C++20 CMake-Emscripten Template

Setup for Native and Web build of C++20 source code.

🤔 Why this repository?

Problem: There is currently an issue when using C++20 with Emscripten's emcmake (emscripten#22305). There is a fix proposed in PR#21987, but it has not been merged yet.

Solution: This repository provides a minimal setup that imports the fix proposed by PR#21987 without the need to modify emscripten itself.

🥸 Using as a template

You may use this repository as a template, then replace the following strings in the code base:

• my_project is the name of the CMake project (and IDE solution).
• my_target is the name of the CMake target, i.e., the name of the generated executable or HTML file.

🏗️ Building

This is a regular CMake project, that builds like a CMake project. The only exception is the extra option needed for Web build (see below).

These instructions show how to manually call CMake, but a CMakePresets.json file is also provided as an alternative.

Native

# Configure
cmake -B build-native
# or 'cmake --preset native'

# Build
cmake --build build-native

# Run (Windows & MSVC)
build/src/Debug/my_target.exe

# Run (other)
build/src/my_target

WebAssembly

NB The workaround for issue emscripten#22305 consists in pointing CMAKE_CXX_COMPILER_CLANG_SCAN_DEPS to the local fix that we have in cmake/EmscriptenScanDepsFix.

# Activate emscripten env (Windows)
C:/path/to/emsdk/emsdk_env.bat

# Activate emscripten env (other)
. /path/to/emsdk/emsdk_env.sh

# Configure
emcmake cmake -B build -DCMAKE_CXX_COMPILER_CLANG_SCAN_DEPS=cmake/EmscriptenScanDepsFix/emscan-deps
# or 'emcmake cmake --preset web'

# Build
cmake --build build

# Host
python -m http.server 8000
# The browse to http://localhost:8000/build-web/src/my_target.html