Merge pull request #26 from rust-lang/master

Sync to rust-lang/rust master

11 files changed, 95 insertions, 79 deletions

diff --git a/src/libsyntax/parse/attr.rs b/src/libsyntax/parse/attr.rs
index 9aa1ec0b14f..cf6151d17b1 100644
--- a/src/libsyntax/parse/attr.rs
+++ b/src/libsyntax/parse/attr.rs
@@ -19,13 +19,6 @@ const DEFAULT_UNEXPECTED_INNER_ATTR_ERR_MSG: &str = "an inner attribute is not \
                                                      permitted in this context";
 
 impl<'a> Parser<'a> {
-    crate fn parse_param_attributes(&mut self) -> PResult<'a, Vec<ast::Attribute>> {
-        let attrs = self.parse_outer_attributes()?;
-        self.sess.gated_spans.param_attrs.borrow_mut()
-            .extend(attrs.iter().map(|a| a.span));
-        Ok(attrs)
-    }
-
     /// Parses attributes that appear before an item.
     crate fn parse_outer_attributes(&mut self) -> PResult<'a, Vec<ast::Attribute>> {
         let mut attrs: Vec<ast::Attribute> = Vec::new();
@@ -309,14 +302,14 @@ impl<'a> Parser<'a> {
             Ok(lit) => {
                 return Ok(ast::NestedMetaItem::Literal(lit))
             }
-            Err(ref mut err) => self.diagnostic().cancel(err)
+            Err(ref mut err) => err.cancel(),
         }
 
         match self.parse_meta_item() {
             Ok(mi) => {
                 return Ok(ast::NestedMetaItem::MetaItem(mi))
             }
-            Err(ref mut err) => self.diagnostic().cancel(err)
+            Err(ref mut err) => err.cancel(),
         }
 
         let found = self.this_token_to_string();
diff --git a/src/libsyntax/parse/diagnostics.rs b/src/libsyntax/parse/diagnostics.rs
index b74f2492c35..59de5f14123 100644
--- a/src/libsyntax/parse/diagnostics.rs
+++ b/src/libsyntax/parse/diagnostics.rs
@@ -11,7 +11,7 @@ use crate::ptr::P;
 use crate::symbol::{kw, sym};
 use crate::ThinVec;
 use crate::util::parser::AssocOp;
-use errors::{Applicability, DiagnosticBuilder, DiagnosticId};
+use errors::{Applicability, DiagnosticBuilder, DiagnosticId, pluralise};
 use rustc_data_structures::fx::FxHashSet;
 use syntax_pos::{Span, DUMMY_SP, MultiSpan, SpanSnippetError};
 use log::{debug, trace};
@@ -197,10 +197,6 @@ impl<'a> Parser<'a> {
         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
     }
@@ -426,15 +422,13 @@ impl<'a> Parser<'a> {
     /// 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: &[&TokenKind]) {
-        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);
+            err.cancel();
         }
     }
 
@@ -532,15 +526,15 @@ impl<'a> Parser<'a> {
             self.eat_to_tokens(&[&end]);
             let span = lo.until(self.token.span);
 
