[nightscape]

Description

Fix bytecode generation ordering bug in core/translate/insert.rs where index key registers were
copied before NOT NULL default substitution, causing index entries to contain NULL while the
table row contained the default value. This led to PRAGMA integrity_check failures
("row N missing from index").

The fix swaps emit_notnulls() before emit_preflight_constraint_checks() in translate_insert(),
matching SQLite's bytecode ordering.

Motivation and context

Found by the differential fuzzer. When an INSERT OR REPLACE has a column expression that evaluates
to NULL at runtime (e.g. expr + NULL) on a NOT NULL DEFAULT column with a secondary UNIQUE index,
the index entry gets NULL while the table row gets the default value. This causes:

• PRAGMA integrity_check → "row N missing from index"
• Subsequent DELETE fails to find the index entry via IdxDelete

Minimal reproducer:

CREATE TABLE t (a INTEGER PRIMARY KEY, b INTEGER, c INTEGER NOT NULL DEFAULT 0, d INTEGER CHECK (d > 0));
CREATE UNIQUE INDEX idx ON t (b DESC, c, d DESC);
INSERT OR REPLACE INTO t (a, b, c, d) VALUES (1, NULL, 1892229699219097912 + -NULL, 100);
PRAGMA integrity_check;
-- Returns: row 1 missing from index idx

Description of AI Usage

Claude Code was used as a pair programmer to implement the fix and create the test file. The root
cause analysis was done in a prior session and documented in a handoff file. Claude implemented
the one-line fix (swapping two function calls), created the sqltest reproducer with 7 test cases,
and updated the 12 affected bytecode snapshot tests.

🤖 Generated with Claude Code

Closes #5823

[turso-bot]

Please review @sivukhin

[Copilot]

Pull request overview

Fixes an INSERT bytecode ordering bug where NOT NULL DEFAULT substitution occurred after copying index key registers during preflight constraint checks, leading to NULL index entries and PRAGMA integrity_check failures.

Changes:

• Reorder insert bytecode emission so NOT NULL default substitution runs before preflight constraint checks (and their index-key register copies).
• Add a targeted sqltest regression suite covering NOT NULL DEFAULT + secondary UNIQUE index cases that previously produced index/table mismatches.
• Update insert-related bytecode snapshot expectations to reflect the new opcode ordering.

Reviewed changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
core/translate/insert.rs	Moves emit_notnulls() earlier so defaults are applied before preflight uniqueness/index handling.
testing/runner/tests/insert_not_null_default_index.sqltest	New regression tests reproducing the NULL-in-index vs default-in-row mismatch and verifying integrity_check/results.
testing/runner/tests/snapshot_tests/modifications/snapshots/modifications__insert-single-row.snap	Snapshot updated for reordered NOT NULL/constraint opcodes.
testing/runner/tests/snapshot_tests/modifications/snapshots/modifications__insert-select.snap	Snapshot updated for reordered NOT NULL/constraint opcodes.
testing/runner/tests/snapshot_tests/modifications/snapshots/modifications__insert-or-rollback-multi-unique.snap	Snapshot updated for reordered NOT NULL/constraint opcodes.
testing/runner/tests/snapshot_tests/modifications/snapshots/modifications__insert-or-replace.snap	Snapshot updated for reordered NOT NULL/constraint/index opcodes in OR REPLACE flow.
testing/runner/tests/snapshot_tests/modifications/snapshots/modifications__insert-or-replace-multi-unique.snap	Snapshot updated for reordered NOT NULL/constraint/index opcodes in multi-unique OR REPLACE flow.
testing/runner/tests/snapshot_tests/modifications/snapshots/modifications__insert-or-replace-multi-notnull-default.snap	Snapshot updated: NOT NULL default substitution now precedes replace/preflight steps.
testing/runner/tests/snapshot_tests/modifications/snapshots/modifications__insert-or-replace-multi-notnull-default-partial.snap	Snapshot updated: NOT NULL default substitution now precedes replace/preflight steps (partial column set).
testing/runner/tests/snapshot_tests/modifications/snapshots/modifications__insert-or-ignore.snap	Snapshot updated: NOT NULL/NULL skipping checks occur earlier in OR IGNORE flow.
testing/runner/tests/snapshot_tests/modifications/snapshots/modifications__insert-or-ignore-multi-unique.snap	Snapshot updated for reordered NOT NULL/constraint checks in multi-unique OR IGNORE flow.
testing/runner/tests/snapshot_tests/modifications/snapshots/modifications__insert-or-fail-multi-unique.snap	Snapshot updated for reordered NOT NULL/constraint checks in multi-unique OR FAIL flow.
testing/runner/tests/snapshot_tests/modifications/snapshots/modifications__insert-or-abort-multi-unique.snap	Snapshot updated for reordered NOT NULL/constraint checks in multi-unique OR ABORT flow.
testing/runner/tests/snapshot_tests/modifications/snapshots/modifications__insert-multiple-rows.snap	Snapshot updated for reordered NOT NULL/constraint checks in multi-row insert flow.

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[nightscape]

@sivukhin @jussisaurio Copilot suggestion of updating the PR description is done.
This is good to merge from my side.