xref: /freebsd/share/man/man5/style.Makefile.5 (revision ef91670a0ecbb570f0c08af1f617f3b40c41038a)

.\" Copyright (c) 2002-2003 David O'Brien <obrien@FreeBSD.org>
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.\" $FreeBSD$
.\"
.Dd February 28, 2003
.Dt STYLE.MAKEFILE 5
.Os
.Sh NAME
.Nm style.Makefile
.Nd
.Fx
.Pa Makefile
file style guide
.Sh DESCRIPTION
This file specifies the preferred style for makefiles in the
.Fx
source tree.
.Bl -bullet
.It
All makefiles should have an SCM ID at the start of the file,
followed by a blank line.
.Bd -literal
# $FreeBSD\&$

.Ed
.It
.Cm .PATH :
comes next if needed, and is spelled
.Dq Li ".PATH: " ,
with a single
.Tn ASCII
space after a colon.
.It
Special variables (i.e.,
.Va LIB , SRCS , MLINKS ,
etc.) are listed in order of
.Dq product ,
then building and installing a binary.
The general order is:
.Va PROG Ns / Ns Va LIB Ns / Ns Va SCRIPT
.Va FILES
.Va LINKS
.Oo Va NO Oc Ns Va MAN
.Va MLINKS
.Va INCS
.Va SRCS
.Va WARNS
.Va CFLAGS
.Va DPADD
.Va LDADD .
.It
Omit
.Va SRCS
when using
.Aq Pa bsd.prog.mk
and there is a single source file named the same as the
.Va PROG .
.It
Omit
.Va MAN
when using
.Aq Pa bsd.prog.mk
and the manual page is named the same as the
.Va PROG ,
and is in section 1.
.It
All variable assignments are spelled
.Dq Va VAR Ns Ic = ,
i.e., no space between the variable name and the
.Ic = .
Keep values sorted alphabetically, if possible.
.It
Do not use
.Ic +=
to set variables that are only set once
(or to set variables for the first time).
.It
Do not use vertical whitespace in simple makefiles,
but do use it to group locally related things in more complex/longer ones.
.It
.Va WARNS
comes before
.Va CFLAGS ,
as it is basically a
.Va CFLAGS
modifier.
It comes before
.Va CFLAGS
rather than after
.Va CFLAGS
so it does not get lost in a sea of
.Va CFLAGS
statements as
.Va WARNS
is an important thing.
.It
Unconditional
.Dq Li "NO_WERROR= yes"
should not be used,
it defeats the purpose of
.Va WARNS .
.It
.Va CFLAGS
is spelled
.Dq Li "CFLAGS+= " .
.It
Listing
.Fl D Ns 's
before
.Fl I Ns 's
in
.Va CFLAGS
is preferred for alphabetical ordering and to make
.Fl D Ns 's
easier to see.
The
.Fl D Ns 's
often affect conditional compilation,
and
.Fl I Ns 's
tend to be quite long.
.It
Do not use GCCisms (such as
.Fl g
and
.Fl Wall )
in
.Va CFLAGS .
.It
Typically, there is one
.Tn ASCII
tab between
.Va VAR Ns Ic =
and the value in order to start the value in column 9.
An
.Tn ASCII
space is allowed for variable names that extend beyond column 9.
A lack of whitespace is also allowed for very long variable names.
.It
.Ic .include Aq Pa bsd.*.mk
goes last.
.El
.Pp
The desire to express a logical grouping often means not obeying some of the
above.
.Sh EXAMPLE
The simplest program
.Pa Makefile
is:
.Bd -literal -offset indent
# $FreeBSD\&$

PROG=	foo

\&.include <bsd.prog.mk>
.Ed
.Pp
The simplest library
.Pa Makefile
is:
.Bd -literal -offset indent
# $FreeBSD\&$

LIB=	foo
SHLIB_MAJOR= 1
MAN=	libfoo.3
SRCS=	foo.c

\&.include <bsd.lib.mk>
.Ed
.Sh SEE ALSO
.Xr make 1 ,
.Xr style 9
.Sh HISTORY
This manual page is inspired from the same source as
.Xr style 9
manual page in
.Fx .
.Sh BUGS
There are few hard and fast style rules here.
The style of many things is too dependent on the context of the whole makefile,
or the lines surrounding it.