From fe9704dbd6b27dee8e0433b4ae64ab2a43a6a0f0 Mon Sep 17 00:00:00 2001
From: Juan Carrano <j.carrano@fu-berlin.de>
Date: Tue, 6 Nov 2018 18:59:15 +0100
Subject: [PATCH] makefiles/tools/serial: ensure PORT is set and fail early.

By ensuring the PORT auto-detection worked, we can give meaningful
error messages and fail earlier.

This uses ensure_value from makefiles/utils/checks.mk. An include was
added to Makefile.include to make this fuction available to all other
makefiles.
---
 Makefile.include              | 3 +++
 makefiles/tools/serial.inc.mk | 7 ++-----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/Makefile.include b/Makefile.include
index da39ecaadf..b93ab1d273 100644
--- a/Makefile.include
+++ b/Makefile.include
@@ -106,6 +106,9 @@ OS := $(shell uname)
 # set python path, e.g. for tests
 PYTHONPATH := $(RIOTBASE)/dist/pythonlibs/:$(PYTHONPATH)
 
+# Basic utilities included before anything else
+include $(RIOTMAKE)/utils/checks.mk
+
 # Include Docker settings near the top because we need to build the environment
 # command line before some of the variable origins are overwritten below when
 # using abspath, strip etc.
diff --git a/makefiles/tools/serial.inc.mk b/makefiles/tools/serial.inc.mk
index 215a5057e8..84144166e0 100644
--- a/makefiles/tools/serial.inc.mk
+++ b/makefiles/tools/serial.inc.mk
@@ -1,12 +1,9 @@
 # set default port depending on operating system
 OS := $(shell uname)
 ifeq ($(OS),Linux)
-  PORT ?= $(PORT_LINUX)
+  PORT ?= $(call ensure_value,$(PORT_LINUX),No port set)
 else ifeq ($(OS),Darwin)
-  PORT ?= $(PORT_DARWIN)
-endif
-ifeq ($(PORT),)
-  $(info Warning: no PORT set!)
+  PORT ?= $(call ensure_value,$(PORT_DARWIN),No port set)
 endif
 
 export BAUD ?= 115200