1 files changed, 330 insertions, 0 deletions
diff --git a/src/runtime/error.go b/src/runtime/error.go
new file mode 100644
index 0000000..b507f25
--- /dev/null
+++ b/src/runtime/error.go
@@ -0,0 +1,330 @@
+// 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 "internal/bytealg"
+
+// 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 {
+	_interface    *_type
+	concrete      *_type
+	asserted      *_type
+	missingMethod string // one method needed by Interface, missing from Concrete
+}
+
+func (*TypeAssertionError) RuntimeError() {}
+
+func (e *TypeAssertionError) Error() string {
+	inter := "interface"
+	if e._interface != nil {
+		inter = toRType(e._interface).string()
+	}
+	as := toRType(e.asserted).string()
+	if e.concrete == nil {
+		return "interface conversion: " + inter + " is nil, not " + as
+	}
+	cs := toRType(e.concrete).string()
+	if e.missingMethod == "" {
+		msg := "interface conversion: " + inter + " is " + cs + ", not " + as
+		if cs == as {
+			// provide slightly clearer error message
+			if toRType(e.concrete).pkgpath() != toRType(e.asserted).pkgpath() {
+				msg += " (types from different packages)"
+			} else {
+				msg += " (types from different scopes)"
+			}
+		}
+		return msg
+	}
+	return "interface conversion: " + cs + " is not " + as +
+		": missing method " + e.missingMethod
+}
+
+// itoa converts val to a decimal representation. The result is
+// written somewhere within buf and the location of the result is returned.
+// buf must be at least 20 bytes.
+//
+//go:nosplit
+func itoa(buf []byte, val uint64) []byte {
+	i := len(buf) - 1
+	for val >= 10 {
+		buf[i] = byte(val%10 + '0')
+		i--
+		val /= 10
+	}
+	buf[i] = byte(val + '0')
+	return buf[i:]
+}
+
+// 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)
+}
+
+type errorAddressString struct {
+	msg  string  // error message
+	addr uintptr // memory address where the error occurred
+}
+
+func (e errorAddressString) RuntimeError() {}
+
+func (e errorAddressString) Error() string {
+	return "runtime error: " + e.msg
+}
+
+// Addr returns the memory address where a fault occurred.
+// The address provided is best-effort.
+// The veracity of the result may depend on the platform.
+// Errors providing this method will only be returned as
+// a result of using [runtime/debug.SetPanicOnFault].
+func (e errorAddressString) Addr() uintptr {
+	return e.addr
+}
+
+// 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)
+}
+
+// A boundsError represents an indexing or slicing operation gone wrong.
+type boundsError struct {
+	x int64
+	y int
+	// Values in an index or slice expression can be signed or unsigned.
+	// That means we'd need 65 bits to encode all possible indexes, from -2^63 to 2^64-1.
+	// Instead, we keep track of whether x should be interpreted as signed or unsigned.
+	// y is known to be nonnegative and to fit in an int.
+	signed bool
+	code   boundsErrorCode
+}
+
+type boundsErrorCode uint8
+
+const (
+	boundsIndex boundsErrorCode = iota // s[x], 0 <= x < len(s) failed
+
+	boundsSliceAlen // s[?:x], 0 <= x <= len(s) failed
+	boundsSliceAcap // s[?:x], 0 <= x <= cap(s) failed
+	boundsSliceB    // s[x:y], 0 <= x <= y failed (but boundsSliceA didn't happen)
+
+	boundsSlice3Alen // s[?:?:x], 0 <= x <= len(s) failed
+	boundsSlice3Acap // s[?:?:x], 0 <= x <= cap(s) failed
+	boundsSlice3B    // s[?:x:y], 0 <= x <= y failed (but boundsSlice3A didn't happen)
+	boundsSlice3C    // s[x:y:?], 0 <= x <= y failed (but boundsSlice3A/B didn't happen)
+
+	boundsConvert // (*[x]T)(s), 0 <= x <= len(s) failed
+	// Note: in the above, len(s) and cap(s) are stored in y
+)
+
+// boundsErrorFmts provide error text for various out-of-bounds panics.
+// Note: if you change these strings, you should adjust the size of the buffer
+// in boundsError.Error below as well.
+var boundsErrorFmts = [...]string{
+	boundsIndex:      "index out of range [%x] with length %y",
+	boundsSliceAlen:  "slice bounds out of range [:%x] with length %y",
+	boundsSliceAcap:  "slice bounds out of range [:%x] with capacity %y",
+	boundsSliceB:     "slice bounds out of range [%x:%y]",
+	boundsSlice3Alen: "slice bounds out of range [::%x] with length %y",
+	boundsSlice3Acap: "slice bounds out of range [::%x] with capacity %y",
+	boundsSlice3B:    "slice bounds out of range [:%x:%y]",
+	boundsSlice3C:    "slice bounds out of range [%x:%y:]",
+	boundsConvert:    "cannot convert slice with length %y to array or pointer to array with length %x",
+}
+
+// boundsNegErrorFmts are overriding formats if x is negative. In this case there's no need to report y.
