Auto merge of #96495 - Dylan-DPC:rollup-9lm4tpp, r=Dylan-DPC

Rollup of 7 pull requests

Successful merges:

 - #96377 (make `fn() -> _ { .. }` suggestion MachineApplicable)
 - #96397 (Make EncodeWide implement FusedIterator)
 - #96421 (Less `NoDelim`)
 - #96432 (not need `Option` for `dbg_scope`)
 - #96466 (Better error messages when collecting into `[T; n]`)
 - #96471 (replace let else with `?`)
 - #96483 (Add missing `target_feature` to the list of well known cfg names)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

5 files changed, 51 insertions, 53 deletions

diff --git a/compiler/rustc_parse/src/lexer/unicode_chars.rs b/compiler/rustc_parse/src/lexer/unicode_chars.rs
index 1d63b79adc5..2e8e23a50eb 100644
--- a/compiler/rustc_parse/src/lexer/unicode_chars.rs
+++ b/compiler/rustc_parse/src/lexer/unicode_chars.rs
@@ -338,9 +338,7 @@ pub(super) fn check_for_substitution<'a>(
     ch: char,
     err: &mut Diagnostic,
 ) -> Option<token::TokenKind> {
-    let Some(&(_u_char, u_name, ascii_char)) = UNICODE_ARRAY.iter().find(|&&(c, _, _)| c == ch) else {
-        return None;
-    };
+    let &(_u_char, u_name, ascii_char) = UNICODE_ARRAY.iter().find(|&&(c, _, _)| c == ch)?;
 
     let span = Span::with_root_ctxt(pos, pos + Pos::from_usize(ch.len_utf8()));
 
diff --git a/compiler/rustc_parse/src/parser/attr_wrapper.rs b/compiler/rustc_parse/src/parser/attr_wrapper.rs
index 02749088c31..575b01180df 100644
--- a/compiler/rustc_parse/src/parser/attr_wrapper.rs
+++ b/compiler/rustc_parse/src/parser/attr_wrapper.rs
@@ -5,7 +5,7 @@ use rustc_ast::tokenstream::{AttrAnnotatedTokenTree, DelimSpan, LazyTokenStream,
 use rustc_ast::{self as ast};
 use rustc_ast::{AstLike, AttrVec, Attribute};
 use rustc_errors::PResult;
-use rustc_span::{sym, Span, DUMMY_SP};
+use rustc_span::{sym, Span};
 
 use std::convert::TryInto;
 use std::ops::Range;
@@ -400,24 +400,26 @@ fn make_token_stream(
 ) -> AttrAnnotatedTokenStream {
     #[derive(Debug)]
     struct FrameData {
-        open: Span,
-        open_delim: DelimToken,
+        // This is `None` for the first frame, `Some` for all others.
+        open_delim_sp: Option<(DelimToken, Span)>,
         inner: Vec<(AttrAnnotatedTokenTree, Spacing)>,
     }
-    let mut stack =
-        vec![FrameData { open: DUMMY_SP, open_delim: DelimToken::NoDelim, inner: vec![] }];
+    let mut stack = vec![FrameData { open_delim_sp: None, inner: vec![] }];
     let mut token_and_spacing = iter.next();
     while let Some((token, spacing)) = token_and_spacing {
         match token {
             FlatToken::Token(Token { kind: TokenKind::OpenDelim(delim), span }) => {
-                stack.push(FrameData { open: span, open_delim: delim, inner: vec![] });
+                stack.push(FrameData { open_delim_sp: Some((delim, span)), inner: vec![] });
             }
             FlatToken::Token(Token { kind: TokenKind::CloseDelim(delim), span }) => {
                 // HACK: If we encounter a mismatched `None` delimiter at the top
                 // level, just ignore it.
                 if matches!(delim, DelimToken::NoDelim)
                     && (stack.len() == 1
-                        || !matches!(stack.last_mut().unwrap().open_delim, DelimToken::NoDelim))
+                        || !matches!(
+                            stack.last_mut().unwrap().open_delim_sp.unwrap().0,
+                            DelimToken::NoDelim
+                        ))
                 {
                     token_and_spacing = iter.next();
                     continue;
@@ -430,7 +432,7 @@ fn make_token_stream(
                 // merge our current frame with the one above it. That is, transform
                 // `[ { < first second } third ]` into `[ { first second } third ]`
                 if !matches!(delim, DelimToken::NoDelim)
-                    && matches!(frame_data.open_delim, DelimToken::NoDelim)
+                    && matches!(frame_data.open_delim_sp.unwrap().0, DelimToken::NoDelim)
                 {
                     stack.last_mut().unwrap().inner.extend(frame_data.inner);
                     // Process our closing delimiter again, this time at the previous
@@ -439,12 +441,13 @@ fn make_token_stream(
                     continue;
                 }
 