-            let plural = number_of_gt > 1 || number_of_shr >= 1;
+            let total_num_of_gt = number_of_gt + number_of_shr * 2;
             self.diagnostic()
                 .struct_span_err(
                     span,
-                    &format!("unmatched angle bracket{}", if plural { "s" } else { "" }),
+                    &format!("unmatched angle bracket{}", pluralise!(total_num_of_gt)),
                 )
                 .span_suggestion(
                     span,
-                    &format!("remove extra angle bracket{}", if plural { "s" } else { "" }),
+                    &format!("remove extra angle bracket{}", pluralise!(total_num_of_gt)),
                     String::new(),
                     Applicability::MachineApplicable,
                 )
diff --git a/src/libsyntax/parse/lexer/tests.rs b/src/libsyntax/parse/lexer/tests.rs
index c1ec41902e2..de301b1fc49 100644
--- a/src/libsyntax/parse/lexer/tests.rs
+++ b/src/libsyntax/parse/lexer/tests.rs
@@ -18,6 +18,7 @@ fn mk_sess(sm: Lrc<SourceMap>) -> ParseSess {
         false,
         false,
         None,
+        false,
     );
     ParseSess::with_span_handler(Handler::with_emitter(true, None, Box::new(emitter)), sm)
 }
diff --git a/src/libsyntax/parse/mod.rs b/src/libsyntax/parse/mod.rs
index 2441a027f99..fa4c1043122 100644
--- a/src/libsyntax/parse/mod.rs
+++ b/src/libsyntax/parse/mod.rs
@@ -49,8 +49,6 @@ static_assert_size!(PResult<'_, bool>, 16);
 /// used and should be feature gated accordingly in `check_crate`.
 #[derive(Default)]
 pub struct GatedSpans {
-    /// Spans collected for gating `param_attrs`, e.g. `fn foo(#[attr] x: u8) {}`.
-    pub param_attrs: Lock<Vec<Span>>,
     /// Spans collected for gating `let_chains`, e.g. `if a && let b = c {}`.
     pub let_chains: Lock<Vec<Span>>,
     /// Spans collected for gating `async_closure`, e.g. `async || ..`.
@@ -306,7 +304,7 @@ fn file_to_source_file(sess: &ParseSess, path: &Path, spanopt: Option<Span>)
     match try_file_to_source_file(sess, path, spanopt) {
         Ok(source_file) => source_file,
         Err(d) => {
-            DiagnosticBuilder::new_diagnostic(&sess.span_diagnostic, d).emit();
+            sess.span_diagnostic.emit_diagnostic(&d);
             FatalError.raise();
         }
     }
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index fcebfa29962..b2b6504919e 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -979,7 +979,7 @@ impl<'a> Parser<'a> {
         is_name_required: impl Fn(&token::Token) -> bool,
     ) -> PResult<'a, Param> {
         let lo = self.token.span;
-        let attrs = self.parse_param_attributes()?;
+        let attrs = self.parse_outer_attributes()?;
         if let Some(mut param) = self.parse_self_param()? {
             param.attrs = attrs.into();
             return self.recover_bad_self_param(param, is_trait_item);
@@ -1362,7 +1362,7 @@ impl<'a> Parser<'a> {
     /// Returns the parsed optional self parameter with attributes and whether a self
     /// shortcut was used.
     fn parse_self_parameter_with_attrs(&mut self) -> PResult<'a, Option<Param>> {
-        let attrs = self.parse_param_attributes()?;
+        let attrs = self.parse_outer_attributes()?;
         let param_opt = self.parse_self_param()?;
         Ok(param_opt.map(|mut param| {
             param.attrs = attrs.into();
diff --git a/src/libsyntax/parse/parser/expr.rs b/src/libsyntax/parse/parser/expr.rs
index 31b28443abb..d0c865a7b8e 100644
--- a/src/libsyntax/parse/parser/expr.rs
+++ b/src/libsyntax/parse/parser/expr.rs
@@ -66,6 +66,10 @@ pub(super) enum LhsExpr {
 }
 
 impl From<Option<ThinVec<Attribute>>> for LhsExpr {
+    /// Converts `Some(attrs)` into `LhsExpr::AttributesParsed(attrs)`
+    /// and `None` into `LhsExpr::NotYetParsed`.
+    ///
+    /// This conversion does not allocate.
     fn from(o: Option<ThinVec<Attribute>>) -> Self {
         if let Some(attrs) = o {
             LhsExpr::AttributesParsed(attrs)
@@ -76,6 +80,9 @@ impl From<Option<ThinVec<Attribute>>> for LhsExpr {
 }
 
