cmake: introduce gnu and llvm detection when Zephyr toolchain is unset.

cmake/Zephyr-sdkConfig.cmake

@@ -11,8 +11,28 @@ set(SDK_MAJOR_MINOR_MICRO ${SDK_VERSION})
 
 get_filename_component(ZEPHYR_SDK_INSTALL_DIR ${CMAKE_CURRENT_LIST_DIR}/.. ABSOLUTE)
 set(ZEPHYR_SDK_INSTALL_DIR ${ZEPHYR_SDK_INSTALL_DIR})
-set(ZEPHYR_TOOLCHAIN_VARIANT zephyr)
+
+if(ZEPHYR_TOOLCHAIN_VARIANT STREQUAL "zephyr")
+  set(ZEPHYR_TOOLCHAIN_VARIANT "zephyr-gnu")
+endif()
+
+if(NOT DEFINED ZEPHYR_TOOLCHAIN_VARIANT)
+  file(GLOB use_gnu "${ZEPHYR_SDK_INSTALL_DIR}/gnu/*/bin/*zephyr-*-gcc")
+  if(use_gnu)
+    set(ZEPHYR_TOOLCHAIN_VARIANT zephyr-gnu)
+  elseif(EXISTS "${ZEPHYR_SDK_INSTALL_DIR}/llvm/bin/clang")
+    set(ZEPHYR_TOOLCHAIN_VARIANT zephyr-llvm)
+  else()
+    # We are in a Zephyr-sdk but gnu nor llvm was properly detected.
+    # Warn the user and set toolchain to zephyr-gnu.
+    message(WARNING
+      "Zephyr SDK found in ${ZEPHYR_SDK_INSTALL_DIR} but gcc nor clang was properly detected.\n"
+      "Please check you Zephyr SDK installation. Defaulting to 'zephyr-gnu'"
+    )
+    set(ZEPHYR_TOOLCHAIN_VARIANT zephyr-gnu)
+  endif()
+endif()
 
 # Those are CMake package parameters.
 set(Zephyr-sdk_FOUND True)
-set(Zephyr-sdk_DIR   ${ZEPHYR_SDK_INSTALL_DIR})
+set(Zephyr-sdk_dir   ${ZEPHYR_SDK_INSTALL_DIR})

cmake/Zephyr-sdkConfigVersion.cmake

@@ -11,21 +11,27 @@ string(STRIP ${SDK_VERSION} PACKAGE_VERSION)
 if(PACKAGE_VERSION VERSION_LESS PACKAGE_FIND_VERSION)
   set(PACKAGE_VERSION_COMPATIBLE FALSE)
 else()
-  # Currently, this Zephyr SDK is expected to work with any Zephyr project
-  # requiring this version or any older version.
-  #
-  # In case this version of Zephyr SDK is no longer backwards compatible with
-  # previous versions of Zephyr SDK, this is the place to test if the caller
-  # requested an older (incompatible) revision.
-  # For example, imagine caller requests Zephyr SDK v0.10, and this Zephyr SDK
-  # is revision v0.11, then the below snippet can be activated to ensure that
-  # this Zephyr SDK (v0.11) is marked as not compatible if caller requested an
-  # older version, like v0.10
-  # set(ZEPHYR_SDK_MINIMUM_COMPATIBLE_VERSION 0.11)
-  # if(PACKAGE_FIND_VERSION VERSION_LESS ZEPHYR_SDK_MINIMUM_COMPATIBLE_VERSION)
-  #   set(PACKAGE_VERSION_COMPATIBLE FALSE)
-  #   return()
-  # endif()
+  # This Zephyr SDK will not work with Zephyr projects requiring Zephyr SDK <0.18.x
+  set(ZEPHYR_SDK_MINIMUM_COMPATIBLE_VERSION 0.18)
+  if(PACKAGE_FIND_VERSION VERSION_LESS ZEPHYR_SDK_MINIMUM_COMPATIBLE_VERSION)
+    set(PACKAGE_VERSION_COMPATIBLE FALSE)
+    return()
+  endif()
+
+  # Basic validation if user requests 'zephyr-gnu' ('zephyr') or 'zephyr-llvm'.
+  # We must ensure gcc is available, likewise with clang.
+  if(ZEPHYR_TOOLCHAIN_VARIANT STREQUAL "zephyr-gnu" OR ZEPHYR_TOOLCHAIN_VARIANT STREQUAL "zephyr")
+    file(GLOB has_gnu "${CMAKE_CURRENT_LIST_DIR}/../gnu/*/bin/*zephyr-*-gcc")
+    if(NOT has_gnu)
+      set(PACKAGE_VERSION_COMPATIBLE FALSE)
+      return()
+    endif()
+  elseif(ZEPHYR_TOOLCHAIN_VARIANT STREQUAL "zephyr-llvm")
+    if(NOT EXISTS "${CMAKE_CURRENT_LIST_DIR}/../llvm/bin/clang")
+      set(PACKAGE_VERSION_COMPATIBLE FALSE)
+      return()
+    endif()
+  endif()
 
   set(PACKAGE_VERSION_COMPATIBLE TRUE)
   if(PACKAGE_FIND_VERSION STREQUAL PACKAGE_VERSION)