Fix compilation error with migration file when CREATE UNIQUE INDEX referenced by FOREIGN KEY

[griffio]

Fixes sqldelight/sqldelight#4503

Compile error Table table_b does not have a unique index on columns occurs because CREATE UNIQUE INDEX is filtered out of the schema statements used in the check.

This foreign key check could be an ⚔️ edge case where the schema contributor processing needs to include statements (index stmt) that are defined after the statement (table stmt) that triggers the lookup. By design, a statement cannot see tables, views defined later in the same file.

🔮 Attempt to fix migration files using CREATE UNIQUE INDEX and FOREIGN KEY references

This small fix on containingFile.schema<SqlCreateIndexStmt>(this) to remove this (e.g table_b in example below) allows all the schema statements in a containingFile to be accessible not just statements up-to table_b.

This fix now allows a couple of options:

Single migration file - previously even this failed to compile

CREATE TABLE table_a(
    id INTEGER PRIMARY KEY
);

CREATE TABLE table_b(
    id   INTEGER PRIMARY KEY,
    a_id INTEGER NOT NULL REFERENCES table_a (id)
);

CREATE UNIQUE INDEX uk_table_b_a_id_id ON table_b (a_id, id);

-- test that unique index can be validated in same migration file
CREATE TABLE table_c (
    id   INTEGER PRIMARY KEY,
    a_id INTEGER NOT NULL REFERENCES table_a (id),
    b_id INTEGER DEFAULT NULL,
    FOREIGN KEY (a_id, b_id) REFERENCES table_b (a_id, id)
)

Split statements across migrations, however table_b must be in same file as unique index as only includes statements from files with a smaller migration order value.

CREATE TABLE table_a(
    id INTEGER PRIMARY KEY
);

CREATE TABLE table_b(
    id   INTEGER PRIMARY KEY,
    a_id INTEGER NOT NULL REFERENCES table_a (id)
);

CREATE UNIQUE INDEX uk_table_b_a_id_id ON table_b (a_id, id);

More tables with FOREIGN KEY references

-- test that unique index can be validated from external migration file
CREATE TABLE table_c (
    id   INTEGER PRIMARY KEY,
    a_id INTEGER NOT NULL REFERENCES table_a (id),
    b_id INTEGER DEFAULT NULL,
    FOREIGN KEY (a_id, b_id) REFERENCES table_b (a_id, id)
)

Note:
💥 The blast radius of this change is minimized to foreign key index checks and doesn't change the "by design" processing of schema in com.alecstrong.sql.psi.core.SqlFileBase

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• CHANGELOG.md's "Unreleased" section has been updated, if applicable.

[griffio]

Thanks, needs 🧜 to merge as unable to in this project.