Auto merge of #42902 - petrochenkov:keydcrate, r=jseyfried

Make `$crate` a keyword

Fixes https://github.com/rust-lang/rust/issues/42898

r? @jseyfried or @nrc

src/librustc/hir/print.rs

@@ -1527,7 +1527,8 @@ impl<'a> State<'a> {
             if i > 0 {
                 word(&mut self.s, "::")?
             }
-            if segment.name != keywords::CrateRoot.name() && segment.name != "$crate" {
+            if segment.name != keywords::CrateRoot.name() &&
+               segment.name != keywords::DollarCrate.name() {
                 self.print_name(segment.name)?;
                 self.print_path_parameters(&segment.parameters, colons_before_params)?;
             }
@@ -1554,7 +1555,8 @@ impl<'a> State<'a> {
                     if i > 0 {
                         word(&mut self.s, "::")?
                     }
-                    if segment.name != keywords::CrateRoot.name() && segment.name != "$crate" {
+                    if segment.name != keywords::CrateRoot.name() &&
+                       segment.name != keywords::DollarCrate.name() {
                         self.print_name(segment.name)?;
                         self.print_path_parameters(&segment.parameters, colons_before_params)?;
                     }

src/librustc_resolve/build_reduced_graph.rs

@@ -149,14 +149,15 @@ impl<'a> Resolver<'a> {
                             resolve_error(self,
                                           view_path.span,
                                           ResolutionError::SelfImportsOnlyAllowedWithin);
-                        } else if source_name == "$crate" && full_path.segments.len() == 1 {
+                        } else if source_name == keywords::DollarCrate.name() &&
+                                  full_path.segments.len() == 1 {
                             let crate_root = self.resolve_crate_root(source.ctxt);
                             let crate_name = match crate_root.kind {
                                 ModuleKind::Def(_, name) => name,
                                 ModuleKind::Block(..) => unreachable!(),
                             };
                             source.name = crate_name;
-                            if binding.name == "$crate" {
+                            if binding.name == keywords::DollarCrate.name() {
                                 binding.name = crate_name;
                             }
 

src/librustc_resolve/lib.rs

@@ -2665,7 +2665,8 @@ impl<'a> Resolver<'a> {
         };
 
         if path.len() > 1 && !global_by_default && result.base_def() != Def::Err &&
-           path[0].name != keywords::CrateRoot.name() && path[0].name != "$crate" {
+           path[0].name != keywords::CrateRoot.name() &&
+           path[0].name != keywords::DollarCrate.name() {
             let unqualified_result = {
                 match self.resolve_path(&[*path.last().unwrap()], Some(ns), false, span) {
                     PathResult::NonModule(path_res) => path_res.base_def(),
@@ -2718,7 +2719,7 @@ impl<'a> Resolver<'a> {
             if i == 0 && ns == TypeNS && ident.name == keywords::CrateRoot.name() {
                 module = Some(self.resolve_crate_root(ident.ctxt.modern()));
                 continue
-            } else if i == 0 && ns == TypeNS && ident.name == "$crate" {
+            } else if i == 0 && ns == TypeNS && ident.name == keywords::DollarCrate.name() {
                 module = Some(self.resolve_crate_root(ident.ctxt));
                 continue
             }

src/librustc_resolve/macros.rs

@@ -128,7 +128,7 @@ impl<'a> base::Resolver for Resolver<'a> {
         impl<'a, 'b> Folder for EliminateCrateVar<'a, 'b> {
             fn fold_path(&mut self, mut path: ast::Path) -> ast::Path {
                 let ident = path.segments[0].identifier;
-                if ident.name == "$crate" {
+                if ident.name == keywords::DollarCrate.name() {
                     path.segments[0].identifier.name = keywords::CrateRoot.name();
                     let module = self.0.resolve_crate_root(ident.ctxt);
                     if !module.is_local() {

src/librustdoc/html/highlight.rs

@@ -300,7 +300,7 @@ impl<'a> Classifier<'a> {
                     "Some" | "None" | "Ok" | "Err" => Class::PreludeVal,
 
                     "$crate" => Class::KeyWord,
-                    _ if tas.tok.is_any_keyword() => Class::KeyWord,
+                    _ if tas.tok.is_reserved_ident() => Class::KeyWord,
 
