Get filename from $@ in Makefile

Question

this makefile works great when all the cpp files are in one directory. upon creating subdirectories it fails to create the *.o files because its missing subdirectories:

Directory Structure

.
├── Makefile
├── README.md
├── src
│   ├── Adventurer
│   │   └── Adventurer.cpp
│   ├── Board
│   │   ├── AdventureTile.cpp
│   │   └── Board.cpp

Makefile

CC := g++ # This is the main compiler
SRCDIR := src
BUILDDIR := build
TARGET := bin/forbidden-island
 
SRCEXT := cpp
SOURCES := $(shell find $(SRCDIR) -type f -name *.$(SRCEXT))
OBJECTS := $(patsubst $(SRCDIR)/%,$(BUILDDIR)/%,$(SOURCES:.$(SRCEXT)=.o))
CFLAGS := -g -Wall
LIB := -lsfml-graphics -lsfml-window -lsfml-system 
INC := -I include


$(BUILDDIR)/%.o: $(SRCDIR)/%.$(SRCEXT)
# BUILDPATH=$($(BUILDDIR)/%.o) # missing step of creating subdirectories 
# OFILE=$(basename $@)
    @mkdir -p $(BUILDDIR)
    @echo " $(CC) $(CFLAGS) $(INC) -c -o $@ $<"; $(CC) $(CFLAGS) $(INC) -c -o $@ $<

an example output of this code is:

 g++  -g -Wall -I include -c -o build/Board/Board.o src/Board/Board.cpp
 src/Board/Board.cpp: In member function ‘AdventureTile Board::getTile(int, int)’:
 src/Board/Board.cpp:13:1: warning: no return statement in function returning non-void [-Wreturn-type]
}
^
Assembler messages:
Fatal error: can't create build/Board/Board.o: No such file or directory
Makefile:23: recipe for target 'build/Board/Board.o' failed
make: *** [build/Board/Board.o] Error 1

how can the command be changed so that it is just the name of the o file and not the full path. using the special variable $@.

(basename $@) returned build/Board/Board but need it to be board.o

=============== Solution ===============

The Makefile was failing because the subdirectories were not created. the line @mkdir -p $(BUILDDIR) needed to become @mkdir -p $(dir $@) to remedy this.

Answer 1

I don't really understand what you mean by how can the command be changed so that it is just the name of the o file ... which command?

It's not correct for a recipe to create a file which is not exactly the value of $@. That's what make expects you to create and things won't work correctly if your recipe creates some other file.

In any event the functions GNU make supports are available here. The one you want is $(notdir $@). However you don't even need that, because there are variants of the automatic variables for the directory ($(@D)) and file ($(@F)).