Address review feedbacks

Also addressed merge conflicts upon rebasing.

Author: hkmatsumoto

compiler/rustc_parse/src/parser/stmt.rs

@@ -567,6 +567,7 @@ impl<'a> Parser<'a> {
                         // integer literal (e.g. `1:42`), it's likely a range
                         // expression for Pythonistas and we can suggest so.
                         if self.prev_token.is_integer_lit()
+                            && self.may_recover()
                             && self.look_ahead(1, |token| token.is_integer_lit())
                         {
                             // FIXME(hkmatsumoto): Might be better to trigger
@@ -577,22 +578,22 @@ impl<'a> Parser<'a> {
                                 "..",
                                 Applicability::MaybeIncorrect,
                             );
-                        }
-
-                        // if next token is following a colon, it's likely a path
-                        // and we can suggest a path separator
-                        self.bump();
-                        if self.token.span.lo() == self.prev_token.span.hi() {
-                            err.span_suggestion_verbose(
-                                self.prev_token.span,
-                                "maybe write a path separator here",
-                                "::",
-                                Applicability::MaybeIncorrect,
-                            );
-                        }
-                        if self.sess.unstable_features.is_nightly_build() {
-                            // FIXME(Nilstrieb): Remove this again after a few months.
-                            err.note("type ascription syntax has been removed, see issue #101728 <https://github.com/rust-lang/rust/issues/101728>");
+                        } else {
+                            // if next token is following a colon, it's likely a path
+                            // and we can suggest a path separator
+                            self.bump();
+                            if self.token.span.lo() == self.prev_token.span.hi() {
+                                err.span_suggestion_verbose(
+                                    self.prev_token.span,
+                                    "maybe write a path separator here",
+                                    "::",
+                                    Applicability::MaybeIncorrect,
+                                );
+                            }
+                            if self.sess.unstable_features.is_nightly_build() {
+                                // FIXME(Nilstrieb): Remove this again after a few months.
+                                err.note("type ascription syntax has been removed, see issue #101728 <https://github.com/rust-lang/rust/issues/101728>");
+                            }
                         }
                     }
 

tests/ui/suggestions/range-index-instead-of-colon.rs

@@ -4,5 +4,4 @@ fn main() {
     &[1, 2, 3][1:2];
     //~^ ERROR: expected one of
     //~| HELP: you might have meant to make a slice with range index
-    //~| HELP: maybe write a path separator here
 }

tests/ui/suggestions/range-index-instead-of-colon.stderr

@@ -4,15 +4,10 @@ error: expected one of `.`, `?`, `]`, or an operator, found `:`
 LL |     &[1, 2, 3][1:2];
    |                 ^ expected one of `.`, `?`, `]`, or an operator
    |
-   = note: type ascription syntax has been removed, see issue #101728 <https://github.com/rust-lang/rust/issues/101728>
 help: you might have meant to make a slice with range index
    |
 LL |     &[1, 2, 3][1..2];
    |                 ~~
-help: maybe write a path separator here
-   |
-LL |     &[1, 2, 3][1::2];
-   |                 ~~
 
 error: aborting due to previous error