test-gmp-mac-cross-compilation repo-dump.md

# CMakeLists.txt

```
cmake_minimum_required(VERSION 3.10)
project(TestGMPModule)

set(GMP_INCLUDE_DIR "$ENV{BUILD_ROOT}/deps/${CMAKE_OSX_ARCHITECTURES}/gmp-6.3.0/include")
set(GMP_LIBRARY "$ENV{BUILD_ROOT}/deps/${CMAKE_OSX_ARCHITECTURES}/gmp-6.3.0/lib/libgmp.a")
include_directories(${GMP_INCLUDE_DIR})
add_library(hello MODULE hello_pure_gmp.cpp)
target_link_libraries(hello ${GMP_LIBRARY})
set_target_properties(hello PROPERTIES PREFIX "" SUFFIX ".so")

```

# hello_pure_gmp.cpp

```
#include <stdio.h>
#include <stdlib.h>
#include <gmp.h>

// Adds two numbers represented as strings and returns a newly allocated string
char* gmp_add(const char* a, const char* b) {
    mpz_t num1, num2, sum;
    mpz_init_set_str(num1, a, 10);
    mpz_init_set_str(num2, b, 10);
    mpz_init(sum);

    mpz_add(sum, num1, num2);

    // Convert result to string
    char* result_str = mpz_get_str(NULL, 10, sum);

    // Clean up
    mpz_clear(num1);
    mpz_clear(num2);
    mpz_clear(sum);

    return result_str; // caller must free() it
}

```

# .github\workflows\build.yml

```
name: Test GMP Cross Compilation

on:
  workflow_dispatch:

jobs:
  build:
    runs-on: macos-14

    steps:
    - uses: actions/checkout@v3

    - name: Setup build environment
      run: |
        export BUILD_ROOT=`pwd`
        echo "BUILD_ROOT=$BUILD_ROOT" >> $GITHUB_ENV
        mkdir -p deps/arm64 deps/x86_64
        export CFLAGS="-mmacosx-version-min=10.15"
        echo "CFLAGS=$CFLAGS" >> $GITHUB_ENV

    - name: Extract GMP
      run: tar -xf gmp-6.3.0.tar.bz2

    - name: Build GMP for arm64
      run: |
        cd gmp-6.3.0
        mkdir build && cd build
        ../configure --enable-static --disable-shared --with-pic --prefix="$BUILD_ROOT/deps/arm64/gmp-6.3.0"
        make -j10
        make install

    - name: Build GMP for x86_64
      run: |
        cd gmp-6.3.0/build
        rm -rf ./*
        CC="clang -arch x86_64" ../configure --enable-static --disable-shared --with-pic --host=x86_64-apple-darwin --prefix="$BUILD_ROOT/deps/x86_64/gmp-6.3.0"
        make -j10
        make install

    - name: Create build directory
      run: |
        mkdir -p build

    - name: Build module for arm64 (without LDFLAGS)
      run: |
        # Works OK.
        cd build
        rm -rf ./*
        cmake .. -G Ninja -DCMAKE_OSX_ARCHITECTURES=arm64
        ninja -v

    - name: Build module for arm64 (with LDFLAGS)
      run: |
        # Works OK.
        cd build
        export LDFLAGS="-Wl,-flat_namespace"
        rm -rf ./*
        cmake .. -G Ninja -DCMAKE_OSX_ARCHITECTURES=arm64
        ninja -v

    - name: Build module for x86_64 (without LDFLAGS)
      run: |
        # Works OK.
        cd build
        unset LDFLAGS
        rm -rf ./*
        cmake .. -G Ninja -DCMAKE_OSX_ARCHITECTURES=x86_64
        ninja -v

    - name: Build module for x86_64 (with LDFLAGS)
      run: |
        # BREAKS.
        cd build
        export LDFLAGS="-Wl,-flat_namespace"
        rm -rf ./*
        cmake .. -G Ninja -DCMAKE_OSX_ARCHITECTURES=x86_64
        ninja -v

```