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YLang Compiler Architecture

YLang 2.0.0 uses a conventional multi-stage compiler pipeline. The stable core compiles through generated C and GCC/Clang; named imports, structs, enums, GUI/Game2D, and the NASM backend are explicitly experimental extensions.

  1. Lexer (src/lexer.c) — turns source text into positioned tokens.
  2. Parser (src/parser.c) — builds the program representation and calls shared diagnostics when syntax is invalid.
  3. Frontend utilities — src/arena.c owns arena allocation and arena-backed vectors; src/strbuf.c owns generated-text buffers; src/diagnostics.c formats source-located errors and warnings.
  4. Semantic analysis (src/sema.c) — resolves names, validates initialization and constant assignment, and checks types.
  5. Module loader (src/module.c) — recursively loads imported files, detects cycles, resolves named imports, and merges module ASTs while retaining per-module visibility.
  6. C code generator (src/codegen.c) — writes C for the checked program, including runtime helpers for supported checked arithmetic operations.
  7. Driver (src/driver.c) — orchestrates module loading and checking, writes generated C, and invokes GCC or Clang without going through a shell.
  8. CLI (src/main.c) — parses user commands and their options.

The internal compiler model is declared in src/internal.h; the public-facing compiler and token declarations are in include/ylang/.

Experimental NASM backend (Linux x86-64)

The optional emit-asm command writes NASM syntax for a deliberately limited subset of YLang. Unlike the default C backend, the generated program uses the Linux x86-64 system-call ABI for output and process exit, so a generated program can be assembled with NASM and linked directly with ld without GCC/Clang or a C runtime:

./build/ylang emit-asm tests/asm-basic.yl -o build/asm-basic.asm
nasm -f elf64 build/asm-basic.asm -o build/asm-basic.o
ld -o build/asm-basic build/asm-basic.o
./build/asm-basic

For the same steps in one command, use build-asm:

./build/ylang build-asm tests/asm-basic.yl -o build/asm-basic
./build/asm-basic

The initial subset supports scalar int, bool, char, and string values, local variables, up to six scalar function parameters, user-defined function calls, integer arithmetic and comparisons, if/else, loops, break, continue, return, and print. Integer overflow and invalid integer division terminate the program with status 70.

The experimental backend currently rejects global declarations, arrays, floats, f-strings, string comparisons, and/or, standard-library or conversion calls, and multi-file imports. The standard build command continues to use the established C backend. The separate build-asm command runs NASM and ld for supported programs; emit-asm writes the assembly source for inspection. The experimental backend is Linux x86-64 specific and is not supported on macOS or other architectures.

Diagnostic policy

Compiler errors are intended to be stable, user-facing output. Changes should preserve useful codes where practical and include regression tests for source locations and hints. A check failure must not be reported as a native build failure. Code generation is only entered after parsing and semantic analysis report no errors.

Native backend

The v1.0 backend generates C17 and invokes the selected native compiler (gcc by default or clang when selected). Linux builds use GNU linker RELRO/NOW hardening and _FORTIFY_SOURCE; macOS builds omit GNU/Linux-specific flags and use the platform linker. Generated programs are ordinary native executables, not sandboxed. For native builds, generated C is placed in a private temporary directory and removed after the native compiler exits. This avoids clobbering a project file and avoids collisions between concurrent build invocations. emit-c writes to the requested path, or build/ylang-generated.c if no output path is given.

Scope

This architecture documents the current implementation, not a promise of features outside docs/language-spec.md. Arrays, pointers/references, classes, exception syntax, and a finalized memory model are intentionally outside the original 1.0.0 feature set. Named imports are supported by the default C backend; the NASM backend remains a limited experimental subset.