File use-system-pybind11.patch of Package python-dm-tree

From 5dd767f3e60d9e4c58f6ee7764b24e1dec2c5edb Mon Sep 17 00:00:00 2001
From: Alexander Tsvyashchenko <ndl@endl.ch>
Date: Sat, 1 Jan 2022 13:22:47 +0100
Subject: [PATCH] Use system pybind11 and absl when available

Current CMakeLists.txt always downloads and builds `pybind11` and `absl` which conflicts with packaging best practices in some of the distributions. This change uses system libraries (if available) and falls back to the old behavior (if not).
---
 tree/CMakeLists.txt | 122 ++++++++++++++++++++++++--------------------
 1 file changed, 66 insertions(+), 56 deletions(-)

Index: dm-tree-0.1.8/tree/CMakeLists.txt
===================================================================
--- dm-tree-0.1.8.orig/tree/CMakeLists.txt
+++ dm-tree-0.1.8/tree/CMakeLists.txt
@@ -50,18 +50,21 @@ if(APPLE)
   set (CMAKE_FIND_FRAMEWORK LAST)
 endif()
 
-# Fetch pybind to be able to use pybind11_add_module symbol.
-set(PYBIND_VER v2.10.1)
-include(FetchContent)
-FetchContent_Declare(
-  pybind11
-  GIT_REPOSITORY https://github.com/pybind/pybind11
-  GIT_TAG        ${PYBIND_VER}
-)
-if(NOT pybind11_POPULATED)
-    FetchContent_Populate(pybind11)
-    add_subdirectory(${pybind11_SOURCE_DIR} ${pybind11_BINARY_DIR})
-    include_directories(${pybind11_INCLUDE_DIR})
+find_package(pybind11 CONFIG)
+if (NOT pybind11_FOUND)
+  # Fetch pybind to be able to use pybind11_add_module symbol.
+  set(PYBIND_VER v2.10.1)
+  include(FetchContent)
+  FetchContent_Declare(
+    pybind11
+    GIT_REPOSITORY https://github.com/pybind/pybind11
+    GIT_TAG        ${PYBIND_VER}
+  )
+  if(NOT pybind11_POPULATED)
+      FetchContent_Populate(pybind11)
+      add_subdirectory(${pybind11_SOURCE_DIR} ${pybind11_BINARY_DIR})
+      include_directories(${pybind11_INCLUDE_DIR})
+  endif()
 endif()
 
 # Define pybind11 tree module.