codekingpro/portable-devtools

1// run2 3// Copyright 2021 The Go Authors. All rights reserved.4// Use of this source code is governed by a BSD-style5// license that can be found in the LICENSE file.6 7// Check that the compiler refuses excessively long constants.8 9package main10 11import (12	"bytes"13	"fmt"14	"io/ioutil"15	"log"16	"os"17	"os/exec"18	"path/filepath"19	"runtime"20	"strings"21)22 23// testProg creates a package called name, with path dir/name.go,24// which declares an untyped constant of the given length.25// testProg compiles this package and checks for the absence or26// presence of a constant literal error.27func testProg(dir, name string, length int, msg string) {28	var buf bytes.Buffer29 30	fmt.Fprintf(&buf,31		"package %s; const _ = 0b%s // %d bits",32		name, strings.Repeat("1", length), length,33	)34 35	filename := filepath.Join(dir, fmt.Sprintf("%s.go", name))36	if err := os.WriteFile(filename, buf.Bytes(), 0666); err != nil {37		log.Fatal(err)38	}39 40	cmd := exec.Command("go", "tool", "compile", "-p=p", filename)41	cmd.Dir = dir42	output, err := cmd.CombinedOutput()43 44	if msg == "" {45		// no error expected46		if err != nil {47			log.Fatalf("%s: compile failed unexpectedly: %v", name, err)48		}49		return50	}51 52	// error expected53	if err == nil {54		log.Fatalf("%s: compile succeeded unexpectedly", name)55	}56	if !bytes.Contains(output, []byte(msg)) {57		log.Fatalf("%s: wrong compiler error message:\n%s\n", name, output)58	}59}60 61func main() {62	if runtime.GOOS == "js" || runtime.GOOS == "wasip1" || runtime.Compiler != "gc" {63		return64	}65 66	dir, err := ioutil.TempDir("", "const7_")67	if err != nil {68		log.Fatalf("creating temp dir: %v\n", err)69	}70	defer os.RemoveAll(dir)71 72	const bitLimit = 51273	const charLimit = 10000 // compiler-internal constant length limit74	testProg(dir, "x1", bitLimit, "")75	testProg(dir, "x2", bitLimit+1, "constant overflow")76	testProg(dir, "x3", charLimit-2, "constant overflow") // -2 because literal contains 0b prefix77	testProg(dir, "x4", charLimit-1, "excessively long constant")78}79