build system: add pkg-config support (#674)

CMakeLists.txt

@@ -96,6 +96,12 @@ endif()
 
 target_compile_features(EnTT INTERFACE cxx_std_17)
 
+#
+# Set pkg-config variables
+#
+set(EnTT_PKGCONFIG ${PROJECT_BINARY_DIR}/entt.pc)
+set(EnTT_PKGCONFIG_DESTDIR ${CMAKE_INSTALL_LIBDIR}/pkgconfig)
+
 #
 # Install EnTT
 #
@@ -114,6 +120,12 @@ write_basic_package_version_file(
     COMPATIBILITY AnyNewerVersion
 )
 
+configure_file(
+  "${EnTT_SOURCE_DIR}/cmake/in/entt.pc.in"
+  "${EnTT_PKGCONFIG}"
+  @ONLY
+)
+
 configure_package_config_file(
     ${EnTT_SOURCE_DIR}/cmake/in/EnTTConfig.cmake.in
     EnTTConfig.cmake
@@ -142,6 +154,8 @@ install(
 
 install(DIRECTORY src/ DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
 
+install(FILES "${EnTT_PKGCONFIG}" DESTINATION "${EnTT_PKGCONFIG_DESTDIR}")
+
 export(PACKAGE EnTT)
 
 #

cmake/in/entt.pc.in

@@ -0,0 +1,8 @@
+prefix=@CMAKE_INSTALL_PREFIX@
+includedir=${prefix}/@CMAKE_INSTALL_INCLUDEDIR@
+
+Name: EnTT
+Description: Fast and reliable entity component system (ECS)
+Url: https://github.com/skypjack/entt
+Version: @EnTT_VERSION@
+Cflags: -I${includedir}