Fix autodetection of workarounds for GCC 12.x 13.x and 14.x under Windows

.github/workflows/githubci.yml

@@ -17,7 +17,7 @@ jobs:
       matrix: ${{ steps.set-matrix.outputs.matrix }}
     steps:
       - name: Checkout Code
-        uses: actions/checkout@v7
+        uses: actions/checkout@v6
 
       - name: Set matrix
         id: set-matrix
@@ -36,7 +36,7 @@ jobs:
         board: ${{ fromJSON(needs.set-matrix.outputs.matrix) }}
     steps:
     - name: Checkout Code
-      uses: actions/checkout@v7
+      uses: actions/checkout@v6
       with:
         fetch-depth: 0
         submodules: true
@@ -55,7 +55,7 @@ jobs:
         make BOARD=${{ matrix.board }} all
         make BOARD=${{ matrix.board }} copy-artifact
 
-    - uses: actions/upload-artifact@v7
+    - uses: actions/upload-artifact@v6
       with:
         name: ${{ matrix.board }}
         path: _bin/${{ matrix.board }}
@@ -67,7 +67,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Collect all board artifacts
-      uses: actions/download-artifact@v8
+      uses: actions/download-artifact@v6
       with:
         path: _bin
         merge-multiple: true
@@ -85,4 +85,4 @@ jobs:
         files: |
           _bin/*_bootloader-*.zip
           _bin/*_bootloader-*.hex
-          _bin/update-*_bootloader-*.uf2
+          _bin/update-*_bootloader-*.uf2

Makefile

@@ -33,6 +33,15 @@ SD_HEX       = $(SD_PATH)/$(SD_FILENAME)_softdevice.hex
 
 MBR_HEX			 = lib/softdevice/mbr/hex/mbr_nrf52_2.4.1_mbr.hex
 
+# Detect the operating system
+# The "OS" environment variable on Windows is always "Windows_NT"
+# when running under a modern shell like cmd.exe or powershell
+ifeq ($(OS),Windows_NT)
+	NULL_DEVICE = NUL
+else
+	NULL_DEVICE = /dev/null
+endif
+
 # linker by MCU eg. nrf52840.ld
 ifeq ($(DEBUG), 1)
   LD_FILE = linker/$(MCU_SUB_VARIANT)_debug.ld
@@ -337,7 +346,7 @@ CFLAGS += -DDFU_APP_DATA_RESERVED=$(DFU_APP_DATA_RESERVED)
 
 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105523
 # Fixes for gcc version 12, 13 and 14.
-ifneq (,$(filter 12.% 13.% 14.%,$(shell $(CC) -dumpversion 2>/dev/null)))
+ifneq (,$(filter 12.% 13.% 14.%,$(shell $(CC) -dumpversion 2>$(NULL_DEVICE))))
 	CFLAGS += --param=min-pagesize=0
 endif