auto merge of #10642 : cmr/rust/strict_doccomment, r=alexcrichton

Previously, `//// foo` and `/*** foo ***/` were accepted as doc comments. This
changes that, so that only `/// foo` and `/** foo ***/` are accepted. This
confuses many newcomers and it seems weird.

Also update the manual for these changes, and modernify the EBNF for comments.

Closes #10638

1 files changed, 2 insertions, 4 deletions

diff --git a/src/libsyntax/parse/lexer.rs b/src/libsyntax/parse/lexer.rs
index e4b93c3b4d5..fa93c5f8977 100644
--- a/src/libsyntax/parse/lexer.rs
+++ b/src/libsyntax/parse/lexer.rs
@@ -317,8 +317,7 @@ fn consume_whitespace_and_comments(rdr: @mut StringReader)
 }
 
 pub fn is_line_non_doc_comment(s: &str) -> bool {
-    let s = s.trim_right();
-    s.len() > 3 && s.chars().all(|ch| ch == '/')
+    s.starts_with("////")
 }
 
 // PRECONDITION: rdr.curr is not whitespace
@@ -378,8 +377,7 @@ fn consume_any_line_comment(rdr: @mut StringReader)
 }
 
 pub fn is_block_non_doc_comment(s: &str) -> bool {
-    assert!(s.len() >= 1u);
-    s.slice(1u, s.len() - 1u).chars().all(|ch| ch == '*')
+    s.starts_with("/***")
 }
 
 // might return a sugared-doc-attr