Zuo: support cross compilation via configure and CC_FOR_BUILD

Makefile.in

@@ -17,14 +17,19 @@ CPPFLAGS = @CPPFLAGS@
 LDFLAGS = @LDFLAGS@
 LIBS = @LIBS@
 
+CC_FOR_BUILD = @CC_FOR_BUILD@
+CFLAGS_FOR_BUILD = @CFLAGS_FOR_BUILD@
+LDFLAGS_FOR_BUILD = @LDFLAGS_FOR_BUILD@
+LIBS_FOR_BUILD = @LIBS_FOR_BUILD@
+
 EMBED_LIBS = @EMBED_LIBS@
 
 .PHONY: zuos-to-run-and-install
 zuos-to-run-and-install: zuo
 	./zuo . zuos-to-run-and-install
 
 zuo: $(srcdir)/zuo.c
-	$(CC) $(CPPFLAGS) $(CFLAGS) -DZUO_LIB_PATH='"'"$(srcdir)/lib"'"' -o zuo $(srcdir)/zuo.c $(LDFLAGS) $(LIBS)
+	$(CC_FOR_BUILD) $(FLAGS_FOR_BUILD) -DZUO_LIB_PATH='"'"$(srcdir)/lib"'"' -o zuo $(srcdir)/zuo.c $(LDFLAGS_FOR_BUILD) $(LIBS_FOR_BUILD)
 
 .PHONY: check
 check: zuo

README.md

@@ -87,6 +87,16 @@ A boot image is machine-independent, whether in a stand-alone file or
 embedded in `.c` source.
 
 
+Cross Compiling
+---------------
+
+If you use `./configure --host=...` to cross compile, then you will
+also need to add something like `CC_FOR_BUILD=cc` as a `./configure`
+argument to specify the compiler for a `zuo` to use on the build
+machine. If necessary, you can also specify `CFLAGS_FOR_BUILD`,
+`LDFLAGS_FOR_BUILD`, and/or `LIBS_FOR_BUILD`.
+
+
 Embedding Zuo in Another Application
 ------------------------------------
 

configure

@@ -589,6 +589,10 @@ enable_embed="zuo"
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
 EMBED_LIBS
+LIBS_FOR_BUILD
+LDFLAGS_FOR_BUILD
+CFLAGS_FOR_BUILD
+CC_FOR_BUILD
 OBJEXT
 EXEEXT
 ac_ct_CC
@@ -2584,6 +2588,17 @@ ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $
 ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
 
+if test "${CC_FOR_BUILD}" = ""; then
+  CC_FOR_BUILD='$(CC) -O2'
+  CFLAGS_FOR_BUILD='$(CPPFLAGS) $(CFLAGS)'
+  LDFLAGS_FOR_BUILD='$(LDFLAGS)'
+  LIBS_FOR_BUILD='$(LIBS)'
+fi
+
+
+
+
+
 
 { $as_echo "$as_me:${as_lineno-$LINENO}: zuo libraries to embed: \"${EMBED_LIBS}\"" >&5
 $as_echo "$as_me: zuo libraries to embed: \"${EMBED_LIBS}\"" >&6;}

configure.ac

@@ -25,6 +25,17 @@ AS_IF([test "x$enable_embed" = xno],
 AC_PROG_MAKE_SET()
 AC_PROG_CC
 
+if test "${CC_FOR_BUILD}" = ""; then
+  CC_FOR_BUILD='$(CC) -O2'
+  CFLAGS_FOR_BUILD='$(CPPFLAGS) $(CFLAGS)'
+  LDFLAGS_FOR_BUILD='$(LDFLAGS)'
+  LIBS_FOR_BUILD='$(LIBS)'
+fi
+AC_SUBST(CC_FOR_BUILD)
+AC_SUBST(CFLAGS_FOR_BUILD)
+AC_SUBST(LDFLAGS_FOR_BUILD)
+AC_SUBST(LIBS_FOR_BUILD)
+
 AC_SUBST(EMBED_LIBS)
 AC_MSG_NOTICE([zuo libraries to embed: "${EMBED_LIBS}"])