From 982afa6bbcf48b2254e9fe532add5e57be36d237 Mon Sep 17 00:00:00 2001
From: Aaron LI <aly@aaronly.me>
Date: Sat, 15 Jun 2019 16:29:40 +0800
Subject: [PATCH] Makefile: Require explicit target

Explicit target (e.g., buildworld, buildkernel) is required, otherwise
fail with an error.

Obtained-from: FreeBSD
Bug-report: #3158
---
 Makefile | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index 5d02dc434c..66773c1b7b 100644
--- a/Makefile
+++ b/Makefile
@@ -118,10 +118,17 @@ ${TGTS} ${BITGTS}: .PHONY
 	@cd ${.CURDIR}; \
 		${MAKE} ${.TARGET}
 
-# Set a reasonable default
-.MAIN:	all
+# Fail with an error when no target is given.
+.MAIN: _guard
+
+_guard: .PHONY
+	@echo
+	@echo "Explicit target required.  See build(7)."
+	@echo
+	@false
 
 STARTTIME!= LC_ALL=C date
+
 #
 # world
 #
-- 
2.41.0