Added support for pkg-config. (#213)

* Added support for pkg-config.

* Update CMakeLists.txt

* Update OpenCL-Headers.pc.in

* Try to add CI for Linux.

* Try to add CI for pkg-config for MacOS.

* Update to same scheme as OpenCL Loader.

* Update CMakeLists.txt

.github/workflows/linux.yml

@@ -199,4 +199,17 @@ jobs:
         else
           $CTEST_EXE --output-on-failure -C Debug   --parallel `nproc`;
           $CTEST_EXE --output-on-failure -C Release --parallel `nproc`;
-        fi;
+        fi;
+
+    - name: Test install
+      shell: bash
+      run: if [[ "${{matrix.GEN}}" == "Unix Makefiles" ]];
+        then
+          $CMAKE_EXE --build $GITHUB_WORKSPACE/build --target install -- -j`nproc`;
+        else
+          $CMAKE_EXE --build $GITHUB_WORKSPACE/build --target install --config Release -- -j`nproc`;
+        fi;
+
+    - name: Test pkg-config
+      shell: bash
+      run: PKG_CONFIG_PATH="$GITHUB_WORKSPACE/install/lib/pkgconfig" pkg-config OpenCL-Headers --cflags | grep -q "\-I$GITHUB_WORKSPACE/install/include"

.github/workflows/macos.yml

@@ -50,4 +50,12 @@ jobs:
       shell: bash
       run: |
         ctest -C Release --output-on-failure --parallel `sysctl -n hw.logicalcpu`
-        ctest -C Debug   --output-on-failure --parallel `sysctl -n hw.logicalcpu`
+        ctest -C Debug   --output-on-failure --parallel `sysctl -n hw.logicalcpu`
+
+    - name: Test install
+      shell: bash
+      run: cmake --build $GITHUB_WORKSPACE/build --target install --config Release
+
+    - name: Test pkg-config
+      shell: bash
+      run: PKG_CONFIG_PATH="$GITHUB_WORKSPACE/install/lib/pkgconfig" pkg-config OpenCL-Headers --cflags | grep -q "\-I$GITHUB_WORKSPACE/install/include"

CMakeLists.txt

@@ -15,6 +15,9 @@ project(OpenCLHeaders
 option(OPENCL_HEADERS_BUILD_TESTING "Enable support for OpenCL C headers testing." OFF)
 option(OPENCL_HEADERS_BUILD_CXX_TESTS "Enable support for OpenCL C headers testing in C++ mode." ON)
 
+set (CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
+include(JoinPaths)
+
 include(GNUInstallDirs)
 
 add_library(Headers INTERFACE)
@@ -93,3 +96,11 @@ endif()
 if((CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME OR OPENCL_HEADERS_BUILD_TESTING) AND BUILD_TESTING)
   add_subdirectory(tests)
 endif()
+
+join_paths(OPENCL_INCLUDEDIR_PC "\${prefix}" "${CMAKE_INSTALL_INCLUDEDIR}")
+
+configure_file(OpenCL-Headers.pc.in OpenCL-Headers.pc @ONLY)
+set(pkg_config_location ${CMAKE_INSTALL_LIBDIR}/pkgconfig)
+install(
+  FILES ${CMAKE_CURRENT_BINARY_DIR}/OpenCL-Headers.pc
+  DESTINATION ${pkg_config_location})

OpenCL-Headers.pc.in

@@ -0,0 +1,7 @@
+prefix=@CMAKE_INSTALL_PREFIX@
+includedir=@OPENCL_INCLUDEDIR_PC@
+
+Name: OpenCL-Headers
+Description: Khronos OpenCL Headers
+Version: 3.0
+Cflags: -I${includedir}

cmake/JoinPaths.cmake

@@ -0,0 +1,26 @@
+# This module provides function for joining paths
+# known from from most languages
+#
+# Original license:
+# SPDX-License-Identifier: (MIT OR CC0-1.0)
+# Explicit permission given to distribute this module under
+# the terms of the project as described in /LICENSE.rst.
+# Copyright 2020 Jan Tojnar
+# https://github.com/jtojnar/cmake-snips
+#
+# Modelled after Python’s os.path.join
+# https://docs.python.org/3.7/library/os.path.html#os.path.join
+# Windows not supported
+function(join_paths joined_path first_path_segment)
+    set(temp_path "${first_path_segment}")
+    foreach(current_segment IN LISTS ARGN)
+        if(NOT ("${current_segment}" STREQUAL ""))
+            if(IS_ABSOLUTE "${current_segment}")
+                set(temp_path "${current_segment}")
+            else()
+                set(temp_path "${temp_path}/${current_segment}")
+            endif()
+        endif()
+    endforeach()
+    set(${joined_path} "${temp_path}" PARENT_SCOPE)
+endfunction()