+                let (open_delim, open_sp) = frame_data.open_delim_sp.unwrap();
                 assert_eq!(
-                    frame_data.open_delim, delim,
+                    open_delim, delim,
                     "Mismatched open/close delims: open={:?} close={:?}",
-                    frame_data.open, span
+                    open_delim, span
                 );
-                let dspan = DelimSpan::from_pair(frame_data.open, span);
+                let dspan = DelimSpan::from_pair(open_sp, span);
                 let stream = AttrAnnotatedTokenStream::new(frame_data.inner);
                 let delimited = AttrAnnotatedTokenTree::Delimited(dspan, delim, stream);
                 stack
@@ -472,7 +475,7 @@ fn make_token_stream(
     // HACK: If we don't have a closing `None` delimiter for our last
     // frame, merge the frame with the top-level frame. That is,
     // turn `< first second` into `first second`
-    if stack.len() == 2 && stack[1].open_delim == DelimToken::NoDelim {
+    if stack.len() == 2 && stack[1].open_delim_sp.unwrap().0 == DelimToken::NoDelim {
         let temp_buf = stack.pop().unwrap();
         stack.last_mut().unwrap().inner.extend(temp_buf.inner);
     }
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index 7efc0ca2da2..e4370809ebc 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -2043,7 +2043,8 @@ impl<'a> Parser<'a> {
             self.sess.gated_spans.gate(sym::async_closure, span);
         }
 
-        if self.token.kind == TokenKind::Semi && self.token_cursor.frame.delim == DelimToken::Paren
+        if self.token.kind == TokenKind::Semi
+            && matches!(self.token_cursor.frame.delim_sp, Some((DelimToken::Paren, _)))
         {
             // It is likely that the closure body is a block but where the
             // braces have been removed. We will recover and eat the next
diff --git a/compiler/rustc_parse/src/parser/mod.rs b/compiler/rustc_parse/src/parser/mod.rs
index 1686c5873e1..dfe758d0cdf 100644
--- a/compiler/rustc_parse/src/parser/mod.rs
+++ b/compiler/rustc_parse/src/parser/mod.rs
@@ -244,14 +244,13 @@ struct TokenCursor {
 
 #[derive(Clone)]
 struct TokenCursorFrame {
-    delim: token::DelimToken,
-    span: DelimSpan,
+    delim_sp: Option<(DelimToken, DelimSpan)>,
     tree_cursor: tokenstream::Cursor,
 }
 
 impl TokenCursorFrame {
-    fn new(span: DelimSpan, delim: DelimToken, tts: TokenStream) -> Self {
-        TokenCursorFrame { delim, span, tree_cursor: tts.into_trees() }
+    fn new(delim_sp: Option<(DelimToken, DelimSpan)>, tts: TokenStream) -> Self {
+        TokenCursorFrame { delim_sp, tree_cursor: tts.into_trees() }
     }
 }
 
@@ -266,7 +265,7 @@ impl TokenCursor {
         loop {
             // FIXME: we currently don't return `NoDelim` open/close delims. To fix #67062 we will
             // need to, whereupon the `delim != DelimToken::NoDelim` conditions below can be
-            // removed, as well as the loop.
+            // removed.
             if let Some((tree, spacing)) = self.frame.tree_cursor.next_with_spacing_ref() {
                 match tree {
                     &TokenTree::Token(ref token) => match (desugar_doc_comments, token) {
@@ -277,7 +276,7 @@ impl TokenCursor {
                     },
                     &TokenTree::Delimited(sp, delim, ref tts) => {
                         // Set `open_delim` to true here because we deal with it immediately.
-                        let frame = TokenCursorFrame::new(sp, delim, tts.clone());
+                        let frame = TokenCursorFrame::new(Some((delim, sp)), tts.clone());
                         self.stack.push(mem::replace(&mut self.frame, frame));
                         if delim != DelimToken::NoDelim {
                             return (Token::new(token::OpenDelim(delim), sp.open), Spacing::Alone);
@@ -286,12 +285,11 @@ impl TokenCursor {
                     }
                 };
             } else if let Some(frame) = self.stack.pop() {
-                let delim = self.frame.delim;
-                let span = self.frame.span;
-                self.frame = frame;
-                if delim != DelimToken::NoDelim {
+                if let Some((delim, span)) = self.frame.delim_sp && delim != DelimToken::NoDelim {
+                    self.frame = frame;
                     return (Token::new(token::CloseDelim(delim), span.close), Spacing::Alone);
                 }
+                self.frame = frame;
                 // No close delimiter to return; continue on to the next iteration.
             } else {
                 return (Token::new(token::Eof, DUMMY_SP), Spacing::Alone);
@@ -330,8 +328,7 @@ impl TokenCursor {
         self.stack.push(mem::replace(
             &mut self.frame,
             TokenCursorFrame::new(
-                delim_span,
-                token::NoDelim,
+                None,
                 if attr_style == AttrStyle::Inner {
                     [TokenTree::token(token::Pound, span), TokenTree::token(token::Not, span), body]
                         .iter()
@@ -431,10 +428,6 @@ impl<'a> Parser<'a> {
         desugar_doc_comments: bool,
         subparser_name: Option<&'static str>,
     ) -> Self {
-        // Note: because of the way `TokenCursor::inlined_next` is structured, the `span` and
-        // `delim` arguments here are never used.
-        let start_frame = TokenCursorFrame::new(DelimSpan::dummy(), token::NoDelim, tokens);
-
         let mut parser = Parser {
             sess,
             token: Token::dummy(),
@@ -444,7 +437,7 @@ impl<'a> Parser<'a> {
             restrictions: Restrictions::empty(),
             expected_tokens: Vec::new(),
             token_cursor: TokenCursor {
-                frame: start_frame,
+                frame: TokenCursorFrame::new(None, tokens),
                 stack: Vec::new(),
                 num_next_calls: 0,
                 desugar_doc_comments,
@@ -1025,7 +1018,7 @@ impl<'a> Parser<'a> {
         }
 
