ext-cryptopp/GNUmakefile-cross

# Default CXXFLAGS if none were provided
CXXFLAGS ?= -DNDEBUG -g2 -O3 -fPIC -pipe

AR ?= ar
ARFLAGS ?= cr
RANLIB ?= ranlib
CP ?= cp
MV ?= mv
CHMOD ?= chmod
MKDIR ?= mkdir
EGREP ?= egrep
LN ?= ln -sf

IS_i686 := $(shell $(CXX) -dumpmachine 2>&1 | $(EGREP) -i -c 'i.86')
IS_x86_64 := $(shell $(CXX) -dumpmachine 2>&1 | $(EGREP) -i -c 'x86_64|amd64')
IS_ARM := $(shell $(CXX) -dumpmachine 2>&1 | $(EGREP) -i -c 'arm')
IS_ARMv8 := $(shell $(CXX) -dumpmachine 2>&1 | $(EGREP) -i -c 'aarch32|aarch64')
CLANG_COMPILER := $(shell $(CXX) --version 2>&1 | $(EGREP) -i -c "clang")

IS_IOS ?= 0
IS_ANDROID ?= 0
IS_ARM_EMBEDDED ?= 0
IS_NEON ?= 0

# Fixup ARM
ifeq ($(IS_ARMv8),1)
  IS_ARM := 0
endif

# Can be used by Android and Embeeded cross-compiles. Disable by default because
#   Android and embedded users typically don't run this configuration.
HAS_SOLIB_VERSION ?= 0

# Default prefix for make install
ifeq ($(PREFIX),)
PREFIX = /usr/local
endif

# http://www.gnu.org/prep/standards/html_node/Directory-Variables.html
ifeq ($(DATADIR),)
DATADIR := $(PREFIX)/share
endif
ifeq ($(LIBDIR),)
LIBDIR := $(PREFIX)/lib
endif
ifeq ($(BINDIR),)
BINDIR := $(PREFIX)/bin
endif
ifeq ($(INCLUDEDIR),)
INCLUDEDIR := $(PREFIX)/include
endif

# We honor ARFLAGS, but the "v" option used by default causes a noisy make
ifeq ($(ARFLAGS),rv)
ARFLAGS = r
endif

# Sadly, we can't actually use GCC_PRAGMA_AWARE because of GCC bug 53431.
# Its a shame because GCC has so much to offer by the way of analysis.
# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53431
ifneq ($(CLANG_COMPILER),0)
CXXFLAGS += -Wall
endif

# iOS cross-compile configuration.
#   See http://www.cryptopp.com/wiki/iOS_(Command_Line).
ifeq ($(IS_IOS),1)
  CXX = clang++

  CXXFLAGS += $(IOS_FLAGS) -arch $(IOS_ARCH)
  CXXFLAGS += -isysroot $(IOS_SYSROOT) -stdlib=libc++

  AR = libtool
  ARFLAGS = -static -o
  RANLIB = ranlib
endif

# Android cross-compile configuration.
#   See http://www.cryptopp.com/wiki/Android_(Command_Line).
ifeq ($(IS_ANDROID),1)
  # CPP, CXX, AR, RANLIB, LD, etc are set in 'setenv-android.sh'
  CXXFLAGS += $(AOSP_FLAGS) -DANDROID --sysroot=$(AOSP_SYSROOT)
  CXXFLAGS += -Wa,--noexecstack -I$(AOSP_STL_INC)

  # c++config.h shows up in odd places at times.
  ifneq ($(AOSP_BITS_INC),)
    CXXFLAGS += -I$(AOSP_BITS_INC)
  endif

  # STL headers
  LDLIBS += $(AOSP_STL_LIB)

  # Source files copied into PWD for Android cpu-features
  # setenv-android.sh does the copying. Its a dirty compile.
  AOSP_CPU_OBJ = cpu-features.o
endif

# ARM embedded cross-compile configuration.
#   See http://www.cryptopp.com/wiki/ARM_Embedded_(Command_Line)
#   and http://www.cryptopp.com/wiki/ARM_Embedded_(Bare Metal).
ifeq ($(IS_ARM_EMBEDDED),1)
  # CPP, CXX, AR, RANLIB, LD, etc are set in 'setenv-embedded.sh'
  CXXFLAGS += $(ARM_EMBEDDED_FLAGS) --sysroot=$(ARM_EMBEDDED_SYSROOT)
endif

