tree f468c3b8ab7127cd4e5c1d682f7df768258a3db0
parent 79e03670c2a328bea3c1a3f80ea913f296a487e6
author David 'Digit' Turner <digit+github@google.com> 1574185946 +0100
committer Lenny Komow <lenny@lunarg.com> 1574354662 -0700

build: Fix Vulkan headers detection with CMake.

The logic used to find the location of the Vulkan headers and
registry used simple find_path() calls with HINTS. Unfortunately,
this doesn't work when using a custom toolchain file that sets
CMAKE_FIND_ROOT_PATH_INCLUDE to ONLY, which can happen when
cross-compiling with a custom sysroot.

This patch changes the logic so that:

  - If VULKAN_HEADERS_INSTALL_DIR is specified on the command-line,
    or if it is set in the environment, or if VULKAN_SDK is set in
    the environment, the corresponding paths will be searched for
    the Vulkan headers and register, ignoring the
    CMAKE_FIND_ROOT_PATH. This does not affect other parts of the
    build.

  - Otherwise, use a regular find_path() call which may be restricted
    to the CMAKE_FIND_ROOT_PATH depending on previous configuration
    settings.

This should be equivalent to the previous behaviour, except when
CMAKE_FIND_ROOT_PATH_INCLUDE is set to ONLY.