Makefile.compiler

# -*- makefile-bsdmake -*-

#
#	Makefile.compiler - set CFLAGS et al nicely
#
#	This should be included in your project's top-level Makefile.inc after
#	any include of <bsd.own.mk>

# You can define USE_UBSAN or USE_ASAN on the command line to enable the
# Undefined or Address sanitizers with recent enough Clang or GCC.  Note if your
# system supports these you may of course use its way of enabling them instead
# (e.g. on NetBSD set "MKSANITIZER=yes USE_SANITIZER=address").
#
# N.B.:  The address sanitizer is not available when the PaX ASLR (Address Space
# Layout Randomization) feature is enabled on a given system, but it can be
# disabled for a given binary with paxctl(8):  paxctl +a ${prog}

# You can usually find all CC pre-defines with:
#
#	echo "" | cc -E -dM -x c - | sort
#
# to see what specific optimizations are enabled by -O*:
#
#	echo "" | gcc -O[0123] -S -fverbose-asm -o - -x c -
#
# to show search paths and "as" and linker commands:
#
#	echo "" | gcc -v -x c -
#
#
# N.B.:  these tricks do not work for lcc

.if !defined(__GNUC__)
__GNUC__ !=		echo __GNUC__ | $(CC) -E - | sed '/\#/d;s/__GNUC__//'
.endif
.if empty(__GNUC__)
. undef __GNUC__
.else
. if !defined(__GNUC_MINOR__)
__GNUC_MINOR__ !=	echo __GNUC_MINOR__ | $(CC) -E - | sed '/\#/d;s/__GNUC_MINOR__//'
. endif
. if !defined(__GNUC_PATCHLEVEL__)
__GNUC_PATCHLEVEL__ !=	echo __GNUC_PATCHLEVEL__ | $(CC) -E - | sed '/\#/d;s/__GNUC_PATCHLEVEL__//'
. endif
.endif

# Note: for now Clang also defines the __GNUC*__ macros above...

# Note: on all recent Mac OS X (and soon FreeBSD), "cc" is "clang"
# On Mac OS X 10.8 and newer "gcc" is actually "llvm-gcc" too!

.if !defined(__clang__)
__clang__ !=		echo __clang__ | $(CC) -E - | sed '/\#/d;s/__clang__//'
.endif
.if empty(__clang__)
. undef __clang__
.else
. if !defined(__clang_major__)
__clang_major__ !=	echo __clang_major__ | $(CC) -E - | sed '/\#/d;s/__clang_major__//'
. endif
. if !defined(__clang_minor__)
__clang_minor__ !=	echo __clang_minor__ | $(CC) -E - | sed '/\#/d;s/__clang_minor__//'
. endif
. if !defined(__clang_patchlevel__)
__clang_patchlevel__ !=	echo __clang_patchlevel__ | $(CC) -E - | sed '/\#/d;s/__clang_patchlevel__//'
. endif
.endif

# borrowed from sjg's Mk-files.
.if !defined(_HOST_OSNAME)
# use .MAKE.OS if available
# avoid :U for older bmakes
. if !defined(.MAKE.OS)
_HOST_OSNAME := ${uname -s:L:sh}
. else
_HOST_OSNAME := ${.MAKE.OS}
. endif
.endif
#TARGET_OSNAME?= ${_HOST_OSNAME}

# Note:  TARGET_OSNAME is from sjg's Mk-files (host-target.mk, own.mk), and
# OS is from pkgsrc bootstrap-mk.  .FreeBSD is a trick shared by FreeBSD and old
# MacOS bsdmake.
#
.if ((defined(TARGET_OSNAME) && (${TARGET_OSNAME} == "Darwin")) || \
	(defined(OS) && (${OS} == "Darwin")) || \
	(defined(.FreeBSD) && (empty(.FreeBSD) || (${.FreeBSD} == "false"))))
#
# NOTE: Mac OS X does not use GNU ld, but....
#
.else
. if !defined(__GNULD__)
__GNULD__ !=		$(LD) -v | awk '{print int($$NF);}' | tr -d ' \012'
. endif
.endif

