File 0001-Optionally-use-system-provided-Catch2.patch of Package netgen

From f1017faee9a057f86be34abd3926189623d73cf9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Stefan=20Br=C3=BCns?= <stefan.bruens@rwth-aachen.de>
Date: Wed, 3 Mar 2021 18:45:22 +0100
Subject: [PATCH] Optionally use system provided Catch2

Most external_projects are only fetched on Windows and/or MacOS, but are
assumed to be available on Linux. The only outlier is Catch2.

In case netgen is build in an isolated environment, fetching Catch2 will
fail, even when Catch2 is available as a system package.
---
 CMakeLists.txt         | 13 ++++++++++++-
 cmake/SuperBuild.cmake |  1 +
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 20c01740..caca0bfc 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -33,6 +33,8 @@ option( DEBUG_LOG "Enable more debug output (may increase computation time) - on
 option( CHECK_RANGE "Check array range access, automatically enabled if built in debug mode" OFF)
 option( BUILD_STUB_FILES "Build stub files for better autocompletion" ON)
 option( BUILD_FOR_CONDA "Link python libraries only to executables" OFF)
+option( DOWNLOAD_DEPENDENCIES "Download any dependencies not found on the system" ON)
+
 
 option( USE_SUPERBUILD       "build dependencies automatically" ON)
 option( TRACE_MEMORY     "Enable memory tracing" OFF)
@@ -479,7 +481,16 @@ enable_testing()
 include(CTest)
 
 if(ENABLE_UNIT_TESTS)
-  include(${CMAKE_CURRENT_LIST_DIR}/cmake/external_projects/catch.cmake)
+  if(DOWNLOAD_DEPENDENCIES)
+    include(${CMAKE_CURRENT_LIST_DIR}/cmake/external_projects/catch.cmake)
+  else(DOWNLOAD_DEPENDENCIES)
+    find_package(Catch2 REQUIRED)
+    set_target_properties(Catch2::Catch2 PROPERTIES IMPORTED_GLOBAL TRUE)
+    add_library(project_catch ALIAS Catch2::Catch2)
+    get_target_property(_CATCH_INCLUDE_DIR_BASE Catch2::Catch2 INTERFACE_INCLUDE_DIRECTORIES)
+    string(CONCAT CATCH_INCLUDE_DIR ${_CATCH_INCLUDE_DIR_BASE} "/catch2")
+  endif(DOWNLOAD_DEPENDENCIES)
+  message(STATUS "Catch2 include dir: ${CATCH_INCLUDE_DIR}")
 endif(ENABLE_UNIT_TESTS)
 
 
diff --git a/cmake/SuperBuild.cmake b/cmake/SuperBuild.cmake
index 13d6915a..6c33d6e9 100644
--- a/cmake/SuperBuild.cmake
+++ b/cmake/SuperBuild.cmake
@@ -232,6 +232,7 @@ set_vars( NETGEN_CMAKE_ARGS
   INTEL_MIC
   CMAKE_INSTALL_PREFIX
   ENABLE_UNIT_TESTS
+  DOWNLOAD_DEPENDENCIES
   ENABLE_CPP_CORE_GUIDELINES_CHECK
   USE_SPDLOG
   DEBUG_LOG
-- 
2.36.1