Use default field values in markdown::parse::Context

Author: estebank

Diff for: compiler/rustc_errors/src/lib.rs

@@ -14,6 +14,7 @@
 #![feature(associated_type_defaults)]
 #![feature(box_into_inner)]
 #![feature(box_patterns)]
+#![feature(default_field_values)]
 #![feature(error_reporter)]
 #![feature(if_let_guard)]
 #![feature(let_chains)]

Diff for: compiler/rustc_errors/src/markdown/parse.rs

@@ -40,11 +40,13 @@ type ParseResult<'a> = Option<Parsed<'a>>;
 
 /// Parsing context
 #[derive(Clone, Copy, Debug, PartialEq)]
+// The default values are the most common setting for non top-level parsing: not top block, not at
+// line start (yes leading whitespace, not escaped).
 struct Context {
     /// If true, we are at a the topmost level (not recursing a nested tt)
-    top_block: bool,
+    top_block: bool = false,
     /// Previous character
-    prev: Prev,
+    prev: Prev = Prev::Whitespace,
 }
 
 /// Character class preceding this one
@@ -57,14 +59,6 @@ enum Prev {
     Any,
 }
 
-impl Default for Context {
-    /// Most common setting for non top-level parsing: not top block, not at
-    /// line start (yes leading whitespace, not escaped)
-    fn default() -> Self {
-        Self { top_block: false, prev: Prev::Whitespace }
-    }
-}
-
 /// Flags to simple parser function
 #[derive(Clone, Copy, Debug, PartialEq)]
 enum ParseOpt {
@@ -248,7 +242,7 @@ fn parse_heading(buf: &[u8]) -> ParseResult<'_> {
     }
 
     let (txt, rest) = parse_to_newline(&buf[1..]);
-    let ctx = Context { top_block: false, prev: Prev::Whitespace };
+    let ctx = Context { .. };
     let stream = parse_recursive(txt, ctx);
 
     Some((MdTree::Heading(level.try_into().unwrap(), stream), rest))
@@ -257,7 +251,7 @@ fn parse_heading(buf: &[u8]) -> ParseResult<'_> {
 /// Bulleted list
 fn parse_unordered_li(buf: &[u8]) -> Parsed<'_> {
     let (txt, rest) = get_indented_section(&buf[2..]);
-    let ctx = Context { top_block: false, prev: Prev::Whitespace };
+    let ctx = Context { .. };
     let stream = parse_recursive(trim_ascii_start(txt), ctx);
     (MdTree::UnorderedListItem(stream), rest)
 }
@@ -266,7 +260,7 @@ fn parse_unordered_li(buf: &[u8]) -> Parsed<'_> {
 fn parse_ordered_li(buf: &[u8]) -> Parsed<'_> {
     let (num, pos) = ord_list_start(buf).unwrap(); // success tested in caller
     let (txt, rest) = get_indented_section(&buf[pos..]);
-    let ctx = Context { top_block: false, prev: Prev::Whitespace };
+    let ctx = Context { .. };
     let stream = parse_recursive(trim_ascii_start(txt), ctx);
     (MdTree::OrderedListItem(num, stream), rest)
 }