No rule to make target in GCC Makefile - c

Question

This is the following Makefile at issue:
#
# Compiler flags
#
CC = gcc
CFLAGS = -Wall -Werror -Wextra
#
# Project files
# example -
# SRCS = hash_table.c linked_list.c utils.c common.c business_logic.c user_interface.c
# SRCS = test/gc_test.c src/gc.c
SRCS := $(shell find . -name "*")
OBJS = $(SRCS:.c=.o)
EXE = output.out
FILENAMES := $(shell find . -type f -name "*.c" -printf "%f\n")
FILENAMES_OUT = $(FILENAMES:.c=.o)
#
# Default build settings
#
BUILDDIR = build
BUILDCFLAGS = -g -O0
BUILDEXE = $(BUILDDIR)/$(EXE)
BUILDOBJS = $(addprefix $(BUILDDIR)/, $(FILENAMES_OUT))
# Rules for default build
all: clean build
build: $(BUILDEXE)
$(BUILDEXE): $(BUILDOBJS)
$(CC) $(CFLAGS) $(BUILDCFLAGS) -o $(BUILDEXE) $^ -lcunit
$(BUILDDIR)/%.o: %.c
$(CC) $(CFLAGS) $(BUILDCFLAGS) -c $< -o $#
memtest: $(BUILDEXE)
valgrind --leak-check=full ./$<
#
# Other rules
#
clean:
mkdir -p $(BUILDDIR)
PROBLEM -> make: *** No rule to make target `build/gc_test.o', needed by `build/output.out'. Stop.
PROJECT TREE
.
├── build
├── doc
│   └── design.md
├── Makefile
├── proj
│   ├── code_quality_report.md
│   ├── deviations.md
│   ├── individual_reflection.md
│   ├── team_reflection.md
│   └── test_report.md
├── README.md
├── src
│   ├── gc.c
│   └── headers
│   └── gc.h
└── tests
└── gc_test.c
The issue itself happens in $(BUILDEXE): $(BUILDOBJS) where the dependencies are gc_test.c gc.c. Those dependencies SHOULD get caught in the function below it, because it's input is all the .c files in the build directory. Those files SHOULD get properly matched and then compiled to .o files which then should climb up the tree and produce an executable. I'm confused because $(BUILDOBJS) should be the same as $(BUILDDIR)/%.o.
I'm new to making Makefiles, but I want to get better at it. Please point out better naming conventions or terminology that could have been used better for this post. Thanks!

Answer 1

The problem is here:
FILENAMES := $(shell find . -type f -name "*.c" -printf "%f\n")
This is wrong because -printf "%f\n" prints only the filenames, without any path. You're losing all information about the path where files are found, so how can make find them?
You should change this to simply -print then it will work.