.testing: Target build uses its own Makefile

The build/target/MOM6 rule was modified so that build/target is now a
symlink into build/target_codebase/.testing/build/symmetric.

In other words, build/target now uses the entire build system of
target_codebase (i.e. the reference codebase) rather than borrowing from
bits and pieces of the current codebase.

This should prevent potential false positives in future regression tests
related to buildsystem changes.

Several apparently unused blocks of rules and other content in
.testing/Makefile have also been removed.

.testing/Makefile

@@ -133,9 +133,6 @@ TIME ?= time
 WORKSPACE ?= .
 
 # Set directories for build/ and work/
-#BUILD ?= $(WORKSPACE)build
-#DEPS ?= $(BUILD)/deps
-#WORK ?= $(WORKSPACE)work
 BUILD ?= $(WORKSPACE)/build
 DEPS ?= $(BUILD)/deps
 WORK ?= $(WORKSPACE)/work
@@ -207,34 +204,6 @@ else
 endif
 
 
-# List of source files to link this Makefile's dependencies to model Makefiles
-# Assumes a depth of two, and the following extensions: F90 inc c h
-# (1): Root directory
-# NOTE: extensions could be a second variable
-SOURCE = \
-  $(foreach ext,F90 inc c h,$(wildcard $(1)/*/*.$(ext) $(1)/*/*/*.$(ext)))
-
-MOM_SOURCE = \
-  $(call SOURCE,../src) \
-  $(wildcard ../config_src/drivers/solo_driver/*.F90) \
-  $(wildcard ../config_src/ext*/*/*.F90)
-
-TARGET_SOURCE = \
-  $(call SOURCE,$(BUILD)/target_codebase/src) \
-  $(wildcard $(BUILD)/target_codebase/config_src/drivers/solo_driver/*.F90) \
-  $(wildcard $(BUILD)target_codebase/config_src/ext*/*.F90)
-
-ifeq ($(FRAMEWORK), fms1)
-  MOM_SOURCE += $(wildcard ../config_src/infra/FMS1/*.F90)
-  TARGET_SOURCE += $(wildcard $(BUILD)/target_codebase/config_src/infra/FMS1/*.F90)
-else
-  MOM_SOURCE +=$(wildcard ../config_src/infra/FMS2/*.F90)
-  TARGET_SOURCE += $(wildcard $(BUILD)/target_codebase/config_src/infra/FMS2/*.F90)
-endif
-
-FMS_SOURCE = $(call SOURCE,$(DEPS)/fms/src)
-
-
 ## Rules
 
 .PHONY: all build.regressions build.prof
@@ -297,11 +266,21 @@ $(BUILD)/timing/Makefile: MOM_ACFLAGS += --with-driver=timing_tests
 $(BUILD)/unit/test_%: $(BUILD)/unit/Makefile FORCE
 	cd $(@D) && $(TIME) $(MAKE) $(@F) -j
 $(BUILD)/unit/Makefile: $(foreach e,$(UNIT_EXECS),../config_src/drivers/unit_tests/$(e).F90)
+
 $(BUILD)/timing/time_%: $(BUILD)/timing/Makefile FORCE
 	cd $(@D) && $(TIME) $(MAKE) $(@F) -j
 $(BUILD)/timing/Makefile: $(foreach e,$(TIMING_EXECS),../config_src/drivers/timing_tests/$(e).F90)
+
 $(BUILD)/%/MOM6: $(BUILD)/%/Makefile FORCE
 	cd $(@D) && $(TIME) $(MAKE) $(@F) -j
+
+# Target codebase should use its own build system
+$(BUILD)/target/MOM6: $(BUILD)/target FORCE | $(TARGET_CODEBASE)
+	$(MAKE) -C $(TARGET_CODEBASE)/.testing build/symmetric/MOM6
+
+$(BUILD)/target: | $(TARGET_CODEBASE)
+	ln -s $(abspath $(TARGET_CODEBASE))/.testing/build/symmetric $@
+
 FORCE:
 
 
@@ -333,27 +312,12 @@ $(BUILD)/%/configure.ac: ../ac/configure.ac | $(BUILD)/%/
 $(BUILD)/%/m4/: ../ac/m4/ | $(BUILD)/%/
 	cp -r ../ac/m4 $(@D)
 
-ALL_EXECS = symmetric asymmetric repro openmp target opt opt_target coupled \
-  nuopc cov unit timing
+ALL_EXECS = symmetric asymmetric repro openmp opt opt_target coupled nuopc \
+  cov unit timing
 $(foreach b,$(ALL_EXECS),$(BUILD)/$(b)/):
 	mkdir -p $@
 
 # Fetch the regression target codebase
-
-$(BUILD)/target/config.status: $(BUILD)/target/configure $(DEPS)/lib/libFMS.a
-	cd $(@D) && $(MOM_ENV) ./configure -n \
-	  --srcdir=$(abspath $(BUILD))/target_codebase/ac $(MOM_ACFLAGS) \
-	|| (cat config.log && false)
-
-$(BUILD)/target/Makefile.in: | $(TARGET_CODEBASE) $(BUILD)/target/
-	cp $(TARGET_CODEBASE)/ac/Makefile.in $(@D)
-
-$(BUILD)/target/configure.ac: | $(TARGET_CODEBASE) $(BUILD)/target/
-	cp $(TARGET_CODEBASE)/ac/configure.ac $(@D)
-
-$(BUILD)/target/m4/: | $(TARGET_CODEBASE) $(BUILD)/target/
-	cp -r $(TARGET_CODEBASE)/ac/m4 $(@D)
-
 $(TARGET_CODEBASE):
 	git clone --recursive $(MOM_TARGET_URL) $@
 	cd $@ && git checkout --recurse-submodules $(MOM_TARGET_BRANCH)