# Note:  FreeBSD's mk-files (<bsd.sys.mk>) use this directly, and luckily
# correctly as it blindly adds its own value to CFLAGS after the one added
# below....
#
CSTD ?= c89

# prevent NetBSD's mk-files from adding -std=gnu99 to CFLAGS
#
.if !empty(unix:M*NetBSD*)
# XXX this is very ad-hoc, obviously, but until something better is done...
COVERITY_TOP_CONFIG =	1
.endif

# Enable system-specific warnings -- this would likely double up on many of the
# flags added by here, but on rare occasions it may also add some host-specific
# flags that might be useful.
#
# Of course this is just for developers, and beware it often includes
# -Wsystem-headers leading to miles of useless warnings and sometimes
# unavoidable errors!
#
# XXX so far no system has required this be explicitly set to "0", though for at
# least recent NetBSD when using Clang there may be some advantage as just being
# defined adds "-Wno-sign-compare -Wno-pointer-sign".
#
#WARNS ?= 0

# Do not enable/allow -Werror -- But oh soooo very many ways to do it!
#
NOGCCERROR = 1			# NetBSD
NOCLANGERROR = 1		# NetBSD
# more recent FreeBSDs deprecate NO_WERROR
# (Note the really old bsdmake on OSX/macOS has a wonky huge MAKE_VERSION.)
.if defined(MAKE_VERSION) && (${MAKE_VERSION} >= 20210106 && ${MAKE} != "bsdmake")
MK_WERROR = no
.else
NO_WERROR = 1
.endif
# Just turn off all sjg's Mk-files warnings -- those herein are better tuned to
# the supported compilers....
NO_CFLAGS_WARNINGS = 1

#
# Set ${CWARNFLAGS} based on the detected compiler and its version.
#
# Note we do depend on the mk-files (notably <bsd.sys.mk>) to add ${CWARNFLAGS}
# to ${CFLAGS}, and so far only sjg's Mk-files don't do this...
#
# xxx consider ${CWARNFLAGS.${COMPILER_TYPE}} ala FreeBSD to hopefully simplify
# the .if logic somewhat....
#
# xxx there's also the ${EXPR:? flim : flam} form used by NetBSD....
#

# -Winline
#
#	- seems pointless
#
# -Wnested-externs
#
#	- possibly useful, though -Wshadow covers worst case
#	- see tnested-externs.c
#
# -Wredundant-decls
#
#	- seems pointless


.if defined(__GNUC__) && ${__GNUC__} >= 1
CWARNFLAGS += -Wall
# this one is just plain annoying much of the time:
CWARNFLAGS += -Wno-missing-field-initializers
# these aren't always in "-Wall"
CWARNFLAGS += -Wimplicit
CWARNFLAGS += -Wreturn-type
CWARNFLAGS += -Wswitch
CWARNFLAGS += -Wcomment
CWARNFLAGS += -Wcast-qual
CWARNFLAGS += -Wpointer-arith
CWARNFLAGS += -Wshadow
# xxx some code may not be quite ready for full const-ification yet...
CWARNFLAGS += -Wwrite-strings
# this isn't mentioned in 1.42's manual but causes no error
CWARNFLAGS += -Wstrict-prototypes
#XXX# -Wsystem-headers does not go well on many systems!
#XXX#CWARNFLAGS += -Wsystem-headers
CWARNFLAGS += -Wno-system-headers
.endif # ${__GNUC__} >= 1

# in addition to -Wall
#
.if defined(__GNUC__)
. if ${__GNUC__} <= 2
# "-Wid-clash-LEN" is sadly no longer supported in 3.2.2 or 3.3.3
# (but is still in 3.0.4)
CWARNFLAGS += -Wid-clash-30
. endif

