Fix broken span and related tests

Author: poliorcetics

compiler/rustc_parse/src/parser/item.rs

@@ -1987,7 +1987,7 @@ impl<'a> Parser<'a> {
                             // There was no explicit visibility
                             if matches!(orig_vis.kind, VisibilityKind::Inherited) {
                                 err.span_suggestion(
-                                    sp,
+                                    sp_start.to(self.prev_token.span),
                                     &format!("visibility `{}` must come before `{}`", vs, snippet),
                                     format!("{} {}", vs, snippet),
                                     Applicability::MachineApplicable,

src/test/ui/parser/duplicate-visibility.rs

@@ -1,6 +1,9 @@
 fn main() {}
 
-extern "C" {
+extern "C" { //~ NOTE while parsing this item list starting here
     pub pub fn foo();
     //~^ ERROR expected one of `(`, `async`, `const`, `default`, `extern`, `fn`, `pub`, `unsafe`, or `use`, found keyword `pub`
-}
+    //~| NOTE expected one of 9 possible tokens
+    //~| HELP there is already a visibility, remove this one
+    //~| NOTE explicit visibility first seen here
+} //~ NOTE the item list ends here

src/test/ui/parser/duplicate-visibility.stderr

@@ -7,10 +7,16 @@ LL |     pub pub fn foo();
    |         ^^^
    |         |
    |         expected one of 9 possible tokens
-   |         help: visibility `pub` must come before `pub pub`: `pub pub pub`
-LL |
+   |         help: there is already a visibility, remove this one
+...
 LL | }
    | - the item list ends here
+   |
+note: explicit visibility first seen here
+  --> $DIR/duplicate-visibility.rs:4:5
+   |
+LL |     pub pub fn foo();
+   |     ^^^
 
 error: aborting due to previous error
 

src/test/ui/parser/issue-87694-misplaced-pub.stderr

@@ -2,8 +2,9 @@ error: expected one of `async`, `extern`, `fn`, or `unsafe`, found keyword `pub`
   --> $DIR/issue-87694-misplaced-pub.rs:1:7
    |
 LL | const pub fn test() {}
-   | ----- ^^^ expected one of `async`, `extern`, `fn`, or `unsafe`
-   | |
+   | ------^^^
+   | |     |
+   | |     expected one of `async`, `extern`, `fn`, or `unsafe`
    | help: visibility `pub` must come before `const`: `pub const`
 
 error: aborting due to previous error