Auto merge of #53433 - kennytm:rollup, r=kennytm

Rollup of 10 pull requests

Successful merges:

 - #52946 (Documented impl From on line 367 of libserialize/json.rs)
 - #53234 (Remove Travis shutdown debug scripts, and remove CI-specific DNS settings)
 - #53313 (Two small improvements)
 - #53360 (Addressed #51602)
 - #53364 (Warn if the user tries to use GATs)
 - #53373 (Tweak unclosed delimiter parser error)
 - #53377 (std: Use target_pointer_width for BACKTRACE_ELF_SIZE)
 - #53395 (Use #[non_exhaustive] on internal enums)
 - #53399 (Tidy: ignore non-Markdown files when linting for the Unstable Book)
 - #53412 (syntax_ext: remove leftover span_err_if_not_stage0 macro.)

1 files changed, 7 insertions, 1 deletions

diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index b1e1cdee2ee..345464c6664 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -4719,7 +4719,12 @@ impl<'a> Parser<'a> {
         if !self.eat(&token::OpenDelim(token::Brace)) {
             let sp = self.span;
             let tok = self.this_token_to_string();
+            let mut do_not_suggest_help = false;
             let mut e = self.span_fatal(sp, &format!("expected `{{`, found `{}`", tok));
+            if self.token.is_keyword(keywords::In) || self.token == token::Colon {
+                do_not_suggest_help = true;
+                e.span_label(sp, "expected `{`");
+            }
 
             // Check to see if the user has written something like
             //
@@ -4729,7 +4734,8 @@ impl<'a> Parser<'a> {
             // Which is valid in other languages, but not Rust.
             match self.parse_stmt_without_recovery(false) {
                 Ok(Some(stmt)) => {
-                    if self.look_ahead(1, |t| t == &token::OpenDelim(token::Brace)) {
+                    if self.look_ahead(1, |t| t == &token::OpenDelim(token::Brace))
+                        || do_not_suggest_help {
                         // if the next token is an open brace (e.g., `if a b {`), the place-
                         // inside-a-block suggestion would be more likely wrong than right
                         return Err(e);