Default value constraint re-added when using .HasComment()

[kaspertygesen]

If I use .HasComment on a property which also has a default value, then the migration tries to ADD the constraint even if its already there.

modelBuilder.HasSequence<int>("TransactionId", "dbo")
   .StartsAt(100000);

modelBuilder.Entity<TransactionEntity>()
   .Property(o => o.TransactionId)
   .HasDefaultValueSql("NEXT VALUE FOR TransactionId");

modelBuilder.Entity<TransactionEntity>()
   .Property(_ => _.TransactionId)
   .HasComment("The id of the transaction. IMPORTANT: TransactionId must only be set to values returned by the sequence \"TransactionId\".");

The migration looks like this:

migrationBuilder.AlterColumn<int>(
    name: "TransactionId",
    table: "Transaction",
    type: "int",
    nullable: false,
    defaultValueSql: "NEXT VALUE FOR TransactionId",
    comment: "The id of the transaction. IMPORTANT: TransactionId must only be set to values returned by the sequence \"TransactionId\".",
    oldClrType: typeof(int),
    oldType: "int",
    oldDefaultValueSql: "NEXT VALUE FOR TransactionId",
    oldComment: "The id of the transaction IMPORTANT: TransactionId must only be set to values returned by the sequence \"TransactionId\".");

As the defaultValueSql and oldDefaultValueSql are identical I wouldn't expect a ALTER TABLE in my migration script.
But the migration script looks like this:

BEGIN TRANSACTION;
GO

ALTER TABLE [Transaction] ADD DEFAULT (NEXT VALUE FOR TransactionId) FOR [TransactionId];
DECLARE @defaultSchema AS sysname;
SET @defaultSchema = SCHEMA_NAME();
DECLARE @description AS sql_variant;
EXEC sp_dropextendedproperty 'MS_Description', 'SCHEMA', @defaultSchema, 'TABLE', N'Transaction', 'COLUMN', N'TransactionId';
SET @description = N'The id of the transaction. IMPORTANT: TransactionId must only be set to values returned by the sequence "TransactionId".';
EXEC sp_addextendedproperty 'MS_Description', @description, 'SCHEMA', @defaultSchema, 'TABLE', N'Transaction', 'COLUMN', N'TransactionId';
GO

INSERT INTO [__EFMigrationsHistory] ([MigrationId], [ProductVersion])
VALUES (N'20210225103305_Doc2', N'5.0.3');
GO

COMMIT;
GO

This results in the following error on on runtime:

Column already has a DEFAULT bound to it.
Could not create constraint or index. See previous errors.

EF CLI 5.0.3 (dotnet CLI)
Microsoft.EntityFrameworkCore 5.0.3
Microsoft.EntityFrameworkCore.SqlServer 5.0.3
MSSQL

[roji]

Thanks for reporting this - I can reproduce it and will look into it.

[ajcvickers]

/cc @bricelam to take a look.

[bricelam]

This is a regression from 3.1 where we always dropped the default constraint every alter.

[roji]

5.0.x patch proposal in #24305