go/types: untyped shifted constants must fit their expected int type

Fixes #22969.

Change-Id: Ie9d1748c36864a81a633f0016594912ac7dfc005
Reviewed-on: https://go-review.googlesource.com/c/144385
Reviewed-by: Alan Donovan <adonovan@google.com>

diff --git a/src/go/types/expr.go b/src/go/types/expr.go
index 35e9b36f31c63372c51d892b438b082ff943d96b..0dc007069fadfff623587568d486f35b3b7a9780 100644 (file)
--- a/src/go/types/expr.go
+++ b/src/go/types/expr.go
@@ -461,7 +461,11 @@ func (check *Checker) updateExprType(x ast.Expr, typ Type, final bool) {
                        check.invalidOp(x.Pos(), "shifted operand %s (type %s) must be integer", x, typ)
                        return
                }
-       } else if old.val != nil {
+               // Even if we have an integer, if the value is a constant we
+               // still must check that it is representable as the specific
+               // int type requested (was issue #22969). Fall through here.
+       }
+       if old.val != nil {
                // If x is a constant, it must be representable as a value of typ.
                c := operand{old.mode, x, old.typ, old.val, 0}
                check.convertUntyped(&c, typ)

diff --git a/src/go/types/testdata/shifts.src b/src/go/types/testdata/shifts.src
index ca288290d69cea9bd6932f9858d33b017d760517..52e340ec65cb3659b4aafe6911f336525eaa3de8 100644 (file)
--- a/src/go/types/testdata/shifts.src
+++ b/src/go/types/testdata/shifts.src
@@ -354,3 +354,15 @@ func issue21727() {
        var _ = string(1 << s)
        var _ = string(1.0 /* ERROR "cannot convert" */ << s)
 }
+
+func issue22969() {
+       var s uint
+       var a []byte
+       _ = a[0xffffffffffffffff /* ERROR "overflows int" */ <<s] // example from issue 22969
+       _ = make([]int, 0xffffffffffffffff /* ERROR "overflows int" */ << s)
+       _ = make([]int, 0, 0xffffffffffffffff /* ERROR "overflows int" */ << s)
+       var _ byte = 0x100 /* ERROR "overflows byte" */ << s
+       var _ int8 = 0xff /* ERROR "overflows int8" */ << s
+       var _ int16 = 0xffff /* ERROR "overflows int16" */ << s
+       var _ int32 = 0x80000000 /* ERROR "overflows int32" */ << s
+}
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