+var boundsNegErrorFmts = [...]string{
+	boundsIndex:      "index out of range [%x]",
+	boundsSliceAlen:  "slice bounds out of range [:%x]",
+	boundsSliceAcap:  "slice bounds out of range [:%x]",
+	boundsSliceB:     "slice bounds out of range [%x:]",
+	boundsSlice3Alen: "slice bounds out of range [::%x]",
+	boundsSlice3Acap: "slice bounds out of range [::%x]",
+	boundsSlice3B:    "slice bounds out of range [:%x:]",
+	boundsSlice3C:    "slice bounds out of range [%x::]",
+}
+
+func (e boundsError) RuntimeError() {}
+
+func appendIntStr(b []byte, v int64, signed bool) []byte {
+	if signed && v < 0 {
+		b = append(b, '-')
+		v = -v
+	}
+	var buf [20]byte
+	b = append(b, itoa(buf[:], uint64(v))...)
+	return b
+}
+
+func (e boundsError) Error() string {
+	fmt := boundsErrorFmts[e.code]
+	if e.signed && e.x < 0 {
+		fmt = boundsNegErrorFmts[e.code]
+	}
+	// max message length is 99: "runtime error: slice bounds out of range [::%x] with capacity %y"
+	// x can be at most 20 characters. y can be at most 19.
+	b := make([]byte, 0, 100)
+	b = append(b, "runtime error: "...)
+	for i := 0; i < len(fmt); i++ {
+		c := fmt[i]
+		if c != '%' {
+			b = append(b, c)
+			continue
+		}
+		i++
+		switch fmt[i] {
+		case 'x':
+			b = appendIntStr(b, e.x, e.signed)
+		case 'y':
+			b = appendIntStr(b, int64(e.y), true)
+		}
+	}
+	return string(b)
+}
+
+type stringer interface {
+	String() string
+}
+
+// printany prints an argument passed to panic.
+// If panic is called with a value that has a String or Error method,
+// it has already been converted into a string by preprintpanics.
+func printany(i any) {
+	switch v := i.(type) {
+	case nil:
+		print("nil")
+	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:
+		printanycustomtype(i)
+	}
+}
+
+func printanycustomtype(i any) {
+	eface := efaceOf(&i)
+	typestring := toRType(eface._type).string()
+
+	switch eface._type.Kind_ {
+	case kindString:
+		print(typestring, `("`, *(*string)(eface.data), `")`)
+	case kindBool:
+		print(typestring, "(", *(*bool)(eface.data), ")")
+	case kindInt:
+		print(typestring, "(", *(*int)(eface.data), ")")
+	case kindInt8:
+		print(typestring, "(", *(*int8)(eface.data), ")")
+	case kindInt16:
+		print(typestring, "(", *(*int16)(eface.data), ")")
+	case kindInt32:
+		print(typestring, "(", *(*int32)(eface.data), ")")
+	case kindInt64:
+		print(typestring, "(", *(*int64)(eface.data), ")")
+	case kindUint:
+		print(typestring, "(", *(*uint)(eface.data), ")")
+	case kindUint8:
+		print(typestring, "(", *(*uint8)(eface.data), ")")
+	case kindUint16:
+		print(typestring, "(", *(*uint16)(eface.data), ")")
+	case kindUint32:
+		print(typestring, "(", *(*uint32)(eface.data), ")")
+	case kindUint64:
+		print(typestring, "(", *(*uint64)(eface.data), ")")
+	case kindUintptr:
+		print(typestring, "(", *(*uintptr)(eface.data), ")")
+	case kindFloat32:
+		print(typestring, "(", *(*float32)(eface.data), ")")
+	case kindFloat64:
+		print(typestring, "(", *(*float64)(eface.data), ")")
+	case kindComplex64:
+		print(typestring, *(*complex64)(eface.data))
+	case kindComplex128:
+		print(typestring, *(*complex128)(eface.data))
+	default:
+		print("(", typestring, ") ", eface.data)
+	}
+}
+
+// panicwrap generates a panic for a call to a wrapped value method
+// with a nil pointer receiver.
+//
+// It is called from the generated wrapper code.
+func panicwrap() {
+	pc := getcallerpc()
+	name := funcNameForPrint(funcname(findfunc(pc)))
+	// 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 := bytealg.IndexByteString(name, '(')
+	if i < 0 {
+		throw("panicwrap: no ( in " + name)
+	}
+	pkg := name[:i-1]
+	if i+2 >= len(name) || name[i-1:i+2] != ".(*" {
+		throw("panicwrap: unexpected string after package name: " + name)
+	}
+	name = name[i+2:]
+	i = bytealg.IndexByteString(name, ')')
+	if i < 0 {
+		throw("panicwrap: no ) in " + name)
+	}
+	if i+2 >= len(name) || name[i:i+2] != ")." {
+		throw("panicwrap: unexpected string after type name: " + name)
+	}
+	typ := name[:i]
+	meth := name[i+2:]
+	panic(plainError("value method " + pkg + "." + typ + "." + meth + " called using nil *" + typ + " pointer"))
+}