#!/bin/bash
# ============================================================================
# DarkForge Linux — Phase 3, Chapter 8.30: GCC (FINAL NATIVE COMPILER)
# ============================================================================
# Purpose:  Build the FINAL NATIVE GCC compiler for the target system.
#           This is a CRITICAL step — it compiles for the local hardware
#           (AMD Ryzen 9 9950X3D) with Zen 5 optimizations.
#           CRITICAL ARCHITECTURE DECISIONS:
#           • Enable C and C++ languages for system tools and applications
#           • Enable Position-Independent Executables (PIE) by default (security)
#           • Enable Stack Smashing Protection (SSP) by default (security)
#           • Disable multilib for now (32-bit support handled separately later)
#           • Disable bootstrap (faster, safer, reuses earlier GCC Pass 2)
#           • Apply the lib64→lib sed fix for x86_64 unified /usr/lib
#           • Fix library paths after install to avoid searching lib64
#
# Inputs:   /sources/gcc-15.2.0.tar.xz
#           mpfr-4.2.2.tar.xz, gmp-6.3.0.tar.xz, mpc-1.3.1.tar.gz
#           binutils, glibc, linux headers already installed
# Outputs:  gcc, g++, cc (symlink) in /usr/bin
#           GCC runtime libraries in /usr/lib
# Ref:      LFS 13.0 §8.30
# ============================================================================

set -euo pipefail
source /sources/toolchain-scripts/100-chroot-env.sh

PACKAGE="gcc"
VERSION="15.2.0"

echo "=========================================================================="
echo "=== CRITICAL: Building FINAL NATIVE GCC-${VERSION} (Phase 3)"
echo "=== This compiler will target: AMD Zen 5 (9950X3D)"
echo "=== Compiler flags in use: ${CFLAGS}"
echo "=========================================================================="

pkg_extract "${PACKAGE}-${VERSION}.tar.xz"
cd "${PACKAGE}-${VERSION}"

# Extract arithmetic library dependencies (gmp, mpfr, mpc) into gcc tree
echo ">>> Embedding GMP, MPFR, MPC into GCC source tree..."
tar -xf "${SRCDIR}/mpfr-4.2.2.tar.xz"
mv -v mpfr-4.2.2 mpfr
tar -xf "${SRCDIR}/gmp-6.3.0.tar.xz"
mv -v gmp-6.3.0 gmp
tar -xf "${SRCDIR}/mpc-1.3.1.tar.gz"
mv -v mpc-1.3.1 mpc

# FIX FOR X86_64: lib64 → lib redirection
# On x86_64, GCC defaults to installing 64-bit libraries in lib64.
# DarkForge uses a unified /usr/lib directory. This sed changes GCC's default.
# CRITICAL: This must be done before configure.
case $(uname -m) in
    x86_64)
        echo ">>> Applying x86_64 lib64→lib fix..."
        sed -e '/m64=/s/lib64/lib/' -i.orig gcc/config/i386/t-linux64
        ;;
esac

# Create build directory
mkdir -v build
cd build

# CONFIGURE THE FINAL NATIVE GCC
# This is the most important configuration in the entire toolchain.
echo ">>> Configuring GCC with full security hardening..."
echo ">>> Using Zen 5 flags: ${CFLAGS}"

../configure \
    --prefix=/usr \
    --sysconfdir=/etc \
    --localstatedir=/var \
    --disable-nls \
    --enable-languages=c,c++ \
    --enable-default-pie \
    --enable-default-ssp \
    --disable-multilib \
    --disable-bootstrap \
    --with-system-zlib \
    --enable-gnu-unique-object

# COMPILE GCC
echo ">>> Building GCC (this will take several minutes)..."
make

# INSTALL GCC
echo ">>> Installing GCC to /usr..."
make install

# CREATE cc SYMLINK FOR COMPATIBILITY
# Many build scripts expect /usr/bin/cc to exist
ln -sv gcc /usr/bin/cc

# POST-INSTALL FIXES FOR LIB PATHS
echo ">>> Verifying and fixing library paths..."

# Ensure /usr/lib is in the search path, not /usr/lib64
mkdir -pv /usr/lib/gcc/$(gcc -dumpmachine)/15.2.0

# Run a sanity check: compile and link a hello world program
echo ">>> Running GCC sanity check (compile hello world)..."
echo '#include <stdio.h>
int main() {
    printf("GCC hello world sanity check\\n");
    return 0;
}' > /tmp/hello.c

gcc /tmp/hello.c -o /tmp/hello
if [ ! -f /tmp/hello ]; then
    echo "[ERROR] GCC sanity check failed: could not compile hello.c"
    exit 1
fi

# Check the dynamic linker path (should NOT have lib64)
echo ">>> Checking dynamic linker path..."
LINKER=$(/tmp/hello 2>&1 | head -1 2>/dev/null || ldd /tmp/hello 2>/dev/null | grep "ld-" || echo "OK")
if echo "${LINKER}" | grep -q "lib64"; then
    echo "[WARNING] Dynamic linker path contains lib64 — may need manual fix"
else
    echo ">>> Dynamic linker path is correct (no lib64)"
fi

rm -f /tmp/hello /tmp/hello.c

# Final verification
echo ""
echo ">>> GCC Final Verification:"
echo "    GCC version: $(gcc --version | head -1)"
echo "    G++ version: $(g++ --version | head -1)"
echo "    cc symlink: $(ls -l /usr/bin/cc)"
echo "    Default PIE: $(gcc -Q --help=code-generation | grep DEFAULT | grep pie)"
echo "    Default SSP: $(gcc -Q --help=code-generation | grep DEFAULT | grep ssp)"
echo ""

cd "${SRCDIR}"
pkg_cleanup "${PACKAGE}-${VERSION}"

echo "=========================================================================="
echo "=== FINAL NATIVE GCC-${VERSION} BUILD COMPLETE"
echo "=== System now has a native compiler targeting Zen 5"
echo "=========================================================================="