Update and fix staticcheck

vendor/honnef.co/go/tools/ir/const.go

@@ -0,0 +1,153 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+// This file defines the Const SSA value type.
+
+import (
+	"fmt"
+	"go/constant"
+	"go/types"
+	"strconv"
+)
+
+// NewConst returns a new constant of the specified value and type.
+// val must be valid according to the specification of Const.Value.
+//
+func NewConst(val constant.Value, typ types.Type) *Const {
+	return &Const{
+		register: register{
+			typ: typ,
+		},
+		Value: val,
+	}
+}
+
+// intConst returns an 'int' constant that evaluates to i.
+// (i is an int64 in case the host is narrower than the target.)
+func intConst(i int64) *Const {
+	return NewConst(constant.MakeInt64(i), tInt)
+}
+
+// nilConst returns a nil constant of the specified type, which may
+// be any reference type, including interfaces.
+//
+func nilConst(typ types.Type) *Const {
+	return NewConst(nil, typ)
+}
+
+// stringConst returns a 'string' constant that evaluates to s.
+func stringConst(s string) *Const {
+	return NewConst(constant.MakeString(s), tString)
+}
+
+// zeroConst returns a new "zero" constant of the specified type,
+// which must not be an array or struct type: the zero values of
+// aggregates are well-defined but cannot be represented by Const.
+//
+func zeroConst(t types.Type) *Const {
+	switch t := t.(type) {
+	case *types.Basic:
+		switch {
+		case t.Info()&types.IsBoolean != 0:
+			return NewConst(constant.MakeBool(false), t)
+		case t.Info()&types.IsNumeric != 0:
+			return NewConst(constant.MakeInt64(0), t)
+		case t.Info()&types.IsString != 0:
+			return NewConst(constant.MakeString(""), t)
+		case t.Kind() == types.UnsafePointer:
+			fallthrough
+		case t.Kind() == types.UntypedNil:
+			return nilConst(t)
+		default:
+			panic(fmt.Sprint("zeroConst for unexpected type:", t))
+		}
+	case *types.Pointer, *types.Slice, *types.Interface, *types.Chan, *types.Map, *types.Signature:
+		return nilConst(t)
+	case *types.Named:
+		return NewConst(zeroConst(t.Underlying()).Value, t)
+	case *types.Array, *types.Struct, *types.Tuple:
+		panic(fmt.Sprint("zeroConst applied to aggregate:", t))
+	}
+	panic(fmt.Sprint("zeroConst: unexpected ", t))
+}
+
+func (c *Const) RelString(from *types.Package) string {
+	var p string
+	if c.Value == nil {
+		p = "nil"
+	} else if c.Value.Kind() == constant.String {
+		v := constant.StringVal(c.Value)
+		const max = 20
+		// TODO(adonovan): don't cut a rune in half.
+		if len(v) > max {
+			v = v[:max-3] + "..." // abbreviate
+		}
+		p = strconv.Quote(v)
+	} else {
+		p = c.Value.String()
+	}
+	return fmt.Sprintf("Const <%s> {%s}", relType(c.Type(), from), p)
+}
+
+func (c *Const) String() string {
+	return c.RelString(c.Parent().pkg())
+}
+
+// IsNil returns true if this constant represents a typed or untyped nil value.
+func (c *Const) IsNil() bool {
+	return c.Value == nil
+}
+
+// Int64 returns the numeric value of this constant truncated to fit
+// a signed 64-bit integer.
+//
+func (c *Const) Int64() int64 {
+	switch x := constant.ToInt(c.Value); x.Kind() {
+	case constant.Int:
+		if i, ok := constant.Int64Val(x); ok {
+			return i
+		}
+		return 0
+	case constant.Float:
+		f, _ := constant.Float64Val(x)
+		return int64(f)
+	}
+	panic(fmt.Sprintf("unexpected constant value: %T", c.Value))
+}
+
+// Uint64 returns the numeric value of this constant truncated to fit
+// an unsigned 64-bit integer.
+//
+func (c *Const) Uint64() uint64 {
+	switch x := constant.ToInt(c.Value); x.Kind() {
+	case constant.Int:
+		if u, ok := constant.Uint64Val(x); ok {
+			return u
+		}
+		return 0
+	case constant.Float:
+		f, _ := constant.Float64Val(x)
+		return uint64(f)
+	}
+	panic(fmt.Sprintf("unexpected constant value: %T", c.Value))
+}
+
+// Float64 returns the numeric value of this constant truncated to fit
+// a float64.
+//
+func (c *Const) Float64() float64 {
+	f, _ := constant.Float64Val(c.Value)
+	return f
+}
+
+// Complex128 returns the complex value of this constant truncated to
+// fit a complex128.
+//
+func (c *Const) Complex128() complex128 {
+	re, _ := constant.Float64Val(constant.Real(c.Value))
+	im, _ := constant.Float64Val(constant.Imag(c.Value))
+	return complex(re, im)
+}