py/mkrules: Add GIT_SUBMODULES_FAIL_IF_EMPTY flag for CMake ports.

projectgus · projectgus · commit 06c0de6c66d5 · 2025-01-14T16:41:26.000+11:00
The way CMake gathers the submodule list, it can quietly be empty
if the previous step fails. This makes it an explicit error.

This work was funded through GitHub Sponsors.

Signed-off-by: Angus Gratton &lt;angus@redyak.com.au&gt;
diff --git a/ports/esp32/Makefile b/ports/esp32/Makefile
@@ -114,4 +114,4 @@ size-files:
 submodules:
 	@GIT_SUBMODULES=$$(IDF_COMPONENT_MANAGER=0 idf.py $(IDFPY_FLAGS) -B $(BUILD)/submodules -D ECHO_SUBMODULES=1 build 2>&1 | \
 	                  grep '^GIT_SUBMODULES=' | cut -d= -f2); \
-	$(MAKE) -f ../../py/mkrules.mk GIT_SUBMODULES="$${GIT_SUBMODULES}" submodules
+	$(MAKE) -f ../../py/mkrules.mk GIT_SUBMODULES="$${GIT_SUBMODULES}" GIT_SUBMODULES_FAIL_IF_EMPTY=1 submodules
diff --git a/ports/rp2/Makefile b/ports/rp2/Makefile
@@ -76,4 +76,4 @@ submodules:
 	$(MAKE) -f ../../py/mkrules.mk GIT_SUBMODULES="lib/pico-sdk" submodules
 	@GIT_SUBMODULES=$$(cmake -B $(BUILD)/submodules -DECHO_SUBMODULES=1 ${CMAKE_ARGS} -S . 2>&1 | \
 	                  grep '^GIT_SUBMODULES=' | cut -d= -f2); \
-	$(MAKE) -f ../../py/mkrules.mk GIT_SUBMODULES="$${GIT_SUBMODULES}" submodules
+	$(MAKE) -f ../../py/mkrules.mk GIT_SUBMODULES="$${GIT_SUBMODULES}" GIT_SUBMODULES_FAIL_IF_EMPTY=1 submodules
diff --git a/py/mkrules.mk b/py/mkrules.mk
@@ -257,6 +257,13 @@ ifneq ($(GIT_SUBMODULES),)
 	# Fallback to standard submodule update if blobless isn't available (earlier than 2.36.0)
 	$(Q)cd $(TOP) && git submodule update --init --filter=blob:none $(GIT_SUBMODULES) || \
 	  git submodule update --init $(GIT_SUBMODULES)
+else
+ifeq ($(GIT_SUBMODULES_FAIL_IF_EMPTY),1)
+	# If you see this error, it may mean the internal step run by the port's build
+	# system to find git submodules has failed. Double-check dependencies are set correctly.
+	$(ECHO) "Internal build error: The submodule list should not be empty."
+	exit 1
+endif
 endif
 .PHONY: submodules
 
