dasSQLITE: schema_from + check_schema — compile-time schema introspection

[borisbat]

Summary

• [sql_table(schema_from="path.db")] — opens the .db at compile time, reads pragma_table_info, and synthesizes the struct's fields from the actual schema. Hand-declared fields stay as contract assertions: name/PK/nullability checked at macro time, SqlType checked at typecheck via concept_assert emitted into _sql_table_name. Schema drift becomes a compile error at the exact lines that need updating — the macro-advantage analog to EF Core's runtime model snapshot, at zero runtime cost.
• check_schema(db, type<T>) / try_check_schema → SqlError — runtime validator over (name, SqlType, NOT NULL, PRIMARY KEY). Works on any [sql_table] struct, not just schema_from-derived ones. Recommended startup-defense pattern for code that opens a DB it didn't just create.
• Bonus fix: [sql_function] ExprAddr target switched to __::name so the typer's findMatchingFunctions scopes resolution to user's module — funcType-only disambiguation ties on same-signature imports (now that sqlite_boost requires daslib/fio, fio_core::normalize and a user def normalize(s : string) collide on (string)→string; tut 02 + test_78 prove the collision is now handled).
• Tutorials: 39-schema_from (basics + affinity table + partial-body contracts), 42-schema_evolution (multi-version ETL via typeinfo has_field + _each_sql streaming), and a check_schema section folded into 02-insert_data.
• C++ shim: sqlite3_open_v2_no_vfs (READONLY-no-create open with NULL vfs; daslang string can't represent C NULL).

Affinity → daslang type

SQLite affinity	Declared types	daslang type
INTEGER	INT/INTEGER/BIGINT/etc.	int64
REAL	REAL/DOUBLE/FLOAT	double
TEXT	TEXT/CHAR/VARCHAR/CLOB	string
BLOB	BLOB or no declared type	array<uint8>
NUMERIC	NUMERIC/DECIMAL/BOOLEAN/DATE/DATETIME	double

NOT NULL → T; otherwise → Option<T>. INTEGER PRIMARY KEY columns get @sql_primary_key synthesized. SQLite's INTEGER-PK-reports-notnull=0 quirk handled at both macro and runtime sides.

Tests

• 4 compile-pass tests: test_95_schema_from_basic (all-affinities sweep), test_96_schema_from_partial_body (type narrowing + PK redundancy + round-trip), test_97_schema_from_typeinfo (multi-version has_field branching + _each_sql), test_98_check_schema (7-case match/mismatch matrix incl. panic propagation).
• 7 failed_* compile-error tests: field-not-in-DB / table-not-in-file / file-missing / type-mismatch / nullable-strict / nullable-loose / pk-disagreement.
• 5 small (8 KB each) .db fixtures under tests/dasSQLITE/test_data/ plus companion .sql and a _gen_fixtures.das builder for regeneration.

Test plan

• bin/Release/daslang.exe dastest/dastest.das -- --test tests/dasSQLITE/ → 673/673 pass
• bin/Release/test_aot.exe -use-aot dastest/dastest.das -- --use-aot --test tests/dasSQLITE/ → 673/673 pass
• MCP format_file clean on every changed .das
• MCP lint clean on sqlite_boost.das + tutorials + tests

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR extends dasSQLITE with compile-time SQLite schema introspection ([sql_table(schema_from="...")]) and a runtime validator (check_schema / try_check_schema) to detect schema drift early. It also includes a small [sql_function] resolution fix, adds tutorials documenting the new workflow, and introduces fixtures/tests to cover success and failure modes.

Changes:

• Add schema_from support to [sql_table] in sqlite_boost.das, synthesizing struct fields from PRAGMA table_info at compile time and emitting contract checks.
• Add runtime schema validation helpers (check_schema, try_check_schema) and tests/fixtures validating match and mismatch scenarios.
• Add tutorials + Sphinx docs for schema_from and multi-version ETL patterns, plus a C++ shim (sqlite3_open_v2_no_vfs) for READONLY open semantics.

Reviewed changes

Copilot reviewed 28 out of 33 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
tutorials/sql/42-schema_evolution.das	New tutorial demonstrating multi-version ETL using schema_from + typeinfo has_field + _each_sql.
tutorials/sql/39-schema_from.das	New tutorial introducing schema_from basics, affinity mapping, and check_schema.
tutorials/sql/02-insert_data.das	Adds check_schema startup-defense guidance to an existing tutorial.
tests/dasSQLITE/test_data/schema_from_v2.sql	Fixture DDL (v2 Logs table) for schema_from tests/tutorials.
tests/dasSQLITE/test_data/schema_from_v1.sql	Fixture DDL (v1 Logs table) for schema_from tests/tutorials.
tests/dasSQLITE/test_data/schema_from_nullable.sql	Fixture DDL for nullable column handling tests.
tests/dasSQLITE/test_data/schema_from_blob.sql	Fixture DDL for BLOB affinity handling tests.
tests/dasSQLITE/test_data/schema_from_all_affinities.sql	Fixture DDL covering all SQLite affinity classes.
tests/dasSQLITE/test_data/README.md	Documents what fixtures are and how to regenerate them.
tests/dasSQLITE/test_data/_gen_fixtures.das	Script to regenerate committed .db fixtures from SQL.
tests/dasSQLITE/test_98_check_schema.das	New runtime check_schema/try_check_schema tests.
tests/dasSQLITE/test_97_schema_from_typeinfo.das	New tests for typeinfo has_field branching on schema_from-synthesized structs.
tests/dasSQLITE/test_96_schema_from_partial_body.das	New tests validating partial-body contracts and narrowing behavior.
tests/dasSQLITE/test_95_schema_from_basic.das	New tests validating basic synthesis across affinities and nullability.
tests/dasSQLITE/failed_schema_from_type_mismatch.das	Compile-fail test for schema/type mismatch diagnostics.
tests/dasSQLITE/failed_schema_from_table_not_in_file.das	Compile-fail test for missing table in schema_from DB.
tests/dasSQLITE/failed_schema_from_pk_disagreement.das	Compile-fail test for PK disagreement between struct and DB.
tests/dasSQLITE/failed_schema_from_nullable_strict.das	Compile-fail test for non-optional field declared against nullable column.
tests/dasSQLITE/failed_schema_from_nullable_loose.das	Compile-fail test for optional field declared against NOT NULL/PK column.
tests/dasSQLITE/failed_schema_from_file_missing.das	Compile-fail test for missing schema_from DB file.
tests/dasSQLITE/failed_schema_from_field_not_in_db.das	Compile-fail test for extra struct field not present in DB schema.
modules/dasSQLITE/src/dasSQLITE.main.cpp	Adds sqlite3_open_v2_no_vfs shim and exports it to daslang.
modules/dasSQLITE/src/aot_sqlite.h	Declares the new shim for AOT builds.
modules/dasSQLITE/daslib/sqlite_boost.das	Implements schema_from, check_schema, PRAGMA helpers, and [sql_function] ExprAddr scoping fix.
doc/source/reference/tutorials/sql_42_schema_evolution.rst	Sphinx documentation page for the new SQL-42 tutorial.
doc/source/reference/tutorials/sql_39_schema_from.rst	Sphinx documentation page for the new SQL-39 tutorial.
doc/source/reference/tutorials/sql_02_insert_data.rst	Adds check_schema section to SQL-02 tutorial docs.
doc/source/reference/tutorials.rst	Adds the new SQL-39 and SQL-42 tutorials to the index.

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Copilot reviewed 29 out of 34 changed files in this pull request and generated 2 comments.

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Copilot reviewed 31 out of 37 changed files in this pull request and generated no new comments.

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