         let frame = &self.token_cursor.frame;
-        if frame.delim != DelimToken::NoDelim {
+        if let Some((delim, span)) = frame.delim_sp && delim != DelimToken::NoDelim {
             let all_normal = (0..dist).all(|i| {
                 let token = frame.tree_cursor.look_ahead(i);
                 !matches!(token, Some(TokenTree::Delimited(_, DelimToken::NoDelim, _)))
@@ -1038,7 +1031,7 @@ impl<'a> Parser<'a> {
                             looker(&Token::new(token::OpenDelim(*delim), dspan.open))
                         }
                     },
-                    None => looker(&Token::new(token::CloseDelim(frame.delim), frame.span.close)),
+                    None => looker(&Token::new(token::CloseDelim(delim), span.close)),
                 };
             }
         }
@@ -1198,8 +1191,7 @@ impl<'a> Parser<'a> {
                 // Grab the tokens from this frame.
                 let frame = &self.token_cursor.frame;
                 let stream = frame.tree_cursor.stream.clone();
-                let span = frame.span;
-                let delim = frame.delim;
+                let (delim, span) = frame.delim_sp.unwrap();
 
                 // Advance the token cursor through the entire delimited
                 // sequence. After getting the `OpenDelim` we are *within* the
diff --git a/compiler/rustc_parse/src/parser/stmt.rs b/compiler/rustc_parse/src/parser/stmt.rs
index 5b7ae5f7a7b..14f1208b71f 100644
--- a/compiler/rustc_parse/src/parser/stmt.rs
+++ b/compiler/rustc_parse/src/parser/stmt.rs
@@ -164,25 +164,29 @@ impl<'a> Parser<'a> {
         let delim = args.delim();
         let hi = self.prev_token.span;
 
-        let style =
-            if delim == token::Brace { MacStmtStyle::Braces } else { MacStmtStyle::NoBraces };
+        let style = match delim {
+            Some(token::Brace) => MacStmtStyle::Braces,
+            Some(_) => MacStmtStyle::NoBraces,
+            None => unreachable!(),
+        };
 
         let mac = MacCall { path, args, prior_type_ascription: self.last_type_ascription };
 
-        let kind =
-            if (delim == token::Brace && self.token != token::Dot && self.token != token::Question)
-                || self.token == token::Semi
-                || self.token == token::Eof
-            {
-                StmtKind::MacCall(P(MacCallStmt { mac, style, attrs, tokens: None }))
-            } else {
-                // Since none of the above applied, this is an expression statement macro.
-                let e = self.mk_expr(lo.to(hi), ExprKind::MacCall(mac), AttrVec::new());
-                let e = self.maybe_recover_from_bad_qpath(e, true)?;
-                let e = self.parse_dot_or_call_expr_with(e, lo, attrs.into())?;
-                let e = self.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(e))?;
-                StmtKind::Expr(e)
-            };
+        let kind = if (style == MacStmtStyle::Braces
+            && self.token != token::Dot
+            && self.token != token::Question)
+            || self.token == token::Semi
+            || self.token == token::Eof
+        {
+            StmtKind::MacCall(P(MacCallStmt { mac, style, attrs, tokens: None }))
+        } else {
+            // Since none of the above applied, this is an expression statement macro.
+            let e = self.mk_expr(lo.to(hi), ExprKind::MacCall(mac), AttrVec::new());
+            let e = self.maybe_recover_from_bad_qpath(e, true)?;
+            let e = self.parse_dot_or_call_expr_with(e, lo, attrs.into())?;
+            let e = self.parse_assoc_expr_with(0, LhsExpr::AlreadyParsed(e))?;
+            StmtKind::Expr(e)
+        };
         Ok(self.mk_stmt(lo.to(hi), kind))
     }