Remove desugar_doc_comments arg from Parser::new().

It's only true at one call site; do the desugaring there instead.

compiler/rustc_expand/src/mbe/macro_rules.rs

@@ -249,7 +249,7 @@ fn expand_macro<'cx>(
                 trace_macros_note(&mut cx.expansions, sp, msg);
             }
 
-            let p = Parser::new(sess, tts, false, None);
+            let p = Parser::new(sess, tts, None);
 
             if is_local {
                 cx.resolver.record_macro_rule_usage(node_id, i);
@@ -446,7 +446,7 @@ pub fn compile_declarative_macro(
 
     let create_parser = || {
         let body = macro_def.body.tokens.clone();
-        Parser::new(&sess.parse_sess, body, false, rustc_parse::MACRO_ARGUMENTS)
+        Parser::new(&sess.parse_sess, body, rustc_parse::MACRO_ARGUMENTS)
     };
 
     let parser = create_parser();
@@ -1417,6 +1417,11 @@ fn quoted_tt_to_string(tt: &mbe::TokenTree) -> String {
     }
 }
 
-pub(super) fn parser_from_cx(sess: &ParseSess, tts: TokenStream, recovery: Recovery) -> Parser<'_> {
-    Parser::new(sess, tts, true, rustc_parse::MACRO_ARGUMENTS).recovery(recovery)
+pub(super) fn parser_from_cx(
+    sess: &ParseSess,
+    mut tts: TokenStream,
+    recovery: Recovery,
+) -> Parser<'_> {
+    tts.desugar_doc_comments();
+    Parser::new(sess, tts, rustc_parse::MACRO_ARGUMENTS).recovery(recovery)
 }

compiler/rustc_parse/src/lib.rs

@@ -205,7 +205,7 @@ pub fn stream_to_parser<'a>(
     stream: TokenStream,
     subparser_name: Option<&'static str>,
 ) -> Parser<'a> {
-    Parser::new(sess, stream, false, subparser_name)
+    Parser::new(sess, stream, subparser_name)
 }
 
 /// Runs the given subparser `f` on the tokens of the given `attr`'s item.
@@ -215,7 +215,7 @@ pub fn parse_in<'a, T>(
     name: &'static str,
     mut f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
 ) -> PResult<'a, T> {
-    let mut parser = Parser::new(sess, tts, false, Some(name));
+    let mut parser = Parser::new(sess, tts, Some(name));
     let result = f(&mut parser)?;
     if parser.token != token::Eof {
         parser.unexpected()?;

compiler/rustc_parse/src/parser/mod.rs

@@ -388,14 +388,9 @@ pub(super) fn token_descr(token: &Token) -> String {
 impl<'a> Parser<'a> {
     pub fn new(
         sess: &'a ParseSess,
-        mut stream: TokenStream,
-        desugar_doc_comments: bool,
+        stream: TokenStream,
         subparser_name: Option<&'static str>,
     ) -> Self {
-        if desugar_doc_comments {
-            stream.desugar_doc_comments();
-        }
-
         let mut parser = Parser {
             sess,
             token: Token::dummy(),