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// Copyright 2010 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 runtime
import _ "unsafe" // for go:linkname
// The Error interface identifies a run time error.
type Error interface {
error
// RuntimeError is a no-op function but
// serves to distinguish types that are run time
// errors from ordinary errors: a type is a
// run time error if it has a RuntimeError method.
RuntimeError()
}
// A TypeAssertionError explains a failed type assertion.
type TypeAssertionError struct {
interfaceString string
concreteString string
assertedString string
missingMethod string // one method needed by Interface, missing from Concrete
}
func (*TypeAssertionError) RuntimeError() {}
func (e *TypeAssertionError) Error() string {
inter := e.interfaceString
if inter == "" {
inter = "interface"
}
if e.concreteString == "" {
return "interface conversion: " + inter + " is nil, not " + e.assertedString
}
if e.missingMethod == "" {
return "interface conversion: " + inter + " is " + e.concreteString +
", not " + e.assertedString
}
return "interface conversion: " + e.concreteString + " is not " + e.assertedString +
": missing method " + e.missingMethod
}
// An errorString represents a runtime error described by a single string.
type errorString string
func (e errorString) RuntimeError() {}
func (e errorString) Error() string {
return "runtime error: " + string(e)
}
// plainError represents a runtime error described a string without
// the prefix "runtime error: " after invoking errorString.Error().
// See Issue #14965.
type plainError string
func (e plainError) RuntimeError() {}
func (e plainError) Error() string {
return string(e)
}
type stringer interface {
String() string
}
func typestring(x interface{}) string {
e := efaceOf(&x)
return e._type.string()
}
// For calling from C.
// Prints an argument passed to panic.
func printany(i interface{}) {
switch v := i.(type) {
case nil:
print("nil")
case stringer:
print(v.String())
case error:
print(v.Error())
case bool:
print(v)
case int:
print(v)
case int8:
print(v)
case int16:
print(v)
case int32:
print(v)
case int64:
print(v)
case uint:
print(v)
case uint8:
print(v)
case uint16:
print(v)
case uint32:
print(v)
case uint64:
print(v)
case uintptr:
print(v)
case float32:
print(v)
case float64:
print(v)
case complex64:
print(v)
case complex128:
print(v)
case string:
print(v)
default:
print("(", typestring(i), ") ", i)
}
}
// strings.IndexByte is implemented in runtime/asm_$goarch.s
// but amusingly we need go:linkname to get access to it here in the runtime.
//go:linkname stringsIndexByte strings.IndexByte
func stringsIndexByte(s string, c byte) int
// called from generated code
func panicwrap() {
pc := make([]uintptr, 1)
n := Callers(2, pc)
if n == 0 {
throw("panicwrap: Callers failed")
}
frames := CallersFrames(pc)
frame, _ := frames.Next()
name := frame.Function
// name is something like "main.(*T).F".
// We want to extract pkg ("main"), typ ("T"), and meth ("F").
// Do it by finding the parens.
i := stringsIndexByte(name, '(')
if i < 0 {
throw("panicwrap: no ( in " + frame.Function)
}
pkg := name[:i-1]
if i+2 >= len(name) || name[i-1:i+2] != ".(*" {
throw("panicwrap: unexpected string after package name: " + frame.Function)
}
name = name[i+2:]
i = stringsIndexByte(name, ')')
if i < 0 {
throw("panicwrap: no ) in " + frame.Function)
}
if i+2 >= len(name) || name[i:i+2] != ")." {
throw("panicwrap: unexpected string after type name: " + frame.Function)
}
typ := name[:i]
meth := name[i+2:]
panic(plainError("value method " + pkg + "." + typ + "." + meth + " called using nil *" + typ + " pointer"))
}