get the correct diagnostic for functions, at least

Author: spanishpear

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -340,21 +340,27 @@ impl<'a> Parser<'a> {
             let _ = self.parse_generics().map(|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.
                 // FIXME: shreys what does this look like with invalid generic
                 // FIXME: 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(),
+                debug!(?generic.span);
+                 
+                match self.sess.source_map().span_to_snippet(generic.span) {
+                    Ok(_snippet) => match self.sess.source_map().span_to_snippet(self.token.span) {
+                        Ok(ident) => {
+                            err.span_suggestion(
+                                generic.span.to(self.token.span),
+                                "help: place the generic parameter list after the function name:",
+                                format!(" {ident}{_snippet}"),
+                                Applicability::MachineApplicable,
+                            );
+                        } 
+                        Err(_) => todo!() //FIXME: shreys - what to do here?
+                    }
+                    Err(_) => todo!(), //FIXME: shreys - what to do here?
+                    
                 };
 
-                err.span_suggestion(
-                    self.token.span.to(generic.span.shrink_to_hi()),
-                    "help: place the generic parameter list after the function name:",
-                    snippet,
-                    Applicability::MachineApplicable,
-                );
+
             });
         }