Adding go 1.2.

It doesn't include godoc anymore.

I could reproduce this, building this package:
http://code.google.com/p/go/issues/detail?id=6999

pkgs/development/compilers/go/1.2.nix

@@ -0,0 +1,88 @@
+{ stdenv, fetchurl, bison, glibc, bash, coreutils, makeWrapper, tzdata, iana_etc
+, removeGodocExternals ? false }:
+
+let
+  loader386 = "${glibc}/lib/ld-linux.so.2";
+  loaderAmd64 = "${glibc}/lib/ld-linux-x86-64.so.2";
+  loaderArm = "${glibc}/lib/ld-linux.so.3";
+in
+
+stdenv.mkDerivation {
+  name = "go-1.2";
+
+  src = fetchurl {
+    url = http://go.googlecode.com/files/go1.2.src.tar.gz;
+    sha1 = "7dd2408d40471aeb30a9e0b502c6717b5bf383a5";
+  };
+
+  buildInputs = [ bison glibc bash makeWrapper ];
+
+  # I'm not sure what go wants from its 'src', but the go installation manual
+  # describes an installation keeping the src.
+  preUnpack = ''
+    mkdir -p $out/share
+    cd $out/share
+  '';
+
+  prePatch = ''
+    cd ..
+    if [ ! -d go ]; then
+      mv * go
+    fi
+    cd go
+
+    patchShebangs ./ # replace /bin/bash
+    # !!! substituteInPlace does not seems to be effective.
+    sed -i 's,/lib/ld-linux.so.2,${loader386},' src/cmd/8l/asm.c
+    sed -i 's,/lib64/ld-linux-x86-64.so.2,${loaderAmd64},' src/cmd/6l/asm.c
+    sed -i 's,/lib64/ld-linux-x86-64.so.3,${loaderArm},' src/cmd/5l/asm.c
+    sed -i 's,/usr/share/zoneinfo/,${tzdata}/share/zoneinfo/,' src/pkg/time/zoneinfo_unix.go
+    sed -i 's,/etc/protocols,${iana_etc}/etc/protocols,' src/pkg/net/lookup_unix.go
+
+    #sed -i -e 's,/bin/cat,${coreutils}/bin/cat,' \
+    #  -e 's,/bin/echo,${coreutils}/bin/echo,' \
+    #  src/pkg/exec/exec_test.go
+
+    # Disabling the 'os/http/net' tests (they want files not available in
+    # chroot builds)
+    rm src/pkg/net/{multicast_test.go,parse_test.go,port_test.go}
+    # The os test wants to read files in an existing path. Just it don't be /usr/bin.
+    sed -i 's,/usr/bin,'"`pwd`", src/pkg/os/os_test.go
+    sed -i 's,/bin/pwd,'"`type -P pwd`", src/pkg/os/os_test.go
+    # Disable the hostname test
+    sed -i '/TestHostname/areturn' src/pkg/os/os_test.go
+  '' + stdenv.lib.optionalString removeGodocExternals ''
+    sed -i -e '/googleapi/d' -e '/javascript">$/,+6d' lib/godoc/godoc.html 
+  '';
+
+  patches = [ ./cacert-1.2.patch ];
+
+  GOOS = "linux";
+  GOARCH = if stdenv.system == "i686-linux" then "386"
+          else if stdenv.system == "x86_64-linux" then "amd64"
+          else if stdenv.system == "armv5tel-linux" then "arm"
+          else throw "Unsupported system";
+  GOARM = stdenv.lib.optionalString (stdenv.system == "armv5tel-linux") "5";
+
+  installPhase = ''
+    mkdir -p "$out/bin"
+    export GOROOT="$(pwd)/"
+    export GOBIN="$out/bin"
+    export PATH="$GOBIN:$PATH"
+    cd ./src
+    ./all.bash
+    cd -
+
+    # Copy the emacs configuration for Go files.
+    mkdir -p "$out/share/emacs/site-lisp"
+    cp ./misc/emacs/* $out/share/emacs/site-lisp/
+  '';
+
+  meta = {
+    homepage = http://golang.org/;
+    description = "The Go Programming language";
+    license = "BSD";
+    maintainers = with stdenv.lib.maintainers; [ pierron viric ];
+    platforms = stdenv.lib.platforms.linux;
+  };
+}

pkgs/development/compilers/go/cacert-1.2.patch

@@ -0,0 +1,15 @@
+Go comes with hardcoded cacert. We add the usual in NixOS,
+for easier NixOS life.
+
+diff --git a/src/pkg/crypto/x509/root_unix.go b/src/pkg/crypto/x509/root_unix.go
+index 76e79f4..6ef1dd3 100644
+--- a/src/pkg/crypto/x509/root_unix.go
++++ b/src/pkg/crypto/x509/root_unix.go
+@@ -15,6 +15,7 @@ var certFiles = []string{
+	"/etc/ssl/ca-bundle.pem",                 // OpenSUSE
+	"/etc/ssl/cert.pem",                      // OpenBSD
+	"/usr/local/share/certs/ca-root-nss.crt", // FreeBSD/DragonFly
++	"/etc/ssl/certs/ca-bundle.crt",           // NixOS
+ }
+ 
+ func (c *Certificate) systemVerify(opts *VerifyOptions) (chains [][]*Certificate, err error) {

pkgs/top-level/all-packages.nix

@@ -2789,6 +2789,8 @@ let
     else
       callPackage ../development/compilers/go/1.1.nix { };
 
+  go_1_2 = callPackage ../development/compilers/go/1.2.nix { };
+
   go = go_1_1;
 
   gprolog = callPackage ../development/compilers/gprolog { };