Building PEP on macOS

The following instructions were successful on a M2 mac, with macOS Sonoma 14.1.1

Download Homebrew by copying the following line from https://brew.sh to Terminal:
```
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
```
Homebrew will also install the Command Line Tools, which includes software essential for developers such as Git and clang.
After completing the install, run the following two commands in your terminal to add Homebrew to your PATH:
```
(echo; echo 'eval "$(/opt/homebrew/bin/brew shellenv)"') >> /Users/<username>/.zprofile
eval "$(/opt/homebrew/bin/brew shellenv)"
```
where <username> should be replaced with your username. These commands export environment variables needed for brew to work to .zprofile, a file that runs in your (Z-)shell when signing in as user.

Next, the following packages should be installed:

brew install cmake
brew install ninja
brew install openssl
brew install qt@6
brew install boost
brew install jq

You should now be able to build PEP.

Additional tweaks

To speed up recompilation time run:

brew install ccache

Set cmake to use ccache as compiler-launcher by running the following line from the build directory:

cmake -DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_CXX_COMPILER_LAUNCHER=ccache ..

The following instructions were successful on macOS Sierra

Install brew, xcode (currently macports has an outdated version of the boost lib).
Though brew install the following packages:
```
brew install protobuf
brew install qt6
brew install boost
brew install cmake
brew install openssl
```
Or use MacPorts: protobuf3-cpp, qt5, boost -no_static, cmake.

From the core directory run:

git submodule sync
git submodule update --init

Start compiling.

Potential errors when building PEP core

Incorrect homebrew path

(echo; echo 'eval "$(/usr/local/bin/brew shellenv)"') >> /Users/<username>/.zprofile
eval "$(/usr/local/bin/brew shellenv)"

Library location conflict (OpenSSL and Qt5)

There can be conflicts between the OpenSSL and Qt6 libraries provided by the macOS system and those available through Homebrew. Explicitly specify the libraries' locations to resolve these conflicts.

cmake \
    -DOPENSSL_ROOT_DIR=$(brew --prefix openssl) \
    -DOPENSSL_CRYPTO_LIBRARY=$(brew --prefix openssl)/lib/libcrypto.dylib \
    -DOPENSSL_SSL_LIBRARY=$(brew --prefix openssl)/lib//libssl.dylib \
    -DQt6_DIR=$(brew --prefix qt)/lib/cmake/Qt6 \
     <source directory>

or setup the environment variable:

CMAKE_PREFIX_PATH=/usr/local/opt/qt:/usr/local/opt/openssl

MacPorts has a similar issue; in this case setting CMAKE_PREFIX_PATH=/opt/local does the trick.

If you don't want to do it explicitly via CMake, you can set up global environment variables for finding the path to OpenSSL and Qt5 libraries. You can set these variables in the .zprofile file in your home directory. You can access this file via your command line. Add

export OPENSSL_ROOT_DIR=$(brew --prefix openssl@3)
export Qt6_DIR=$(brew --prefix qt6)/lib/cmake/Qt6

to this file.

arm64 architecture not supported

ninja

If you use a newer Mac, it can be the case that your CPU has an arm64 architecture, instead of x86_64. This is a problem, because there is a bug in ninja that doesn't support arm64. See the bug explained here: https://discourse.cmake.org/t/building-application-using-externalproject-add-on-m1-cpu/4931/7. This bug has already been evaded in the code base, by setting the CMake generator to your default generator instead of using ninja. But it can be the case that your IDE negates this. If you use VS code, you can change this in the settings.

Go to Extensions >> CMake Tools
Click the small gear, and go to Extension Settings
Search for "Generator"
Fill in Unix Makefiles in the CMake: Generator field.

boost

If you use the boost::filesystem library you can get the error Undefined symbols for architecture arm64. This is because the boost filesystem is not linked. You can link it in your tasks.json file:

Add "-lboost_system", "-lboost_filesystem","-I/opt/homebrew/include", "-L/opt/homebrew/lib", as arguments to "args".

Include errors

If you use VS code, it can be the case that not all CMake headers will be included. Add

"configurationProvider": "ms-vscode.cmake-tools"

as an argument in configurations in the c_cpp_properties.json file. You can find this file in your .vscode folder.

You can also get the warning:

include file not found in browse.path

add

  "browse": {
  "path": ["${workspaceFolder}/**"],
  "limitSymbolsToIncludedHeaders": true,
  "databaseFilename": ""
}

as an argument in the c_cpp_properties.json file.