Makefile example with CGO

# make <target>
#
# Targets:
# + all (the default)
#   - This will build all of the dependencies for and link gobir
# + clean
#   - This will delete the binary and the object directory
# + format
#   - This will format all of your source code with gofmt

### Directories and files
# Search/output directories
ROOT   = $(subst " ",\ ,$(GOROOT))
GOBIN  = $(subst " ",\ ,$(HOME))/bin
OBJDIR = _obj/
LIBDIR = _lib/

# CGO output files and extensions
CGC = _cgo_defun.c
CGG = _cgo_gotypes.go
CG1 = cgo1.go
CG2 = cgo2.c

### Load architecture variables
include $(ROOT)/src/Make.$(GOARCH)
include $(ROOT)/src/Make.$(GOOS)

### Compiling and Linking
# Go commands
COMP = $(GOBIN)/$(GC) -I$(OBJDIR)
LINK = $(GOBIN)/$(LD) -L$(OBJDIR)
PACK = $(GOBIN)/gopack grc
GFMT = $(GOBIN)/gofmt -w

# C commands
CGO    = $(GOBIN)/cgo
C_COMP = gcc $(_CGO_CFLAGS_$(GOARCH)) -fPIC -O2 -c
C_LDSO = gcc $(_CGO_CFLAGS_$(GOARCH)) $(_CGO_LDFLAGS_$(GOOS))
C_GOCC = $(GOBIN)/$(CC) $(CFLAGS) $(RUNTIME_CFLAGS_$(GOARCH))

### Packages and Dependencies
# Package: config
CONFIG_OBJECT = config
CONFIG_SOURCE = config.go

# Package: main
MAIN_OBJECT = gobir
MAIN_SOURCE = gobir.go

# Package: ibot
IBOT_OBJECT = ibot
IBOT_SOURCE = ibot.go ibot_util.go ibot_botuser.go ctcp.go golang.go nickserv.go ibot_botchannel.go admin.go ibot_botcore.go ibot_registration.go seen.go

# Package: clibrary
CLIBRARY_OBJECT = clibrary
CLIBRARY_SOURCE = c_library.go
CLIBRARY_CFILES = test_library.c

# Package: irc
IRC_OBJECT = irc
IRC_SOURCE = irc.go irc_constants.go irc_parser.go

# Normal Go packages in dependencies-first order
PACKAGES = CONFIG IRC IBOT CLIBRARY MAIN

# Packages that require cgo processing
CGOPKGS = CLIBRARY

### Aggregates
OBJECTS = $(patsubst %,$(OBJDIR)%.$O,$(foreach PKG,$(PACKAGES),$($(PKG)_OBJECT)))
DLOBJS = $(patsubst %,$(LIBDIR)%.so,$(foreach PKG,$(CGOPKGS),$($(PKG)_OBJECT)))

### Default rule
all : $(OBJDIR) $(LIBDIR) $(OBJECTS) $(MAIN_OBJECT) $(DLOBJS)

### Main binary
ifdef MAIN_OBJECT
$(MAIN_OBJECT) : $(OBJECTS)
    $(LINK) -o $@ $(OBJDIR)$@.$O
endif

### Objects
define package_template
$$(OBJDIR)$$($(1)_OBJECT).$$O: $$($(1)_SOURCE)
    $$(COMP) -o $$@ $$^
    $$(PACK) $$(@:.$$O=.a) $$@
endef
$(foreach PKG,$(filter-out $(CGOPKGS),$(PACKAGES)),$(eval $(call package_template,$(PKG))))

### CGo Objects
define cgopkg_template
$$($(1)_SOURCE:.go=.$$(CG1)) $$($(1)_SOURCE:.go=.$$(CG2)) $$(CGC) $$(CGG) : $$($(1)_SOURCE)
    CGOPKGPATH=$$(PWD)/_lib $$(CGO) $$^

$$(OBJDIR)$$($(1)_OBJECT).$$O : $$($(1)_SOURCE:.go=.$$(CG1)) $$(CGG) $$(CGC:.c=.6)
    $$(COMP) -o $$@ $$(filter-out %.6,$$^)
    $$(PACK) $$(@:.$$O=.a) $$@ $$(filter %.6,$$^)

$$(LIBDIR)$$($(1)_OBJECT).so : $$($(1)_SOURCE:.go=.$$(CG2:.c=.o)) $$($(1)_CFILES:.c=.o)
    $$(C_LDSO) -o $$@ $$^

endef
$(foreach PKG,$(CGOPKGS),$(eval $(call cgopkg_template,$(PKG))))

### Utility
clean :
    rm -rf $(OBJDIR) $(LIBDIR) *.$(CG1) *.$(CG2) $(CGC) $(CGG) *.o *.$O $O.out $(MAIN_OBJECT)

format :
    $(GFMT) $(foreach PKG,$(PACKAGES),$($(PKG)_SOURCE))

$(OBJDIR) $(LIBDIR) :
    mkdir -p $@

### CGO implicit rules
# Don't delete intermediate .6 files
.PRECIOUS : %.6

%.6 : %.c
    $(C_GOCC) -I$(GOROOT)/src/pkg/runtime $^

%.o : %.c
    $(C_COMP) $^