FindVulkan fixes. Bump CMake minimum version. (#1101)

* Bump cmake minimum version. Support pre-3.28 in FindVulkan.

Fixes #1100.

* Fix use of undefined variable and errant brace.

* Set CMAKE_FIND_FRAMEWORK for correct operation.

* Fix incorrect variable name and formatting.

Only set CMAKE_FIND_FRAMEWORK when not previously defined.

* Delete unnecessary unset.

CMAKE_FIND_FRAMEWORK is not set if _Vulkan_saved_cmake_find_framework
is unset.

* Revert CMake version bumps.

Instead:
* Add fatal error in app/CMakeLists.txt when IOS and version < 3.20.
* Change version <3.28 workaround in FindVulkan to work with CMake versions
  back to 3.16 and earlier.

Author: MarkCallow

app/CMakeLists.txt

@@ -21,6 +21,10 @@ include(android_package)
 # create sample app project
 project(vulkan_samples LANGUAGES C CXX)
 
+if(IOS AND CMAKE_VERSION VERSION_LESS 3.20)
+    message(FATAL_ERROR "Configuring iOS apps requires a minimum CMake version of 3.20")
+endif()
+
 add_subdirectory(plugins)
 add_subdirectory(apps)
 
@@ -169,4 +173,4 @@ if(IOS)
             XCODE_ATTRIBUTE_DEAD_CODE_STRIPPING NO
             XCODE_SCHEME_ARGUMENTS "sample hello_triangle"
     )
-endif ()
+endif ()

bldsys/cmake/module/FindVulkan.cmake

@@ -233,6 +233,17 @@ if("FATAL_ERROR" IN_LIST Vulkan_FIND_COMPONENTS)
     list(REMOVE_ITEM Vulkan_FIND_COMPONENTS "FATAL_ERROR")
 endif()
 
+# FindVulkan only works correctly with the default CMAKE_FIND_FRAMEWORK
+# value: FIRST. If LAST it will find the macOS dylibs instead of the iOS
+# frameworks when IOS is true. If ALWAYS it will fail to find the macOS
+# dylibs. If NEVER it will fail to find the iOS frameworks. If frameworks
+# are ever included in the SDK for macOS, the search mechanism will need
+# revisiting.
+if(DEFINED CMAKE_FIND_FRAMEWORK)
+    set(_Vulkan_saved_cmake_find_framework ${CMAKE_FIND_FRAMEWORK})
+    set(CMAKE_FIND_FRAMEWORK FIRST)
+endif()
+
 if(IOS)
     get_filename_component(Vulkan_Target_SDK "$ENV{VULKAN_SDK}/.." REALPATH)
     list(APPEND CMAKE_FRAMEWORK_PATH "${Vulkan_Target_SDK}/iOS/lib")
@@ -287,7 +298,7 @@ else()
             "$ENV{VULKAN_SDK}/lib"
     )
 endif()
-if(APPLE AND DEFINED ENV{VULKAN_SDK})
+if(APPLE AND DEFINED Vulkan_Target_SDK)
     list(APPEND _Vulkan_hint_include_search_paths
             "${Vulkan_Target_SDK}/macOS/include"
     )
@@ -301,7 +312,7 @@ if(APPLE AND DEFINED ENV{VULKAN_SDK})
         )
     else()
         list(APPEND _Vulkan_hint_library_search_paths
-                "${Vulkan_Target_SDK}}/lib"
+                "${Vulkan_Target_SDK}/lib"
         )
     endif()
 endif()
@@ -318,7 +329,7 @@ find_library(Vulkan_LIBRARY
         HINTS
         ${_Vulkan_hint_library_search_paths}
 )
-message(STATUS vulkan_library ${Vulkan_LIBRARY} search paths ${_Vulkan_hint_library_search_paths})
+message(STATUS "vulkan_library ${Vulkan_LIBRARY} search paths ${_Vulkan_hint_library_search_paths}")
 mark_as_advanced(Vulkan_LIBRARY)
 
 find_library(Vulkan_Layer_API_DUMP
@@ -522,6 +533,11 @@ if (dxc IN_LIST Vulkan_FIND_COMPONENTS)
     mark_as_advanced(Vulkan_dxc_EXECUTABLE)
 endif()
 
+if(DEFINED _Vulkan_saved_cmake_find_framework)
+    set(CMAKE_FIND_FRAMEWORK ${_Vulkan_saved_cmake_find_framework})
+    unset(_Vulkan_saved_cmake_find_framework)
+endif()
+
 if(Vulkan_GLSLC_EXECUTABLE)
     set(Vulkan_glslc_FOUND TRUE)
 else()
@@ -652,9 +668,18 @@ find_package_handle_standard_args(Vulkan
 
 if(Vulkan_FOUND AND NOT TARGET Vulkan::Vulkan)
     add_library(Vulkan::Vulkan UNKNOWN IMPORTED)
+    get_filename_component(_Vulkan_lib_extension ${Vulkan_LIBRARIES} LAST_EXT)
+    if(_Vulkan_lib_extension STREQUAL ".framework" AND CMAKE_VERSION VERSION_LESS 3.28)
+        set_target_properties(Vulkan::Vulkan PROPERTIES
+                # Prior to 3.28 must reference library just inside the framework.
+                IMPORTED_LOCATION "${Vulkan_LIBRARIES}/vulkan")
+    else()
+        set_target_properties(Vulkan::Vulkan PROPERTIES
+                IMPORTED_LOCATION "${Vulkan_LIBRARIES}")
+    endif()
     set_target_properties(Vulkan::Vulkan PROPERTIES
-            IMPORTED_LOCATION "${Vulkan_LIBRARIES}"
             INTERFACE_INCLUDE_DIRECTORIES "${Vulkan_INCLUDE_DIRS}")
+    unset(_Vulkan_lib_extension)
 endif()
 
 if(Vulkan_FOUND AND NOT TARGET Vulkan::Headers)
@@ -934,4 +959,4 @@ unset(_Vulkan_hint_include_search_paths)
 unset(_Vulkan_hint_executable_search_paths)
 unset(_Vulkan_hint_library_search_paths)
 
-cmake_policy(POP)
+cmake_policy(POP)