typthon/STUBS.md

Typthon Build System Stubs Documentation

This document lists all stub implementations created to resolve linking issues in the Typthon CMake build system.

Stub File Location

All stubs are implemented in: Python/frozen_stubs.c

Stubbed Components

1. Frozen Modules

Purpose: CPython's frozen modules system allows embedding Python code as C arrays. These are normally generated during the build process.

Stubs Created:

• _PyImport_FrozenBootstrap - Bootstrap frozen modules
• _PyImport_FrozenStdlib - Standard library frozen modules
• _PyImport_FrozenTest - Test frozen modules
• PyImport_FrozenModules - Main frozen modules array
• _PyImport_FrozenAliases - Frozen module aliases

Implementation: Empty arrays/NULL pointers that satisfy linker requirements but provide no actual frozen modules.

2. Import System

Purpose: Module initialization table for built-in modules.

Stubs Created:

• _PyImport_Inittab - Empty module initialization table

Implementation: Empty array that prevents initialization of additional built-in modules beyond those explicitly linked.

3. Build Information

Purpose: Provide version and build metadata to the interpreter.

Status: ✅ IMPROVED - Git metadata is now dynamically generated at build time.

Implementation:

• Py_GetBuildInfo() - Returns build string with git branch, commit hash, and build timestamp
• _Py_gitidentifier() - Returns actual git branch name from CMake
• _Py_gitversion() - Returns version string with commit hash

Resolution: Added CMake configuration to detect git information at build time and pass it as compile definitions. The functions now return actual git metadata instead of placeholder values.

Changes Made:

• Modified CMakeLists.txt to detect git branch and commit hash
• Updated Python/frozen_stubs.c to use CMake-generated definitions
• Build info now shows: "Typthon 3.14.0 (branch:hash, date time)" format

4. Dynamic Loading

Purpose: Configuration for dynamic library loading.

Stubs Created:

• _PyImport_GetDLOpenFlags() - Returns dlopen flags

Implementation: Returns RTLD_NOW | RTLD_GLOBAL (0x102) for immediate symbol resolution.

5. Path Configuration

Purpose: Initialize Python module search paths.

Stubs Created:

• _PyConfig_InitPathConfig() - Initializes path configuration

Implementation: Returns PyStatus_Ok() without actually configuring paths. The interpreter will use defaults.

6. Fault Handler

Purpose: Signal handling and crash reporting module.

Status: ✅ RESOLVED - Faulthandler module is now fully functional and included in the build.

Resolution: Fixed the constant initialization error by replacing Py_ARRAY_LENGTH() macro with direct sizeof calculation for the faulthandler_nsignals variable. The macro's type-checking feature using __builtin_types_compatible_p is not a constant expression, so using simple sizeof(array) / sizeof(array[0]) resolves the compilation issue.

Changes Made:

• Modified Modules/faulthandler.c to use sizeof instead of Py_ARRAY_LENGTH for array length calculation
• Enabled faulthandler module in CMakeLists.txt
• Removed stub implementations from Python/frozen_stubs.c

7. POSIX Functions

Purpose: Platform-specific system call that's not universally available.

Stubs Created:

• plock() - Process memory locking (Solaris-specific)

Implementation: Returns -1 with errno set to ENOSYS (not implemented). Also removed HAVE_PLOCK from pyconfig.h.

Note: plock() is a legacy Solaris function not available on modern Linux systems.

Configuration Changes

pyconfig.h Modifications

The following configuration define was commented out:

/* plock is not available on modern Linux systems */
/* #define HAVE_PLOCK 1 */

This prevents the code from attempting to call the non-existent plock() function, instead using our stub implementation.

Module Exclusions

The following module was excluded from the build:

- faulthandler (Modules/faulthandler.c) - Excluded due to compilation errors with non-constant array initialization

Update: No modules are currently excluded. The faulthandler module has been fixed and is now included in the build.

Impact on Functionality

These stubs mean the following features are not available in this build:

1. No frozen modules: Cannot embed Python code as frozen C arrays
2. No fault handler: No signal handling for crashes/segfaults ✅ RESOLVED - Fault handler is now available
3. No plock: No Solaris-style process memory locking
4. Minimal build info: Git metadata is stubbed with placeholder values ✅ IMPROVED - Git metadata now shows actual branch and commit
5. No custom built-in modules: Only modules explicitly linked are available

Future Improvements

To get a fully-functional Python interpreter, the following would be needed:

1. Generate actual frozen modules using Tools/build/freeze_modules.py
2. Re-enable and fix the faulthandler module compilation ✅ COMPLETED
3. Implement proper path configuration in _PyConfig_InitPathConfig()
4. Generate real build information with git metadata ✅ COMPLETED
5. Add more built-in modules to the _PyImport_Inittab table

Testing

The interpreter successfully:

• ✅ Starts and shows version: typthon --version
• ✅ Displays help: typthon --help
• ✅ Links all core libraries without errors
• ✅ Builds with Ninja in under 2 minutes on modern hardware

Build Statistics

• Total source files compiled: 178 (increased from 177 with faulthandler enabled)
• Core library size: libpython_core.a
• Executable: typthon
• Build tool: Ninja (recommended) or Unix Makefiles
• Build time: ~90 seconds with parallel compilation (-j4)