ifneq (,$(filter gcc%,$(CC)))
    _gccversion:=$(shell $(CC) -dumpversion)
    _gccmachine:=$(shell $(CC) -dumpmachine)
    _cobjs := .objs-$(_gccmachine:-linux-gnu=)-$(_gccversion)

    # Use pipes and not temp files.
    CFLAGS += -pipe
    # optimize even more
    CFLAGS += -O2
    # let the type char be unsigned by default
    CFLAGS += -funsigned-char
    CFLAGS += -fstrict-aliasing
    # turn on all common warnings
    CFLAGS += -Wall
    # turn on extra warnings
    CFLAGS += $(if $(filter 4.%,$(GCCVERSION)),-W,-Wextra)
    # treat warnings as errors
    CFLAGS += -Werror
    CFLAGS += -Wchar-subscripts
    # warn about undefined preprocessor identifiers
    CFLAGS += -Wundef
    # warn about local variable shadowing another local variable
    CFLAGS += -Wshadow
    # warn about casting of pointers to increased alignment requirements
    CFLAGS += -Wcast-align
    # make string constants const
    CFLAGS += -Wwrite-strings
    # warn about implicit conversions with side effects
    # fgets, calloc and friends take an int, not size_t...
    #CFLAGS += -Wconversion
    # warn about comparisons between signed and unsigned values
    CFLAGS += -Wsign-compare
    # warn about unused declared stuff
    CFLAGS += -Wunused
    # don not warn about unused return value
    CFLAGS += -Wno-unused-value
    # warn about variable use before initialization
    CFLAGS += -Wuninitialized
    # warn about pointer arithmetic on void* and function pointers
    CFLAGS += -Wpointer-arith
    # warn about multiple declarations
    CFLAGS += -Wredundant-decls
    # warn if the format string is not a string literal
    CFLAGS += -Wformat-nonliteral
    # do not warn about strftime format with y2k issues
    CFLAGS += -Wno-format-y2k

    CFLAGS += -I$(DEPTH)
else
    CFLAGS += -Wall
    _cobjs := .objs
endif

LDFLAGS += -Wl,--warn-common