From c5809d320f60028d7c9c890def36fcc652a5c463 Mon Sep 17 00:00:00 2001
From: Markus Blatt <markus@dr-blatt.de>
Date: Tue, 28 Apr 2026 17:19:44 +0200
Subject: [PATCH] [cmake] Recover sibling builds supporting DUNE in build tree

This was broken by the build system refactoring and the build system
always picked up the DUNE version that was installed on the system
even for activated

To recover it we need to construct a FULL chain of all DUNE modules
that we might depend on. This has to be specified in dune.module
currently. This list is constructed in cmake/Modules/OpmInit.cmake.

Note that both opm-common_DIR and dune-common_DIR need to be set in
each module's toplevel CMakeLists.txt file because the are needed for
the initial find_package(opm-common) call there which happens before
including cmake/Modules/OpmInit.cmake
---
 CMakeLists.txt | 44 ++++++++++++++++++++++++--------------------
 dune.module    |  6 +++++-
 2 files changed, 29 insertions(+), 21 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index a240cd865c2..c822c1e25a5 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -916,6 +916,10 @@ if(CONVERT_CUDA_TO_HIP)
   set(USE_GPU_BRIDGE OFF)
 endif()
 
+# These modules are special because they search with the first
+# find_package call in here
+set(initial_depends opm-common dune-common)
+
 if(SIBLING_SEARCH AND NOT opm-common_DIR)
   # guess the sibling dir
   get_filename_component(_leaf_dir_name ${PROJECT_BINARY_DIR} NAME)
@@ -923,28 +927,28 @@ if(SIBLING_SEARCH AND NOT opm-common_DIR)
   get_filename_component(_parent_dir_name ${_parent_full_dir} NAME)
   #Try if <module-name>/<build-dir> is used
   get_filename_component(_modules_dir ${_parent_full_dir} DIRECTORY)
-  if(IS_DIRECTORY ${_modules_dir}/opm-common/${_leaf_dir_name})
-    set(opm-common_DIR ${_modules_dir}/opm-common/${_leaf_dir_name})
-    set(opm-grid_DIR ${_modules_dir}/opm-grid/${_leaf_dir_name})
-  else()
-    string(REPLACE ${PROJECT_NAME} opm-common _opm_common_leaf ${_leaf_dir_name})
-    if(NOT _leaf_dir_name STREQUAL _opm_common_leaf
-        AND IS_DIRECTORY ${_parent_full_dir}/${_opm_common_leaf})
-      # We are using build directories named <prefix><module-name><postfix>
-      set(opm-common_DIR ${_parent_full_dir}/${_opm_common_leaf})
-      string(REPLACE ${PROJECT_NAME} opm-grid _opm_grid_leaf ${_leaf_dir_name})
-      set(opm-grid_DIR ${_parent_full_dir}/${_opm_grid_leaf})
-    elseif(IS_DIRECTORY ${_parent_full_dir}/opm-common)
-      # All modules are in a common build dir
-      set(opm-common_DIR "${_parent_full_dir}/opm-common")
-      set(opm-grid_DIR "${_parent_full_dir}/opm-grid")
+  foreach(module ${initial_depends})
+    if(IS_DIRECTORY ${_modules_dir}/${module}/${_leaf_dir_name})
+      set(${module}_DIR ${_modules_dir}/${module}/${_leaf_dir_name})
+    else()
+      string(REPLACE ${PROJECT_NAME} ${module} _module_leaf ${_leaf_dir_name})
+      if(NOT _leaf_dir_name STREQUAL _module_leaf
+          AND IS_DIRECTORY ${_parent_full_dir}/${_module_leaf})
+        # We are using build directories named <prefix><module-name><postfix>
+        set(${module}_DIR ${_parent_full_dir}/${_module_leaf})
+      elseif(IS_DIRECTORY ${_parent_full_dir}/${module})
+        # All modules are in a common build dir
+        set(${module}_DIR "${_parent_full_dir}/${module}")
+      endif()
     endif()
-  endif()
-endif()
-if(opm-common_DIR AND NOT IS_DIRECTORY ${opm-common_DIR})
-  message(WARNING "Value ${opm-common_DIR} passed to variable"
-    " opm-common_DIR is not a directory")
+  endforeach()
 endif()
+foreach(module ${initial_depends})
+  if(${module}_DIR AND NOT IS_DIRECTORY ${${module}_DIR})
+    message(WARNING "Value ${${module}_DIR} passed to variable"
+      " ${module}_DIR is not a directory")
+  endif()
+endforeach()
 
 find_package(opm-common REQUIRED)
 
diff --git a/dune.module b/dune.module
index c2d0e182489..eb91e2829f5 100644
--- a/dune.module
+++ b/dune.module
@@ -10,4 +10,8 @@ Label: 2026.10-pre
 Maintainer: atgeirr@sintef.no
 MaintainerName: Atgeirr F. Rasmussen
 Url: http://opm-project.org
-Depends: dune-istl (>= 2.9) opm-common opm-grid
+# We need the full list of dependencies below, because we need to set
+# *_DIR for each of them when doing a sibling build (done using
+# CMakeLists.txt and cmake/Module/OpmSiblingSearch.cmake).
+Depends: dune-istl (>= 2.9) opm-common dune-grid (>= 2.9) dune-geometry (>= 2.9) opm-grid
+Suggests: dune-uggrid (>= 2.9) dune-fem (>= 2.9) dune-alugrid (>= 2.9) dune-localfunctions (>= 2.9)