Merge #4851

4851: Add quickfix to add a struct field r=TimoFreiberg a=TimoFreiberg

Related to #4563 
I created a quickfix for record literals first because the NoSuchField diagnostic was already there.
To offer that quickfix for FieldExprs with unknown fields I'd need to add a new diagnostic (or create a `NoSuchField` diagnostic for those cases)

I think it'd make sense to make this a snippet completion (to select the generated type), but this would require changing the `Analysis` API and I'd like some feedback before I touch that.

Co-authored-by: Timo Freiberg <timo.freiberg@gmail.com>

crates/ra_syntax/src/ast/make.rs

@@ -75,6 +75,10 @@ pub fn record_field(name: ast::NameRef, expr: Option<ast::Expr>) -> ast::RecordF
     }
 }
 
+pub fn record_field_def(name: ast::NameRef, ty: ast::TypeRef) -> ast::RecordFieldDef {
+    ast_from_text(&format!("struct S {{ {}: {}, }}", name, ty))
+}
+
 pub fn block_expr(
     stmts: impl IntoIterator<Item = ast::Stmt>,
     tail_expr: Option<ast::Expr>,