Compile error - Make error: *** multiple target patterns. Stop - makefile

Question

I have a problem with a makefile that's part of a repository. I already posted this question but don't know how to add some code lines after, so I'm trying it here.There is a problem with the makefile that has the common make rules. When I run make, I get the following error: C:\Mios32/include/makefile/common.mk:143: *** multiple target patterns. Stop.
Here's the code from common.mk file from line 142 to 144:
# rule to create .elf file
$(PROJECT_OUT)/$(PROJECT).elf: $(ALL_OBJS)
#$(CC) $(CFLAGS) $(ALL_OBJS) $(LIBS) $(LDFLAGS) -o$#
I'm guessing it's a problem with all_objs, cause these lines right before seem to work:
# rule to create a .hex and .bin file
%.bin : $(PROJECT_OUT)/$(PROJECT).elf
#$(OBJCOPY) $< -O binary $#
%.hex : $(PROJECT_OUT)/$(PROJECT).elf
#$(OBJCOPY) $< -O ihex $#
# rule to create a listing file from .elf
%.lss: $(PROJECT_OUT)/$(PROJECT).elf
#$(OBJDUMP) -w -h -S -C $< > $#
# rule to create a symbol table from .elf
%.sym: $(PROJECT_OUT)/$(PROJECT).elf
#$(NM) -n $< > $#
Here's some additional lines with all_objs:
# list of all objects
ALL_OBJS = $(addprefix $(PROJECT_OUT)/, $(THUMB_OBJS) $(THUMB_CPP_OBJS) $(THUMB_AS_OBJS)
$(ARM_OBJS) $(ARM_CPP_OBJS) $(ARM_AS_OBJS))
# list of all dependency files
ALL_DFILES = $(ALL_OBJS:.o=.d)
And here's some additional lines with Project_out and project:
# where should the output files be located
PROJECT_OUT ?= $(PROJECT)_build
# default linker flags
LDFLAGS += -T $(LD_FILE) -mthumb -u _start -Wl,--gc-section -Xlinker -M -Xlinker -
Map=$(PROJECT_OUT)/$(PROJECT).map -nostartfiles -lstdc++
# default rule
all: dirs cleanhex $(PROJECT).hex $(PROJECT_OUT)/$(PROJECT).bin
$(PROJECT_OUT)/$(PROJECT).lss $(PROJECT_OUT)/$(PROJECT).sym projectinfo
# create the output directories
dirs:
#-if [ ! -e $(PROJECT_OUT) ]; then mkdir $(PROJECT_OUT); fi;
#-$(foreach DIR,$(DIRS), if [ ! -e $(PROJECT_OUT)/$(DIR) ]; \
then mkdir -p $(PROJECT_OUT)/$(DIR); fi; )
I'm pretty new to the whole Make and Makefile topic, so I'm having a hard time figuring out the problem. I appreciate every help.

Answer 1

You should be clear in your question what OS you're working on. It seems from the error message above you're working on Windows. The makefile you're trying to use is very clearly targeted at a UNIX system like GNU/Linux or possibly MacOS.
If you are not familiar with the differences between Windows and UNIX (which are vast and deep) you will definitely have a lot of learning to do before you can even start to get this working.
To use UNIX environments on Windows you need to use something like WSL, or Cygwin, or at least install a MinGW shell environment. When you do that you need to be using UNIX paths, not Windows paths. Windows paths use backslashes (which are escape sequences in UNIX) and drive letters (which have no equivalent in UNIX) and in makefiles in particular the : character is special to make so using paths with drive letters is a problem.
You can debug your makefile by adding $(info ...) functions to show you the value of variables:
# rule to create .elf file
$(info PROJECT_OUT = $(PROJECT_OUT))
$(info PROJECT = $(PROJECT))
$(info ALL_OBJS = $(ALL_OBJS))
$(PROJECT_OUT)/$(PROJECT).elf: $(ALL_OBJS)
#$(CC) $(CFLAGS) $(ALL_OBJS) $(LIBS) $(LDFLAGS) -o$#