#12 Foundation and Architecture: Development Environment for Language Implementation -> Setting up C++20/23 for Building Interpreters

In recent years, the evolution of the C++ language has provided language designers and systems developers with powerful tools for implementing interpreters with better maintainability, modularity, and performance. C++20 and C++23 introduce features such as concepts, ranges, modules, coroutines, constexpr enhancements, pattern matching proposals, and better compile-time diagnostics. For building interpreters—especially with a modern architecture involving lexers, parsers, ASTs, symbol tables, and execution runtimes—these language improvements offer practical advantages.

This section focuses on configuring a robust C++20/23 development environment tailored for designing interpreters and domain-specific languages. It addresses compiler choices, build systems, editor setups, and the adoption of modern C++ idioms, libraries, and tooling.

1. Compiler Requirements and Setup

1.1. Choosing a Modern Compiler

To work with the most recent features of C++20 and C++23, ensure that your compiler supports them fully or at least substantially. As of the past five years, the most reliable compilers include:

• GCC (10 and above for C++20, 13+ for C++23 support)

• Clang (12 and above for C++20, 16+ for C++23 previews)

• MSVC (Visual Studio 2019 v16.10 and above for C++20, VS2022 for C++23)

For interpreter development, Clang is often preferred for its detailed diagnostics, while GCC offers broad cross-platform performance. MSVC is excellent for Windows-native tooling, especially if you target Windows APIs or use tools like Visual Studio or C++Builder.

Recommended build flags for compiling with modern C++ features:

g++ -std=c++23 -Wall -Wextra -Wpedantic -O2 -g your_source.cpp -o interpreter

2. Build Systems and Project Organization

2.1. CMake for Cross-Platform Builds

CMake remains the dominant build system for C++ projects. With C++20 modules and newer header units becoming more prevalent, CMake has introduced better support in versions 3.20+. CMake allows scalable multi-target projects, separating lexer/parser generation, runtime engines, and test tools efficiently.

Use modern CMake practices:

cmake_minimum_required(VERSION 3.26)
project(MyLangInterpreter LANGUAGES CXX)
set(CMAKE_CXX_STANDARD 23)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

add_executable(interpreter src/main.cpp src/lexer.cpp src/parser.cpp)
target_include_directories(interpreter PRIVATE include)

2.2. Logical Folder Structure

A typical interpreter should have a folder layout like:

/MyLangInterpreter
  /src
    main.cpp
    lexer.cpp
    parser.cpp
    ast.cpp
    runtime.cpp
  /include
    lexer.hpp
    parser.hpp
    ast.hpp
    runtime.hpp
  /tests
    test_lexer.cpp
    test_parser.cpp
  /tools
    codegen.cpp
  CMakeLists.txt

Modularity supports testing, separation of concerns, and fast iteration.

3. IDE and Editor Configuration

To work efficiently with modern C++, consider tools that support:

• Real-time syntax checking

• Integration with clang-tidy, clang-format

• Code navigation, refactoring, and debugging support

• Git integration

Recommended IDEs:

• CLion: Deep CMake integration, built-in Clang engine, seamless support for C++20/23

• Visual Studio 2022: Best for Windows-native development, IntelliSense, and debugging

• VSCode with C++ Extension: Lightweight, customizable, and multiplatform

• Emacs/Vim with LSP and clangd for experienced users

4. Compiler Tooling and Diagnostics

4.1. clang-tidy and clang-format

Use clang-tidy for code quality checks. It helps detect modern best practice violations, especially in template-heavy or constexpr-heavy components like parsers or evaluators.

Enable C++20/23 checkers:

clang-tidy -checks="modernize-*,readability-*,performance-*,cppcoreguidelines-*" ...

Use .clang-format with custom rules based on LLVM or Google style, adjusted for your project's clarity needs.

5. Testing Environment for Interpreters

Unit testing is essential, especially for language features. Integrate modern C++ testing frameworks:

• doctest: Header-only, fast compile time, perfect for TDD

• Catch2: More expressive syntax, very popular in open-source projects

• GoogleTest: Large-scale, stable, and powerful for integration testing

Organize tests in the /tests folder, and compile them as separate targets. Test lexers, parsers, AST walkers, and execution logic independently.

6. C++20/23 Specific Practices Beneficial to Interpreters

6.1. Concepts

Use concepts to constrain template-based parser generators or AST visitors:

template<typename T>
concept TokenStream = requires(T stream) {
    { stream.next_token() } -> std::same_as<Token>;
};

6.2. constexpr for Compile-Time Token Tables

C++20 allows complex structures at compile-time. Lexer tables and parser rules can be declared constexpr, speeding up runtime startup and improving testability.

constexpr std::array<TokenRule, N> token_rules = {
  TokenRule{"+", TokenType::Plus},
  TokenRule{"-", TokenType::Minus},
  ...
};

6.3. std::ranges and Views

In interpreter pipelines—like transforming token streams into filtered views—std::ranges enhances readability and lazy computation:

auto filtered = tokens | std::views::filter([](const Token& t){ return t.type != TokenType::Whitespace; });

6.4. Modules (Experimental)

Start modularizing if your compiler supports C++20 modules. Begin with internal tools like:

module; // global module fragment
#include <string>
#include <vector>

export module lexer;
export class Lexer {
  ...
};

Use cautiously until module support becomes fully stable in your toolchain.

7. Optional Tools for Interpreter Development

• Godbolt Compiler Explorer for checking generated assembly of critical routines

• Valgrind / AddressSanitizer for memory leak detection

• Fuzzing Tools (like libFuzzer) for input testing of lexer/parser

• Graphviz integration to visualize ASTs or CFGs

• REPL Shell using C++ coroutines or threads to test runtime interactively

Conclusion

Setting up a solid, modern C++20/23 environment is foundational for building a future-proof, extensible interpreter. With proper tooling, modular project layout, and modern language features, you can accelerate development and enforce clean design practices.

This preparation phase ensures that upcoming chapters—focusing on lexical analysis, parsing strategies, semantic checks, and runtime behavior—are built on a stable, maintainable, and scalable foundation.