# No ASM for Travis testing
ifeq ($(findstring no-asm,$(MAKECMDGOALS)),no-asm)
  ifeq ($(findstring -DCRYPTOPP_DISABLE_ASM,$(CXXFLAGS)),)
    CXXFLAGS += -DCRYPTOPP_DISABLE_ASM
  endif # CXXFLAGS
endif # No ASM

# Undefined Behavior Sanitizer (UBsan) testing. Issue 'make ubsan'.
ifeq ($(findstring ubsan,$(MAKECMDGOALS)),ubsan)
  ifeq ($(findstring -fsanitize=undefined,$(CXXFLAGS)),)
    CXXFLAGS += -fsanitize=undefined
  endif # CXXFLAGS
  ifeq ($(findstring -DCRYPTOPP_COVERAGE,$(CXXFLAGS)),)
    CXXFLAGS += -DCRYPTOPP_COVERAGE
  endif # CXXFLAGS
endif # UBsan

# Address Sanitizer (Asan) testing. Issue 'make asan'.
ifeq ($(findstring asan,$(MAKECMDGOALS)),asan)
  ifeq ($(findstring -fsanitize=address,$(CXXFLAGS)),)
    CXXFLAGS += -fsanitize=address
  endif # CXXFLAGS
  ifeq ($(findstring -DCRYPTOPP_COVERAGE,$(CXXFLAGS)),)
    CXXFLAGS += -DCRYPTOPP_COVERAGE
  endif # CXXFLAGS
  ifeq ($(findstring -fno-omit-frame-pointer,$(CXXFLAGS)),)
    CXXFLAGS += -fno-omit-frame-pointer
  endif # CXXFLAGS
endif # Asan

# LD gold linker testing. Triggered by 'LD=ld.gold'.
ifeq ($(findstring ld.gold,$(LD)),ld.gold)
  ifeq ($(findstring -fuse-ld=gold,$(CXXFLAGS)),)
    ELF_FORMAT := $(shell file `which ld.gold` 2>&1 | cut -d":" -f 2 | $(EGREP) -i -c "elf")
    ifneq ($(ELF_FORMAT),0)
      LDFLAGS += -fuse-ld=gold
    endif # ELF/ELF64
  endif # CXXFLAGS
endif # Gold

# Valgrind testing. Issue 'make valgrind'.
ifneq ($(filter valgrind,$(MAKECMDGOALS)),)
  # Tune flags; see http://valgrind.org/docs/manual/quick-start.html
  CXXFLAGS := $(CXXFLAGS:-g%=-g3)
  CXXFLAGS := $(CXXFLAGS:-O%=-O1)
  CXXFLAGS := $(CXXFLAGS:-xO%=-xO1)
  ifeq ($(findstring -DCRYPTOPP_VALGRIND,$(CXXFLAGS)),)
    CXXFLAGS += -DCRYPTOPP_VALGRIND
  endif # -DCRYPTOPP_VALGRIND
endif # Valgrind

# Debug testing on GNU systems. Triggered by -DDEBUG.
#   Newlib test due to http://sourceware.org/bugzilla/show_bug.cgi?id=20268
ifneq ($(filter -DDEBUG -DDEBUG=1,$(CXXFLAGS)),)
  USING_GLIBCXX := $(shell $(CXX) -x c++ $(CXXFLAGS) -E adhoc.cpp.proto 2>&1 | $(EGREP) -i -c "__GLIBCXX__")
  ifneq ($(USING_GLIBCXX),0)
    ifeq ($(HAS_NEWLIB),0)
      ifeq ($(findstring -D_GLIBCXX_DEBUG,$(CXXFLAGS)),)
        CXXFLAGS += -D_GLIBCXX_DEBUG
      endif # CXXFLAGS
    endif # HAS_NEWLIB
  endif # USING_GLIBCXX
endif # GNU Debug build