 impl From<P<Expr>> for LhsExpr {
+    /// Converts the `expr: P<Expr>` into `LhsExpr::AlreadyParsed(expr)`.
+    ///
+    /// This conversion does not allocate.
     fn from(expr: P<Expr>) -> Self {
         LhsExpr::AlreadyParsed(expr)
     }
@@ -770,7 +777,7 @@ impl<'a> Parser<'a> {
                         ex = ExprKind::Lit(literal);
                     }
                     Err(mut err) => {
-                        self.cancel(&mut err);
+                        err.cancel();
                         return Err(self.expected_expression_found());
                     }
                 }
@@ -1176,7 +1183,7 @@ impl<'a> Parser<'a> {
     /// Parses a parameter in a closure header (e.g., `|arg, arg|`).
     fn parse_fn_block_param(&mut self) -> PResult<'a, Param> {
         let lo = self.token.span;
-        let attrs = self.parse_param_attributes()?;
+        let attrs = self.parse_outer_attributes()?;
         let pat = self.parse_pat(PARAM_EXPECTED)?;
         let t = if self.eat(&token::Colon) {
             self.parse_ty()?
diff --git a/src/libsyntax/parse/parser/generics.rs b/src/libsyntax/parse/parser/generics.rs
index 3e6118ad86f..2ecd9cca3c6 100644
--- a/src/libsyntax/parse/parser/generics.rs
+++ b/src/libsyntax/parse/parser/generics.rs
@@ -100,13 +100,31 @@ impl<'a> Parser<'a> {
             } else if self.check_ident() {
                 // Parse type parameter.
                 params.push(self.parse_ty_param(attrs)?);
+            } else if self.token.can_begin_type() {
+                // Trying to write an associated type bound? (#26271)
+                let snapshot = self.clone();
+                match self.parse_ty_where_predicate() {
+                    Ok(where_predicate) => {
+                        self.struct_span_err(
+                            where_predicate.span(),
+                            "bounds on associated types do not belong here",
+                        )
+                        .span_label(where_predicate.span(), "belongs in `where` clause")
+                        .emit();
+                    }
+                    Err(mut err) => {
+                        err.cancel();
+                        std::mem::replace(self, snapshot);
+                        break
+                    }
+                }
             } else {
                 // Check for trailing attributes and stop parsing.
                 if !attrs.is_empty() {
                     if !params.is_empty() {
                         self.struct_span_err(
                             attrs[0].span,
-                            &format!("trailing attribute after generic parameter"),
+                            "trailing attribute after generic parameter",
                         )
                         .span_label(attrs[0].span, "attributes must go before parameters")
                         .emit();
@@ -202,43 +220,7 @@ impl<'a> Parser<'a> {
                     }
                 ));
             } else if self.check_type() {
-                // Parse optional `for<'a, 'b>`.
-                // This `for` is parsed greedily and applies to the whole predicate,
-                // the bounded type can have its own `for` applying only to it.
-                // Examples:
-                // * `for<'a> Trait1<'a>: Trait2<'a /* ok */>`
-                // * `(for<'a> Trait1<'a>): Trait2<'a /* not ok */>`
-                // * `for<'a> for<'b> Trait1<'a, 'b>: Trait2<'a /* ok */, 'b /* not ok */>`
-                let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
-
-                // Parse type with mandatory colon and (possibly empty) bounds,
-                // or with mandatory equality sign and the second type.
-                let ty = self.parse_ty()?;
-                if self.eat(&token::Colon) {
-                    let bounds = self.parse_generic_bounds(Some(self.prev_span))?;
-                    where_clause.predicates.push(ast::WherePredicate::BoundPredicate(
-                        ast::WhereBoundPredicate {
-                            span: lo.to(self.prev_span),
-                            bound_generic_params: lifetime_defs,
-                            bounded_ty: ty,
-                            bounds,
-                        }
-                    ));
-                // FIXME: Decide what should be used here, `=` or `==`.
-                // FIXME: We are just dropping the binders in lifetime_defs on the floor here.
-                } else if self.eat(&token::Eq) || self.eat(&token::EqEq) {
-                    let rhs_ty = self.parse_ty()?;
-                    where_clause.predicates.push(ast::WherePredicate::EqPredicate(
-                        ast::WhereEqPredicate {
-                            span: lo.to(self.prev_span),
-                            lhs_ty: ty,
-                            rhs_ty,
-                            id: ast::DUMMY_NODE_ID,
-                        }
-                    ));
-                } else {
-                    return self.unexpected();
-                }
+                where_clause.predicates.push(self.parse_ty_where_predicate()?);
             } else {
                 break
             }
@@ -252,6 +234,47 @@ impl<'a> Parser<'a> {
         Ok(where_clause)
     }
 
