all: move from os.IsFoo to errors.Is(err, ErrFoo)

builder/build.go

@@ -14,6 +14,7 @@ import (
 	"fmt"
 	"go/types"
 	"hash/crc32"
+	"io/fs"
 	"math/bits"
 	"os"
 	"os/exec"
@@ -147,7 +148,7 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 		libcDependencies = append(libcDependencies, libcJob)
 	case "wasi-libc":
 		path := filepath.Join(root, "lib/wasi-libc/sysroot/lib/wasm32-wasi/libc.a")
-		if _, err := os.Stat(path); os.IsNotExist(err) {
+		if _, err := os.Stat(path); errors.Is(err, fs.ErrNotExist) {
 			return errors.New("could not find wasi-libc, perhaps you need to run `make wasi-libc`?")
 		}
 		libcDependencies = append(libcDependencies, dummyCompileJob(path))

builder/cc.go

@@ -10,6 +10,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"io/fs"
 	"os"
 	"path/filepath"
 	"sort"
@@ -107,11 +108,11 @@ func compileAndCacheCFile(abspath, tmpdir string, cflags []string, thinlto bool,
 		if err == nil {
 			if _, err := os.Stat(outpath); err == nil {
 				return outpath, nil
-			} else if !os.IsNotExist(err) {
+			} else if !errors.Is(err, fs.ErrNotExist) {
 				return "", err
 			}
 		}
-	} else if !os.IsNotExist(err) {
+	} else if !errors.Is(err, fs.ErrNotExist) {
 		// expected either nil or IsNotExist
 		return "", err
 	}

builder/env.go

@@ -1,6 +1,8 @@
 package builder
 
 import (
+	"errors"
+	"io/fs"
 	"io/ioutil"
 	"os"
 	"os/exec"
@@ -17,13 +19,13 @@ import (
 func getClangHeaderPath(TINYGOROOT string) string {
 	// Check whether we're running from the source directory.
 	path := filepath.Join(TINYGOROOT, "llvm-project", "clang", "lib", "Headers")
-	if _, err := os.Stat(path); !os.IsNotExist(err) {
+	if _, err := os.Stat(path); !errors.Is(err, fs.ErrNotExist) {
 		return path
 	}
 
 	// Check whether we're running from the installation directory.
 	path = filepath.Join(TINYGOROOT, "lib", "clang", "include")
-	if _, err := os.Stat(path); !os.IsNotExist(err) {
+	if _, err := os.Stat(path); !errors.Is(err, fs.ErrNotExist) {
 		return path
 	}
 

builder/library.go

@@ -1,6 +1,8 @@
 package builder
 
 import (
+	"errors"
+	"io/fs"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -109,10 +111,10 @@ func (l *Library) load(config *compileopts.Config, tmpdir string) (job *compileJ
 			err = os.Rename(temporaryHeaderPath, headerPath)
 			if err != nil {
 				switch {
-				case os.IsExist(err):
+				case errors.Is(err, fs.ErrExist):
 					// Another invocation of TinyGo also seems to have already created the headers.
 
-				case runtime.GOOS == "windows" && os.IsPermission(err):
+				case runtime.GOOS == "windows" && errors.Is(err, fs.ErrPermission):
 					// On Windows, a rename with a destination directory that already
 					// exists does not result in an IsExist error, but rather in an
 					// access denied error. To be sure, check for this case by checking