link_test.go

Documentation: text/template

		 1  // Copyright 2019 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 template_test
		 6  
		 7  import (
		 8  	"bytes"
		 9  	"internal/testenv"
		10  	"os"
		11  	"os/exec"
		12  	"path/filepath"
		13  	"testing"
		14  )
		15  
		16  // Issue 36021: verify that text/template doesn't prevent the linker from removing
		17  // unused methods.
		18  func TestLinkerGC(t *testing.T) {
		19  	if testing.Short() {
		20  		t.Skip("skipping in short mode")
		21  	}
		22  	testenv.MustHaveGoBuild(t)
		23  	const prog = `package main
		24  
		25  import (
		26  	_ "text/template"
		27  )
		28  
		29  type T struct{}
		30  
		31  func (t *T) Unused() { println("THIS SHOULD BE ELIMINATED") }
		32  func (t *T) Used() {}
		33  
		34  var sink *T
		35  
		36  func main() {
		37  	var t T
		38  	sink = &t
		39  	t.Used()
		40  }
		41  `
		42  	td := t.TempDir()
		43  
		44  	if err := os.WriteFile(filepath.Join(td, "x.go"), []byte(prog), 0644); err != nil {
		45  		t.Fatal(err)
		46  	}
		47  	cmd := exec.Command(testenv.GoToolPath(t), "build", "-o", "x.exe", "x.go")
		48  	cmd.Dir = td
		49  	if out, err := cmd.CombinedOutput(); err != nil {
		50  		t.Fatalf("go build: %v, %s", err, out)
		51  	}
		52  	slurp, err := os.ReadFile(filepath.Join(td, "x.exe"))
		53  	if err != nil {
		54  		t.Fatal(err)
		55  	}
		56  	if bytes.Contains(slurp, []byte("THIS SHOULD BE ELIMINATED")) {
		57  		t.Error("binary contains code that should be deadcode eliminated")
		58  	}
		59  }
		60
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