link_test.go

Documentation: math/big

		 1  // Copyright 2020 The Go Authors. All rights reserved.
		 2  // Use of this source code is governed by a BSD-style
		 3  // license that can be found in the LICENSE file.
		 4  
		 5  package big
		 6  
		 7  import (
		 8  	"bytes"
		 9  	"internal/testenv"
		10  	"os"
		11  	"os/exec"
		12  	"path/filepath"
		13  	"testing"
		14  )
		15  
		16  // Tests that the linker is able to remove references to Float, Rat,
		17  // and Int if unused (notably, not used by init).
		18  func TestLinkerGC(t *testing.T) {
		19  	if testing.Short() {
		20  		t.Skip("skipping in short mode")
		21  	}
		22  	t.Parallel()
		23  	tmp := t.TempDir()
		24  	goBin := testenv.GoToolPath(t)
		25  	goFile := filepath.Join(tmp, "x.go")
		26  	file := []byte(`package main
		27  import _ "math/big"
		28  func main() {}
		29  `)
		30  	if err := os.WriteFile(goFile, file, 0644); err != nil {
		31  		t.Fatal(err)
		32  	}
		33  	cmd := exec.Command(goBin, "build", "-o", "x.exe", "x.go")
		34  	cmd.Dir = tmp
		35  	if out, err := cmd.CombinedOutput(); err != nil {
		36  		t.Fatalf("compile: %v, %s", err, out)
		37  	}
		38  
		39  	cmd = exec.Command(goBin, "tool", "nm", "x.exe")
		40  	cmd.Dir = tmp
		41  	nm, err := cmd.CombinedOutput()
		42  	if err != nil {
		43  		t.Fatalf("nm: %v, %s", err, nm)
		44  	}
		45  	const want = "runtime.main"
		46  	if !bytes.Contains(nm, []byte(want)) {
		47  		// Test the test.
		48  		t.Errorf("expected symbol %q not found", want)
		49  	}
		50  	bad := []string{
		51  		"math/big.(*Float)",
		52  		"math/big.(*Rat)",
		53  		"math/big.(*Int)",
		54  	}
		55  	for _, sym := range bad {
		56  		if bytes.Contains(nm, []byte(sym)) {
		57  			t.Errorf("unexpected symbol %q found", sym)
		58  		}
		59  	}
		60  	if t.Failed() {
		61  		t.Logf("Got: %s", nm)
		62  	}
		63  }
		64
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