Rollup of 7 pull requests

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -387,23 +387,23 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
         self.print_string(sym.as_str(), style);
     }
 
-    fn print_inner_attributes(&mut self, attrs: &[ast::Attribute]) {
+    fn print_inner_attributes(&mut self, attrs: &[ast::Attribute]) -> bool {
         self.print_either_attributes(attrs, ast::AttrStyle::Inner, false, true)
     }
 
-    fn print_inner_attributes_no_trailing_hardbreak(&mut self, attrs: &[ast::Attribute]) {
+    fn print_inner_attributes_no_trailing_hardbreak(&mut self, attrs: &[ast::Attribute]) -> bool {
         self.print_either_attributes(attrs, ast::AttrStyle::Inner, false, false)
     }
 
-    fn print_outer_attributes(&mut self, attrs: &[ast::Attribute]) {
+    fn print_outer_attributes(&mut self, attrs: &[ast::Attribute]) -> bool {
         self.print_either_attributes(attrs, ast::AttrStyle::Outer, false, true)
     }
 
-    fn print_inner_attributes_inline(&mut self, attrs: &[ast::Attribute]) {
+    fn print_inner_attributes_inline(&mut self, attrs: &[ast::Attribute]) -> bool {
         self.print_either_attributes(attrs, ast::AttrStyle::Inner, true, true)
     }
 
-    fn print_outer_attributes_inline(&mut self, attrs: &[ast::Attribute]) {
+    fn print_outer_attributes_inline(&mut self, attrs: &[ast::Attribute]) -> bool {
         self.print_either_attributes(attrs, ast::AttrStyle::Outer, true, true)
     }
 
@@ -413,20 +413,21 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
         kind: ast::AttrStyle,
         is_inline: bool,
         trailing_hardbreak: bool,
-    ) {
-        let mut count = 0;
+    ) -> bool {
+        let mut printed = false;
         for attr in attrs {
             if attr.style == kind {
                 self.print_attribute_inline(attr, is_inline);
                 if is_inline {
                     self.nbsp();
                 }
-                count += 1;
+                printed = true;
             }
         }
-        if count > 0 && trailing_hardbreak && !is_inline {
+        if printed && trailing_hardbreak && !is_inline {
             self.hardbreak_if_not_bol();
         }
+        printed
     }
 
     fn print_attribute(&mut self, attr: &ast::Attribute) {
@@ -1646,7 +1647,7 @@ impl<'a> State<'a> {
         self.ann.pre(self, AnnNode::Block(blk));
         self.bopen();
 
-        self.print_inner_attributes(attrs);
+        let has_attrs = self.print_inner_attributes(attrs);
 
         for (i, st) in blk.stmts.iter().enumerate() {
             match st.kind {
@@ -1660,7 +1661,7 @@ impl<'a> State<'a> {
             }
         }
 
-        let empty = attrs.is_empty() && blk.stmts.is_empty();
+        let empty = !has_attrs && blk.stmts.is_empty();
         self.bclose_maybe_open(blk.span, empty, close_box);
         self.ann.post(self, AnnNode::Block(blk))
     }
@@ -2780,34 +2781,34 @@ impl<'a> State<'a> {
                 self.word_space(",");
             }
 
-            match *predicate {
-                ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate {
-                    ref bound_generic_params,
-                    ref bounded_ty,
-                    ref bounds,
-                    ..
-                }) => {
-                    self.print_formal_generic_params(bound_generic_params);
-                    self.print_type(bounded_ty);
-                    self.print_type_bounds(":", bounds);
-                }
-                ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate {
-                    ref lifetime,
-                    ref bounds,
-                    ..
-                }) => {
-                    self.print_lifetime_bounds(*lifetime, bounds);
-                }
-                ast::WherePredicate::EqPredicate(ast::WhereEqPredicate {
-                    ref lhs_ty,
-                    ref rhs_ty,
-                    ..
-                }) => {
-                    self.print_type(lhs_ty);
-                    self.space();
-                    self.word_space("=");
-                    self.print_type(rhs_ty);
-                }
+            self.print_where_predicate(predicate);
+        }
+    }
+
+    pub fn print_where_predicate(&mut self, predicate: &ast::WherePredicate) {
+        match predicate {
+            ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate {
+                bound_generic_params,
+                bounded_ty,
+                bounds,
+                ..
+            }) => {
+                self.print_formal_generic_params(bound_generic_params);
+                self.print_type(bounded_ty);
+                self.print_type_bounds(":", bounds);
+            }
+            ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate {
+                lifetime,
+                bounds,
+                ..
+            }) => {
+                self.print_lifetime_bounds(*lifetime, bounds);
+            }
+            ast::WherePredicate::EqPredicate(ast::WhereEqPredicate { lhs_ty, rhs_ty, .. }) => {
+                self.print_type(lhs_ty);
+                self.space();
+                self.word_space("=");
+                self.print_type(rhs_ty);
             }
         }
     }
@@ -2908,10 +2909,7 @@ impl<'a> State<'a> {
         generic_params: &[ast::GenericParam],
     ) {
         self.ibox(INDENT_UNIT);
-        if !generic_params.is_empty() {
-            self.word("for");
-            self.print_generic_params(generic_params);
-        }
+        self.print_formal_generic_params(generic_params);
         let generics = ast::Generics {
             params: Vec::new(),
             where_clause: ast::WhereClause {