.if ${__GNUC__} > 3 || \
	(${__GNUC__} == 3 && ${__GNUC_MINOR__} == 4 && ${__GNUC_PATCHLEVEL__} >=6) || \
	(${__GNUC__} == 3 && ${__GNUC_MINOR__} >= 5)
# "-W" was replaced by "-Wextra" since at least 3.4.6
# and in clang, which presents as GCC 4.2.1, this is also true
CWARNFLAGS += -Wextra
. else
CWARNFLAGS += -W
. endif
.endif

.if defined(__GNUC__) && \
	${__GNUC__} >= 2
# functions are SUPPOSED to be able to return structs!!!
#CWARNFLAGS += -Waggregate-return
CWARNFLAGS += -Wcast-align
CWARNFLAGS += -Wchar-subscripts
# -Wconversion changes meanings in GCC-4.4 and newer, but we may still want it
CWARNFLAGS += -Wconversion
CWARNFLAGS += -Wmissing-declarations
CWARNFLAGS += -Wmissing-prototypes
CWARNFLAGS += -Wno-long-long
# the rest aren't in the manual, but work on at least 2.9x.x
CWARNFLAGS += -Wformat-extra-args
# -Wundef isn't in 2.7.2, but then again if you're still using 2.7.2 you may be
# suffering from far more code generation bugs and other compiler problems than
# you might know!
CWARNFLAGS += -Wundef
# we may intentionally have large arrays
#CWARNFLAGS += -Wlarger-than-65536
# N.B.:  -Wbad-function-cast can be extremely annoying as it complains about
# conversions by casts which even -Wconversion doesn't complain about.  In
# theory it does warn about cases where UB(?)/IDB can happen because the return
# value is out-of-bounds for the target type.
CWARNFLAGS += -Wbad-function-cast
.endif

.if defined(__GNUC__) && \
	${__GNUC__} >= 3
# Yuck:  this is broken in at least 3.2.2...
#CWARNFLAGS += -Wunreachable-code
CWARNFLAGS += -Wdeclaration-after-statement
# -Wformat is included in -Wall, but not "-Wformat-nonliteral -Wformat-security"
# but -Wformat-y2k is stupid
CWARNFLAGS += -Wformat=2 -Wno-format-y2k
# note: will only have effect if '-fstrict-aliasing' is enabled, but normally we
# do the opposite and disable that option
# xxx maybe only in >= 3.3?
CWARNFLAGS += -Wstrict-aliasing=2
.endif

.if (defined(__GNUC__) && \
	${__GNUC__} >= 4 && \
	!defined(__clang__)) || \
	(defined(__clang__) && defined(__clang_major__) && ${__clang_major__} > 1)

. if(${__GNUC_MINOR__} >= 4)
# hmmm...  this can sometimes be annoying, but....
CWARNFLAGS += -Wtraditional-conversion
. endif
CWARNFLAGS += -Wunreachable-code
# note: this only works if we don't turn off -fstrict-overflow (which we
# normally do) _and_ we have -O2 or greater (see below)
. if(${__GNUC_MINOR__} >= 1)
# xxx not in 4.0.1, and in 4.2.1, but when first?
CWARNFLAGS += -Wstrict-overflow=5
. endif
.endif

# maybe this is right? (it's always enabled in more recent GCC's)
.if !empty(unix:M*NetBSD*) && ${__GNUC__} < 3 && ${__GNUC__} > 2
CWARNFLAGS += -Wnetbsd-format-audit
.endif

