Simplify passing of build variables, show them in logs

Makefile

@@ -5,45 +5,45 @@ GPRBUILD_OPTIONS                        := -j4
 
 # Build flags are commonly found in the environment, but if they are
 # set on our Make command line, forward them to GNAT projects.
-export ADAFLAGS                         ?=
-export LDFLAGS                          ?=
+ADAFLAGS                                ?=
+LDFLAGS                                 ?=
 
 # For the library, a static archive is built by default but a
 # non-empty shared object version selects a relocatable library
-export latin_utils_soversion            :=
+latin_utils_soversion                   :=
 
 # Directory where dictionnary files are created and searched for.
 # This variable is expected to be overridden at build time, with some
 # architecture-specific value like $(prefix)/share/whitakers-words).
 # At run time, another directory can be selected via the
 # WHITAKERS_WORDS_DATADIR environment variable.
 datadir                                 := .
-# During (re)builds, the tools must read and test the fresh data and
-# ignore any previous version already installed in $(datadir).
-export WHITAKERS_WORDS_DATADIR := .
+
+generated_sources := src/latin_utils/latin_utils-config.adb
 
 # If a relocatable library has been selected, tell the dynamic loader
 # where to find it during tests or generation of the dictionaries.
 ifneq (,$(latin_utils_soversion))
-  export LD_LIBRARY_PATH := $(if $(LD_LIBRARY_PATH),$(LD_LIBRARY_PATH):)lib/latin_utils-dynamic
+  maybe_lib_path := \
+    LD_LIBRARY_PATH=$(if $(LD_LIBRARY_PATH),'$(LD_LIBRARY_PATH)':)lib/latin_utils-dynamic \
+    $()
 endif
 
-generated_sources := src/latin_utils/latin_utils-config.adb
-
 # It is convenient to let gprbuild deal with Ada dependencies, and
 # only then let a submake decide which data must be refreshed
 # according to the now up-to-date timestamps of the generators.
 .PHONY: all
 all: commands
-	$(MAKE) -f Makefile.data.mk
+	$(maybe_lib_path)WHITAKERS_WORDS_DATADIR=. $(MAKE) -f Makefile.data.mk
 
 # This target is more efficient than separate gprbuild runs because
 # the dependency graph is only constructed once.
 # It is run either because by an explicit 'commands' target, or
 # because a generated file requires it.
 .PHONY: commands
 commands: $(generated_sources)
-	$(GPRBUILD) -p $(GPRBUILD_OPTIONS) commands.gpr
+	$(GPRBUILD) -p $(GPRBUILD_OPTIONS) commands.gpr \
+	  $(foreach v,ADAFLAGS LDFLAGS latin_utils_soversion,-X$(v)='$($(v))')
 
 .PHONY: clean
 clean:
@@ -56,4 +56,4 @@ $(generated_sources): %: %.in Makefile
 
 .PHONY: test
 test: all
-	cd test && ./run-tests.sh
+	$(maybe_lib_path)test/run-tests.sh