                     _ => {
                         if self.in_macro_nonterminal {

src/libsyntax/ast.rs

@@ -97,9 +97,8 @@ impl Path {
     }
 
     pub fn default_to_global(mut self) -> Path {
-        let name = self.segments[0].identifier.name;
+        if !self.is_global() &&
-        if !self.is_global() && name != "$crate" &&
+           !::parse::token::Ident(self.segments[0].identifier).is_path_segment_keyword() {
-           name != keywords::SelfValue.name() && name != keywords::Super.name() {
             self.segments.insert(0, PathSegment::crate_root());
         }
         self

src/libsyntax/ext/tt/quoted.rs

@@ -12,7 +12,7 @@ use ast;
 use ext::tt::macro_parser;
 use parse::{ParseSess, token};
 use print::pprust;
-use symbol::{keywords, Symbol};
+use symbol::keywords;
 use syntax_pos::{DUMMY_SP, Span, BytePos};
 use tokenstream;
 
@@ -196,7 +196,7 @@ fn parse_tree<I>(tree: tokenstream::TokenTree,
             Some(tokenstream::TokenTree::Token(ident_span, token::Ident(ident))) => {
                 let span = Span { lo: span.lo, ..ident_span };
                 if ident.name == keywords::Crate.name() {
-                    let ident = ast::Ident { name: Symbol::intern("$crate"), ..ident };
+                    let ident = ast::Ident { name: keywords::DollarCrate.name(), ..ident };
                     TokenTree::Token(span, token::Ident(ident))
                 } else {
                     TokenTree::Token(span, token::SubstNt(ident))

src/libsyntax/parse/lexer/mod.rs

@@ -1283,7 +1283,7 @@ impl<'a> StringReader<'a> {
                     });
                     let keyword_checking_token = &token::Ident(keyword_checking_ident);
                     let last_bpos = self.pos;
-                    if keyword_checking_token.is_any_keyword() &&
+                    if keyword_checking_token.is_reserved_ident() &&
                        !keyword_checking_token.is_keyword(keywords::Static) {
                         self.err_span_(start, last_bpos, "lifetimes cannot use keyword names");
                     }

src/libsyntax/parse/parser.rs

@@ -511,14 +511,13 @@ impl<'a> Parser<'a> {
     }
 
     pub fn this_token_descr(&self) -> String {
-        let s = self.this_token_to_string();
+        let prefix = match &self.token {
-        if self.token.is_strict_keyword() {
+            t if t.is_special_ident() => "reserved identifier ",
-            format!("keyword `{}`", s)
+            t if t.is_used_keyword() => "keyword ",
-        } else if self.token.is_reserved_keyword() {
+            t if t.is_unused_keyword() => "reserved keyword ",
-            format!("reserved keyword `{}`", s)
+            _ => "",
-        } else {
+        };
-            format!("`{}`", s)
+        format!("{}`{}`", prefix, self.this_token_to_string())
-        }
     }
 
     pub fn unexpected_last<T>(&self, t: &token::Token) -> PResult<'a, T> {
@@ -637,10 +636,12 @@ impl<'a> Parser<'a> {
     }
 
     pub fn parse_ident(&mut self) -> PResult<'a, ast::Ident> {
-        self.check_strict_keywords();
-        self.check_reserved_keywords();
         match self.token {
             token::Ident(i) => {
+                if self.token.is_reserved_ident() {
+                    self.span_err(self.span, &format!("expected identifier, found {}",
+                                                      self.this_token_descr()));
+                }
                 self.bump();
                 Ok(i)
             }
@@ -713,25 +714,6 @@ impl<'a> Parser<'a> {
         }
     }
 
