构建ROOT项目遇CMake错误：需采用源码外构建方式求助

Hey there, let's get this ROOT build sorted out quickly! That error is telling you exactly what's wrong: ROOT requires an out-of-source build, which means you can't run cmake in a way that mixes your source code files with build-generated artifacts.

Step-by-step fix to get your build working: #

First, let's set up a clean build structure separate from your ROOT source code:

• Navigate to the parent folder of your ROOT source directory (I’ll assume your source lives in a folder named root).
• Create a dedicated build directory (this keeps all compiled files, logs, and intermediate outputs away from your clean source code):

  mkdir root-build
  

• Move into this new build directory:

  cd root-build
  

• Now run cmake pointing to your ROOT source folder:

  cmake ../root
  

• Once CMake completes without errors, you can start building ROOT with:

  make -j$(sysctl -n hw.ncpu)  # Uses all your Mac's CPU cores for faster builds
  

Why this matters: #

Out-of-source builds are a standard best practice for large CMake projects like ROOT. They:

• Keep your source directory completely clean (no generated files cluttering up your code)
• Let you create multiple build directories for different configurations (e.g., one for debug builds, one for optimized releases) without overlapping files
• Make it trivial to start fresh if something goes wrong—just delete the build directory and start over!

Your original error output for reference: #

Harshits-Air:root harshitprasad$ cmake ../root
-- Found a Mac OS X System 10.13
-- Found a 64bit system
-- Found LLVM compiler collection
-- ROOT Platform: macosx
-- ROOT Architecture: macosx64
-- Build Type: RelWithDebInfo
-- Compiler Flags: -Wc++11-narrowing -Wsign-compare -Wsometimes-uninitialized -Wconditional-uninitialized -Wheader-guard -Warra
CMake error: ROOT should be built as an out of source build

内容的提问来源于stack exchange，提问作者Harshit