Rollup merge of #56426 - petrochenkov:syntweak, r=nikomatsakis

libsyntax_pos: A few tweaks

7 files changed, 23 insertions, 37 deletions

diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index 227017a9073..87225711871 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -73,7 +73,7 @@ impl fmt::Debug for Lifetime {
 pub struct Path {
     pub span: Span,
     /// The segments in the path: the things separated by `::`.
-    /// Global paths begin with `keywords::CrateRoot`.
+    /// Global paths begin with `keywords::PathRoot`.
     pub segments: Vec<PathSegment>,
 }
 
@@ -105,19 +105,8 @@ impl Path {
         }
     }
 
-    // Make a "crate root" segment for this path unless it already has it
-    // or starts with something like `self`/`super`/`$crate`/etc.
-    pub fn make_root(&self) -> Option<PathSegment> {
-        if let Some(ident) = self.segments.get(0).map(|seg| seg.ident) {
-            if ident.is_path_segment_keyword() {
-                return None;
-            }
-        }
-        Some(PathSegment::crate_root(self.span.shrink_to_lo()))
-    }
-
     pub fn is_global(&self) -> bool {
-        !self.segments.is_empty() && self.segments[0].ident.name == keywords::CrateRoot.name()
+        !self.segments.is_empty() && self.segments[0].ident.name == keywords::PathRoot.name()
     }
 }
 
@@ -144,8 +133,8 @@ impl PathSegment {
     pub fn from_ident(ident: Ident) -> Self {
         PathSegment { ident, id: DUMMY_NODE_ID, args: None }
     }
-    pub fn crate_root(span: Span) -> Self {
-        PathSegment::from_ident(Ident::new(keywords::CrateRoot.name(), span))
+    pub fn path_root(span: Span) -> Self {
+        PathSegment::from_ident(Ident::new(keywords::PathRoot.name(), span))
     }
 }
 
@@ -1688,7 +1677,7 @@ pub type ExplicitSelf = Spanned<SelfKind>;
 impl Arg {
     pub fn to_self(&self) -> Option<ExplicitSelf> {
         if let PatKind::Ident(BindingMode::ByValue(mutbl), ident, _) = self.pat.node {
-            if ident.name == keywords::SelfValue.name() {
+            if ident.name == keywords::SelfLower.name() {
                 return match self.ty.node {
                     TyKind::ImplicitSelf => Some(respan(self.pat.span, SelfKind::Value(mutbl))),
                     TyKind::Rptr(lt, MutTy { ref ty, mutbl }) if ty.node.is_implicit_self() => {
@@ -1706,7 +1695,7 @@ impl Arg {
 
     pub fn is_self(&self) -> bool {
         if let PatKind::Ident(_, ident, _) = self.pat.node {
-            ident.name == keywords::SelfValue.name()
+            ident.name == keywords::SelfLower.name()
         } else {
             false
         }
diff --git a/src/libsyntax/ext/build.rs b/src/libsyntax/ext/build.rs
index cacec867cf1..5770f6bb8a2 100644
--- a/src/libsyntax/ext/build.rs
+++ b/src/libsyntax/ext/build.rs
@@ -318,9 +318,13 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
                 args: Vec<ast::GenericArg>,
                 bindings: Vec<ast::TypeBinding> )
                 -> ast::Path {
+        assert!(!idents.is_empty());
+        let add_root = global && !idents[0].is_path_segment_keyword();
+        let mut segments = Vec::with_capacity(idents.len() + add_root as usize);
+        if add_root {
+            segments.push(ast::PathSegment::path_root(span));
+        }
         let last_ident = idents.pop().unwrap();
-        let mut segments: Vec<ast::PathSegment> = vec![];
-
         segments.extend(idents.into_iter().map(|ident| {
             ast::PathSegment::from_ident(ident.with_span_pos(span))
         }));
@@ -334,13 +338,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
             id: ast::DUMMY_NODE_ID,
             args,
         });
-        let mut path = ast::Path { span, segments };
-        if global {
-            if let Some(seg) = path.make_root() {
-                path.segments.insert(0, seg);
-            }
-        }
-        path
+        ast::Path { span, segments }
     }
 
     /// Constructs a qualified path.
@@ -625,7 +623,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         self.expr_path(self.path_ident(span, id))
     }
     fn expr_self(&self, span: Span) -> P<ast::Expr> {
-        self.expr_ident(span, keywords::SelfValue.ident())
+        self.expr_ident(span, keywords::SelfLower.ident())
     }
 
     fn expr_binary(&self, sp: Span, op: ast::BinOpKind,
diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index 68a96293891..67f3dc1bb52 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -204,7 +204,7 @@ fn macro_bang_format(path: &ast::Path) -> ExpnFormat {
             path_str.push_str("::");
         }
 
