# CMake 2026 Project Setup Plan

## Overview
This document outlines the technical plan for setting up a CMake-based C++ project with the following requirements:
- clang++ compiler with C++23 defaults
- Automatic source file discovery in src/ directory
- Executable generation from files containing 'main' in filename
- External dependency handling for git submodules
- Organized compile flags and variables

## Key Components

### 1. Compiler Configuration
- Use clang++ as the C++ compiler
- Set C++ standard to C++23
- Configure appropriate compiler flags for clang

### 2. Source File Discovery
- Scan src/ directory for all .cpp files
- Use regex pattern `.*main.*\.cpp$` to identify main files
- Separate main files from other source files

### 3. Executable Generation
- Automatically create executables from files with 'main' in filename
- Create a library from all non-main source files
- Link the library to each executable

### 4. External Dependency Management
- Handle dependencies in external/ directory
- Example: spdlog in external/spdlog with namespace spdlog
- Create interface libraries for external dependencies

### 5. Compile Flags Organization
- Debug build flags: -g -O0 -Wall -Wextra
- Release build flags: -O3 -DNDEBUG -Wall -Wextra
- Common flags: -std=c++23 -fPIC

## Implementation Details

### Regex Pattern
```
.*main.*\.cpp$
```
Used to detect files containing 'main' in their filename.

### Directory Structure
- `src/` - Source files directory
- `external/` - Git submodules directory
- `include/` - Header files directory

### File Processing Logic
1. Find all .cpp files in src/
2. Separate main files from other source files
3. Create library from non-main files
4. Generate executables from main files
5. Link library and external dependencies to each executable

## CMake Commands Used
- `cmake_minimum_required(VERSION 3.15)`
- `project(ProjectEuler CXX)`
- `file(GLOB_RECURSE)`
- `list(APPEND)`
- `add_executable()`
- `add_library()`
- `target_link_libraries()`
- `target_compile_features()`
- `find_package()`
- `add_subdirectory()`