-    /// Signal an error if the given string is a strict keyword
-    pub fn check_strict_keywords(&mut self) {
-        if self.token.is_strict_keyword() {
-            let token_str = self.this_token_to_string();
-            let span = self.span;
-            self.span_err(span,
-                          &format!("expected identifier, found keyword `{}`",
-                                  token_str));
-        }
-    }
-
-    /// Signal an error if the current token is a reserved keyword
-    pub fn check_reserved_keywords(&mut self) {
-        if self.token.is_reserved_keyword() {
-            let token_str = self.this_token_to_string();
-            self.fatal(&format!("`{}` is a reserved keyword", token_str)).emit()
-        }
-    }
-
     fn check_ident(&mut self) -> bool {
         if self.token.is_ident() {
             true
@@ -2301,7 +2283,7 @@ impl<'a> Parser<'a> {
                     ex = ExprKind::Break(lt, e);
                     hi = self.prev_span;
                 } else if self.token.is_keyword(keywords::Let) {
-                    // Catch this syntax error here, instead of in `check_strict_keywords`, so
+                    // Catch this syntax error here, instead of in `parse_ident`, so
                     // that we can explicitly mention that let is not to be used as an expression
                     let mut db = self.fatal("expected expression, found statement (`let`)");
                     db.note("variable declaration using `let` is a statement");
@@ -3540,7 +3522,7 @@ impl<'a> Parser<'a> {
                 // Parse box pat
                 let subpat = self.parse_pat()?;
                 pat = PatKind::Box(subpat);
-            } else if self.token.is_ident() && !self.token.is_any_keyword() &&
+            } else if self.token.is_ident() && !self.token.is_reserved_ident() &&
                       self.parse_as_ident() {
                 // Parse ident @ pat
                 // This can give false positives and parse nullary enums,
@@ -3815,7 +3797,7 @@ impl<'a> Parser<'a> {
 
     fn is_union_item(&self) -> bool {
         self.token.is_keyword(keywords::Union) &&
-        self.look_ahead(1, |t| t.is_ident() && !t.is_any_keyword())
+        self.look_ahead(1, |t| t.is_ident() && !t.is_reserved_ident())
     }
 
     fn is_defaultness(&self) -> bool {

src/libsyntax/parse/token.rs

@@ -87,7 +87,7 @@ impl Lit {
 fn ident_can_begin_expr(ident: ast::Ident) -> bool {
     let ident_token: Token = Ident(ident);
 
-    !ident_token.is_any_keyword() ||
+    !ident_token.is_reserved_ident() ||
     ident_token.is_path_segment_keyword() ||
     [
         keywords::Do.name(),
@@ -110,7 +110,7 @@ fn ident_can_begin_expr(ident: ast::Ident) -> bool {
 fn ident_can_begin_type(ident: ast::Ident) -> bool {
     let ident_token: Token = Ident(ident);
 
-    !ident_token.is_any_keyword() ||
+    !ident_token.is_reserved_ident() ||
     ident_token.is_path_segment_keyword() ||
     [
         keywords::For.name(),
@@ -315,7 +315,7 @@ impl Token {
 
     pub fn is_path_start(&self) -> bool {
         self == &ModSep || self.is_qpath_start() || self.is_path() ||
-        self.is_path_segment_keyword() || self.is_ident() && !self.is_any_keyword()
+        self.is_path_segment_keyword() || self.is_ident() && !self.is_reserved_ident()
     }
 
     /// Returns `true` if the token is a given keyword, `kw`.
@@ -327,18 +327,23 @@ impl Token {
         match self.ident() {
             Some(id) => id.name == keywords::Super.name() ||
                         id.name == keywords::SelfValue.name() ||
-                        id.name == keywords::SelfType.name(),
+                        id.name == keywords::SelfType.name() ||
+                        id.name == keywords::DollarCrate.name(),
             None => false,
         }
     }
 
-    /// Returns `true` if the token is either a strict or reserved keyword.
+    // Returns true for reserved identifiers used internally for elided lifetimes,
-    pub fn is_any_keyword(&self) -> bool {
+    // unnamed method parameters, crate root module, error recovery etc.
-        self.is_strict_keyword() || self.is_reserved_keyword()
+    pub fn is_special_ident(&self) -> bool {
+        match self.ident() {
+            Some(id) => id.name <= keywords::DollarCrate.name(),
+            _ => false,
+        }
     }
 
-    /// Returns `true` if the token is a strict keyword.
+    /// Returns `true` if the token is a keyword used in the language.
-    pub fn is_strict_keyword(&self) -> bool {
+    pub fn is_used_keyword(&self) -> bool {
         match self.ident() {
             Some(id) => id.name >= keywords::As.name() && id.name <= keywords::While.name(),
             _ => false,
@@ -346,12 +351,17 @@ impl Token {
     }
 
