chore(build): make build.sh generic (macOS + Linux) and configurable

[SizzleUnrlsd]

chore(build): make build.sh generic (macOS + Linux) and configurable

Context

The current build.sh is macOS/Homebrew-specific:

mkdir -p build && cd build

cmake .. \
  -DLLVM_DIR=$(brew --prefix llvm)/lib/cmake/llvm \
  -DClang_DIR=$(brew --prefix llvm)/lib/cmake/clang \
  -DCMAKE_BUILD_TYPE=Release \
&& make -j$(sysctl -n hw.logicalcpu)

Issues:

• brew --prefix llvm does not exist on Linux (or not necessarily).
• sysctl -n hw.logicalcpu is macOS-only.
• No configurability (build type, Ninja generator, build directory, LLVM/Clang overrides, etc.).

Goal

Have a single script that:

• works on macOS and Linux
• auto-detects a sensible parallel build jobs count
• can be configured for:
  • BUILD_TYPE (Release/Debug/RelWithDebInfo)
  • BUILD_DIR
  • GENERATOR (Makefiles/Ninja)
  • LLVM_DIR and Clang_DIR via environment variables or auto-detection
• keeps a simple UX (./build.sh, ./build.sh --clean, etc.)

Proposal (spec)

Inputs (CLI or env)

• --build-dir <dir> (default: build)
• --type <Release|Debug|RelWithDebInfo> (default: Release)
• --generator <Ninja|Unix Makefiles> (optional)
• --clean (delete the build directory)
• --llvm-dir <path> / LLVM_DIR=...
• --clang-dir <path> / Clang_DIR=...
• --jobs <n> (override)

Expected detections

• OS via uname -s
• jobs:
  • macOS: sysctl -n hw.logicalcpu
  • Linux: nproc (fallback: getconf _NPROCESSORS_ONLN)
• LLVM/Clang CMake dirs:
  • macOS: if brew is present, try brew --prefix llvm
  • Linux:
    • if llvm-config is present: use llvm-config --cmakedir (often reliable)
    • otherwise fallback to common paths (/usr/lib/llvm-*/lib/cmake/llvm, etc.) if found
  • Otherwise: fail with a clear message explaining how to provide LLVM_DIR/Clang_DIR.

Tasks

• Create scripts/build.sh (or replace build.sh) with set -euo pipefail
• Add minimal argument parsing (case "$1" in ...) + --help
• Implement cross-platform JOBS detection
• Implement LLVM/Clang auto-detection (brew + llvm-config) + fallbacks + clean errors
• Support Ninja if installed (command -v ninja)
• Use cmake --build . -j "$JOBS" instead of calling make directly (more portable)
• Document usage in README.md (Build on macOS/Linux section)
• Add a quick CI check that validates:
  • the script can configure (at least cmake -S -B)
  • on ubuntu-latest + macos-latest (GitHub Actions)

Acceptance criteria

• ./build.sh works on macOS with LLVM installed via Homebrew.
• ./build.sh works on Linux with LLVM/Clang installed via packages/llvm-config or via LLVM_DIR/Clang_DIR.
• ./build.sh --clean cleans and rebuilds.
• The script does not rely on OS-specific commands without fallback.
• Error messages are actionable (e.g., “export LLVM_DIR=… and re-run”).

Notes / usage examples

• macOS (brew):
  • ./build.sh --type Release
• Linux (packages):
  • ./build.sh --type Debug
• Manual override:
  • LLVM_DIR=/opt/llvm/lib/cmake/llvm Clang_DIR=/opt/llvm/lib/cmake/clang ./build.sh --generator Ninja