Fix ICE when misplaced visibility cannot be properly parsed

Author: rylev

compiler/rustc_parse/src/parser/item.rs

@@ -1791,7 +1791,13 @@ impl<'a> Parser<'a> {
                     if self.check_keyword(kw::Pub) {
                         let sp = sp_start.to(self.prev_token.span);
                         if let Ok(snippet) = self.span_to_snippet(sp) {
-                            let vis = self.parse_visibility(FollowedByType::No)?;
+                            let vis = match self.parse_visibility(FollowedByType::No) {
+                                Ok(v) => v,
+                                Err(mut d) => {
+                                    d.cancel();
+                                    return Err(err);
+                                }
+                            };
                             let vs = pprust::vis_to_string(&vis);
                             let vs = vs.trim_end();
                             err.span_suggestion(

src/test/ui/parser/issue-86895.rs

@@ -0,0 +1,3 @@
+const pub () {}
+//~^ ERROR expected one of `async`, `extern`, `fn`, or `unsafe`
+pub fn main() {}

src/test/ui/parser/issue-86895.stderr

@@ -0,0 +1,8 @@
+error: expected one of `async`, `extern`, `fn`, or `unsafe`, found keyword `pub`
+  --> $DIR/issue-86895.rs:1:7
+   |
+LL | const pub () {}
+   |       ^^^ expected one of `async`, `extern`, `fn`, or `unsafe`
+
+error: aborting due to previous error
+