# Dead code stripping. Issue 'make lean'.
ifeq ($(findstring lean,$(MAKECMDGOALS)),lean)
  ifeq ($(findstring -ffunction-sections,$(CXXFLAGS)),)
    CXXFLAGS += -ffunction-sections
  endif # CXXFLAGS
  ifeq ($(findstring -fdata-sections,$(CXXFLAGS)),)
    CXXFLAGS += -fdata-sections
  endif # CXXFLAGS
  ifneq ($(IS_IOS),0)
    ifeq ($(findstring -Wl,-dead_strip,$(LDFLAGS)),)
      LDFLAGS += -Wl,-dead_strip
    endif # CXXFLAGS
  else # BSD, Linux and Unix
    ifeq ($(findstring -Wl,--gc-sections,$(LDFLAGS)),)
      LDFLAGS += -Wl,--gc-sections
    endif # LDFLAGS
  endif # MAKECMDGOALS
endif # Dead code stripping

# Pickup ARMv7 and NEON. Do it after Android, iOS and Embedded flags have been set.
ifeq ($(IS_ARM),1)
  IS_ARMv7 := $(shell echo | $(CXX) -x c++ $(CXXFLAGS) -dM -E - 2>/dev/null | $(EGREP) -i -c '__ARM_ARCH 7')
  ifeq ($(IS_ARMv7),1)
    IS_NEON := 1
  else
    IS_NEON := $(shell echo | $(CXX) -x c++ $(CXXFLAGS) -dM -E - 2>/dev/null | $(EGREP) -i -c -E '\<__ARM_NEON\>')
  endif
endif

# ARMv7-a
ifeq ($(IS_ARMv7),1)
  ifeq ($(findstring -march=armv7-a,$(CXXFLAGS)),)
    NEON_FLAG = -march=armv7-a
    GCM_FLAG = -march=armv7-a
    ARIA_FLAG = -march=armv7-a
    BLAKE2_FLAG = -march=armv7-a
  endif
endif

# NEON
ifeq ($(IS_NEON),1)
  ifeq ($(findstring -mfpu=neon,$(CXXFLAGS)),)
    NEON_FLAG += -mfpu=neon
    GCM_FLAG += -mfpu=neon
    ARIA_FLAG += -mfpu=neon
    BLAKE2_FLAG += -mfpu=neon
    ifeq ($(IS_ANDROID),1)
      ifeq ($(findstring -mfloat-abi=softfp,$(CXXFLAGS)),)
        NEON_FLAG += -mfloat-abi=softfp
        GCM_FLAG += -mfloat-abi=softfp
        ARIA_FLAG += -mfloat-abi=softfp
        BLAKE2_FLAG += -mfloat-abi=softfp
      endif
    endif
  endif
endif

# ARMv8-a
ifneq ($(IS_ARMv8),0)
  IS_NEON := $(shell echo | $(CXX) -x c++ $(CXXFLAGS) -march=armv8-a -dM -E - 2>/dev/null | $(EGREP) -i -c __ARM_NEON)
  ifeq ($(IS_NEON),1)
    ARIA_FLAG = -march=armv8-a
    BLAKE2_FLAG = -march=armv8-a
    NEON_FLAG = -march=armv8-a
  endif
  HAVE_CRC := $(shell echo | $(CXX) -x c++ $(CXXFLAGS) -march=armv8-a+crc -dM -E - 2>/dev/null | $(EGREP) -i -c __ARM_FEATURE_CRC32)
  ifeq ($(HAVE_CRC),1)
    CRC_FLAG = -march=armv8-a+crc
  endif
  HAVE_CRYPTO := $(shell echo | $(CXX) -x c++ $(CXXFLAGS) -march=armv8-a+crypto -dM -E - 2>/dev/null | $(EGREP) -i -c __ARM_FEATURE_CRYPTO)
  ifeq ($(HAVE_CRYPTO),1)
    AES_FLAG = -march=armv8-a+crypto
    GCM_FLAG = -march=armv8-a+crypto
    SHA_FLAG = -march=armv8-a+crypto
  endif
endif

