variants: Add _default configuration

Add `_default` for provides default `variant.h`
Accordingly, delete the empty variant.h.

Signed-off-by: TOKITA Hiroshi <tokita.hiroshi@gmail.com>

Author: soburi

CMakeLists.txt

@@ -3,12 +3,16 @@
 if (CONFIG_ARDUINO_API)
   string(REPLACE "__" "_" NORMALIZED_BOARD_TARGET "${NORMALIZED_BOARD_TARGET}")
 
-  if (IS_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/variants/${BOARD})
+  message(CHECK_START "Arduino variant dir")
+  if (EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/variants/${BOARD}/variant.h)
+    message(CHECK_PASS "Found: variant/${BOARD}")
     set(variant_dir variants/${BOARD})
-  elseif (IS_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/variants/${NORMALIZED_BOARD_TARGET})
+  elseif (EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/variants/${NORMALIZED_BOARD_TARGET}/variant.h)
+    message(CHECK_PASS "Found: variant/${NORMALIZED_BOARD_TARGET}")
     set(variant_dir variants/${NORMALIZED_BOARD_TARGET})
   else()
-    message(FATAL_ERROR "Variant dir not found: variants/${BOARD}, variants/${NORMALIZED_BOARD_TARGET}")
+    message(CHECK_FAIL "Not found, use variants/_default: variants/${BOARD}, variants/${NORMALIZED_BOARD_TARGET}")
+    set(variant_dir variants/_default)
   endif()
 
   add_subdirectory(cores)

…nts/arduino_mkrzero_samd21g18a/variant.h variants/_default/variant.hvariants/arduino_mkrzero_samd21g18a/variant.h renamed to variants/_default/variant.h variants/arduino_mkrzero_samd21g18a/variant.h renamed to variants/_default/variant.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022 Dhruva Gole
+ * Copyright (c) 2026 TOKITA Hiroshi
  *
  * SPDX-License-Identifier: Apache-2.0
  */