Fed up with pattern rules ( make 3.79.1 on Redhat 8 Linux )

[funtoosh]

Hi

Consider this simple makefile :

SRC = a.c
SRC += b.c

DIROBJ = obj
DIRBIN = bin
PLATFORM = linux

OBJ := $(SRC:.c=.o)
OBJ := $(addprefix $(DIROBJ)/$(PLATFORM)/, $(OBJ))

$(DIROBJ)/$(PLATFORM)/%.o: %.c
       @echo "running via pattern rule"

TARGET  := run

target: $(DIRBIN) $(TARGET)

$(DIROBJ):
        mkdir -p obj/linux

$(DIRBIN):
        mkdir -p bin

$(TARGET): $(DIROBJ) $(OBJ)
        @echo target

-----------------------------
make target
make: *** No rule to make target `obj/linux/a.o', needed by `run'. 
Stop.

man page of makefile is nicely written but somehow doesnt answer why
the above error ?

Thanks