[esp32] Fix idedata generation failing on unset ESPHOME_ARDUINO (#16925)

esphome/components/esp32/pre_build.py.script

@@ -1,3 +1,5 @@
+import os
+
 Import("env")  # noqa: F821
 
 # Remove custom_sdkconfig from the board config as it causes
@@ -7,3 +9,8 @@ if "espidf.custom_sdkconfig" in board:
     del board._manifest["espidf"]["custom_sdkconfig"]
     if not board._manifest["espidf"]:
         del board._manifest["espidf"]
+
+# Referenced by rules in esphome/idf_component.yml; an unset env var is a
+# fatal error there. Always 0: in PlatformIO builds arduino is not a managed
+# IDF component.
+os.environ.setdefault("ESPHOME_ARDUINO_COMPONENT", "0")

esphome/espidf/clang_tidy.py

@@ -162,7 +162,7 @@ def _setup_core(work_dir: Path, settings: _Settings) -> None:
 
     # Gates arduino-only components in esphome/idf_component.yml (IDF reads it at
     # reconfigure time). Set here -- before the manifest is written/reconfigured.
-    os.environ["ESPHOME_ARDUINO"] = (
+    os.environ["ESPHOME_ARDUINO_COMPONENT"] = (
         "1" if settings.target_framework == "arduino" else "0"
     )
 

esphome/idf_component.yml

@@ -109,4 +109,4 @@ dependencies:
     git: https://github.com/FastLED/FastLED.git
     version: d44c800a9e876a8394caefc2ce4915dd96dac77b
     rules:
-      - if: "$ESPHOME_ARDUINO == 1"
+      - if: "$ESPHOME_ARDUINO_COMPONENT == 1"