What version of Go are you using (go version)?

$ go version
go version go1.9rc2 linux/amd64

What operating system and processor architecture are you using (go env)?

$ go env
GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/esmarques/go"
GORACE=""
GOROOT="/usr/local/go1.9rc2.linux-amd64"
GOTOOLDIR="/usr/local/go1.9rc2.linux-amd64/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build080353435=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"

What did you do?

Need API to retrieve error from GetAttribLocation().

What did you expect to see?

GetAttribLocation() returns -1 on error:
https://www.khronos.org/registry/OpenGL-Refpages/es3.0/html/glGetAttribLocation.xhtml
I would expect to be able to detect the -1 using the API in https://godoc.org/golang.org/x/mobile/gl

What did you see instead?

GetAttribLocation() currently returns result as Attrib.Value (uint) which can't deliver the error -1.
https://godoc.org/golang.org/x/mobile/gl#Attrib