Auto merge of #38232 - jseyfried:refactor_global_paths, r=nrc

Refactor global paths

This PR removes the field `global: bool` from `ast::Path` and `hir::Path`, instead representing a global path `::foo::bar` as `{{root}}::foo::bar`, where `{{root}}` is a virtual keyword `keywords::CrateRoot`.

Also, fixes #38016.

r? @nrc

2 files changed, 12 insertions, 14 deletions

diff --git a/src/libsyntax/parse/mod.rs b/src/libsyntax/parse/mod.rs
index b9e6605639e..24178e1f675 100644
--- a/src/libsyntax/parse/mod.rs
+++ b/src/libsyntax/parse/mod.rs
@@ -633,7 +633,6 @@ mod tests {
                     id: ast::DUMMY_NODE_ID,
                     node: ast::ExprKind::Path(None, ast::Path {
                         span: sp(0, 1),
-                        global: false,
                         segments: vec![Ident::from_str("a").into()],
                     }),
                     span: sp(0, 1),
@@ -647,8 +646,9 @@ mod tests {
                     id: ast::DUMMY_NODE_ID,
                     node: ast::ExprKind::Path(None, ast::Path {
                         span: sp(0, 6),
-                        global: true,
-                        segments: vec![Ident::from_str("a").into(), Ident::from_str("b").into()],
+                        segments: vec![ast::PathSegment::crate_root(),
+                                       Ident::from_str("a").into(),
+                                       Ident::from_str("b").into()]
                     }),
                     span: sp(0, 6),
                     attrs: ThinVec::new(),
@@ -757,7 +757,6 @@ mod tests {
                         id: ast::DUMMY_NODE_ID,
                         node:ast::ExprKind::Path(None, ast::Path{
                             span: sp(7, 8),
-                            global: false,
                             segments: vec![Ident::from_str("d").into()],
                         }),
                         span:sp(7,8),
@@ -775,7 +774,6 @@ mod tests {
                            id: ast::DUMMY_NODE_ID,
                            node: ast::ExprKind::Path(None, ast::Path {
                                span:sp(0,1),
-                               global:false,
                                segments: vec![Ident::from_str("b").into()],
                             }),
                            span: sp(0,1),
@@ -817,7 +815,6 @@ mod tests {
                                     ty: P(ast::Ty{id: ast::DUMMY_NODE_ID,
                                                   node: ast::TyKind::Path(None, ast::Path{
                                         span:sp(10,13),
-                                        global:false,
                                         segments: vec![Ident::from_str("i32").into()],
                                         }),
                                         span:sp(10,13)
@@ -860,7 +857,6 @@ mod tests {
                                                 node: ast::ExprKind::Path(None,
                                                       ast::Path{
                                                         span:sp(17,18),
-                                                        global:false,
                                                         segments: vec![Ident::from_str("b").into()],
                                                       }),
                                                 span: sp(17,18),
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 72462b74e68..cd4f255b5e3 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -1614,7 +1614,6 @@ impl<'a> Parser<'a> {
         } else {
             ast::Path {
                 span: span,
-                global: false,
                 segments: vec![]
             }
         };
@@ -1658,7 +1657,7 @@ impl<'a> Parser<'a> {
         // Parse any number of segments and bound sets. A segment is an
         // identifier followed by an optional lifetime and a set of types.
         // A bound set is a set of type parameter bounds.
-        let segments = match mode {
+        let mut segments = match mode {
             PathStyle::Type => {
                 self.parse_path_segments_without_colons()?
             }
@@ -1670,13 +1669,16 @@ impl<'a> Parser<'a> {
             }
         };
 
+        if is_global {
+            segments.insert(0, ast::PathSegment::crate_root());
+        }
+
         // Assemble the span.
         let span = mk_sp(lo, self.prev_span.hi);
 
         // Assemble the result.
         Ok(ast::Path {
             span: span,
-            global: is_global,
             segments: segments,
         })
     }
@@ -5180,7 +5182,7 @@ impl<'a> Parser<'a> {
         } else if self.eat_keyword(keywords::Crate) {
             pub_crate(self)
         } else {
-            let path = self.parse_path(PathStyle::Mod)?;
+            let path = self.parse_path(PathStyle::Mod)?.default_to_global();
             self.expect(&token::CloseDelim(token::Paren))?;
             Ok(Visibility::Restricted { path: P(path), id: ast::DUMMY_NODE_ID })
         }
@@ -6068,9 +6070,9 @@ impl<'a> Parser<'a> {
         if self.check(&token::OpenDelim(token::Brace)) || self.check(&token::BinOp(token::Star)) ||
            self.is_import_coupler() {
             // `{foo, bar}`, `::{foo, bar}`, `*`, or `::*`.
+            self.eat(&token::ModSep);
             let prefix = ast::Path {
-                global: self.eat(&token::ModSep),
-                segments: Vec::new(),
+                segments: vec![ast::PathSegment::crate_root()],
                 span: mk_sp(lo, self.span.hi),
             };
             let view_path_kind = if self.eat(&token::BinOp(token::Star)) {
@@ -6080,7 +6082,7 @@ impl<'a> Parser<'a> {
             };
             Ok(P(spanned(lo, self.span.hi, view_path_kind)))
         } else {
-            let prefix = self.parse_path(PathStyle::Mod)?;
+            let prefix = self.parse_path(PathStyle::Mod)?.default_to_global();
             if self.is_import_coupler() {
                 // `foo::bar::{a, b}` or `foo::bar::*`
                 self.bump();