compiler/rustc_error_codes/src/error_codes.rs

@@ -120,6 +120,7 @@ E0223: include_str!("./error_codes/E0223.md"),
 E0224: include_str!("./error_codes/E0224.md"),
 E0225: include_str!("./error_codes/E0225.md"),
 E0226: include_str!("./error_codes/E0226.md"),
+E0227: include_str!("./error_codes/E0227.md"),
 E0228: include_str!("./error_codes/E0228.md"),
 E0229: include_str!("./error_codes/E0229.md"),
 E0230: include_str!("./error_codes/E0230.md"),
@@ -530,7 +531,6 @@ E0786: include_str!("./error_codes/E0786.md"),
 //  E0217, // ambiguous associated type, defined in multiple supertraits
 //  E0218, // no associated type defined
 //  E0219, // associated type defined in higher-ranked supertrait
-    E0227, // ambiguous lifetime bound, explicit lifetime bound required
 //  E0233,
 //  E0234,
 //  E0235, // structure constructor specifies a structure of type but

compiler/rustc_error_codes/src/error_codes/E0227.md

@@ -0,0 +1,33 @@
+This error indicates that the compiler is unable to determine whether there is
+exactly one unique region in the set of derived region bounds.
+
+Example of erroneous code:
+
+```compile_fail,E0227
+trait Foo<'foo>: 'foo {}
+trait Bar<'bar>: 'bar {}
+
+trait FooBar<'foo, 'bar>: Foo<'foo> + Bar<'bar> {}
+
+struct Baz<'foo, 'bar> {
+    baz: dyn FooBar<'foo, 'bar>,
+}
+```
+
+Here, `baz` can have either `'foo` or `'bar` lifetimes.
+
+To resolve this error, provide an explicit lifetime:
+
+```rust
+trait Foo<'foo>: 'foo {}
+trait Bar<'bar>: 'bar {}
+
+trait FooBar<'foo, 'bar>: Foo<'foo> + Bar<'bar> {}
+
+struct Baz<'foo, 'bar, 'baz>
+where
+    'baz: 'foo + 'bar,
+{
+    obj: dyn FooBar<'foo, 'bar> + 'baz,
+}
+```

compiler/rustc_hir_pretty/src/lib.rs

@@ -2327,10 +2327,7 @@ impl<'a> State<'a> {
         arg_names: &[Ident],
     ) {
         self.ibox(INDENT_UNIT);
-        if !generic_params.is_empty() {
-            self.word("for");
-            self.print_generic_params(generic_params);
-        }
+        self.print_formal_generic_params(generic_params);
         let generics = hir::Generics {
             params: &[],
             where_clause: hir::WhereClause { predicates: &[], span: rustc_span::DUMMY_SP },

compiler/rustc_parse/src/parser/item.rs

@@ -794,6 +794,44 @@ impl<'a> Parser<'a> {
         ))
     }
 
+    /// Emits an error that the where clause at the end of a type alias is not
+    /// allowed and suggests moving it.
+    fn error_ty_alias_where(
+        &self,
+        before_where_clause_present: bool,
+        before_where_clause_span: Span,
+        after_predicates: &[WherePredicate],
+        after_where_clause_span: Span,
+    ) {
+        let mut err =
+            self.struct_span_err(after_where_clause_span, "where clause not allowed here");
+        if !after_predicates.is_empty() {
+            let mut state = crate::pprust::State::new();
+            if !before_where_clause_present {
+                state.space();
+                state.word_space("where");
+            } else {
+                state.word_space(",");
+            }
+            let mut first = true;
+            for p in after_predicates.iter() {
+                if !first {
+                    state.word_space(",");
+                }
+                first = false;
+                state.print_where_predicate(p);
+            }
+            let suggestion = state.s.eof();
+            err.span_suggestion(
+                before_where_clause_span.shrink_to_hi(),
+                "move it here",
+                suggestion,
+                Applicability::MachineApplicable,
+            );
+        }
+        err.emit()
+    }
+
     /// Parses a `type` alias with the following grammar:
     /// ```
     /// TypeAlias = "type" Ident Generics {":" GenericBounds}? {"=" Ty}? ";" ;
@@ -806,9 +844,24 @@ impl<'a> Parser<'a> {
         // Parse optional colon and param bounds.
         let bounds =
             if self.eat(&token::Colon) { self.parse_generic_bounds(None)? } else { Vec::new() };
+
         generics.where_clause = self.parse_where_clause()?;
 
         let ty = if self.eat(&token::Eq) { Some(self.parse_ty()?) } else { None };
+
+        if self.token.is_keyword(kw::Where) {
+            let after_where_clause = self.parse_where_clause()?;
+
+            self.error_ty_alias_where(
+                generics.where_clause.has_where_token,
+                generics.where_clause.span,
+                &after_where_clause.predicates,
+                after_where_clause.span,
+            );
+
+            generics.where_clause.predicates.extend(after_where_clause.predicates.into_iter());
+        }
+
         self.expect_semi()?;
 
