Auto merge of #60930 - petrochenkov:nodoc, r=<try>

[experiment] How expensive are doc comments?

What happens if they are interpreted as usual comments and not converted to attributes, and not stored in AST/HIR?

(This cannot be checked at lexer level, unfortunately, since some popular crates (`rayon`) rely on `/** text */` being matched by `#[$meta]` in macros.)

r? @ghost

Author: bors

src/librustc_lint/builtin.rs

@@ -316,6 +316,7 @@ impl MissingDoc {
         *self.doc_hidden_stack.last().expect("empty doc_hidden_stack")
     }
 
+    #[allow(unused)]
     fn check_missing_docs_attrs(&self,
                                 cx: &LateContext<'_, '_>,
                                 id: Option<hir::HirId>,
@@ -344,9 +345,9 @@ impl MissingDoc {
 
         let has_doc = attrs.iter().any(|a| has_doc(a));
         if !has_doc {
-            cx.span_lint(MISSING_DOCS,
-                         cx.tcx.sess.source_map().def_span(sp),
-                         &format!("missing documentation for {}", desc));
+            // cx.span_lint(MISSING_DOCS,
+            //              cx.tcx.sess.source_map().def_span(sp),
+            //              &format!("missing documentation for {}", desc));
         }
     }
 }
@@ -374,9 +375,9 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingDoc {
         for macro_def in &krate.exported_macros {
             let has_doc = macro_def.attrs.iter().any(|a| has_doc(a));
             if !has_doc {
-                cx.span_lint(MISSING_DOCS,
-                             cx.tcx.sess.source_map().def_span(macro_def.span),
-                             "missing documentation for macro");
+                // cx.span_lint(MISSING_DOCS,
+                //              cx.tcx.sess.source_map().def_span(macro_def.span),
+                //              "missing documentation for macro");
             }
         }
     }

src/libsyntax/parse/attr.rs

@@ -38,17 +38,17 @@ impl<'a> Parser<'a> {
                     attrs.push(self.parse_attribute_with_inner_parse_policy(inner_parse_policy)?);
                     just_parsed_doc_comment = false;
                 }
-                token::DocComment(s) => {
-                    let attr = attr::mk_sugared_doc_attr(attr::mk_attr_id(), s, self.span);
-                    if attr.style != ast::AttrStyle::Outer {
-                        let mut err = self.fatal("expected outer doc comment");
-                        err.note("inner doc comments like this (starting with \
-                                  `//!` or `/*!`) can only appear before items");
-                        return Err(err);
-                    }
-                    attrs.push(attr);
+                token::DocComment(_s) => {
+                    // let attr = attr::mk_sugared_doc_attr(attr::mk_attr_id(), s, self.span);
+                    // if attr.style != ast::AttrStyle::Outer {
+                    //     let mut err = self.fatal("expected outer doc comment");
+                    //     err.note("inner doc comments like this (starting with \
+                    //               `//!` or `/*!`) can only appear before items");
+                    //     return Err(err);
+                    // }
+                    // attrs.push(attr);
                     self.bump();
-                    just_parsed_doc_comment = true;
+                    // just_parsed_doc_comment = true;
                 }
                 _ => break,
             }
@@ -199,15 +199,16 @@ impl<'a> Parser<'a> {
                     assert_eq!(attr.style, ast::AttrStyle::Inner);
                     attrs.push(attr);
                 }
-                token::DocComment(s) => {
+                token::DocComment(_s) => {
+                    self.bump();
                     // we need to get the position of this token before we bump.
-                    let attr = attr::mk_sugared_doc_attr(attr::mk_attr_id(), s, self.span);
-                    if attr.style == ast::AttrStyle::Inner {
-                        attrs.push(attr);
-                        self.bump();
-                    } else {
-                        break;
-                    }
+                    // let attr = attr::mk_sugared_doc_attr(attr::mk_attr_id(), s, self.span);
+                    // if attr.style == ast::AttrStyle::Inner {
+                    //     attrs.push(attr);
+                    //     self.bump();
+                    // } else {
+                    //     break;
+                    // }
                 }
                 _ => break,
             }

src/libsyntax/parse/mod.rs

@@ -357,7 +357,6 @@ impl SeqSep {
 mod tests {
     use super::*;
     use crate::ast::{self, Ident, PatKind};
-    use crate::attr::first_attr_value_str_by_name;
     use crate::ptr::P;
     use crate::print::pprust::item_to_string;
     use crate::tokenstream::{DelimSpan, TokenTree};
@@ -575,36 +574,6 @@ mod tests {
         })
     }
 
-    #[test] fn crlf_doc_comments() {
-        with_globals(|| {
-            use crate::symbol::sym;
-
-            let sess = ParseSess::new(FilePathMapping::empty());
-
-            let name_1 = FileName::Custom("crlf_source_1".to_string());
-            let source = "/// doc comment\r\nfn foo() {}".to_string();
-            let item = parse_item_from_source_str(name_1, source, &sess)
-                .unwrap().unwrap();
-            let doc = first_attr_value_str_by_name(&item.attrs, sym::doc).unwrap();
-            assert_eq!(doc.as_str(), "/// doc comment");
-
-            let name_2 = FileName::Custom("crlf_source_2".to_string());
-            let source = "/// doc comment\r\n/// line 2\r\nfn foo() {}".to_string();
-            let item = parse_item_from_source_str(name_2, source, &sess)
-                .unwrap().unwrap();
-            let docs = item.attrs.iter().filter(|a| a.path == sym::doc)
-                        .map(|a| a.value_str().unwrap().to_string()).collect::<Vec<_>>();
-            let b: &[_] = &["/// doc comment".to_string(), "/// line 2".to_string()];
-            assert_eq!(&docs[..], b);
-
-            let name_3 = FileName::Custom("clrf_source_3".to_string());
-            let source = "/** doc comment\r\n *  with CRLF */\r\nfn foo() {}".to_string();
-            let item = parse_item_from_source_str(name_3, source, &sess).unwrap().unwrap();
-            let doc = first_attr_value_str_by_name(&item.attrs, sym::doc).unwrap();
-            assert_eq!(doc.as_str(), "/** doc comment\n *  with CRLF */");
-        });
-    }
-
     #[test]
     fn ttdelim_span() {
         fn parse_expr_from_source_str(