# note: since Clang also defines the __GNUC__ macros we just need to add
# Clang-specific flags here and we get all the GCC warning flags for free...
.if defined(__clang__)
# get all the info!
CWARNFLAGS += -fmessage-length=0
# try this -- good for tests, bad for production!!!
. if ${__clang_major__} <= 5
CWARNFLAGS += -fcatch-undefined-behavior
.  if ${__clang_major__} == 4 || (${__clang_major__} == 3 && ${__clang_minor__} >= 3)
.   if defined(USE_UBSAN)
# i.e. clang 3.3 or clang 4.x (but not clang 5.x)
CWARNFLAGS += -fsanitize=undefined
.   endif
.  endif
. else
.  if ${__clang_major__} >= 7
# N.B.:  It is not possible to combine more than one of the -fsanitize=address,
# -fsanitize=thread, and -fsanitize=memory checkers in the same program.
.   if defined(USE_UBSAN)
# sadly Apple LLVM version 8.1.0 (clang-802.0.42) says:
# clang: error: unsupported option '-fsanitize=memory' for target 'x86_64-apple-darwin16.6.0'
#CWARNFLAGS += -fsanitize=memory
#CWARNFLAGS += -fsanitize=thread
CWARNFLAGS += -fsanitize=undefined
# Apple LLVM version 8.1.0 (clang-802.0.42) says:
# ld: file not found: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/clang/8.1.0/lib/darwin/libclang_rt.safestack_osx.a
# clang: error: linker command failed with exit code 1 (use -v to see invocation)
#CWARNFLAGS += -fsanitize=safe-stack
#xxx this may not be useful?
#CWARNFLAGS += -fsanitize=dataflow --fsanitize=cfi
.   endif
.   if defined(USE_ASAN)
#xxx 'address' may not work (requires intrumentation of all program code)
CWARNFLAGS += -fsanitize=address
# (may also require setting ASAN_OPTIONS in the runtime environment,
# e.g. ASAN_OPTIONS=detect_leaks=1)
.   endif
.  else
# clang > 5.0 < 7.x(?)
.   if defined(USE_UBSAN)
# Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM 3.5svn) says:
#  clang: error: unsupported argument 'undefined' to option 'fsanitize='
#CWARNFLAGS += -fsanitize=undefined
.   endif
.   if defined(USE_ASAN)
# ???
#CWARNFLAGS += -fsanitize=address
.   endif
.  endif
. endif
# -fsanitize must also be provided to the linker (for hidden runtime libraries)
LDFLAGS += ${CWARNFLAGS:M-fsanitize=*}
.endif

.if defined(__GNUC__) && !defined(__clang__)
. if defined(USE_UBSAN)
# xxx hmmmm which, exactly?
.  if ${__GNUC__} >= 5
CWARNFLAGS += -fsanitize=undefined
# -fsanitize=undefined has sub-options
CWARNFLAGS += -fsanitize=alignment
CWARNFLAGS += -fsanitize=bool
CWARNFLAGS += -fsanitize=bounds
CWARNFLAGS += -fsanitize=enum
CWARNFLAGS += -fsanitize=float-cast-overflow
CWARNFLAGS += -fsanitize=float-divide-by-zero
CWARNFLAGS += -fsanitize=integer-divide-by-zero
CWARNFLAGS += -fsanitize=null
CWARNFLAGS += -fsanitize=object-size
CWARNFLAGS += -fsanitize=shift
LDFLAGS += -fsanitize=undefined -pthread
# xxx adding these _almost_ allows static linking on NetBSD, but for shm_open()
# and shm_unlink() not being resolved from librt even when it is specified
#LDADD += -lrt
#LDADD += -pthread
LDSTATIC := # empty -- undefined sanitizer effectively does not support static linking
.  endif
. endif
. if defined(USE_ASAN)
.  if ${__GNUC__} > 4 || \
	(${__GNUC__} == 4 && ${__GNUC_MINOR__} >= 8)
CWARNFLAGS += -fsanitize=address
LDFLAGS += -fsanitize=address
LDSTATIC := # empty -- address sanitizer does not support static linking
.  endif
. endif
# N.B.:  LeakSanitizer is incompatible with -fsanitize=thread.
#
# LeakSanitizer is enabled by default in ASan builds of x86_64 Linux, and can be
# enabled with ASAN_OPTIONS=detect_leaks=1 on x86_64 OS X.
#
# You can fine-tune LeakSanitizer's behavior through the LSAN_OPTIONS
# environment variable.  See:
#
# <https://github.com/google/sanitizers/wiki/AddressSanitizerLeakSanitizer>
#
# Here USE_LEAKSAN is provided for stand-alone leak detection.
#
. if defined(USE_LEAKSAN)
LDFLAGS += -fsanitize=leak
LDSTATIC := # empty -- leak sanitizer does not support static linking
. endif
.endif