+    fn parse_ty_where_predicate(&mut self) -> PResult<'a, ast::WherePredicate> {
+        let lo = self.token.span;
+        // Parse optional `for<'a, 'b>`.
+        // This `for` is parsed greedily and applies to the whole predicate,
+        // the bounded type can have its own `for` applying only to it.
+        // Examples:
+        // * `for<'a> Trait1<'a>: Trait2<'a /* ok */>`
+        // * `(for<'a> Trait1<'a>): Trait2<'a /* not ok */>`
+        // * `for<'a> for<'b> Trait1<'a, 'b>: Trait2<'a /* ok */, 'b /* not ok */>`
+        let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
+
+        // Parse type with mandatory colon and (possibly empty) bounds,
+        // or with mandatory equality sign and the second type.
+        let ty = self.parse_ty()?;
+        if self.eat(&token::Colon) {
+            let bounds = self.parse_generic_bounds(Some(self.prev_span))?;
+            Ok(ast::WherePredicate::BoundPredicate(
+                ast::WhereBoundPredicate {
+                    span: lo.to(self.prev_span),
+                    bound_generic_params: lifetime_defs,
+                    bounded_ty: ty,
+                    bounds,
+                }
+            ))
+        // FIXME: Decide what should be used here, `=` or `==`.
+        // FIXME: We are just dropping the binders in lifetime_defs on the floor here.
+        } else if self.eat(&token::Eq) || self.eat(&token::EqEq) {
+            let rhs_ty = self.parse_ty()?;
+            Ok(ast::WherePredicate::EqPredicate(
+                ast::WhereEqPredicate {
+                    span: lo.to(self.prev_span),
+                    lhs_ty: ty,
+                    rhs_ty,
+                    id: ast::DUMMY_NODE_ID,
+                }
+            ))
+        } else {
+            self.unexpected()
+        }
+    }
+
     pub(super) fn choose_generics_over_qpath(&self) -> bool {
         // There's an ambiguity between generic parameters and qualified paths in impls.
         // If we see `<` it may start both, so we have to inspect some following tokens.
diff --git a/src/libsyntax/parse/parser/pat.rs b/src/libsyntax/parse/parser/pat.rs
index 08ee3a6bd86..3c624959ead 100644
--- a/src/libsyntax/parse/parser/pat.rs
+++ b/src/libsyntax/parse/parser/pat.rs
@@ -537,7 +537,7 @@ impl<'a> Parser<'a> {
         mut err: DiagnosticBuilder<'a>,
         expected: Expected,
     ) -> PResult<'a, P<Pat>> {
-        self.cancel(&mut err);
+        err.cancel();
 
         let expected = expected.unwrap_or("pattern");
         let msg = format!("expected {}, found {}", expected, self.this_token_descr());
diff --git a/src/libsyntax/parse/parser/path.rs b/src/libsyntax/parse/parser/path.rs
index d4b13cc2e01..87839f8c70e 100644
--- a/src/libsyntax/parse/parser/path.rs
+++ b/src/libsyntax/parse/parser/path.rs
@@ -9,7 +9,7 @@ use crate::symbol::kw;
 
 use std::mem;
 use log::debug;
-use errors::{Applicability};
+use errors::{Applicability, pluralise};
 
