Current File : //usr/local/go119/src/cmd/compile/internal/noder/quirks.go
// UNREVIEWED
// Copyright 2021 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 noder
import (
"fmt"
"cmd/compile/internal/syntax"
)
// This file defines helper functions useful for satisfying toolstash
// -cmp when compared against the legacy frontend behavior, but can be
// removed after that's no longer a concern.
// typeExprEndPos returns the position that noder would leave base.Pos
// after parsing the given type expression.
func typeExprEndPos(expr0 syntax.Expr) syntax.Pos {
for {
switch expr := expr0.(type) {
case *syntax.Name:
return expr.Pos()
case *syntax.SelectorExpr:
return expr.X.Pos()
case *syntax.ParenExpr:
expr0 = expr.X
case *syntax.Operation:
assert(expr.Op == syntax.Mul)
assert(expr.Y == nil)
expr0 = expr.X
case *syntax.ArrayType:
expr0 = expr.Elem
case *syntax.ChanType:
expr0 = expr.Elem
case *syntax.DotsType:
expr0 = expr.Elem
case *syntax.MapType:
expr0 = expr.Value
case *syntax.SliceType:
expr0 = expr.Elem
case *syntax.StructType:
return expr.Pos()
case *syntax.InterfaceType:
expr0 = lastFieldType(expr.MethodList)
if expr0 == nil {
return expr.Pos()
}
case *syntax.FuncType:
expr0 = lastFieldType(expr.ResultList)
if expr0 == nil {
expr0 = lastFieldType(expr.ParamList)
if expr0 == nil {
return expr.Pos()
}
}
case *syntax.IndexExpr: // explicit type instantiation
targs := unpackListExpr(expr.Index)
expr0 = targs[len(targs)-1]
default:
panic(fmt.Sprintf("%s: unexpected type expression %v", expr.Pos(), syntax.String(expr)))
}
}
}
func lastFieldType(fields []*syntax.Field) syntax.Expr {
if len(fields) == 0 {
return nil
}
return fields[len(fields)-1].Type
}
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