From 5f6978d603005d04480b45a142cdd4f61c4b92f8 Mon Sep 17 00:00:00 2001
From: Debian Science Maintainers
 <debian-science-maintainers@lists.alioth.debian.org>
Date: Fri, 22 Nov 2024 15:28:16 +0100
Subject: [PATCH] Install cmake config of header-only module in /usr/lib/cmake

Needed to make it work in multiarch settings.
Author: Markus Blatt
Gbp-Pq: Name install-cmake-config-to-lib-headerless
---
 cmake/modules/DuneAddLibrary.cmake |  3 ++-
 cmake/modules/DuneProject.cmake    | 12 ++++++++++--
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/cmake/modules/DuneAddLibrary.cmake b/cmake/modules/DuneAddLibrary.cmake
index 9342c62..744066b 100644
--- a/cmake/modules/DuneAddLibrary.cmake
+++ b/cmake/modules/DuneAddLibrary.cmake
@@ -135,7 +135,6 @@ Add a library to a Dune module.
 #]=======================================================================]
 include_guard(GLOBAL)
 
-
 # Public interface for creating a module library
 function(dune_add_library _name)
   cmake_parse_arguments(ARG "OBJECT;INTERFACE" "" "" ${ARGN})
@@ -210,6 +209,8 @@ function(dune_add_library_normal _name)
       set(ARG_NAMESPACE Dune::)
     endif()
 
+    set_property(GLOBAL PROPERTY ${PROJECT_NAME}_HAS_LIB ON)
+
     set(alias ${ARG_NAMESPACE}${ARG_EXPORT_NAME})
     if(NOT TARGET ${alias})
       add_library(${alias} ALIAS ${_name})
diff --git a/cmake/modules/DuneProject.cmake b/cmake/modules/DuneProject.cmake
index 635dc4c..63d870a 100644
--- a/cmake/modules/DuneProject.cmake
+++ b/cmake/modules/DuneProject.cmake
@@ -343,7 +343,15 @@ endif()")
   if(DEFINED DUNE_INSTALL_LIBDIR)
     message(DEPRECATION "DUNE_INSTALL_LIBDIR is deprecated, use CMAKE_INSTALL_LIBDIR instead")
   else()
-    set(DUNE_INSTALL_LIBDIR ${CMAKE_INSTALL_LIBDIR})
+    # Determine whether this module is header-only
+    # In the case the property is not defined
+    get_property(_has_lib GLOBAL PROPERTY ${PROJECT_NAME}_HAS_LIB SET)
+
+    if(_has_lib)
+      set(DUNE_INSTALL_LIBDIR ${CMAKE_INSTALL_LIBDIR})
+    else()
+      set(DUNE_INSTALL_LIBDIR ${DUNE_INSTALL_NONOBJECTLIBDIR})
+    endif()
   endif()
 
   # Set the location of the doc file source. Needed by custom package configuration
@@ -446,7 +454,7 @@ get_filename_component(_dir \"\${CMAKE_CURRENT_LIST_FILE}\" PATH)
 
     # install library export set
     install(EXPORT ${_export_set}
-      DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/${ProjectName}
+      DESTINATION ${DUNE_INSTALL_LIBDIR}/cmake/${ProjectName}
       NAMESPACE ${_namespace}
       FILE ${_target_file})
 
-- 
2.30.2