 /// Specifies how to parse a path.
 #[derive(Copy, Clone, PartialEq)]
@@ -129,10 +129,11 @@ impl<'a> Parser<'a> {
         self.parse_path(style)
     }
 
-    crate fn parse_path_segments(&mut self,
-                           segments: &mut Vec<PathSegment>,
-                           style: PathStyle)
-                           -> PResult<'a, ()> {
+    crate fn parse_path_segments(
+        &mut self,
+        segments: &mut Vec<PathSegment>,
+        style: PathStyle,
+    ) -> PResult<'a, ()> {
         loop {
             let segment = self.parse_path_segment(style)?;
             if style == PathStyle::Expr {
@@ -201,7 +202,7 @@ impl<'a> Parser<'a> {
             } else {
                 // `(T, U) -> R`
                 let (inputs, _) = self.parse_paren_comma_seq(|p| p.parse_ty())?;
-                let span = lo.to(self.prev_span);
+                let span = ident.span.to(self.prev_span);
                 let output = if self.eat(&token::RArrow) {
                     Some(self.parse_ty_common(false, false, false)?)
                 } else {
@@ -347,20 +348,19 @@ impl<'a> Parser<'a> {
                 let span = lo.with_hi(
                     lo.lo() + BytePos(snapshot.unmatched_angle_bracket_count)
                 );
-                let plural = snapshot.unmatched_angle_bracket_count > 1;
                 self.diagnostic()
                     .struct_span_err(
                         span,
                         &format!(
                             "unmatched angle bracket{}",
-                            if plural { "s" } else { "" }
+                            pluralise!(snapshot.unmatched_angle_bracket_count)
                         ),
                     )
                     .span_suggestion(
                         span,
                         &format!(
                             "remove extra angle bracket{}",
-                            if plural { "s" } else { "" }
+                            pluralise!(snapshot.unmatched_angle_bracket_count)
                         ),
                         String::new(),
                         Applicability::MachineApplicable,
diff --git a/src/libsyntax/parse/parser/stmt.rs b/src/libsyntax/parse/parser/stmt.rs
index 04bd61a4cfb..02da56f6e35 100644
--- a/src/libsyntax/parse/parser/stmt.rs
+++ b/src/libsyntax/parse/parser/stmt.rs
@@ -361,7 +361,7 @@ impl<'a> Parser<'a> {
                 }
                 Err(mut e) => {
                     self.recover_stmt_(SemiColonMode::Break, BlockMode::Ignore);
-                    self.cancel(&mut e);
+                    e.cancel();
                 }
                 _ => ()
             }
diff --git a/src/libsyntax/parse/parser/ty.rs b/src/libsyntax/parse/parser/ty.rs
index 465e31ac57e..5697edd8e48 100644
--- a/src/libsyntax/parse/parser/ty.rs
+++ b/src/libsyntax/parse/parser/ty.rs
@@ -11,7 +11,7 @@ use crate::symbol::{kw};
 
 use rustc_target::spec::abi::Abi;
 
-use errors::{Applicability};
+use errors::{Applicability, pluralise};
 
 /// Returns `true` if `IDENT t` can start a type -- `IDENT::a::b`, `IDENT<u8, u8>`,
 /// `IDENT<<u8 as Trait>::AssocTy>`.
@@ -397,7 +397,7 @@ impl<'a> Parser<'a> {
         }
 
         if !negative_bounds.is_empty() || was_negative {
-            let plural = negative_bounds.len() > 1;
+            let negative_bounds_len = negative_bounds.len();
             let last_span = negative_bounds.last().map(|sp| *sp);
             let mut err = self.struct_span_err(
                 negative_bounds,
@@ -420,7 +420,7 @@ impl<'a> Parser<'a> {
                 }
                 err.span_suggestion_hidden(
                     bound_list,
-                    &format!("remove the trait bound{}", if plural { "s" } else { "" }),
+                    &format!("remove the trait bound{}", pluralise!(negative_bounds_len)),
                     new_bound_list,
                     Applicability::MachineApplicable,
                 );