     /// Returns `true` if the token is a keyword reserved for possible future use.
-    pub fn is_reserved_keyword(&self) -> bool {
+    pub fn is_unused_keyword(&self) -> bool {
         match self.ident() {
             Some(id) => id.name >= keywords::Abstract.name() && id.name <= keywords::Yield.name(),
             _ => false,
         }
     }
+
+    /// Returns `true` if the token is either a special identifier or a keyword.
+    pub fn is_reserved_ident(&self) -> bool {
+        self.is_special_ident() || self.is_used_keyword() || self.is_unused_keyword()
+    }
 }
 
 #[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Hash)]

src/libsyntax/print/pprust.rs

@@ -761,7 +761,7 @@ pub trait PrintState<'a> {
                         word(self.writer(), "::")?
                     }
                     if segment.identifier.name != keywords::CrateRoot.name() &&
-                       segment.identifier.name != "$crate" {
+                       segment.identifier.name != keywords::DollarCrate.name() {
                         word(self.writer(), &segment.identifier.name.as_str())?;
                     }
                 }
@@ -2375,7 +2375,7 @@ impl<'a> State<'a> {
                           -> io::Result<()>
     {
         if segment.identifier.name != keywords::CrateRoot.name() &&
-           segment.identifier.name != "$crate" {
+           segment.identifier.name != keywords::DollarCrate.name() {
             self.print_ident(segment.identifier)?;
             if let Some(ref parameters) = segment.parameters {
                 self.print_path_parameters(parameters, colons_before_params)?;

src/libsyntax_pos/symbol.rs

@@ -237,76 +237,76 @@ macro_rules! declare_keywords {(
 // NB: leaving holes in the ident table is bad! a different ident will get
 // interned with the id from the hole, but it will be between the min and max
 // of the reserved words, and thus tagged as "reserved".
-// After modifying this list adjust `is_strict_keyword`/`is_reserved_keyword`,
+// After modifying this list adjust `is_special_ident`, `is_used_keyword`/`is_unused_keyword`,
 // this should be rarely necessary though if the keywords are kept in alphabetic order.
 declare_keywords! {
-    // Invalid identifier
+    // Special reserved identifiers used internally for elided lifetimes,
+    // unnamed method parameters, crate root module, error recovery etc.
     (0,  Invalid,        "")
+    (1,  CrateRoot,      "{{root}}")
+    (2,  DollarCrate,    "$crate")
 
-    // Strict keywords used in the language.
+    // Keywords used in the language.
-    (1,  As,             "as")
+    (3,  As,             "as")
-    (2,  Box,            "box")
+    (4,  Box,            "box")
-    (3,  Break,          "break")
+    (5,  Break,          "break")
-    (4,  Const,          "const")
+    (6,  Const,          "const")
-    (5,  Continue,       "continue")
+    (7,  Continue,       "continue")
-    (6,  Crate,          "crate")
+    (8,  Crate,          "crate")
-    (7,  Else,           "else")
+    (9,  Else,           "else")
-    (8,  Enum,           "enum")
+    (10, Enum,           "enum")
-    (9,  Extern,         "extern")
+    (11, Extern,         "extern")
-    (10, False,          "false")
+    (12, False,          "false")
-    (11, Fn,             "fn")
+    (13, Fn,             "fn")
-    (12, For,            "for")
+    (14, For,            "for")
-    (13, If,             "if")
+    (15, If,             "if")
-    (14, Impl,           "impl")
+    (16, Impl,           "impl")
-    (15, In,             "in")
+    (17, In,             "in")
-    (16, Let,            "let")
+    (18, Let,            "let")
-    (17, Loop,           "loop")
+    (19, Loop,           "loop")
-    (18, Match,          "match")
+    (20, Match,          "match")
-    (19, Mod,            "mod")
+    (21, Mod,            "mod")
-    (20, Move,           "move")
+    (22, Move,           "move")
-    (21, Mut,            "mut")
+    (23, Mut,            "mut")
-    (22, Pub,            "pub")
+    (24, Pub,            "pub")
-    (23, Ref,            "ref")
+    (25, Ref,            "ref")
-    (24, Return,         "return")
+    (26, Return,         "return")
-    (25, SelfValue,      "self")
+    (27, SelfValue,      "self")
-    (26, SelfType,       "Self")
+    (28, SelfType,       "Self")
-    (27, Static,         "static")
+    (29, Static,         "static")
-    (28, Struct,         "struct")
+    (30, Struct,         "struct")
-    (29, Super,          "super")
+    (31, Super,          "super")
-    (30, Trait,          "trait")
+    (32, Trait,          "trait")
-    (31, True,           "true")
+    (33, True,           "true")
-    (32, Type,           "type")
+    (34, Type,           "type")
-    (33, Unsafe,         "unsafe")
+    (35, Unsafe,         "unsafe")
-    (34, Use,            "use")
+    (36, Use,            "use")
-    (35, Where,          "where")
+    (37, Where,          "where")
-    (36, While,          "while")
+    (38, While,          "while")
 
