compiler/prelude: Keep nil slice nil when slicing. #852
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According to the Go specification: > If the sliced operand of a valid slice expression is a nil slice, > the result is a nil slice. This behavior was not implemented and not caught previously. This change fixes that. The minified prelude was regenerated with: go generate ./compiler/prelude Fixes #851.
Closed
hajimehoshi
reviewed
Aug 20, 2018
tests/misc_test.go
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| var s []int | ||
| s = s[:] | ||
| s = s[0:0] | ||
| s = s[0:0:0] |
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I'd add the same if s != nil above this
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Are you suggesting this in case one of the assigments makes s non-nil, but the following line makes it nil again, and we don't catch it?
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As s is expected to be nil, I thought you don't have to reassign nil, but probably reassiging would be better. Thanks!
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Yeah, I reassigned just to be sure that the error messages would be accurate if printed.
tests/misc_test.go
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| s = s[0:0] | ||
| s = s[0:0:0] | ||
| if s != nil { | ||
| t.Errorf("nil slice became non-nil after slicing: %#v", s) |
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I know the expectation, but would it be better to reword this including expectation?
tests/misc_test.go
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| var s = []int{} | ||
| s = s[:] | ||
| if s == nil { | ||
| t.Errorf("non-nil slice became nil after slicing: %#v", s) |
Use the more common "got <x>, want <y>" style.
|
Done, PTAL. |
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According to the Go specification:
This behavior was not implemented and not caught previously. Slicing a nil slice would incorrectly make it an empty but non-nil slice. This change fixes that.
The minified prelude was regenerated with:
Fixes #851.