         Ok((ident, ItemKind::TyAlias(Box::new(TyAlias { defaultness, generics, bounds, ty }))))

compiler/rustc_resolve/src/late.rs

@@ -1603,10 +1603,13 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
         pat_src: PatternSource,
         bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
     ) {
+        // We walk the pattern before declaring the pattern's inner bindings,
+        // so that we avoid resolving a literal expression to a binding defined
+        // by the pattern.
+        visit::walk_pat(self, pat);
         self.resolve_pattern_inner(pat, pat_src, bindings);
         // This has to happen *after* we determine which pat_idents are variants:
         self.check_consistent_bindings_top(pat);
-        visit::walk_pat(self, pat);
     }
 
     /// Resolve bindings in a pattern. This is a helper to `resolve_pattern`.

src/librustdoc/clean/types.rs

@@ -39,7 +39,6 @@ use crate::clean::Clean;
 use crate::core::DocContext;
 use crate::formats::cache::Cache;
 use crate::formats::item_type::ItemType;
-use crate::html::render::cache::ExternalLocation;
 use crate::html::render::Context;
 use crate::passes::collect_intra_doc_links::UrlFragment;
 
@@ -339,6 +338,16 @@ impl ExternalCrate {
     }
 }
 
+/// Indicates where an external crate can be found.
+crate enum ExternalLocation {
+    /// Remote URL root of the external crate
+    Remote(String),
+    /// This external crate can be found in the local doc/ folder
+    Local,
+    /// The external crate could not be found.
+    Unknown,
+}
+
 /// Anything with a source location and set of attributes and, optionally, a
 /// name. That is, anything that can be documented. This doesn't correspond
 /// directly to the AST's concept of an item; it's a strict superset.

src/librustdoc/formats/cache.rs

@@ -6,13 +6,13 @@ use rustc_middle::middle::privacy::AccessLevels;
 use rustc_middle::ty::TyCtxt;
 use rustc_span::symbol::sym;
 
-use crate::clean::{self, ExternalCrate, ItemId, PrimitiveType};
+use crate::clean::{self, types::ExternalLocation, ExternalCrate, ItemId, PrimitiveType};
 use crate::core::DocContext;
 use crate::fold::DocFolder;
 use crate::formats::item_type::ItemType;
 use crate::formats::Impl;
 use crate::html::markdown::short_markdown_summary;
-use crate::html::render::cache::{get_index_search_type, ExternalLocation};
+use crate::html::render::search_index::get_function_type_for_search;
 use crate::html::render::IndexItem;
 
 /// This cache is used to store information about the [`clean::Crate`] being
@@ -303,7 +303,7 @@ impl<'a, 'tcx> DocFolder for CacheBuilder<'a, 'tcx> {
                             desc,
                             parent,
                             parent_idx: None,
-                            search_type: get_index_search_type(&item, self.tcx, self.cache),
+                            search_type: get_function_type_for_search(&item, self.tcx),
                             aliases: item.attrs.get_doc_aliases(),
                         });
                     }

src/librustdoc/html/format.rs

@@ -21,10 +21,12 @@ use rustc_middle::ty::TyCtxt;
 use rustc_span::def_id::CRATE_DEF_INDEX;
 use rustc_target::spec::abi::Abi;
 
-use crate::clean::{self, utils::find_nearest_parent_module, ExternalCrate, ItemId, PrimitiveType};
+use crate::clean::{
+    self, types::ExternalLocation, utils::find_nearest_parent_module, ExternalCrate, ItemId,
+    PrimitiveType,
+};
 use crate::formats::item_type::ItemType;
 use crate::html::escape::Escape;
-use crate::html::render::cache::ExternalLocation;
 use crate::html::render::Context;
 
 use super::url_parts_builder::UrlPartsBuilder;

src/librustdoc/html/render/context.rs

@@ -13,16 +13,16 @@ use rustc_span::edition::Edition;
 use rustc_span::source_map::FileName;
 use rustc_span::symbol::sym;
 
-use super::cache::{build_index, ExternalLocation};
 use super::print_item::{full_path, item_path, print_item};
+use super::search_index::build_index;
 use super::templates;
 use super::write_shared::write_shared;
 use super::{
     collect_spans_and_sources, print_sidebar, settings, AllTypes, LinkFromSrc, NameDoc, StylePath,
     BASIC_KEYWORDS,
 };
 
-use crate::clean::{self, ExternalCrate};
+use crate::clean::{self, types::ExternalLocation, ExternalCrate};
 use crate::config::RenderOptions;
 use crate::docfs::{DocFS, PathError};
 use crate::error::Error;

src/librustdoc/html/render/mod.rs

@@ -23,7 +23,7 @@
 //! These threads are not parallelized (they haven't been a bottleneck yet), and
 //! both occur before the crate is rendered.
 
-crate mod cache;
+crate mod search_index;
 
 #[cfg(test)]
 mod tests;