fix c6 build again

Author: jonasniesner

platformio.ini

@@ -181,21 +181,17 @@ monitor_speed = 115200
 [env:esp32-c6-N4]
 platform = https://github.com/pioarduino/platform-espressif32/releases/download/stable/platform-espressif32.zip
 framework = arduino
+; C6 + NimBLE: pull r_os_mem* from libble_app (see script header).
+extra_scripts =
+  pre:scripts/factory_config_gen.py
+  pre:scripts/esp32c6_nimble_mempool_link.py
 build_flags =
   -DTARGET_ESP32
   #-DOPENDISPLAY_ZLIB_WINDOW_BITS=15
   -DOPENDISPLAY_ZLIB_USE_HEAP_WINDOW=1
   -DARDUINO_USB_MODE=1
   -DARDUINO_USB_CDC_ON_BOOT=1
   -DCONFIG_FREERTOS_WATCHDOG_TIMEOUT_S=120
-  ; C6 sdkconfig sets CONFIG_BT_LE_CONTROLLER_NPL_OS_PORTING_SUPPORT, so
-  ; NimBLE-Arduino skips compiling os_mempool and expects r_os_mem* from
-  ; libble_app. Force-pull those objects — a single-pass link on GitHub
-  ; Actions otherwise leaves the refs undefined.
-  -lble_app
-  -Wl,-u,r_os_mempool_init
-  -Wl,-u,r_os_memblock_get
-  -Wl,-u,r_os_memblock_put
 board_build.filesystem = littlefs
 board_build.partitions = huge_app.csv
 board = esp32-c6-devkitm-1

scripts/esp32c6_nimble_mempool_link.py

@@ -0,0 +1,31 @@
+"""Force-link libble_app os_mempool for ESP32-C6 + NimBLE-Arduino.
+
+C6 sdkconfig sets CONFIG_BT_LE_CONTROLLER_NPL_OS_PORTING_SUPPORT, so
+NimBLE-Arduino skips compiling os_mempool and calls r_os_mem* instead.
+Those live in libble_app.a(os_mempool.c.o).
+
+On Ubuntu (GitHub Actions), gcc uses --as-needed: an early -lble_app with
+no pending undefs is dropped, and a later single-pass never pulls
+os_mempool.c.o. Fix:
+  1) Prepend -u so the undefs exist before any archive scan
+  2) Append libble_app.a by absolute path after all objects/libs
+"""
+
+from pathlib import Path
+
+Import("env")  # noqa: F821
+
+env.Prepend(
+    LINKFLAGS=[
+        "-Wl,-u,r_os_mempool_init",
+        "-Wl,-u,r_os_memblock_get",
+        "-Wl,-u,r_os_memblock_put",
+    ]
+)
+
+libs_dir = env.PioPlatform().get_package_dir("framework-arduinoespressif32-libs")
+ble_app = Path(libs_dir) / "esp32c6" / "lib" / "libble_app.a"
+if ble_app.is_file():
+    env.Append(LINKFLAGS=[str(ble_app)])
+else:
+    env.Append(LIBS=["ble_app"])