.if !defined(__clang__)
# in GCC -g3 includes macro definitions in debug info
DBG = -g3
.else
DBG = -g
.endif
OPTIM = -O2

.if defined(__GNUC__) && ${__GNUC__} >= 1
. if defined(__GNULD__) && ${__GNULD__} >= 1
#LDFLAGS += -Wl,--warn-common
#LDFLAGS += -Wl,--fatal-warnings
LDFLAGS += -Wl,--unresolved-symbols=report-all
#LDFLAGS += -Wl,--error-unresolved-symbols
. else
.  if !empty(${DBG:M-g})
# hmmm....  GNU ld(1) doesn't need -g, but some linkers do
#LDFLAGS += -Wl,-g
.  endif
. endif
.endif

#
# XXX the rest could/should be split into Makefile.compiler2 that would be
# included after <bsd.{prog,lib}.mk>, but then that has to be done explicitly
# every time, sigh.  Only sjg's Mk-files provide an easy option with
# "Makefile-final.inc"
#

# Since <bsd.sys.mk> hasn't been included yet (i.e. CFLAGS et al are all still
# empty), these will still add the flags anyway, and early near the beginning,
# meaning they won't override anything set in <bsd.sys.mk>.
#
# N.B.:  on most systems COPTS would be strongly preferred as it is usually
# added late to CFLAGS, but on FreeBSD they have, since nearly forever, mostly
# eliminated it and all its variants and added a warning in <bsd.prog.mk>, the
# only remaining use, saying "XXX The use of COPTS in modern makefiles is
# discouraged."
#
.if !empty(DBG) && empty(CFLAGS:M*${DBG}*)
CFLAGS += ${DBG}
.endif
.if !empty(OPTIM) && empty(CFLAGS:M*${OPTIM}*)
CFLAGS += ${OPTIM}
.endif
.if empty(CFLAGS:M*-std=${CSTD}*)
CFLAGS += -std=${CSTD}
.endif
.if !empty(CPPFLAGS) && empty(CFLAGS:M*${CPPFLAGS}*)
CFLAGS += ${CPPFLAGS}
.endif

.if (defined(__GNUC__) && ${__GNUC__} >= 1) || \
	(defined(__clang__) && ${__clang__} >= 1)
. if empty(CFLAGS:M*-pipe*)
CFLAGS +=	-pipe
. endif
.endif

.if defined(__GNUC__) || defined(__clang__) && \
	empty(CFLAGS:M*-fno-strict-aliasing*)
# WARNING: C99 (and C11) allow compilers to perform optimizations based on the
# "strict" aliasing, overflow, and enums rules which _will_ change the behaviour
# of previously correct C90 and earlier code!
CFLAGS += -fno-strict-aliasing
.endif

.if (defined(__GNUC__) && \
	${__GNUC__} >= 4 && ${__GNUC_MINOR__} >= 2) && \
	empty(CFLAGS:M*-fno-strict-overflow*)
# WARNING:  Prevent the optimizer from assuming that the program
# follows the strict signed overflow semantics permitted for the
# language.
CFLAGS += -fno-strict-overflow
.endif

