runtime: improve output of panic(x) where x is numeric

Fixes #19658

Change-Id: I41e46073b75c7674e2ed9d6a90ece367ce92166b
Reviewed-on: https://go-review.googlesource.com/39650
Run-TryBot: Todd Neal <todd@tneal.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/runtime/error.go

@@ -74,8 +74,6 @@ func typestring(x interface{}) string {
 
 // For calling from C.
 // Prints an argument passed to panic.
-// There's room for arbitrary complexity here, but we keep it
-// simple and handle just a few important cases: int, string, and Stringer.
 func printany(i interface{}) {
 	switch v := i.(type) {
 	case nil:
@@ -84,8 +82,38 @@ func printany(i interface{}) {
 		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:

test/fixedbugs/issue19658.go

+// +build !nacl
+// run
+
+// Copyright 2017 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.
+
+// ensure that panic(x) where x is a numeric type displays a readable number
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"os/exec"
+	"path/filepath"
+)
+
+const fn = `
+package main
+
+import  "errors"
+type S struct {
+
+}
+func (s S) String() string {
+	return "s-stringer"
+}
+func main() {
+ 	_ = errors.New
+  panic(%s(%s))
+}
+`
+
+func main() {
+	tempDir, err := ioutil.TempDir("", "")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer os.RemoveAll(tempDir)
+	tmpFile := filepath.Join(tempDir, "tmp.go")
+
+	for _, tc := range []struct {
+		Type   string
+		Input  string
+		Expect string
+	}{{"", "nil", "panic: nil"},
+		{"errors.New", `"test"`, "panic: test"},
+		{"S", "S{}", "panic: s-stringer"},
+		{"byte", "8", "panic: 8"},
+		{"rune", "8", "panic: 8"},
+		{"int", "8", "panic: 8"},
+		{"int8", "8", "panic: 8"},
+		{"int16", "8", "panic: 8"},
+		{"int32", "8", "panic: 8"},
+		{"int64", "8", "panic: 8"},
+		{"uint", "8", "panic: 8"},
+		{"uint8", "8", "panic: 8"},
+		{"uint16", "8", "panic: 8"},
+		{"uint32", "8", "panic: 8"},
+		{"uint64", "8", "panic: 8"},
+		{"uintptr", "8", "panic: 8"},
+		{"bool", "true", "panic: true"},
+		{"complex64", "8 + 16i", "panic: (+8.000000e+000+1.600000e+001i)"},
+		{"complex128", "8+16i", "panic: (+8.000000e+000+1.600000e+001i)"},
+		{"string", `"test"`, "panic: test"}} {
+
+		b := bytes.Buffer{}
+		fmt.Fprintf(&b, fn, tc.Type, tc.Input)
+
+		err = ioutil.WriteFile(tmpFile, b.Bytes(), 0644)
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		cmd := exec.Command("go", "run", tmpFile)
+		var buf bytes.Buffer
+		cmd.Stdout = &buf
+		cmd.Stderr = &buf
+		cmd.Env = os.Environ()
+		cmd.Run() // ignore err as we expect a panic
+
+		out := buf.Bytes()
+		panicIdx := bytes.Index(out, []byte("panic: "))
+		if panicIdx == -1 {
+			log.Fatalf("expected a panic in output for %s, got: %s", tc.Type, out)
+		}
+		eolIdx := bytes.IndexByte(out[panicIdx:], '\n') + panicIdx
+		if panicIdx == -1 {
+			log.Fatalf("expected a newline in output for %s after the panic, got: %s", tc.Type, out)
+		}
+		out = out[0:eolIdx]
+		if string(out) != tc.Expect {
+			log.Fatalf("expected '%s' for panic(%s(%s)), got %s", tc.Expect, tc.Type, tc.Input, out)
+		}
+	}
+}