Split the built-in functions by family, and give int64 a header of its own

[trueqbit]

Summary

Split builtin/functions/core.h by function family

The built-in functions in dev/builtin/functions/ are grouped the way SQLite documents them:

Header	Functions	SQLite docs
core.h	the core scalar functions: abs(), coalesce(), length(), lower(), replace(), substr(), ...	lang_corefunc
datetime.h	date(), time(), datetime(), julianday(), strftime(), unixepoch(), timediff()	lang_datefunc
aggregate.h	count(*), count(), total(), sum(), avg(), max(), min(), group_concat(), string_agg(), median(), percentile*()	lang_aggfunc
math.h	the mathematical functions: acos() ... trunc()	lang_mathfunc
json.h	the JSON functions, including json_group_array() and json_group_object()	json1
window.h	the window functions (unchanged)	windowfunctions

• Each header is laid out like window.h. The C++17 branch holds the legacy name tags and factories; the C++20 branch holds the ""_builtin definitions and their public names. math.h and json.h guard their whole contents with SQLITE_ENABLE_MATH_FUNCTIONS and SQLITE_ORM_JSON_SUPPORTED.
• MAX() and MIN() are in aggregate.h together with their scalar forms MAX(X,Y,...) and MIN(X,Y,...), since one C++20 definition covers both. Their doc comments now say so.
• The general comment on how built-ins are published (copies vs. wrapping function templates, C library name clashes) moves into the umbrella functions.h.
• The overloaded arithmetic and bitwise operators (- + * / % ~ << >> & |) move from core.h to operators.h, next to the nodes they build. The comparison operators already sit next to theirs in conditions.h. With that, core.h no longer needs to include conditions.h or operators.h.
• storage.h includes aggregate.h for its aggregate shortcuts.

int64 and uint64 in sqlite3/sqlite3_types.h

• The int64/uint64 aliases lived in core.h, and several headers saw them only because of include order: storage_base.h, column_result.h and carray.h use int64 outside templates without including anything that declares it.
• They move to sqlite3/sqlite3_types.h, and every header that uses int64 now includes it. The header is not included from config.h. Because it exports public symbols, it is listed in the amalgamation manifest and in the non-amalgamated include instead.
• With the alias available on its own, the headers that spelled sqlite_int64 for want of it use int64 throughout: the built-in functions LAST_INSERT_ROWID(), SQLITE_OFFSET() and UNIXEPOCH(), the column factories, and the integer field predicates. sqlite_int64 now appears only where int64 is defined.

The SQLite C API headers in a top-level sqlite3/

• sqlite3_config.h moves from functional/ to sqlite3/, next to sqlite3_types.h. The folder holds sqlite_orm's interface to the SQLite C library: the configuration derived from <sqlite3.h> and the types republished from it.
• It sits beside functional/ rather than inside it, because functional/ is C++ language and standard library plumbing that knows nothing about SQLite. functional/config.h still pulls in sqlite3_config.h first, so the configuration stays universally available.

AGENTS.md and the vocabulary-layer doc describe the new layout.

Overlap with #1550-#1553

#1552 (refactor/operators-under-ast) also moves the arithmetic operators beside their nodes, in its case into ast/operators.h. #1550 changes the includes of what was core_functions.h. Merging this PR before them will cause conflicts in that stack: the operator overloads end up in whichever header holds the operator nodes, and the include changes apply to the split headers.

Test plan

The changes only move code. Existing tests cover the moved functions and operators:

• tests/builtin_functions_tests/ (core, date/time and math functions), tests/json.cpp, tests/window_function_tests.cpp
• tests/statement_serializer_tests/core_functions.cpp, aggregate_functions.cpp, arithmetic_operators.cpp, bitwise_operators.cpp
• tests/static_tests/core_function_return_types.cpp, aggregate_function_return_types.cpp, builtin_function_static_tests.cpp, arithmetic_operators_result_type.cpp, operators_adl.cpp
• tests/operators/arithmetic_operators.cpp, bitwise_operators.cpp
• the rtree and carray tests, for int64

🤖 Generated with Claude Code