# i686 and x86_64
ifneq ($(IS_i686)$(IS_x86_64),00)
  HAVE_SSSE3 = $(shell echo | $(CXX) -x c++ $(CXXFLAGS) -mssse3 -dM -E - 2>/dev/null | $(EGREP) -i -c __SSSE3__)
  ifeq ($(HAVE_SSSE3),1)
    ARIA_FLAG = -mssse3
    SSSE3_FLAG = -mssse3
  endif
  HAVE_SSE4 = $(shell echo | $(CXX) -x c++ $(CXXFLAGS) -msse4.2 -dM -E - 2>/dev/null | $(EGREP) -i -c __SSE4_2__)
  ifeq ($(HAVE_SSE4),1)
    BLAKE2_FLAG = -msse4.2
    CRC_FLAG = -msse4.2
  endif
  HAVE_CLMUL = $(shell echo | $(CXX) -x c++ $(CXXFLAGS) -mssse3 -mpclmul -dM -E - 2>/dev/null | $(EGREP) -i -c __PCLMUL__ )
  ifeq ($(HAVE_CLMUL),1)
    GCM_FLAG = -mssse3 -mpclmul
  endif
  HAVE_AES = $(shell echo | $(CXX) -x c++ $(CXXFLAGS) -msse4.1 -maes -dM -E - 2>/dev/null | $(EGREP) -i -c __AES__)
  ifeq ($(HAVE_AES),1)
    AES_FLAG = -msse4.1 -maes
  endif
  HAVE_SHA = $(shell echo | $(CXX) -x c++ $(CXXFLAGS) -msse4.2 -msha -dM -E - 2>/dev/null | $(EGREP) -i -c __SHA__)
  ifeq ($(HAVE_SHA),1)
    SHA_FLAG = -msse4.2 -msha
  endif
endif

# List cryptlib.cpp first, then cpu.cpp, then integer.cpp to tame C++ static initialization problems.
SRCS := cryptlib.cpp cpu.cpp integer.cpp $(filter-out cryptlib.cpp cpu.cpp integer.cpp pch.cpp simple.cpp winpipes.cpp cryptlib_bds.cpp,$(sort $(wildcard *.cpp)))

# List cryptlib.cpp first, then cpu.cpp, then integer.cpp to tame C++ static initialization problems.
OBJS := $(SRCS:.cpp=.o)

# List test.cpp first to tame C++ static initialization problems.
TESTSRCS := adhoc.cpp test.cpp bench1.cpp bench2.cpp validat0.cpp validat1.cpp validat2.cpp validat3.cpp datatest.cpp regtest1.cpp regtest2.cpp regtest3.cpp fipsalgt.cpp dlltest.cpp
TESTOBJS := $(TESTSRCS:.cpp=.o)
LIBOBJS := $(filter-out $(TESTOBJS),$(OBJS))

# For Shared Objects, Diff, Dist/Zip rules
LIB_VER := $(shell $(EGREP) "define CRYPTOPP_VERSION" config.h | cut -d" " -f 3)
LIB_MAJOR := $(shell echo $(LIB_VER) | cut -c 1)
LIB_MINOR := $(shell echo $(LIB_VER) | cut -c 2)
LIB_PATCH := $(shell echo $(LIB_VER) | cut -c 3)

ifeq ($(strip $(LIB_PATCH)),)
LIB_PATCH := 0
endif

ifeq ($(HAS_SOLIB_VERSION),1)
# Full version suffix for shared library
SOLIB_VERSION_SUFFIX=.$(LIB_MAJOR).$(LIB_MINOR).$(LIB_PATCH)
# Different patchlevels are compatible, minor versions are not
SOLIB_COMPAT_SUFFIX=.$(LIB_MAJOR).$(LIB_MINOR)
SOLIB_FLAGS=-Wl,-soname,libcryptopp.so$(SOLIB_COMPAT_SUFFIX)
endif # HAS_SOLIB_VERSION

.PHONY: all
all: cryptest.exe

ifneq ($(IS_IOS),0)
static: libcryptopp.a
shared dynamic dylib: libcryptopp.dylib
else
static: libcryptopp.a
shared dynamic: libcryptopp.so$(SOLIB_VERSION_SUFFIX)
endif

test: cryptest.exe
	./cryptest.exe v

# CXXFLAGS are tuned earlier. Applications must use linker flags
#  -Wl,--gc-sections (Linux and Unix) or -Wl,-dead_strip (OS X)
.PHONY: lean
lean: static dynamic cryptest.exe

