From dd6538ba78f731bc81aa461dd8e78629ee85a66c Mon Sep 17 00:00:00 2001
From: Will Ayd <william.ayd@icloud.com>
Date: Tue, 21 Jan 2025 18:06:31 -0500
Subject: [PATCH] GH-45325: [C++] Improved error message when using clang++
 without clang

---
 cpp/cmake_modules/SetupCxxFlags.cmake | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/cpp/cmake_modules/SetupCxxFlags.cmake b/cpp/cmake_modules/SetupCxxFlags.cmake
index fdb28b540e2d2..3f38b517e8edd 100644
--- a/cpp/cmake_modules/SetupCxxFlags.cmake
+++ b/cpp/cmake_modules/SetupCxxFlags.cmake
@@ -23,6 +23,23 @@ include(CheckCXXSourceCompiles)
 
 message(STATUS "System processor: ${CMAKE_SYSTEM_PROCESSOR}")
 
+if(CMAKE_C_COMPILER_ID STREQUAL "AppleClang" OR CMAKE_C_COMPILER_ID STREQUAL "Clang")
+  set(UsingClang TRUE)
+else()
+  set(UsingClang FALSE)
+endif()
+
+# Check for Clang C++ compiler
+if(CMAKE_CXX_COMPILER_ID STREQUAL "AppleClang" OR CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+  set(UsingClangPlusPlus TRUE)
+else()
+  set(UsingClangPlusPlus FALSE)
+endif()
+
+if(${UsingClangPlusPlus} AND NOT ${UsingClang})
+  message(FATAL_ERROR "When using clang++ you must also use clang")
+endif()
+
 if(NOT DEFINED ARROW_CPU_FLAG)
   if(CMAKE_SYSTEM_NAME STREQUAL "Emscripten")
     set(ARROW_CPU_FLAG "emscripten")