     // Keywords reserved for future use.
-    (37, Abstract,       "abstract")
+    (39, Abstract,       "abstract")
-    (38, Alignof,        "alignof")
+    (40, Alignof,        "alignof")
-    (39, Become,         "become")
+    (41, Become,         "become")
-    (40, Do,             "do")
+    (42, Do,             "do")
-    (41, Final,          "final")
+    (43, Final,          "final")
-    (42, Macro,          "macro")
+    (44, Macro,          "macro")
-    (43, Offsetof,       "offsetof")
+    (45, Offsetof,       "offsetof")
-    (44, Override,       "override")
+    (46, Override,       "override")
-    (45, Priv,           "priv")
+    (47, Priv,           "priv")
-    (46, Proc,           "proc")
+    (48, Proc,           "proc")
-    (47, Pure,           "pure")
+    (49, Pure,           "pure")
-    (48, Sizeof,         "sizeof")
+    (50, Sizeof,         "sizeof")
-    (49, Typeof,         "typeof")
+    (51, Typeof,         "typeof")
-    (50, Unsized,        "unsized")
+    (52, Unsized,        "unsized")
-    (51, Virtual,        "virtual")
+    (53, Virtual,        "virtual")
-    (52, Yield,          "yield")
+    (54, Yield,          "yield")
 
     // Weak keywords, have special meaning only in specific contexts.
-    (53, Default,        "default")
+    (55, Default,        "default")
-    (54, StaticLifetime, "'static")
+    (56, StaticLifetime, "'static")
-    (55, Union,          "union")
+    (57, Union,          "union")
-    (56, Catch,          "catch")
+    (58, Catch,          "catch")
-
-    // A virtual keyword that resolves to the crate root when used in a lexical scope.
-    (57, CrateRoot, "{{root}}")
 }
 
 // If an interner exists in TLS, return it. Otherwise, prepare a fresh one.

src/test/compile-fail/dollar-crate-is-keyword-2.rs

@@ -0,0 +1,23 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+mod a {}
+
+macro_rules! m {
+    () => {
+        use a::$crate; //~ ERROR unresolved import `a::$crate`
+        use a::$crate::b; //~ ERROR unresolved import `a::$crate::b`
+        type A = a::$crate; //~ ERROR cannot find type `$crate` in module `a`
+    }
+}
+
+m!();
+
+fn main() {}

src/test/compile-fail/dollar-crate-is-keyword.rs

@@ -0,0 +1,24 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+macro_rules! m {
+    () => {
+        struct $crate {} //~ ERROR expected identifier, found reserved identifier `$crate`
+
+        use $crate; // OK
+                    //~^ WARN `$crate` may not be imported
+        use $crate as $crate; //~ ERROR expected identifier, found reserved identifier `$crate`
+                              //~^ WARN `$crate` may not be imported
+    }
+}
+
+m!();
+
+fn main() {}

src/test/compile-fail/use-self-type.rs

@@ -0,0 +1,21 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+struct S;
+
+impl S {
+    fn f() {}
+    fn g() {
+        use Self::f; //~ ERROR unresolved import
+        pub(in Self::f) struct Z; //~ ERROR Use of undeclared type or module `Self`
+    }
+}
+
+fn main() {}

src/test/parse-fail/macro-keyword.rs

@@ -10,7 +10,7 @@
 
 // compile-flags: -Z parse-only
 
-fn macro() {  //~ ERROR `macro` is a reserved keyword
+fn macro() {  //~ ERROR expected identifier, found reserved keyword `macro`
 }
 
 pub fn main() {