syntax: extract parse_cfg_attr

src/libsyntax/attr/mod.rs

@@ -302,7 +302,6 @@ impl Attribute {
         if self.tokens.is_empty() {
             return Ok(Vec::new());
         }
-
         self.parse(sess, |p| p.parse_derive_paths())
     }
 

src/libsyntax/config.rs

@@ -10,7 +10,6 @@ use crate::attr;
 use crate::ast;
 use crate::edition::Edition;
 use crate::mut_visit::*;
-use crate::parse::token;
 use crate::ptr::P;
 use crate::sess::ParseSess;
 use crate::symbol::sym;
@@ -112,25 +111,7 @@ impl<'a> StripUnconfigured<'a> {
             return vec![];
         }
 
-        let (cfg_predicate, expanded_attrs) = match attr.parse(self.sess, |parser| {
+        let (cfg_predicate, expanded_attrs) = match attr.parse(self.sess, |p| p.parse_cfg_attr()) {
-            parser.expect(&token::OpenDelim(token::Paren))?;
-
-            let cfg_predicate = parser.parse_meta_item()?;
-            parser.expect(&token::Comma)?;
-
-            // Presumably, the majority of the time there will only be one attr.
-            let mut expanded_attrs = Vec::with_capacity(1);
-
-            while !parser.check(&token::CloseDelim(token::Paren)) {
-                let lo = parser.token.span.lo();
-                let item = parser.parse_attr_item()?;
-                expanded_attrs.push((item, parser.prev_span.with_lo(lo)));
-                parser.expect_one_of(&[token::Comma], &[token::CloseDelim(token::Paren)])?;
-            }
-
-            parser.expect(&token::CloseDelim(token::Paren))?;
-            Ok((cfg_predicate, expanded_attrs))
-        }) {
             Ok(result) => result,
             Err(mut e) => {
                 e.emit();

src/libsyntax/parse/parser/attr.rs

@@ -260,6 +260,27 @@ impl<'a> Parser<'a> {
         Ok(lit)
     }
 
+    /// Parses `cfg_attr(pred, attr_item_list)` where `attr_item_list` is comma-delimited.
+    crate fn parse_cfg_attr(&mut self) -> PResult<'a, (ast::MetaItem, Vec<(ast::AttrItem, Span)>)> {
+        self.expect(&token::OpenDelim(token::Paren))?;
+
+        let cfg_predicate = self.parse_meta_item()?;
+        self.expect(&token::Comma)?;
+
+        // Presumably, the majority of the time there will only be one attr.
+        let mut expanded_attrs = Vec::with_capacity(1);
+
+        while !self.check(&token::CloseDelim(token::Paren)) {
+            let lo = self.token.span.lo();
+            let item = self.parse_attr_item()?;
+            expanded_attrs.push((item, self.prev_span.with_lo(lo)));
+            self.expect_one_of(&[token::Comma], &[token::CloseDelim(token::Paren)])?;
+        }
+
+        self.expect(&token::CloseDelim(token::Paren))?;
+        Ok((cfg_predicate, expanded_attrs))
+    }
+
     /// Matches the following grammar (per RFC 1559).
     ///
     ///     meta_item : PATH ( '=' UNSUFFIXED_LIT | '(' meta_item_inner? ')' )? ;