[core] deprecate the master branch

Author: MarcelKoch

CMakeLists.txt

@@ -3,6 +3,17 @@ cmake_minimum_required(VERSION 3.16)
 project(Ginkgo LANGUAGES CXX VERSION 1.9.0 DESCRIPTION "A numerical linear algebra library targeting many-core architectures")
 set(Ginkgo_VERSION_TAG "develop")
 set(PROJECT_VERSION_TAG ${Ginkgo_VERSION_TAG})
+if(Ginkgo_VERSION_TAG STREQUAL "master")
+    set(GINKGO_VERSION_TAG_DEPRECATED ON)
+else()
+    set(GINKGO_VERSION_TAG_DEPRECATED OFF)
+endif()
+if(GINKGO_VERSION_TAG_DEPRECATED)
+    message(
+            WARNING
+            "The branch ${Ginkgo_VERSION_TAG} is deprecated and will stop receiving updates after 2025. "
+            "Please use the main branch for the latest release, or the develop branch for the latest development updates.")
+endif()
 # Cuda and Hip also look for Threads. Set it before any find_package to ensure the Threads setting is not changed.
 set(THREADS_PREFER_PTHREAD_FLAG ON)
 

CONTRIBUTING.md

@@ -151,8 +151,8 @@ improvements from code reviews.
 ### Creating, Reviewing and Merging Pull Requests
 
 * The `develop` branch is the default branch to submit PR's to. From time to
-  time, we merge the `develop` branch to the `master` branch and create tags on
-  the `master` to create new releases of Ginkgo. Therefore, all pull requests
+  time, we merge the `develop` branch to the `main` branch and create tags on
+  the `main` to create new releases of Ginkgo. Therefore, all pull requests
   must be merged into `develop`.
 * Please have a look at the labels and make sure to add the relevant labels.
 * You can mark the PR as a `WIP` if you are still working on it, `Ready for

include/ginkgo/config.hpp.in

@@ -13,6 +13,16 @@
 #define GKO_VERSION_STR @Ginkgo_VERSION_MAJOR@, @Ginkgo_VERSION_MINOR@, @Ginkgo_VERSION_PATCH@
 // clang-format on
 
+
+// clang-format off
+#cmakedefine01 GINKGO_VERSION_TAG_DEPRECATED
+#if GINKGO_VERSION_TAG_DEPRECATED
+#pragma message ("The branch " GKO_VERSION_TAG " is deprecated and will stop receiving updates after 2025. " \
+ "Please use the main branch for the latest release, or the develop branch for the latest development updates.")
+#endif
+// clang-format on
+
+
 /*
  * Controls the amount of messages output by Ginkgo.
  * 0 disables all output (except for test, benchmarks and examples).