1# $NetBSD: deptgt-begin.mk,v 1.5 2020/11/15 22:28:08 rillig Exp $ 2# 3# Tests for the special target .BEGIN in dependency declarations, 4# which is a container for commands that are run before any other 5# commands from the shell lines. 6 7.BEGIN: 8 : $@ 9 10# To register a custom action to be run at the beginning, the simplest way is 11# to directly place some commands on the '.BEGIN' target. This doesn't scale 12# though, since the ':' dependency operator prevents that any other place may 13# add its commands after this. 14# 15# There are several ways to resolve this situation, which are detailed below. 16.BEGIN: 17 : Making another $@. 18 19# One way to run commands at the beginning is to define a custom target and 20# make the .BEGIN depend on that target. This way, the commands from the 21# custom target are run even before the .BEGIN target. 22.BEGIN: before-begin 23before-begin: .PHONY .NOTMAIN 24 : Making $@ before .BEGIN. 25 26# Another way is to define a custom target and make that a .USE dependency. 27# For the .BEGIN target, .USE dependencies do not work though, since in 28# Compat_Run, the .USE and .USEBEFORE nodes are expanded right after the 29# .BEGIN target has been run, which is too late. 30.BEGIN: use 31use: .USE .NOTMAIN 32 : Making $@ from a .USE dependency. 33 34# Same as with .USE, but run the commands before the main commands from the 35# .BEGIN target. 36# 37# For the .BEGIN target, .USEBEFORE dependencies do not work though, since in 38# Compat_Run, the .USE and .USEBEFORE nodes are expanded right after the 39# .BEGIN target has been run, which is too late. 40.BEGIN: use-before 41use-before: .USEBEFORE .NOTMAIN 42 : Making $@ from a .USEBEFORE dependency. 43 44all: 45 : $@ 46 47_!= echo : parse time 1>&2 48