cc: error: this_example.o: No such file or directory-CodePudding

I've a SDK with some examples, but when I want to compile any of these examples, I receive this error:

cc -g -I -o this_example.o -c this_example.c
cc: error: this_example.o: No such file or directory
make: *** [Makefile:15: this_example.o] Error 1

Here is the makefile:

CC ?= gcc
INC_PATH ?= $(realpath ../inc)
LIB_PATH ?= $(realpath ../lib)
LIBS ?= $(wildcard $(LIB_PATH)/*.a) -pthread -lrt -lm
LDFLAGS :=-g -L$(LIB_PATH)
CFLAGS  =-g -I$(INC_PATH)

EXAMPLES=sdk_this_example_folder

.PHONY: all

all: $(EXAMPLES)

%.o: %.c
    $(CC) $(CFLAGS) -o $@ -c $<

this_example: this_example.o  frozen.o
    $(CC) $(CFLAGS) $(LDFLAGS) -o $@ $^ $(LIBS) -Wl,-rpath,'$$ORIGIN/../../lib'

clean:
    rm -f *~ *.o $(EXAMPLES)

In this_example_folder, I've four files: Makefile, this_example.c and frozen.c and frozen.h. Where is the problem? Thank you everybody for your help!

CodePudding user response：

The realpath function returns the empty string if the path you are expanding doesn't exist.

You have:

INC_PATH ?= $(realpath ../inc)

then:

CFLAGS  =-g -I$(INC_PATH)

and your command output is:

cc -g -I -o this_example.o -c this_example.c

Clearly, the value of INC_PATH is empty (since there's nothing after the -I in the command line) which means the directory ../inc does not exist.

As for why you get that failure: the -I option expects a filename afterwards. Since you don't have one, it uses -o (the next word in the command line) as the filename. That means that this_example.o is treated as a file to compile, rather than the output file, and of course it doesn't exist.