[libretiny] Build LN882x with 1-byte enums to match the SDK's WiFi library (#20173)

esphome/components/libretiny/__init__.py

@@ -526,6 +526,10 @@ async def component_to_code(config):
     # RAM-executable output section and prints a post-link placement summary.
     if FAMILY_COMPONENT[config[CONF_FAMILY]] != COMPONENT_BK72XX:
         cg.add_platformio_option("extra_scripts", ["pre:patch_linker.py"])
+    # Match the 1-byte enums of the LN882H SDK's prebuilt WiFi library.
+    if FAMILY_COMPONENT[config[CONF_FAMILY]] == COMPONENT_LN882X:
+        cg.add_build_unflag("-fno-short-enums")
+        cg.add_build_flag("-fshort-enums")
     # dummy version code
     cg.add_define("USE_ARDUINO_VERSION_CODE", cg.RawExpression("VERSION_CODE(0, 0, 0)"))
     # decrease web server stack size (16k words -> 4k words)

esphome/components/libretiny/hal.cpp

@@ -12,6 +12,12 @@
 // libretiny component's API.
 namespace esphome::libretiny {}  // namespace esphome::libretiny
 
+#if defined(USE_LN882X) && !defined(CLANG_TIDY)  // clang-tidy runs without the PlatformIO flags
+// Fail the build if the -fshort-enums swap in __init__.py stops working.
+enum Ln882xEnumSizeCheck { LN882X_ENUM_SIZE_CHECK };
+static_assert(sizeof(Ln882xEnumSizeCheck) == 1, "LN882x must build with -fshort-enums to match the SDK");
+#endif
+
 namespace esphome {
 
 // yield(), delay(), micros(), millis(), millis_64(), delayMicroseconds(),

tests/component_tests/libretiny/config/bk72xx.yaml

@@ -0,0 +1,5 @@
+esphome:
+  name: test
+
+bk72xx:
+  board: generic-bk7231n-qfn32-tuya

tests/component_tests/libretiny/config/ln882x.yaml

@@ -0,0 +1,5 @@
+esphome:
+  name: test
+
+ln882x:
+  board: generic-ln882h

tests/component_tests/libretiny/test_short_enums.py

@@ -0,0 +1,27 @@
+"""LN882x builds with 1-byte enums to match the SDK's prebuilt libraries;
+the other LibreTiny families keep LibreTiny's own enum size."""
+
+from __future__ import annotations
+
+from collections.abc import Callable
+from pathlib import Path
+
+from esphome.core import CORE
+
+
+def test_ln882x_swaps_in_short_enums(
+    generate_main: Callable[[str | Path], str],
+    component_config_path: Callable[[str], Path],
+) -> None:
+    generate_main(component_config_path("ln882x.yaml"))
+    assert "-fno-short-enums" in CORE.build_unflags
+    assert "-fshort-enums" in CORE.build_flags
+
+
+def test_bk72xx_keeps_libretiny_enums(
+    generate_main: Callable[[str | Path], str],
+    component_config_path: Callable[[str], Path],
+) -> None:
+    generate_main(component_config_path("bk72xx.yaml"))
+    assert "-fno-short-enums" not in CORE.build_unflags
+    assert "-fshort-enums" not in CORE.build_flags