Build dub from source on the auto-tester

posix.mak

@@ -518,7 +518,7 @@ build-html:
 ################################################################################
 
 ${TOOLS_DIR}:
-	git clone --depth=1 ${GIT_HOME}/$(@F) $@
+	[ -d $@ ] || git clone --depth=1 ${GIT_HOME}/$(@F) $@
 
 $(TOOLS_DIR)/checkwhitespace.d: | $(TOOLS_DIR)
 $(TOOLS_DIR)/tests_extractor.d: | $(TOOLS_DIR)
@@ -601,13 +601,27 @@ style_lint: dscanner $(LIB)
 	@echo "Check that Ddoc runs without errors"
 	$(DMD) $(DFLAGS) $(NODEFAULTLIB) $(LIB) -w -D -Df/dev/null -main -c -o- $$(find etc std -type f -name '*.d') 2>&1
 
+################################################################################
+# Build dub from source if no dub is available
+################################################################################
+
+DUB_PATH=$(abspath $(shell which $(DUB)))
+ifeq (,$(DUB_PATH))
+	DUB_PATH=$(ROOT)/dub/bin/dub
+	DUB=$(DUB_PATH)
+endif
+
+$(DUB): | $(LIB)
+	[ -d $(ROOT)/dub ] || git clone --depth=1 ${GIT_HOME}/dub $(ROOT)/dub
+	cd $(ROOT)/dub && DFLAGS="$(DFLAGS) $(LIB) $(NODEFAULTLIB) $(LINKDL)" DMD=$(shell pwd)/$(DMD) ./build.sh
+
 ################################################################################
 # Build the test extractor.
 # - extracts and runs public unittest examples to checks for missing imports
 # - extracts and runs @betterC unittests
 ################################################################################
 
-$(TESTS_EXTRACTOR): $(TOOLS_DIR)/tests_extractor.d | $(LIB)
+$(TESTS_EXTRACTOR): $(TOOLS_DIR)/tests_extractor.d | $(DUB) $(LIB)
 	DFLAGS="$(DFLAGS) $(LIB) $(NODEFAULTLIB) $(LINKDL)" $(DUB) build --force --compiler=$${PWD}/$(DMD) --single $<
 	mv $(TOOLS_DIR)/tests_extractor $@
 
@@ -661,6 +675,7 @@ betterc-run-tests: $(subst .d,.run,$(wildcard test/betterC/*.d))
 auto-tester-build: all checkwhitespace
 
 .PHONY : auto-tester-test
-auto-tester-test: unittest betterc
+auto-tester-test: unittest
+	$(MAKE) -f posix.mak betterc
 
 .DELETE_ON_ERROR: # GNU Make directive (delete output files on error)