[go] all: replace calls to errors.As with errors.AsType

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Oct 1, 2025, 4:08:31 PM (12 hours ago) Oct 1

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Commit message

all: replace calls to errors.As with errors.AsType

This change replaces most occurrences (in code as well as in comments) of
errors.As with errors.AsType. It leaves the errors package and vendored
code untouched.

Change-Id: I3bde73f318a0b408bdb8f5a251494af15a13118a

GitHub-Last-Rev: 8aaaa36a5a12d2a6a90c6d51680464e1a3115139

GitHub-Pull-Request: golang/go#75698

Change diff

diff --git a/src/cmd/compile/internal/types2/api_test.go b/src/cmd/compile/internal/types2/api_test.go
index 0d3c8b8..4b7012e 100644
--- a/src/cmd/compile/internal/types2/api_test.go
+++ b/src/cmd/compile/internal/types2/api_test.go
@@ -2468,8 +2468,8 @@
 			t.Fatalf("Instantiate(%v, %v) returned nil error, want non-nil", T, test.targs)
 		}
 
-		var argErr *ArgumentError
-		if !errors.As(err, &argErr) {
+		argErr, ok := errors.AsType[*ArgumentError](err)
+		if !ok {
 			t.Fatalf("Instantiate(%v, %v): error is not an *ArgumentError", T, test.targs)
 		}
 
@@ -2484,8 +2484,8 @@
 		Index: 1,
 		Err:   Error{Msg: "test"},
 	}
-	var e Error
-	if !errors.As(err, &e) {
+	e, ok := errors.AsType[Error](err)
+	if !ok {
 		t.Fatalf("error %v does not wrap types.Error", err)
 	}
 	if e.Msg != "test" {
diff --git a/src/cmd/go/internal/base/path.go b/src/cmd/go/internal/base/path.go
index 5bb7bc3..a7577f6 100644
--- a/src/cmd/go/internal/base/path.go
+++ b/src/cmd/go/internal/base/path.go
@@ -55,8 +55,7 @@
 
 // ShortPathError rewrites the path in err using base.ShortPath, if err is a wrapped PathError.
 func ShortPathError(err error) error {
-	var pe *fs.PathError
-	if errors.As(err, &pe) {
+	if pe, ok := errors.AsType[*fs.PathError](err); ok {
 		pe.Path = ShortPath(pe.Path)
 	}
 	return err
diff --git a/src/cmd/go/internal/doc/pkgsite.go b/src/cmd/go/internal/doc/pkgsite.go
index 06289ac..c173167 100644
--- a/src/cmd/go/internal/doc/pkgsite.go
+++ b/src/cmd/go/internal/doc/pkgsite.go
@@ -81,8 +81,7 @@
 	cmd.Stderr = os.Stderr
 
 	if err := cmd.Run(); err != nil {
-		var ee *exec.ExitError
-		if errors.As(err, &ee) {
+		if ee, ok := errors.AsType[*exec.ExitError](err); ok {
 			// Exit with the same exit status as pkgsite to avoid
 			// printing of "exit status" error messages.
 			// Any relevant messages have already been printed
diff --git a/src/cmd/go/internal/fmtcmd/fmt.go b/src/cmd/go/internal/fmtcmd/fmt.go
index 62b22f6..83fba96 100644
--- a/src/cmd/go/internal/fmtcmd/fmt.go
+++ b/src/cmd/go/internal/fmtcmd/fmt.go
@@ -68,11 +68,10 @@
 			continue
 		}
 		if pkg.Error != nil {
-			var nogo *load.NoGoError
-			var embed *load.EmbedError
-			if (errors.As(pkg.Error, &nogo) || errors.As(pkg.Error, &embed)) && len(pkg.InternalAllGoFiles()) > 0 {
-				// Skip this error, as we will format
-				// all files regardless.
+			if _, ok := errors.AsType[*load.NoGoError](pkg.Error); ok {
+				// Skip this error, as we will format all files regardless.
+			} else if  _, ok := errors.AsType[*load.EmbedError](pkg.Error); ok && len(pkg.InternalAllGoFiles()) > 0 {
+				// Skip this error, as we will format all files regardless.
 			} else {
 				base.Errorf("%v", pkg.Error)
 				continue
diff --git a/src/cmd/go/internal/load/pkg.go b/src/cmd/go/internal/load/pkg.go
index 1f79154..4d536cc 100644
--- a/src/cmd/go/internal/load/pkg.go
+++ b/src/cmd/go/internal/load/pkg.go
@@ -290,8 +290,8 @@
 
