From 2c52e3f969827fbba60224b15b4da0f867e62a26 Mon Sep 17 00:00:00 2001
From: Roland Coeurjoly <rolandcoeurjoly@gmail.com>
Date: Thu, 11 Apr 2024 16:28:36 +0200
Subject: [PATCH] Support out of tree builds

---
 Makefile | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index 8b38e7153..1da42b778 100644
--- a/Makefile
+++ b/Makefile
@@ -5,7 +5,8 @@ AR   := ar
 LD   := $(CXX)
 
 MSG_PREFIX ?=
-ABCSRC = .
+ABCSRC ?= .
+VPATH = $(ABCSRC)
 
 $(info $(MSG_PREFIX)Using CC=$(CC))
 $(info $(MSG_PREFIX)Using CXX=$(CXX))
@@ -41,7 +42,7 @@ default: $(PROG)
 ARCHFLAGS_EXE ?= ./arch_flags
 
 $(ARCHFLAGS_EXE) : arch_flags.c
-	$(CC) arch_flags.c -o $(ARCHFLAGS_EXE)
+	$(CC) $< -o $(ARCHFLAGS_EXE)
 
 INCLUDES += -I$(ABCSRC)/src
 
@@ -173,26 +174,32 @@ DEP := $(OBJ:.o=.d)
 # implicit rules
 
 %.o: %.c
+	@mkdir -p $(dir $@)
 	@echo "$(MSG_PREFIX)\`\` Compiling:" $(LOCAL_PATH)/$<
 	$(VERBOSE)$(CC) -c $(OPTFLAGS) $(INCLUDES) $(CFLAGS) $< -o $@
 
 %.o: %.cc
+	@mkdir -p $(dir $@)
 	@echo "$(MSG_PREFIX)\`\` Compiling:" $(LOCAL_PATH)/$<
 	$(VERBOSE)$(CXX) -c $(OPTFLAGS) $(INCLUDES) $(CXXFLAGS) $< -o $@
 
 %.o: %.cpp
+	@mkdir -p $(dir $@)
 	@echo "$(MSG_PREFIX)\`\` Compiling:" $(LOCAL_PATH)/$<
 	$(VERBOSE)$(CXX) -c $(OPTFLAGS) $(INCLUDES) $(CXXFLAGS) $< -o $@
 
 %.d: %.c
+	@mkdir -p $(dir $@)
 	@echo "$(MSG_PREFIX)\`\` Generating dependency:" $(LOCAL_PATH)/$<
 	$(VERBOSE)$(ABCSRC)/depends.sh "$(CC)" `dirname $*.c` $(OPTFLAGS) $(INCLUDES) $(CFLAGS) $< > $@
 
 %.d: %.cc
+	@mkdir -p $(dir $@)
 	@echo "$(MSG_PREFIX)\`\` Generating dependency:" $(LOCAL_PATH)/$<
 	$(VERBOSE)$(ABCSRC)/depends.sh "$(CXX)" `dirname $*.cc` $(OPTFLAGS) $(INCLUDES) $(CXXFLAGS) $< > $@
 
 %.d: %.cpp
+	@mkdir -p $(dir $@)
 	@echo "$(MSG_PREFIX)\`\` Generating dependency:" $(LOCAL_PATH)/$<
 	$(VERBOSE)$(ABCSRC)/depends.sh "$(CXX)" `dirname $*.cpp` $(OPTFLAGS) $(INCLUDES) $(CXXFLAGS) $< > $@