# XXX in GCC -fstrict-enums apparently only applies to C++
.if defined(__GNUC__) && defined(__clang__) && \
	empty(CFLAGS:M*-fno-strict-enums*)
# WARNING:  Prevent the compiler from optimizing "using the assumption
# that a value of enumerated type can only be one of the values of the
# enumeration"
CFLAGS += -fno-strict-enums
.endif

.if (defined(__GNUC__) && !defined(__clang__) && \
	${__GNUC__} >= 4 && ${__GNUC_MINOR__} >= 2) && \
	empty(CFLAGS:M*-fno-strict-volatile-bitfields*)
# WARNING:  Force the compiler to always read the whole underlying value!
CFLAGS += -fno-strict-volatile-bitfields
.endif

# Dunno for sure if this is right, but Apple's PowerPC GCC-4.0.1 does not have
# stack-protector, however 4.1.x on many systems does....
#
# (gcc 4.4.3 from pkgsrc does not, sadly, as it is forced off in the
# build, but oddly it doesn't complain about the option -- it just
# fails to link programs because the option causes it to ask the
# linker for -lssp)
#
.if defined(__GNUC__) && \
	(${__GNUC__} > 4 || (${__GNUC__} == 4 && ${__GNUC_MINOR__} > 0)) && \
	empty(CFLAGS:M*-fstack-protector-all*)
CFLAGS +=	-fstack-protector-all
.endif

.if !empty(CFLAGS:M*-fstack-protector*) && \
	empty(CFLAGS:M*-Wstack-protector*) && \
	defined(CWARNFLAGS) && \
	empty(CWARNFLAGS:M*-Wstack-protector*)
CWARNFLAGS +=	-Wstack-protector
.endif

# XXX should probably consider adding the following, at least for GCC to avoid
# the worst cases of allowing the optimizer to abuse "undefined behaviour" in
# counter-productive ways (bugs should be bugs!):
#
#	-fwrapv -fno-delete-null-pointer-checks -fno-aggressive-loop-optimizations
#
# XXX the problem is we don't have a firm list of which optimizations are "total
# license" optimizations that abuse "undefined behaviour"
#
# XXX see also:  https://stackoverflow.com/questions/33278757/disable-all-optimization-options-in-gcc
#
# XXX worse yet GCC (and perhaps Clang) only warn about certain issues IFF they
# are abusing them.  For example GCC's -Wstrict-overlfow only works if
# -fstrict-overflow is enabled _and_ you have enabled a sufficient level of
# optimization to trigger it.  WTFH!?!?!?  The manual at least states this:
#
#	Note that it does not warn about all cases where the code might
#	overflow: it only warns about cases where the compiler implements some
#	optimization.  Thus this warning depends on the optimization level.

# This is a hack for my own NetBSD releases where older versions don't include
# CPPFLAGS in the LINK macro, so the ".c:" rule won't get CPPFLAGS..
#
# (Note:  it's tempting to include "&& empty(LINK.c:M*CPPFLAGS*)" in the
# expression, but that won't work because empty() expands the variable entirely
# before applying modifiers.)
.if !defined(MAKE_VERSION) && !empty(unix:M*NetBSD*) && !defined(COMPILE_LINK.c)
LDFLAGS += ${CPPFLAGS}
.endif

# This allows builds with a NetBSD cross-compiler toolchain (i.e. with
# "${TOOLDIR}/bin/nbmake-${MACHINE}")
.if !empty(_CCLINKFLAGS)
LDFLAGS += ${_CCLINKFLAGS}
.endif

# for sjg's Mk-files
#
# we disabled all the <warnings.mk> features above with NO_CFLAGS_WARNINGS, so
# now we need to include our warnings in CFLAGS...
#
.if defined(MAKE_VERSION) && ${MAKE} != "bsdmake" && (!defined(.FreeBSD) || ${.FreeBSD} != "true")
CFLAGS += ${CWARNFLAGS}
# xxx also this, as the default ".c:" rule, using ${LINK.c}, doesn't include it
LDFLAGS += ${LDSTATIC}
.endif