tamer: configure.ac: Configure-time feature flags (via Cargo)

tamer/Makefile.am

@@ -25,7 +25,7 @@
 CARGO_BUILD_FLAGS=@CARGO_BUILD_FLAGS@
 
 all:
-	@CARGO@ build $(CARGO_BUILD_FLAGS)
+	@CARGO@ build $(CARGO_BUILD_FLAGS) @FEATURES@
 
 doc: html
 html-am:
@@ -35,13 +35,13 @@ html-am:
 # note that 'cargo check' is something else; see 'cargo --help'
 test: check
 check-am: check-fmt
-	@CARGO@ test
+	@CARGO@ test @FEATURES@
 
 check-fmt:
 	@CARGO@ fmt -- --check
 
 bench:
-	@CARGO@ @CARGO_BENCH_FLAGS@ bench
+	@CARGO@ @CARGO_BENCH_FLAGS@ bench @FEATURES@
 
 fix: fmt
 fmt:

tamer/configure.ac

@@ -92,6 +92,14 @@ AS_IF([cargo $CARGO_DOC_FLAGS doc --help &>/dev/null],
        AC_MSG_WARN([missing cargo-doc for toolchain])
        AC_MSG_WARN([`make html` will not work])])
 
+AC_ARG_VAR([FEATURES],
+           [Cargo features flags for TAMER, comma-delimited])
+
+test -z "$FEATURES" || {
+  AC_MSG_RESULT([requested features: $FEATURES])
+  FEATURES="--features $FEATURES"
+}
+
 AC_CONFIG_FILES([Makefile])
 
 AC_OUTPUT