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author | Rob Findley <rfindley@google.com> | 2021-02-11 10:17:39 -0500 |
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committer | Robert Findley <rfindley@google.com> | 2021-02-13 00:39:59 +0000 |
commit | a7e9b4b94804a1fbefc0c012ec510f4ee0837ffa (patch) | |
tree | 023f921e5aa81d6394b128b6dc9ddfcad72a91f5 /src/go/types/expr.go | |
parent | 060fa49bd23d758a9062f4cb50e65960ec9662f1 (diff) | |
download | go-a7e9b4b94804a1fbefc0c012ec510f4ee0837ffa.tar.gz go-a7e9b4b94804a1fbefc0c012ec510f4ee0837ffa.zip |
[dev.regabi] go/types: untyped shift counts must fit into uint
This is a port of CL 283872 to go/types. It differs from that CL only in
added error codes.
For #43697
Change-Id: I62277834cef1c0359bcf2c6ee4388731babbc855
Reviewed-on: https://go-review.googlesource.com/c/go/+/291316
Trust: Robert Findley <rfindley@google.com>
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
Diffstat (limited to 'src/go/types/expr.go')
-rw-r--r-- | src/go/types/expr.go | 26 |
1 files changed, 18 insertions, 8 deletions
diff --git a/src/go/types/expr.go b/src/go/types/expr.go index 1a3c486af7..7f8aaed411 100644 --- a/src/go/types/expr.go +++ b/src/go/types/expr.go @@ -730,14 +730,14 @@ func (check *Checker) comparison(x, y *operand, op token.Token) { // If e != nil, it must be the shift expression; it may be nil for non-constant shifts. func (check *Checker) shift(x, y *operand, e ast.Expr, op token.Token) { - untypedx := isUntyped(x.typ) + // TODO(gri) This function seems overly complex. Revisit. var xval constant.Value if x.mode == constant_ { xval = constant.ToInt(x.val) } - if isInteger(x.typ) || untypedx && xval != nil && xval.Kind() == constant.Int { + if isInteger(x.typ) || isUntyped(x.typ) && xval != nil && xval.Kind() == constant.Int { // The lhs is of integer type or an untyped constant representable // as an integer. Nothing to do. } else { @@ -749,16 +749,26 @@ func (check *Checker) shift(x, y *operand, e ast.Expr, op token.Token) { // spec: "The right operand in a shift expression must have integer type // or be an untyped constant representable by a value of type uint." - switch { - case isInteger(y.typ): - // nothing to do - case isUntyped(y.typ): + + // Provide a good error message for negative shift counts. + if y.mode == constant_ { + yval := constant.ToInt(y.val) // consider -1, 1.0, but not -1.1 + if yval.Kind() == constant.Int && constant.Sign(yval) < 0 { + check.invalidOp(y, _InvalidShiftCount, "negative shift count %s", y) + x.mode = invalid + return + } + } + + // Caution: Check for isUntyped first because isInteger includes untyped + // integers (was bug #43697). + if isUntyped(y.typ) { check.convertUntyped(y, Typ[Uint]) if y.mode == invalid { x.mode = invalid return } - default: + } else if !isInteger(y.typ) { check.invalidOp(y, _InvalidShiftCount, "shift count %s must be integer", y) x.mode = invalid return @@ -816,7 +826,7 @@ func (check *Checker) shift(x, y *operand, e ast.Expr, op token.Token) { } // non-constant shift with constant lhs - if untypedx { + if isUntyped(x.typ) { // spec: "If the left operand of a non-constant shift // expression is an untyped constant, the type of the // constant is what it would be if the shift expression |