PATCH RFA: build machinery: Add Go support to libtool

[Ian Lance Taylor <iant at google dot com>]

This patch, similar to the one I just sent for config/go.m4, adds Go
support to libtool.  This is not used by anything at present, but will
be used by libgo when it is committed.  I have proposed a similar patch
to the libtool maintainers.  When gcc includes a version of libtool with
support for Go, this patch can go away.

Bootstrapped on x86_64-unknown-linux-gnu.  OK for mainline?

Ian

Index: libtool.m4
===================================================================
--- libtool.m4	(revision 166249)
+++ libtool.m4	(working copy)
@@ -799,6 +799,7 @@ AC_DEFUN([LT_LANG],
 m4_case([$1],
   [C],			[_LT_LANG(C)],
   [C++],		[_LT_LANG(CXX)],
+  [Go],			[_LT_LANG(GO)],
   [Java],		[_LT_LANG(GCJ)],
   [Fortran 77],		[_LT_LANG(F77)],
   [Fortran],		[_LT_LANG(FC)],
@@ -850,6 +851,10 @@ AC_PROVIDE_IFELSE([AC_PROG_GCJ],
        m4_ifdef([LT_PROG_GCJ],
 	[m4_define([LT_PROG_GCJ], defn([LT_PROG_GCJ])[LT_LANG(GCJ)])])])])])
 
+AC_PROVIDE_IFELSE([AC_PROG_GO],
+  [LT_LANG(GO)],
+  [m4_define([AC_PROG_GO], defn([AC_PROG_GO])[LT_LANG(GO)])])
+
 AC_PROVIDE_IFELSE([LT_PROG_RC],
   [LT_LANG(RC)],
   [m4_define([LT_PROG_RC], defn([LT_PROG_RC])[LT_LANG(RC)])])
@@ -6495,6 +6500,10 @@ public class foo {
   }
 };
 _LT_EOF
+], [$1], [GO], [cat > conftest.$ac_ext <<_LT_EOF
+package foo
+func foo() { }
+_LT_EOF
 ])
 dnl Parse the compiler output and extract the necessary
 dnl objects, libraries and library flags.
@@ -6988,6 +6997,71 @@ GCC=$lt_save_GCC
 CC="$lt_save_CC"
 ])# _LT_LANG_GCJ_CONFIG
 
+# _LT_LANG_GO_CONFIG([TAG])
+# --------------------------
+# Ensure that the configuration variables for the GNU Go compiler
+# are suitably defined.  These variables are subsequently used by _LT_CONFIG
+# to write the compiler configuration to `libtool'.
+m4_defun([_LT_LANG_GO_CONFIG],
+[AC_REQUIRE([LT_PROG_GO])dnl
+AC_LANG_SAVE
+
+# Source file extension for Go test sources.
+ac_ext=go
+
+# Object file extension for compiled Go test sources.
+objext=o
+_LT_TAGVAR(objext, $1)=$objext
+
+# Code to be used in simple compile tests
+lt_simple_compile_test_code="package main; func main() { }"
+
+# Code to be used in simple link tests
+lt_simple_link_test_code='package main; func main() { }'
+
+# ltmain only uses $CC for tagged configurations so make sure $CC is set.
+_LT_TAG_COMPILER
+
+# save warnings/boilerplate of simple test code
+_LT_COMPILER_BOILERPLATE
+_LT_LINKER_BOILERPLATE
+
+# Allow CC to be a program name with arguments.
+lt_save_CC="$CC"
+lt_save_GCC="$GCC"
+GCC=yes
+CC=${GOC-"gccgo"}
+compiler=$CC
+_LT_TAGVAR(compiler, $1)=$CC
+_LT_TAGVAR(LD, $1)="$LD"
+_LT_CC_BASENAME([$compiler])
+
+# Go did not exist at the time GCC didn't implicitly link libc in.
+_LT_TAGVAR(archive_cmds_need_lc, $1)=no
+
+_LT_TAGVAR(old_archive_cmds, $1)=$old_archive_cmds
+
+## CAVEAT EMPTOR:
+## There is no encapsulation within the following macros, do not change
+## the running order or otherwise move them around unless you know exactly
+## what you are doing...
+if test -n "$compiler"; then
+  _LT_COMPILER_NO_RTTI($1)
+  _LT_COMPILER_PIC($1)
+  _LT_COMPILER_C_O($1)
+  _LT_COMPILER_FILE_LOCKS($1)
+  _LT_LINKER_SHLIBS($1)
+  _LT_LINKER_HARDCODE_LIBPATH($1)
+
+  _LT_CONFIG($1)
+fi
+
+AC_LANG_RESTORE
+
+GCC=$lt_save_GCC
+CC="$lt_save_CC"
+])# _LT_LANG_GO_CONFIG
+
 
 # _LT_LANG_RC_CONFIG([TAG])
 # -------------------------
@@ -7054,6 +7128,11 @@ AU_ALIAS([LT_AC_PROG_GCJ], [LT_PROG_GCJ]
 dnl aclocal-1.4 backwards compatibility:
 dnl AC_DEFUN([LT_AC_PROG_GCJ], [])
 
+# LT_PROG_GO
+# -----------
+AC_DEFUN([LT_PROG_GO],
+[AC_CHECK_TOOL(GOC, gccgo,)
+])
 
 # LT_PROG_RC
 # ----------
Index: ltmain.sh
===================================================================
--- ltmain.sh	(revision 166249)
+++ ltmain.sh	(working copy)
@@ -1390,7 +1390,7 @@ func_mode_compile ()
     *.[cCFSifmso] | \
     *.ada | *.adb | *.ads | *.asm | \
     *.c++ | *.cc | *.ii | *.class | *.cpp | *.cxx | \
-    *.[fF][09]? | *.for | *.java | *.obj | *.sx | *.cu | *.cup)
+    *.[fF][09]? | *.for | *.java | *.go | *.obj | *.sx | *.cu | *.cup)
       func_xform "$libobj"
       libobj=$func_xform_result
       ;;