[psteinroe]

Stacked on #891.

Follow-ups to the rules ported from Squawk in #885: where the diagnostics point, and what they cover. Every new error case was checked against Postgres 15 in a rolled-back transaction.

banDuplicateColumnAssignments

• Diagnostics pointed at the whole statement. They now point at the second occurrence: the column name in SET, INSERT and column definitions, and the whole select list entry (e.g. coalesce(a, b) as x) in views, CREATE TABLE AS and SELECT INTO. View column lists and COPY column lists have no locations and still point at the statement.

• A * anywhere in a view's select list turned the check off. It now only hides the names it may expand to:

  create view v as select t.*, 1 as x, 2 as x from t;
  -- before: nothing
  -- after:  × Column x is specified more than once.   (Postgres: 42701)

  If the view's explicit column names reach into the *, we still can't tell what the later entries are called, so create view v (a, c, d) as select t.*, 2 as x, 3 as x stays silent (Postgres accepts it when t has two columns).

• New statements, all rejected by Postgres with 42701: alter table users add column email text, add column email text (also after ADD COLUMN IF NOT EXISTS email; a later IF NOT EXISTS is skipped by Postgres and not reported), create type pair as (a int, a int), copy users (id, id), and create foreign table ... (id int, id int). ADD COLUMN and COPY have their own detail text.

requireTableSchema (opt-in)

• Points at the table name, and the note uses it (e.g. public.posts instead of public.my_table). DROP TABLE a, b points at each name.
• Temporary tables created earlier in the file (create temp table, create table pg_temp.x, select ... into temp x) are no longer reported on later ALTER/DROP/CREATE INDEX, until they are dropped. An unqualified name refers to them since pg_temp comes first in the search path. Squawk reports these too.
• Scope: statements that create, change or drop a table, and the tables they reference by name. Newly covered: CREATE FOREIGN TABLE, ALTER/DROP FOREIGN TABLE, ALTER TABLE ... RENAME (table, column, constraint), SET SCHEMA, SELECT INTO, CREATE INDEX ON, and inside those statements REFERENCES, PARTITION OF, INHERITS, LIKE, ATTACH PARTITION. Queries (the body of a view, CREATE TABLE AS ... SELECT ... FROM x, DML) stay out of scope, otherwise the rule would fire on every query. This is wider than Squawk, which only checks CREATE/ALTER/DROP TABLE; the rule is opt-in, and a user who enables it wants every table name in DDL qualified.

banDropConstraint, banDropDefault (opt-in)

One diagnostic per statement without a name became one per command, with the name, pointing at its DROP CONSTRAINT / DROP DEFAULT:

alter table users drop constraint users_email_key, drop constraint if exists users_name_check;
-- before: ! Dropping a constraint may break existing clients.
-- after:  ! Dropping constraint users_email_key may break existing clients.
--         ! Dropping constraint users_name_check may break existing clients.

renamingObject (opt-in)

Most of its findings on the regression corpus are ALTER INDEX ... RENAME and RENAME CONSTRAINT, which Squawk's renaming-object reports as well, so they stay. We also report collations, text search configurations, FDWs and other objects Squawk doesn't. I kept those: clients do reference collations and text search configurations by name, and the rule is opt-in. The one change is ALTER TYPE ... RENAME ATTRIBUTE, which moves to renamingColumn like in Squawk (an attribute is a column of a composite type).

requireEnumValueOrdering now has applies_to: Migration, like the other DDL rules from #885.

Tests

New spec files for the new duplicate cases (and the accepted ones next to them), the new requireTableSchema positions and temporary tables, multiple commands for banDropConstraint/banDropDefault, and RENAME ATTRIBUTE. The spec snapshots don't show spans, so there are unit tests per rule asserting the text each diagnostic points at, using a small test helper spanned_texts in lib.rs. StatementTokens gets a keyword_pairs helper for the DROP CONSTRAINT / DROP DEFAULT spans.

Not covered

Duplicates that need the catalog (ADD COLUMN of an existing column, LIKE t plus a column of t) and view column lists / COPY column lists still point at the statement.