Auto merge of #54859 - pietroalbini:rollup, r=pietroalbini

Rollup of 11 pull requests

Successful merges:

 - #54078 (Expand the documentation for the `std::sync` module)
 - #54717 (Cleanup rustc/ty part 1)
 - #54781 (Add examples to `TyKind::FnDef` and `TyKind::FnPtr` docs)
 - #54787 (Only warn about unused `mut` in user-written code)
 - #54804 (add suggestion for inverted function parameters)
 - #54812 (Regression test for #32382.)
 - #54833 (make `Parser::parse_foreign_item()` return a foreign item or error)
 - #54834 (rustdoc: overflow:auto doesn't work nicely on small screens)
 - #54838 (Fix typo in src/libsyntax/parse/parser.rs)
 - #54851 (Fix a regression in 1.30 by reverting #53564)
 - #54853 (Remove unneccessary error from test, revealing NLL error.)

Failed merges:

r? @ghost

1 files changed, 31 insertions, 13 deletions

diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 5571a18b596..d653ed819fd 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -1777,7 +1777,26 @@ impl<'a> Parser<'a> {
                    require_name);
             let pat = self.parse_pat()?;
 
-            self.expect(&token::Colon)?;
+            if let Err(mut err) = self.expect(&token::Colon) {
+                // If we find a pattern followed by an identifier, it could be an (incorrect)
+                // C-style parameter declaration.
+                if self.check_ident() && self.look_ahead(1, |t| {
+                    *t == token::Comma || *t == token::CloseDelim(token::Paren)
+                }) {
+                    let ident = self.parse_ident().unwrap();
+                    let span = pat.span.with_hi(ident.span.hi());
+
+                    err.span_suggestion_with_applicability(
+                        span,
+                        "declare the type after the parameter binding",
+                        String::from("<identifier>: <type>"),
+                        Applicability::HasPlaceholders,
+                    );
+                }
+
+                return Err(err);
+            }
+
             (pat, self.parse_ty()?)
         } else {
             debug!("parse_arg_general ident_to_pat");
@@ -6718,10 +6737,9 @@ impl<'a> Parser<'a> {
         attrs.extend(self.parse_inner_attributes()?);
 
         let mut foreign_items = vec![];
-        while let Some(item) = self.parse_foreign_item()? {
-            foreign_items.push(item);
+        while !self.eat(&token::CloseDelim(token::Brace)) {
+            foreign_items.push(self.parse_foreign_item()?);
         }
-        self.expect(&token::CloseDelim(token::Brace))?;
 
         let prev_span = self.prev_span;
         let m = ast::ForeignMod {
@@ -7305,8 +7323,8 @@ impl<'a> Parser<'a> {
     }
 
     /// Parse a foreign item.
-    crate fn parse_foreign_item(&mut self) -> PResult<'a, Option<ForeignItem>> {
-        maybe_whole!(self, NtForeignItem, |ni| Some(ni));
+    crate fn parse_foreign_item(&mut self) -> PResult<'a, ForeignItem> {
+        maybe_whole!(self, NtForeignItem, |ni| ni);
 
         let attrs = self.parse_outer_attributes()?;
         let lo = self.span;
@@ -7326,20 +7344,20 @@ impl<'a> Parser<'a> {
                     ).emit();
             }
             self.bump(); // `static` or `const`
-            return Ok(Some(self.parse_item_foreign_static(visibility, lo, attrs)?));
+            return Ok(self.parse_item_foreign_static(visibility, lo, attrs)?);
         }
         // FOREIGN FUNCTION ITEM
         if self.check_keyword(keywords::Fn) {
-            return Ok(Some(self.parse_item_foreign_fn(visibility, lo, attrs)?));
+            return Ok(self.parse_item_foreign_fn(visibility, lo, attrs)?);
         }
         // FOREIGN TYPE ITEM
         if self.check_keyword(keywords::Type) {
-            return Ok(Some(self.parse_item_foreign_type(visibility, lo, attrs)?));
+            return Ok(self.parse_item_foreign_type(visibility, lo, attrs)?);
         }
 
         match self.parse_assoc_macro_invoc("extern", Some(&visibility), &mut false)? {
             Some(mac) => {
-                Ok(Some(
+                Ok(
                     ForeignItem {
                         ident: keywords::Invalid.ident(),
                         span: lo.to(self.prev_span),
@@ -7348,14 +7366,14 @@ impl<'a> Parser<'a> {
                         vis: visibility,
                         node: ForeignItemKind::Macro(mac),
                     }
-                ))
+                )
             }
             None => {
-                if !attrs.is_empty() {
+                if !attrs.is_empty()  {
                     self.expected_item_err(&attrs);
                 }
 
-                Ok(None)
+                self.unexpected()
             }
         }
     }