Inserting in fill_expr (and sometimes default) doesn't work

• EdgeDB Version: EdgeDB CLI 1.1.0+8bc2c20
• OS Version: Mac OS Monterey version 12.1

Steps to Reproduce:

1. Updated default.esdl to include new table, Union_labor_name, and put in a link to that table into “Labor_union” table.

Please specify an expression to populate existing objects in order to make link 'union_name' of object type 'default::Labor_union' required:
fill_expr> insert Union_labor_name { name:= "AAA" }
Created ./dbschema/migrations/00004.edgeql, id: m1f2ufyzoqfpfypfweuk5bwp2q7fuhuwgsvgq7rzsyqrdcove3pvlq

I did the following and then tried to edgedb migrate’and got the error:

edgedb migrate
edgedb error: UnsupportedBackendFeatureError: WITH clause containing a data-modifying statement must be at the top level 
I tried to just destroy the database and re-run it, but that didn't even work
edgedb instance destroy edgedb 
Do you really want to delete instance "edgedb"? (type Yes)
y
edgedb error: Canceled.

Schema:

  abstract type Named {
    required property name -> str {
      delegated constraint exclusive;
    }
  }
  type Labor_union {
    required link union_name -> Union_labor_name;
    link abbrev -> Abbreviation;

  } 
  type Union_labor_name extending Named {}

[aljazerzen]

Yes, we’ve merged a few PRs but they are about reporting better errors when using mutation in fill_expr or in defaults. This issue is something I’m working on, but I cannot give you an ETA.

[msullivan]

On top of the fill_expr problem, this happens with defaults when a new link is added. The unfortunate bit here is that it does work to create a link with a default containing an insert as part of a new type, but not when altering it onto an existing type.

This is because https://github.com/edgedb/edgedb/pull/3750 makes adding a new link with a default use the fill_expr flow to populate the column with the default. (Previously it just incorrectly did not do that.)