From 4e84419b6c6c9511701f0f11554e9b161380a174 Mon Sep 17 00:00:00 2001
From: heck <heck@pep.foundation>
Date: Sat, 21 Sep 2024 07:51:42 +0200
Subject: [PATCH] Build: fix build conf concept

A build variable is evaluated like:
1.) if the var is already defined in the shell env, use that.
2.) if the var is defined in the the build.conf, use that.
3. fallback to using the var default in Makefile.conf
---
 Makefile.conf      | 14 ++++++--------
 build.conf.example |  8 ++++----
 2 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/Makefile.conf b/Makefile.conf
index 5b1120f..fdb69af 100644
--- a/Makefile.conf
+++ b/Makefile.conf
@@ -1,4 +1,5 @@
 HERE:=$(dir $(lastword $(MAKEFILE_LIST)))
+-include $(HERE)build.conf
 
 # Project Name
 TARGET?=perkons
@@ -7,20 +8,17 @@ TARGET?=perkons
 # common configurations:
 # use DEBUG = 1 and OPT = -Og for debugging
 # or DEBUG = 0 and OPT = -O3 for performance
-DEBUG=0
-OPT=-O3
+DEBUG?=0
+OPT?=-O3
 
 # (optional) Includes FatFS source files within project.
 #USE_FATFS = 1
 
 # Relative to dir 'src'
-LIBDAISY_DIR=../../heck_libDaisy
-DAISYSP_DIR=../../heck_DaisySP
-
- CXXFLAGS+=-Wall -Wno-unused -Wno-reorder-ctor -Wno-switch
+LIBDAISY_DIR?=../../heck_libDaisy
+DAISYSP_DIR?=../../heck_DaisySP
 
-######### Overrides from build.conf #########
--include $(HERE)build.conf
+CXXFLAGS+=-Wall -Wno-unused -Wno-reorder-ctor -Wno-switch
 
 ifneq (,$(findstring g++,$(CXX)))
     CXXFLAGS+=-fdiagnostics-color=always
diff --git a/build.conf.example b/build.conf.example
index de4b963..8f67bd4 100644
--- a/build.conf.example
+++ b/build.conf.example
@@ -3,10 +3,10 @@
 
 # The program to compile and flash
 # the name of the main cxx file without the prefix 'main_'
-TARGET=perkons
+TARGET?=perkons
 
-DEBUG=0
+DEBUG?=0
 
 # Daisy dependencies Relative to dir 'src'
-LIBDAISY_DIR=../../heck_libDaisy
-DAISYSP_DIR=../../heck_DaisySP
+LIBDAISY_DIR?=../../heck_libDaisy
+DAISYSP_DIR?=../../heck_DaisySP