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go/types: remove superfluous code for shift checking

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Negative constant shift counts are already handled
earlier in the code. No need anymore for this extra
section.

With this change, the shift code matches types2
with respect to the function logic.

Change-Id: Ic8b7f382271c79ab66021e30955cd9bac092332b
Reviewed-on: https://go-review.googlesource.com/c/go/+/303093
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
This commit is contained in:
Robert Griesemer 2021-03-18 17:29:02 -07:00
parent e7aa0f9f28
commit cd26192aba
1 changed files with 1 additions and 15 deletions
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16
src/go/types/expr.go
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@ -805,20 +805,6 @@ func (check *Checker) shift(x, y *operand, e ast.Expr, op token.Token) {
return
}
var yval constant.Value
if y.mode == constant_ {
// rhs must be an integer value
// (Either it was of an integer type already, or it was
// untyped and successfully converted to a uint above.)
yval = constant.ToInt(y.val)
assert(yval.Kind() == constant.Int)
if constant.Sign(yval) < 0 {
check.invalidOp(y, _InvalidShiftCount, "negative shift count %s", y)
x.mode = invalid
return
}
}
if x.mode == constant_ {
if y.mode == constant_ {
// if either x or y has an unknown value, the result is unknown
@ -832,7 +818,7 @@ func (check *Checker) shift(x, y *operand, e ast.Expr, op token.Token) {
}
// rhs must be within reasonable bounds in constant shifts
const shiftBound = 1023 - 1 + 52 // so we can express smallestFloat64 (see issue #44057)
s, ok := constant.Uint64Val(yval)
s, ok := constant.Uint64Val(y.val)
if !ok || s > shiftBound {
check.invalidOp(y, _InvalidShiftCount, "invalid shift count %s", y)
x.mode = invalid