get the generic text and put it int he suggestion, but suggestion not working on derive subdiagnostic

Author: spanishpear

compiler/rustc_error_messages/locales/en-US/parser.ftl

@@ -306,7 +306,7 @@ parser_expected_identifier = expected identifier
 parser_sugg_escape_to_use_as_identifier = escape `{$ident_name}` to use it as an identifier
 
 parser_sugg_remove_comma = remove this comma
-parser_sugg_misplaced_generic = place the generic parameter list after the function name:
+parser_sugg_misplaced_generic = place the generic parameter list after the function name: `{$generic_as_string}`
 
 parser_expected_semi_found_reserved_identifier_str = expected `;`, found reserved identifier `{$token}`
 parser_expected_semi_found_keyword_str = expected `;`, found keyword `{$token}`

compiler/rustc_parse/src/errors.rs

@@ -882,10 +882,11 @@ pub(crate) struct SuggRemoveComma {
     pub span: Span,
 }
 
-//SHREYS - should this be help, or a suggestion?
+//TODO: SHREYS - should this be help, or a suggestion?
 #[derive(Subdiagnostic)]
-#[help(parser::sugg_misplaced_generic)]
 pub(crate) struct SuggMisplacedGeneric {
+    pub snippet: String,
+    #[suggestion(code = "<{snippet}>")]
     #[primary_span]
     pub span: Span,
 }

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -330,12 +330,21 @@ impl<'a> Parser<'a> {
         let token = self.token.clone();
         let suggest_misplaced_generic = if self.token == token::Lt {
             // store the span before the generic calculation starts
-            if self.parse_generics().is_ok() {
-                // FIXME: need the span of the whole generic.
-                Some(SuggMisplacedGeneric { span: span.until(self.token.span) })
-            } else {
-                None
-            }
+            self.parse_generics().map_or(None, |generic| {
+                // at this point, token should be Ident with the fn name
+
+                // FIXME: shreys the span should be the span of where the gneeric SHOULD go.
+                // TODO: shreys what does this look like with invalid generic
+                // TODO: shreys - what to do if no snippet? probably just HELP not suggestion
+
+                let snippet = match self.sess.source_map().span_to_snippet(generic.span) {
+                    Ok(snippet) => snippet, 
+                    _ => "".to_string()
+                };
+                
+                Some(SuggMisplacedGeneric { span: self.token.span.to(generic.span.shrink_to_hi()), snippet })
+            })
+
         } else {
             None
         };