Defining custom GNU make functions

Question

What is the problem with the dep2 function in the sample code below?

dep1 = $(eval makefile_list_$1 := $(MAKEFILE_LIST))$(eval -include $1.mk)$(eval MAKEFILE_LIST := $(makefile_list_$1))

define dep2
$(eval makefile_list_$1 := $(MAKEFILE_LIST))
$(eval -include $1.mk)
$(eval MAKEFILE_LIST := $(makefile_list_$1))
endef

$(call dep1,test)
$(call dep2,test)

.DEFAULT_TARGET: all
.PHONY: all
all:
    @echo $@

GNU make 3.81 and 3.82 produce Makefile:10: *** missing separator. Stop. which points to the dep2 call, dep1 is run without errors. The only difference between the two variants is the newlines in dep2 (and the whole point why I'd like to use define).

Answer 1

You forgot the =:
define dep2 =

EDIT:
Put a semicolon at the end of each line. I've tested this and it works (in GNUMake 3.81).

define dep2
$(eval makefile_list_$1 := $(MAKEFILE_LIST));
$(eval -include $1.mk);
$(eval MAKEFILE_LIST := $(makefile_list_$1));
endef

Why these semicolons are necessary I don't know, but in the documentation define seems to be used for multi-line "variables" only when defining sequences of shell commands to be used in recipes, not Make commands, so maybe the rules are a little different.