From c0a2ee9fb8468c7420ff9177d8499bd52dca42a5 Mon Sep 17 00:00:00 2001
From: "Santiago M. Mola" <santi@mola.io>
Date: Fri, 24 Jul 2020 19:35:08 +0200
Subject: [PATCH] cmake: forbid in-source builds

CMake in-source builds will conflict with PHP's autotools-based
Makefiles. Forbidding them avoids confusing the user when things stop
working if they use "cmake ." on the command line.
---
 CMakeLists.txt | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9380f6e..8fdb214 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,6 +1,10 @@
 cmake_minimum_required(VERSION 3.8)
 project(skeleton C)
 
+if(PROJECT_SOURCE_DIR STREQUAL PROJECT_BINARY_DIR)
+    message(SEND_ERROR "In-source builds are not allowed. They conflict with PHP's own Makefiles.")
+endif()
+
 add_compile_definitions(HAVE_SKELETON)
 
 set(SOURCE_FILES php_skeleton skeleton.c)