py/mkrules.mk: Regenerate all qstrs when config files change.

A port can define QSTR_GLOBAL_DEPENDENCIES to add extra files.

py/mkrules.mk

@@ -66,9 +66,13 @@ $(BUILD)/%.pp: %.c
 # to get built before we try to compile any of them.
 $(OBJ): | $(HEADER_BUILD)/qstrdefs.generated.h $(HEADER_BUILD)/mpversion.h
 
-$(HEADER_BUILD)/qstr.i.last: $(SRC_QSTR) | $(HEADER_BUILD)/mpversion.h
+# The logic for qstr regeneration is:
+# - if anything in QSTR_GLOBAL_DEPENDENCIES is newer, then process all source files ($^)
+# - else, if list of newer prerequisites ($?) is not empty, then process just these ($?)
+# - else, process all source files ($^) [this covers "make -B" which can set $? to empty]
+$(HEADER_BUILD)/qstr.i.last: $(SRC_QSTR) $(QSTR_GLOBAL_DEPENDENCIES) | $(HEADER_BUILD)/mpversion.h
 	$(ECHO) "GEN $@"
-	$(Q)$(CPP) $(QSTR_GEN_EXTRA_CFLAGS) $(CFLAGS) $(if $?,$?,$^) >$(HEADER_BUILD)/qstr.i.last;
+	$(Q)$(CPP) $(QSTR_GEN_EXTRA_CFLAGS) $(CFLAGS) $(if $(filter $?,$(QSTR_GLOBAL_DEPENDENCIES)),$^,$(if $?,$?,$^)) >$(HEADER_BUILD)/qstr.i.last;
 
 $(HEADER_BUILD)/qstr.split: $(HEADER_BUILD)/qstr.i.last
 	$(ECHO) "GEN $@"

py/py.mk

@@ -13,6 +13,9 @@ ifneq ($(QSTR_AUTOGEN_DISABLE),1)
 QSTR_DEFS_COLLECTED = $(HEADER_BUILD)/qstrdefs.collected.h
 endif
 
+# Any files listed by this variable will cause a full regeneration of qstrs
+QSTR_GLOBAL_DEPENDENCIES += $(PY_SRC)/mpconfig.h mpconfigport.h
+
 # some code is performance bottleneck and compiled with other optimization options
 CSUPEROPT = -O3