libgo patch committed: Build libnetgo.a

[Ian Lance Taylor]

PR 63731 points out that when using gccgo there is no way to request a
Go program that uses the native Go DNS lookup code rather than using
the system libraries.  This patch from Lynn Boger at least provides a
mechanism for that, by adding a -lnetgo library that can be used to
pick up the Go DNS lookup routines.  This isn't complete fix because
we still need to document it somewhere.  Bootstrapped on
x86_64-unknown-linux-gnu.  Committed to mainline.

Ian

diff -r 9ea7cea1d658 libgo/Makefile.am
--- a/libgo/Makefile.am Mon Apr 06 18:15:34 2015 -0700
+++ b/libgo/Makefile.am Tue Apr 07 11:08:23 2015 -0700
@@ -105,7 +105,7 @@
 toolexeclib_LIBRARIES = libgobegin-llgo.a
 else
 toolexeclib_LTLIBRARIES = libgo.la
-toolexeclib_LIBRARIES = libgobegin.a
+toolexeclib_LIBRARIES = libgobegin.a libnetgo.a
 endif
 
 toolexeclibgo_DATA = \
@@ -774,9 +774,7 @@
 endif
 endif
 
-go_net_files = \
-       go/net/cgo_unix.go \
-       $(go_net_cgo_file) \
+go_net_common_files = \
        $(go_net_cloexec_file) \
        go/net/dial.go \
        go/net/dnsclient.go \
@@ -820,6 +818,15 @@
        go/net/unixsock.go \
        go/net/unixsock_posix.go
 
+go_net_files = \
+       go/net/cgo_unix.go \
+       $(go_net_cgo_file) \
+       $(go_net_common_files)
+
+go_netgo_files = \
+       go/net/cgo_stub.go \
+       $(go_net_common_files)
+
 if LIBGO_IS_SOLARIS
 if LIBGO_IS_386
 go_os_dir_file = go/os/dir_largefile.go
@@ -2025,6 +2032,9 @@
 libgobegin_llgo_a_SOURCES = \
        runtime/go-main.c
 
+libnetgo_a_SOURCES = $(go_netgo_files)
+libnetgo_a_LIBADD = netgo.o
+
 LTLDFLAGS = $(shell $(SHELL) $(top_srcdir)/../libtool-ldflags $(LDFLAGS))
 
 GOCFLAGS = $(CFLAGS)
@@ -2049,6 +2059,12 @@
        files=`echo $^ | sed -e 's/[^ ]*\.gox//g'`; \
        $(LTGOCOMPILE) -I . -c -fgo-pkgpath=`echo $@ | sed -e 's/.lo$$//' -e 
's/-go$$//'` -o $@ $$files
 
+# Build netgo.o.
+BUILDNETGO = \
+       $(MKDIR_P) $(@D); \
+       files=`echo $^ | sed -e 's/[^ ]*\.gox//g'`; \
+       $(GOCOMPILE) -I . -c -fgo-pkgpath=net -o $@ $$files
+
 GOTESTFLAGS =
 GOBENCH = 
 
@@ -2270,6 +2286,12 @@
        @$(CHECK)
 .PHONY: net/check
 
+@go_include@ netgo.o.dep
+netgo.o.dep: $(go_netgo_files)
+       $(BUILDDEPS)
+netgo.o: $(go_netgo_files)
+       $(BUILDNETGO)
+
 @go_include@ os.lo.dep
 os.lo.dep: $(go_os_files)
        $(BUILDDEPS)