.PHONY: clean
clean:
	-$(RM) adhoc.cpp.o adhoc.cpp.proto.o $(LIBOBJS) $(AOSP_CPU_OBJ) $(TESTOBJS) $(DLLOBJS) $(LIBIMPORTOBJS) $(TESTIMPORTOBJS) $(DLLTESTOBJS)
	@-$(RM) libcryptopp.a libcryptopp.dylib cryptopp.dll libcryptopp.dll.a libcryptopp.import.a
	@-$(RM) libcryptopp.so libcryptopp.so$(SOLIB_COMPAT_SUFFIX) libcryptopp.so$(SOLIB_VERSION_SUFFIX)
	@-$(RM) cryptest.exe dlltest.exe cryptest.import.exe cryptest.info ct rdrand-???.o
	@-$(RM) *.gcno *.gcda *.stackdump core-*
	@-$(RM) /tmp/adhoc.exe
	@-$(RM) -r /tmp/cryptopp_test/
	@-$(RM) -r *.exe.dSYM/
	@-$(RM) -r *.dylib.dSYM/
	@-$(RM) -r cov-int/

.PHONY: distclean
distclean: clean
	-$(RM) adhoc.cpp adhoc.cpp.copied cryptopp.mapfile GNUmakefile.deps benchmarks.html cryptest.txt cryptest-*.txt
	@-$(RM) cryptopp.tgz *.o *.bc *.ii *~
	@-$(RM) -r $(SRCS:.cpp=.obj) *.suo *.sdf *.pdb Win32/ x64/ ipch/
	@-$(RM) -r TestCoverage/
	@-$(RM) cryptopp$(LIB_VER)\.*
	@-$(RM) CryptoPPRef.zip

.PHONY: install
install:
	$(MKDIR) -p $(DESTDIR)$(INCLUDEDIR)/cryptopp
	$(CP) *.h $(DESTDIR)$(INCLUDEDIR)/cryptopp
	-$(CHMOD) 755 $(DESTDIR)$(INCLUDEDIR)/cryptopp
	-$(CHMOD) 644 $(DESTDIR)$(INCLUDEDIR)/cryptopp/*.h
ifneq ($(wildcard cryptest.exe),)
	$(MKDIR) -p $(DESTDIR)$(BINDIR)
	$(CP) cryptest.exe $(DESTDIR)$(BINDIR)
	-$(CHMOD) 755 $(DESTDIR)$(BINDIR)/cryptest.exe
endif
ifneq ($(wildcard libcryptopp.a),)
	$(MKDIR) -p $(DESTDIR)$(LIBDIR)
	$(CP) libcryptopp.a $(DESTDIR)$(LIBDIR)
	-$(CHMOD) 644 $(DESTDIR)$(LIBDIR)/libcryptopp.a
endif
ifneq ($(wildcard libcryptopp.dylib),)
	$(MKDIR) -p $(DESTDIR)$(LIBDIR)
	$(CP) libcryptopp.dylib $(DESTDIR)$(LIBDIR)
	-$(CHMOD) 755 $(DESTDIR)$(LIBDIR)/libcryptopp.dylib
endif
ifneq ($(wildcard libcryptopp.so$(SOLIB_VERSION_SUFFIX)),)
	$(CP) libcryptopp.so $(DESTDIR)$(LIBDIR)
	-$(CHMOD) 755 $(DESTDIR)$(LIBDIR)/libcryptopp.so$(SOLIB_VERSION_SUFFIX)
ifeq ($(HAS_SOLIB_VERSION),1)
	-$(LN) -sf libcryptopp.so$(SOLIB_VERSION_SUFFIX) $(DESTDIR)$(LIBDIR)/libcryptopp.so
endif
endif

.PHONY: remove uninstall
remove uninstall:
	-$(RM) -r $(DESTDIR)$(INCLUDEDIR)/cryptopp
	-$(RM) $(DESTDIR)$(LIBDIR)/libcryptopp.a
	-$(RM) $(DESTDIR)$(BINDIR)/cryptest.exe
	@-$(RM) $(DESTDIR)$(LIBDIR)/libcryptopp.dylib
	@-$(RM) $(DESTDIR)$(LIBDIR)/libcryptopp.so$(SOLIB_VERSION_SUFFIX)
	@-$(RM) $(DESTDIR)$(LIBDIR)/libcryptopp.so$(SOLIB_COMPAT_SUFFIX)
	@-$(RM) $(DESTDIR)$(LIBDIR)/libcryptopp.so

libcryptopp.a: $(LIBOBJS) $(AOSP_CPU_OBJ)
	$(AR) $(ARFLAGS) $@ $(LIBOBJS) $(AOSP_CPU_OBJ)
	$(RANLIB) $@

ifeq ($(HAS_SOLIB_VERSION),1)
.PHONY: libcryptopp.so
libcryptopp.so: libcryptopp.so$(SOLIB_VERSION_SUFFIX)
endif

