[tianzhou]

Summary

When a function change is planned as DROP FUNCTION + CREATE FUNCTION (return type, OUT parameter, or parameter-name change), or a procedure body changes (procedures always go through DROP + CREATE), the plan only emitted COMMENT ON when the comment text differed between old and new. DROP discards the comment, so an unchanged comment was silently lost after apply and the next plan showed a one-line diff adding it back.

The DROP + CREATE branches in internal/diff/function.go and internal/diff/procedure.go now re-emit COMMENT ON whenever the new routine has a non-empty comment, so one apply converges.

Not covered here: GRANTs on a recreated function are lost the same way (privileges are diffed independently old-vs-new, so an unchanged grant is not re-granted). That also applies to recreated views and materialized views, so it is a separate cross-cutting fix.

Fixes #677

Test plan

Folded into existing cases rather than adding new embedded-postgres cycles:

• testdata/diff/create_function/issue_326_return_type_change: added an unchanged comment on the function whose return type changes.
• testdata/diff/create_procedure/alter_procedure: added an unchanged comment on the signature-changing procedure (already handled via drop+add) and a new log_event procedure with a body-only change and an unchanged comment (the affected DROP + CREATE modify path).

Both failed before the fix (no COMMENT ON after the CREATE) and pass after:

PGSCHEMA_TEST_FILTER="create_function/issue_326_return_type_change" go test ./internal/diff -run TestDiffFromFiles
PGSCHEMA_TEST_FILTER="create_procedure/alter_procedure" go test ./internal/diff -run TestDiffFromFiles
PGSCHEMA_TEST_FILTER="create_function/issue_326_return_type_change" go test ./cmd -run TestPlanAndApply
PGSCHEMA_TEST_FILTER="create_procedure/alter_procedure" go test ./cmd -run TestPlanAndApply

The TestPlanAndApply runs include the idempotency check (second plan after apply must be empty).

🤖 Generated with Claude Code

[Copilot]

🟢 Approval recommended

The review reports no active issues with the changes to preserve function and procedure comments across recreation.

No open issues 🎉

What changed in this PR

Fixes #677 by preserving function and procedure comments when migrations drop and recreate those routines, preventing a comment-only diff on the next plan.

Changes:

• Re-emits non-empty comments after function and procedure recreation, even when the comment text is unchanged.
• Extends existing regression fixtures for function return-type changes and procedure signature/body changes.
• Updates expected migration SQL and plan outputs. Privilege restoration remains outside this PR’s scope.

File	Description
internal/​diff/​function.go	Restores comments after function recreation.
internal/​diff/​procedure.go	Restores comments after procedure recreation.
testdata/​diff/​create_function/​issue_326_return_type_change/​old.sql	Adds the initial function comment.
testdata/​diff/​create_function/​issue_326_return_type_change/​new.sql	Preserves the comment across a return-type change.
testdata/​diff/​create_function/​issue_326_return_type_change/​diff.sql	Expects comment restoration in migration SQL.
testdata/​diff/​create_function/​issue_326_return_type_change/​plan.sql	Includes comment restoration in the SQL plan.
testdata/​diff/​create_function/​issue_326_return_type_change/​plan.json	Updates the fingerprint and comment step.
testdata/​diff/​create_function/​issue_326_return_type_change/​plan.txt	Updates the plan summary and displayed SQL.
testdata/​diff/​create_procedure/​alter_procedure/​old.sql	Adds comments and the initial body-change fixture.
testdata/​diff/​create_procedure/​alter_procedure/​new.sql	Keeps comments across signature and body changes.
testdata/​diff/​create_procedure/​alter_procedure/​diff.sql	Expects recreation and comment restoration.
testdata/​diff/​create_procedure/​alter_procedure/​plan.sql	Includes procedure changes and restored comments.
testdata/​diff/​create_procedure/​alter_procedure/​plan.json	Updates the fingerprint and procedure steps.
testdata/​diff/​create_procedure/​alter_procedure/​plan.txt	Updates the plan summary and displayed SQL.

_{Review effort: Balanced}

[greptile-apps]

Confidence Score: 5/5

[Low impact] The PR appears safe to merge; it restores comments after recreation without changing comment-only edits.

Summary

Restores non-empty comments after functions or procedures are dropped and recreated, even when the comment text has not changed.

• Function replacements keep their comments.
• Procedure replacements keep their comments.

Acknowledged deferral: tianzhou states that restoring unchanged grants after recreation belongs in a separate cross-cutting fix.

_{Reviews (1) · Last reviewed commit: "fix: re-emit COMMENT when a function or ..." · Reviewed by Greptile}