go/constant: MakeFloat64(0) must return a value of Float kind
Fixes #42641.
Change-Id: I10fdc7c90054b37ab5b303999015262691c12927
Reviewed-on: https://go-review.googlesource.com/c/go/+/273126
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
diff --git a/src/go/constant/value.go b/src/go/constant/value.go
index 4baae2e..4641442 100644
--- a/src/go/constant/value.go
+++ b/src/go/constant/value.go
@@ -370,16 +370,13 @@
}
// MakeFloat64 returns the Float value for x.
+// If x is -0.0, the result is 0.0.
// If x is not finite, the result is an Unknown.
func MakeFloat64(x float64) Value {
if math.IsInf(x, 0) || math.IsNaN(x) {
return unknownVal{}
}
- // convert -0 to 0
- if x == 0 {
- return int64Val(0)
- }
- return ratVal{newRat().SetFloat64(x)}
+ return ratVal{newRat().SetFloat64(x + 0)} // convert -0 to 0
}
// MakeFromLiteral returns the corresponding integer, floating-point,
diff --git a/src/go/constant/value_test.go b/src/go/constant/value_test.go
index 5edc766..2866774 100644
--- a/src/go/constant/value_test.go
+++ b/src/go/constant/value_test.go
@@ -7,6 +7,7 @@
import (
"fmt"
"go/token"
+ "math"
"math/big"
"strings"
"testing"
@@ -620,6 +621,42 @@
}
}
+func TestMakeFloat64(t *testing.T) {
+ var zero float64
+ for _, arg := range []float64{
+ -math.MaxFloat32,
+ -10,
+ -0.5,
+ -zero,
+ zero,
+ 1,
+ 10,
+ 123456789.87654321e-23,
+ 1e10,
+ math.MaxFloat64,
+ } {
+ val := MakeFloat64(arg)
+ if val.Kind() != Float {
+ t.Errorf("%v: got kind = %d; want %d", arg, val.Kind(), Float)
+ }
+
+ // -0.0 is mapped to 0.0
+ got, exact := Float64Val(val)
+ if !exact || math.Float64bits(got) != math.Float64bits(arg+0) {
+ t.Errorf("%v: got %v (exact = %v)", arg, got, exact)
+ }
+ }
+
+ // infinity
+ for sign := range []int{-1, 1} {
+ arg := math.Inf(sign)
+ val := MakeFloat64(arg)
+ if val.Kind() != Unknown {
+ t.Errorf("%v: got kind = %d; want %d", arg, val.Kind(), Unknown)
+ }
+ }
+}
+
type makeTestCase struct {
kind Kind
arg, want interface{}
