args.span(); + let mut err = + self.struct_span_err(generic_args_span, "`Fn` traits cannot take lifetime parameters"); + let snippet = format!( + "for<{}> ", + lifetimes.iter().map(|lt| lt.ident.as_str()).intersperse(", ").collect::<String>(), + ); + let before_fn_path = fn_path.span.shrink_to_lo(); + err.multipart_suggestion( + "consider using a higher-ranked trait bound instead", + vec![(generic_args_span, "".to_owned()), (before_fn_path, snippet)], + Applicability::MaybeIncorrect, + ) + .emit(); + Ok(()) + } + pub(super) fn check_lifetime(&mut self) -> bool { self.expected_tokens.push(TokenType::Lifetime); self.token.is_lifetime() |