-        if segment.ident.name != keywords::CrateRoot.name() &&
+        if segment.ident.name != keywords::PathRoot.name() &&
             segment.ident.name != keywords::DollarCrate.name()
         {
             path_str.push_str(&segment.ident.as_str())
diff --git a/src/libsyntax/ext/tt/quoted.rs b/src/libsyntax/ext/tt/quoted.rs
index edc431be369..a7415e845ca 100644
--- a/src/libsyntax/ext/tt/quoted.rs
+++ b/src/libsyntax/ext/tt/quoted.rs
@@ -444,7 +444,6 @@ where
             macro_node_id,
         ),
         Edition::Edition2018 => parse_sep_and_kleene_op_2018(input, span, sess, features, attrs),
-        _ => unimplemented!(),
     }
 }
 
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 1cd5006f330..8165c0e44c4 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -2082,7 +2082,7 @@ impl<'a> Parser<'a> {
         let mut segments = Vec::new();
         let mod_sep_ctxt = self.span.ctxt();
         if self.eat(&token::ModSep) {
-            segments.push(PathSegment::crate_root(lo.shrink_to_lo().with_ctxt(mod_sep_ctxt)));
+            segments.push(PathSegment::path_root(lo.shrink_to_lo().with_ctxt(mod_sep_ctxt)));
         }
         self.parse_path_segments(&mut segments, style, enable_warning)?;
 
@@ -5508,7 +5508,7 @@ impl<'a> Parser<'a> {
             _ => unreachable!()
         };
         let isolated_self = |this: &mut Self, n| {
-            this.look_ahead(n, |t| t.is_keyword(keywords::SelfValue)) &&
+            this.look_ahead(n, |t| t.is_keyword(keywords::SelfLower)) &&
             this.look_ahead(n + 1, |t| t != &token::ModSep)
         };
 
@@ -6330,7 +6330,7 @@ impl<'a> Parser<'a> {
                 return Ok(vis)
             } else if self.look_ahead(2, |t| t == &token::CloseDelim(token::Paren)) &&
                       self.look_ahead(1, |t| t.is_keyword(keywords::Super) ||
-                                             t.is_keyword(keywords::SelfValue))
+                                             t.is_keyword(keywords::SelfLower))
             {
                 // `pub(self)` or `pub(super)`
                 self.bump(); // `(`
@@ -6782,7 +6782,7 @@ impl<'a> Parser<'a> {
         let error_msg = "crate name using dashes are not valid in `extern crate` statements";
         let suggestion_msg = "if the original crate name uses dashes you need to use underscores \
                               in the code";
-        let mut ident = if self.token.is_keyword(keywords::SelfValue) {
+        let mut ident = if self.token.is_keyword(keywords::SelfLower) {
             self.parse_path_segment_ident()
         } else {
             self.parse_ident()
@@ -7685,7 +7685,7 @@ impl<'a> Parser<'a> {
             let mod_sep_ctxt = self.span.ctxt();
             if self.eat(&token::ModSep) {
                 prefix.segments.push(
-                    PathSegment::crate_root(lo.shrink_to_lo().with_ctxt(mod_sep_ctxt))
+                    PathSegment::path_root(lo.shrink_to_lo().with_ctxt(mod_sep_ctxt))
                 );
             }
 
diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index a9f08fdd411..e50f28897dd 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -724,7 +724,7 @@ pub trait PrintState<'a> {
             if i > 0 {
                 self.writer().word("::")?
             }
-            if segment.ident.name != keywords::CrateRoot.name() &&
+            if segment.ident.name != keywords::PathRoot.name() &&
                segment.ident.name != keywords::DollarCrate.name()
             {
                 self.writer().word(segment.ident.as_str().get())?;
@@ -2463,7 +2463,7 @@ impl<'a> State<'a> {
                           colons_before_params: bool)
                           -> io::Result<()>
     {
-        if segment.ident.name != keywords::CrateRoot.name() &&
+        if segment.ident.name != keywords::PathRoot.name() &&
            segment.ident.name != keywords::DollarCrate.name() {
             self.print_ident(segment.ident)?;
             if let Some(ref args) = segment.args {
diff --git a/src/libsyntax/std_inject.rs b/src/libsyntax/std_inject.rs
index 1210f331b28..5c994558ab0 100644
--- a/src/libsyntax/std_inject.rs
+++ b/src/libsyntax/std_inject.rs
@@ -112,7 +112,7 @@ pub fn maybe_inject_crates_ref(
         vis: respan(span.shrink_to_lo(), ast::VisibilityKind::Inherited),
         node: ast::ItemKind::Use(P(ast::UseTree {
             prefix: ast::Path {
-                segments: iter::once(keywords::CrateRoot.ident())
+                segments: iter::once(keywords::PathRoot.ident())
                     .chain(
                         [name, "prelude", "v1"].iter().cloned()
                             .map(ast::Ident::from_str)