Re: [PATCH v3 06/12] Makefile: Split $(FLAGS) into cpp and cc components

[Stefano Brivio <sbrivio@redhat.com>]

On Tue, 12 May 2026 15:52:50 +1000
David Gibson <david@gibson.dropbear.id.au> wrote:

> The $(FLAGS) variable contains mandatory compiler flags that should not be
> overridden.  However, it contains a mixture of flags for the preprocessor
> and for the compiler proper.  That's causing some inconvenience for other
> Makefile cleanups, so split it into $(BASE_CPPFLAGS) and $(BASE_CFLAGS)
> variables.
> 
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> ---
>  Makefile | 40 ++++++++++++++++++++++++----------------
>  1 file changed, 24 insertions(+), 16 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index a8f8d06e..697f229f 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -30,12 +30,17 @@ ifeq ($(shell $(CC) -O2 -dM -E - < /dev/null 2>&1 | grep ' _FORTIFY_SOURCE ' > /
>  FORTIFY_FLAG := -D_FORTIFY_SOURCE=2
>  endif
>  
> -FLAGS := -Wall -Wextra -Wno-format-zero-length -Wformat-security
> -FLAGS += -pedantic -std=c11 -D_XOPEN_SOURCE=700 -D_GNU_SOURCE
> -FLAGS +=  $(FORTIFY_FLAG) -O2 -pie -fPIE
> -FLAGS += -DPAGE_SIZE=$(shell getconf PAGE_SIZE)
> -FLAGS += -DVERSION=\"$(VERSION)\"
> -FLAGS += -DDUAL_STACK_SOCKETS=$(DUAL_STACK_SOCKETS)
> +# Mandatory preprocessor flags that won't be overridden with $(CPPFLAGS)
> +# FIXME: Could some of these be default, rather than required?
> +BASE_CPPFLAGS := -D_XOPEN_SOURCE=700 -D_GNU_SOURCE $(FORTIFY_FLAG)
> +BASE_CPPFLAGS += -DPAGE_SIZE=$(shell getconf PAGE_SIZE)
> +BASE_CPPFLAGS += -DVERSION=\"$(VERSION)\"
> +BASE_CPPFLAGS += -DDUAL_STACK_SOCKETS=$(DUAL_STACK_SOCKETS)
> +
> +# Mandatory compiler flags that won't be overridden with $(CFLAGS)
> +# FIXME: Could some of these be default, rather than required?
> +BASE_CFLAGS := -std=c11 -pie -fPIE -O2
> +BASE_CFLAGS += -pedantic -Wall -Wextra -Wno-format-zero-length -Wformat-security
>  
>  PASST_SRCS = arch.c arp.c bitmap.c checksum.c conf.c dhcp.c dhcpv6.c \
>  	epoll_ctl.c flow.c fwd.c fwd_rule.c icmp.c igmp.c inany.c iov.c ip.c \
> @@ -62,11 +67,11 @@ PASST_REPAIR_HEADERS = linux_dep.h
>  
>  C := \#include <sys/random.h>\nint main(){int a=getrandom(0, 0, 0);}
>  ifeq ($(shell printf "$(C)" | $(CC) -S -xc - -o - >/dev/null 2>&1; echo $$?),0)
> -	FLAGS += -DHAS_GETRANDOM
> +	BASE_CPPFLAGS += -DHAS_GETRANDOM
>  endif
>  
>  ifeq ($(shell :|$(CC) -fstack-protector-strong -S -xc - -o - >/dev/null 2>&1; echo $$?),0)
> -	FLAGS += -fstack-protector-strong
> +	BASE_CFLAGS += -fstack-protector-strong
>  endif
>  
>  prefix		?= /usr/local
> @@ -89,7 +94,8 @@ endif
>  
>  all: $(BIN) $(MANPAGES) docs
>  
> -static: FLAGS += -static -DGLIBC_NO_STATIC_NSS
> +static: BASE_CPPFLAGS += -DGLIBC_NO_STATIC_NSS
> +static: BASE_CFLAGS += -static 

Trailing whitespace I fixed up on merge.

-- 
Stefano