revert to previous span

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -352,11 +352,12 @@ impl<'a> Parser<'a> {
                             // if there is a `<` after the fn name, then don't show a suggestion, show help
 
                             if !self.look_ahead(1, |t| *t == token::Lt) &&
-                                let Ok(snippet) = self.sess.source_map().span_to_snippet(generic.span) {
+                                let Ok(snippet) = self.sess.source_map().span_to_snippet(generic.span) &&
+                                let Ok(ident) = self.sess.source_map().span_to_snippet(self.token.span) {
                                     err.span_suggestion_verbose(
-                                        self.token.span.shrink_to_hi(),
+                                        generic.span.to(self.token.span),
                                         format!("place the generic parameter name after the {ident_name} name"),
-                                        snippet,
+                                        format!(" {ident}{snippet}"),
                                         Applicability::MaybeIncorrect,
                                     );
                                 } else {

src/test/ui/parser/suggest_misplaced_generics/enum.stderr

@@ -7,7 +7,7 @@ LL | enum<T> Foo { Variant(T) }
 help: place the generic parameter name after the enum name
    |
 LL | enum Foo<T> { Variant(T) }
-   |         ~~~
+   |      ~~~~~~
 
 error: aborting due to previous error
 

src/test/ui/parser/suggest_misplaced_generics/fn-complex-generics.stderr

@@ -7,7 +7,7 @@ LL | fn<'a, B: 'a + std::ops::Add<Output = u32>> f(_x: B) { }
 help: place the generic parameter name after the fn name
    |
 LL | fn f<'a, B: 'a + std::ops::Add<Output = u32>>(_x: B) { }
-   |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+   |    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 error: aborting due to previous error
 

src/test/ui/parser/suggest_misplaced_generics/fn-simple.stderr

@@ -7,7 +7,7 @@ LL | fn<T> id(x: T) -> T { x }
 help: place the generic parameter name after the fn name
    |
 LL | fn id<T>(x: T) -> T { x }
-   |      ~~~
+   |    ~~~~~
 
 error: aborting due to previous error
 

src/test/ui/parser/suggest_misplaced_generics/struct.stderr

@@ -7,7 +7,7 @@ LL | struct<T> Foo { x: T }
 help: place the generic parameter name after the struct name
    |
 LL | struct Foo<T> { x: T }
-   |           ~~~
+   |        ~~~~~~
 
 error: aborting due to previous error
 

src/test/ui/parser/suggest_misplaced_generics/trait.stderr

@@ -7,7 +7,7 @@ LL | trait<T> Foo {
 help: place the generic parameter name after the trait name
    |
 LL | trait Foo<T> {
-   |          ~~~
+   |       ~~~~~~
 
 error: aborting due to previous error
 

src/test/ui/parser/suggest_misplaced_generics/type.stderr

@@ -7,7 +7,7 @@ LL | type<T> Foo = T;
 help: place the generic parameter name after the type name
    |
 LL | type Foo<T> = T;
-   |         ~~~
+   |      ~~~~~~
 
 error: aborting due to previous error