Comparing uncomparable types in 'is' crashes gpython

[xiaxinmeng]

In the following program, we compare two tuples with "is", while tuple types are uncomparable crashing gpython. We test it on the online gpython GO/wasm and Gopherjs.

test.py

e = (1, 2)
f = (1, 2)
print(e is f)

Output on GO/wasm(https://gpython.org/?wasm):

Gpython 3.4.0 running in your browser with go/wasm
>>> e = (1, 2)
>>> f = (1, 2)
>>> e is e
panic: runtime error: comparing uncomparable type py.Tuple
goroutine 5 [running]:
github.com/go-python/gpython/vm.do_COMPARE_OP(0xc0749a0, 0x8, 0x0, 0x0)
    /home/ncw/go/src/github.com/go-python/gpython/vm/eval.go:1051 +0x67
github.com/go-python/gpython/vm.RunFrame(0xc0e0630, 0x0, 0xc07bd18, 0x0, 0x0)
    /home/ncw/go/src/github.com/go-python/gpython/vm/eval.go:1785 +0x3f
github.com/go-python/gpython/vm.EvalCodeEx(0xc04c600, 0xc062db0, 0xc062db0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
    /home/ncw/go/src/github.com/go-python/gpython/vm/eval.go:2162 +0xa3
github.com/go-python/gpython/vm.Run(0xc062db0, 0xc062db0, 0xc04c600, 0x0, 0x0, 0x0, 0x0, 0x1, 0x9d240, 0xc04c600)
    /home/ncw/go/src/github.com/go-python/gpython/vm/eval.go:2182 +0x2
github.com/go-python/gpython/repl.(*REPL).Run(0xc09a6c0, 0xc01e740, 0x6)
    /home/ncw/go/src/github.com/go-python/gpython/repl/repl.go:99 +0x20
main.main.func1(0xc01e730, 0x2, 0x2)
    /home/ncw/go/src/github.com/go-python/gpython/repl/web/main.go:82 +0x4
syscall/js.callbackLoop()
    /opt/go/go1.11/src/syscall/js/callback.go:116 +0x7
created by syscall/js.NewCallback.func1
    /opt/go/go1.11/src/syscall/js/callback.go:40 +0x2
...

Output on Gopherjs (https://gpython.org/)

Gpython 3.4.0 running in your browser with gopherjs
>>> e = (1, 2)
>>> f = (1, 2)
>>> e is e
[USER]: https://gpython.org/gpython.js: runtime error: comparing uncomparable type py.Tuple
$callDeferred@https://gpython.org/gpython.js:4:22511
$panic@https://gpython.org/gpython.js:4:22957
AK@https://gpython.org/gpython.js:10:2429
$interfaceIsEqual@https://gpython.org/gpython.js:4:6214
CC@https://gpython.org/gpython.js:44:59553
DO@https://gpython.org/gpython.js:44:91592
DU@https://gpython.org/gpython.js:44:107450
DW@https://gpython.org/gpython.js:44:109015
G.ptr.prototype.Run@https://gpython.org/gpython.js:56:3575
$b@https://gpython.org/gpython.js:60:3908
$b@https://gpython.org/gpython.js:59:2625
r@https://gpython.org/gpython.js:4:23443
$runScheduled@https://gpython.org/gpython.js:4:24007
$schedule@https://gpython.org/gpython.js:4:24184
$go@https://gpython.org/gpython.js:4:23907
I/$packages["github.com/gopherjs/gopherwasm/js"]<@https://gpython.org/gpython.js:59:2240
$externalizeFunction/e.$externalizeWrapper@https://gpython.org/gpython.js:4:28925
a@https://cdnjs.cloudflare.com/ajax/libs/jquery.terminal/1.23.2/js/jquery.terminal.min.js:40:82615
k@https://cdnjs.cloudflare.com/ajax/libs/jquery.terminal/1.23.2/js/jquery.terminal.min.js:40:83463
ENTER@https://cdnjs.cloudflare.com/ajax/libs/jquery.terminal/1.23.2/js/jquery.terminal.min.js:40:14915
$e@https://cdnjs.cloudflare.com/ajax/libs/jquery.terminal/1.23.2/js/jquery.terminal.min.js:40:28362
dispatch@https://code.jquery.com/jquery-latest.js:4641:9
add/elemData.handle@https://code.jquery.com/jquery-latest.js:4309:28
...

[ncw]

I can confirm this.

I think it is more due to unimplemented parts of gpython than a bug.