libcryptopp.so$(SOLIB_VERSION_SUFFIX): $(LIBOBJS)
	$(CXX) -shared $(SOLIB_FLAGS) -o $@ $(strip $(CXXFLAGS)) -Wl,--exclude-libs,ALL $(LIBOBJS) $(LDFLAGS) $(LDLIBS)
ifeq ($(HAS_SOLIB_VERSION),1)
	-$(LN) libcryptopp.so$(SOLIB_VERSION_SUFFIX) libcryptopp.so
	-$(LN) libcryptopp.so$(SOLIB_VERSION_SUFFIX) libcryptopp.so$(SOLIB_COMPAT_SUFFIX)
endif

libcryptopp.dylib: $(LIBOBJS)
	$(CXX) -dynamiclib -o $@ $(strip $(CXXFLAGS)) -install_name "$@" -current_version "$(LIB_MAJOR).$(LIB_MINOR).$(LIB_PATCH)" -compatibility_version "$(LIB_MAJOR).$(LIB_MINOR)" -headerpad_max_install_names $(LDFLAGS) $(LIBOBJS)

cryptest.exe: libcryptopp.a $(TESTOBJS)
	$(CXX) -o $@ $(strip $(CXXFLAGS)) $(TESTOBJS) ./libcryptopp.a $(LDFLAGS) $(LDLIBS)

# Used to generate list of source files for Autotools, CMakeList and Android.mk
.PHONY: sources
sources:
	$(info Library sources: $(filter-out $(TESTSRCS),$(SRCS)))
	$(info )
	$(info Test sources: $(TESTSRCS))

adhoc.cpp: adhoc.cpp.proto
ifeq ($(wildcard adhoc.cpp),)
	cp adhoc.cpp.proto adhoc.cpp
else
	touch adhoc.cpp
endif

# Include dependencies, if present. You must issue `make deps` to create them.
ifeq ($(wildcard GNUmakefile.deps),GNUmakefile.deps)
-include GNUmakefile.deps
endif # Dependencies

cpu-features.o: cpu-features.h cpu-features.c
	$(CXX) $(strip $(CXXFLAGS) -fpermissive -c) cpu-features.c

# SSE4.2 or NEON available
aria-simd.o : aria-simd.cpp
	$(CXX) $(strip $(CXXFLAGS) $(ARIA_FLAG) -c) $<

# SSE4.2 or ARMv8a available
blake2-simd.o : blake2-simd.cpp
	$(CXX) $(strip $(CXXFLAGS) $(BLAKE2_FLAG) -c) $<

# SSE2 on i586
cpu.o : cpu.cpp
	$(CXX) $(strip $(CXXFLAGS) $(CPU_FLAG) -c) $<

# SSE4.2 or ARMv8a available
crc-simd.o : crc-simd.cpp
	$(CXX) $(strip $(CXXFLAGS) $(CRC_FLAG) -c) $<

# PCLMUL or ARMv7a/ARMv8a available
gcm-simd.o : gcm-simd.cpp
	$(CXX) $(strip $(CXXFLAGS) $(GCM_FLAG) -c) $<

# NEON available
neon-simd.o : neon-simd.cpp
	$(CXX) $(strip $(CXXFLAGS) $(NEON_FLAG) -c) $<

# AESNI or ARMv7a/ARMv8a available
rijndael-simd.o : rijndael-simd.cpp
	$(CXX) $(strip $(CXXFLAGS) $(AES_FLAG) -c) $<

# SSE4.2/SHA-NI or ARMv8a available
sha-simd.o : sha-simd.cpp
	$(CXX) $(strip $(CXXFLAGS) $(SHA_FLAG) -c) $<

# SSE4.2/SHA-NI or ARMv8a available
shacal2-simd.o : shacal2-simd.cpp
	$(CXX) $(strip $(CXXFLAGS) $(SHA_FLAG) -c) $<

%.o : %.cpp
	$(CXX) $(strip $(CXXFLAGS) -c) $<

GNUmakefile.deps:
	$(CXX) $(strip $(CXXFLAGS) -MM) *.cpp > GNUmakefile.deps