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goby-lang / goby

Goby - Yet another programming language written in Go
MIT License
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Invalid`#name` causes panic instead of error in some cases #258

Closed hachi8833 closed 7 years ago

hachi8833 commented 7 years ago

Can be reproduced both normal run and REPL.

a.name #=> UndefinedMethodError: Undefined Method 'a' for <Instance of: Object>
a = "aa"
a.name #=> panic

Looks like #name often causes panic on other objects.

st0012 commented 7 years ago

@hachi8833 Can you also paste stack traces of the panic? Thanks! (This would be helpful so please also paste them in future issues.)

hachi8833 commented 7 years ago

I got it!

Correction: I found the issue above on "enhancement/issue-174-and-issue-194" branch while reviewing. Now I checked this in master branch that the issue persists.

» a = "aa"
#=>
» a.name
Internal Error: interface conversion: vm.Object is *vm.StringObject, not *vm.RClass
panic: interface conversion: vm.Object is *vm.StringObject, not *vm.RClass [recovered]
    panic: interface conversion: vm.Object is *vm.StringObject, not *vm.RClass

goroutine 1 [running]:
github.com/goby-lang/goby/vm.(*thread).execInstruction.func1(0xc42012f1a0)
    /Users/hachi8833/deve/golang/gopath/sys/src/github.com/goby-lang/goby/vm/thread.go:71 +0x81
panic(0x1335bc0, 0xc4200169c0)
    /usr/local/opt/go/libexec/src/runtime/panic.go:489 +0x2cf
github.com/goby-lang/goby/vm.builtinClassClassMethods.func5.1(0xc42012f1a0, 0x155aa38, 0x0, 0x0, 0x0, 0xc42001a592, 0x4)
    /Users/hachi8833/deve/golang/gopath/sys/src/github.com/goby-lang/goby/vm/class.go:525 +0x9b
github.com/goby-lang/goby/vm.(*thread).evalBuiltInMethod(0xc42012f1a0, 0x1512a80, 0xc42000c400, 0xc4200edce0, 0x0, 0x0, 0x1, 0x0)
    /Users/hachi8833/deve/golang/gopath/sys/src/github.com/goby-lang/goby/vm/thread.go:130 +0x202
github.com/goby-lang/goby/vm.glob..func21(0xc42012f1a0, 0xc42001d880, 0xc42000c560, 0x2, 0x2)
    /Users/hachi8833/deve/golang/gopath/sys/src/github.com/goby-lang/goby/vm/instruction.go:363 +0x397
github.com/goby-lang/goby/vm.(*thread).execInstruction(0xc42012f1a0, 0xc42001d880, 0xc420018c30)
    /Users/hachi8833/deve/golang/gopath/sys/src/github.com/goby-lang/goby/vm/thread.go:75 +0x96
github.com/goby-lang/goby/vm.(*thread).evalCallFrame(0xc42012f1a0, 0xc42001d880)
    /Users/hachi8833/deve/golang/gopath/sys/src/github.com/goby-lang/goby/vm/thread.go:42 +0x60
github.com/goby-lang/goby/vm.(*thread).startFromTopFrame(0xc42012f1a0)
    /Users/hachi8833/deve/golang/gopath/sys/src/github.com/goby-lang/goby/vm/thread.go:36 +0x55
github.com/goby-lang/goby/vm.(*VM).startFromTopFrame(0xc420114120)
    /Users/hachi8833/deve/golang/gopath/sys/src/github.com/goby-lang/goby/vm/vm.go:192 +0x2f
github.com/goby-lang/goby/vm.(*VM).REPLExec(0xc420114120, 0xc42000e040, 0x1, 0x1)
    /Users/hachi8833/deve/golang/gopath/sys/src/github.com/goby-lang/goby/vm/repl.go:43 +0x66a
github.com/goby-lang/goby/igb.StartIgb(0x1397639, 0x5)
    /Users/hachi8833/deve/golang/gopath/sys/src/github.com/goby-lang/goby/igb/repl.go:184 +0xb5d
main.main()
    /Users/hachi8833/deve/golang/gopath/sys/src/github.com/goby-lang/goby/goby.go:27 +0x657
st0012 commented 7 years ago

@hachi8833 This is a easy one. It's because String doesn't implement name method, so the method lookup reached Class#name. And since we don't check type assertion's result and returns right error message (my bad), it just panic.

Alexius-Huang commented 7 years ago

Closed with PR #282 Merged