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dmitshurdmitshur
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compiler/prelude: Keep nil slice nil when slicing. (gopherjs#852)
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. Slicing a nil slice would incorrectly make it an empty but non-nil slice. This change fixes that. The minified prelude was regenerated with: go generate ./compiler/prelude Fixes gopherjs#851.
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‎compiler/prelude/prelude.go

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Original file line numberDiff line numberDiff line change
@@ -107,6 +107,9 @@ var $subslice = function(slice, low, high, max) {
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if (low < 0 || high < low || max < high || high > slice.$capacity || max > slice.$capacity) {
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$throwRuntimeError("slice bounds out of range");
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}
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if (slice === slice.constructor.nil) {
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return slice;
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}
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var s = new slice.constructor(slice.$array);
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s.$offset = slice.$offset + low;
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s.$length = high - low;

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