 	// Replace (possibly wrapped) *build.NoGoError with *load.NoGoError.
 	// The latter is more specific about the cause.
-	var nogoErr *build.NoGoError
-	if errors.As(err, &nogoErr) {
+	nogoErr, ok := errors.AsType[*build.NoGoError](err)
+	if ok {
 		if p.Dir == "" && nogoErr.Dir != "" {
 			p.Dir = nogoErr.Dir
 		}
diff --git a/src/cmd/go/internal/modget/get.go b/src/cmd/go/internal/modget/get.go
index 25dbf39..79b54be 100644
--- a/src/cmd/go/internal/modget/get.go
+++ b/src/cmd/go/internal/modget/get.go
@@ -1294,15 +1294,13 @@
 			continue
 		}
 
-		var (
-			importMissing *modload.ImportMissingError
-			ambiguous     *modload.AmbiguousImportError
-		)
-		if !errors.As(err, &importMissing) && !errors.As(err, &ambiguous) {
-			// The package, which is a dependency of something we care about, has some
-			// problem that we can't resolve with a version change.
-			// Leave the error for the final LoadPackages call.
-			continue
+		if _, ok := errors.AsType[*modload.ImportMissingError](err); !ok {
+			if _, ok := errors.AsType[*modload.AmbiguousImportError](err); !ok {
+				// The package, which is a dependency of something we care about, has some
+				// problem that we can't resolve with a version change.
+				// Leave the error for the final LoadPackages call.
+				continue
+			}
 		}
 
 		path := pkgPath
@@ -1674,7 +1672,7 @@
 				}
 
 				base.SetExitStatus(1)
-				if ambiguousErr := (*modload.AmbiguousImportError)(nil); errors.As(err, &ambiguousErr) {
+				if ambiguousErr, ok := errors.AsType[*modload.AmbiguousImportError](err); ok {
 					for _, m := range ambiguousErr.Modules {
 						relevantMods[m] |= hasPkg
 					}
@@ -1717,7 +1715,7 @@
 		i := i
 		r.work.Add(func() {
 			err := modload.CheckRetractions(ctx, retractions[i].m)
-			if retractErr := (*modload.ModuleRetractedError)(nil); errors.As(err, &retractErr) {
+			if _, ok := errors.AsType[*modload.ModuleRetractedError](err); ok {
 				retractions[i].message = err.Error()
 			}
 		})
@@ -1994,8 +1992,8 @@
 			toolchain.SwitchOrFatal(ctx, err)
 		}
 
-		var constraint *modload.ConstraintError
-		if !errors.As(err, &constraint) {
+		constraint, ok := errors.AsType[*modload.ConstraintError](err)
+		if !ok {
 			base.Fatal(err)
 		}
 
@@ -2066,8 +2064,11 @@
 // does not exist at the requested version, either because the module does not
 // exist at all or because it does not include that specific version.
 func isNoSuchModuleVersion(err error) bool {
-	var noMatch *modload.NoMatchingVersionError
-	return errors.Is(err, os.ErrNotExist) || errors.As(err, &noMatch)
+	if errors.Is(err, os.ErrNotExist) {
+		return true
+	}
+	_, ok := errors.AsType[*modload.NoMatchingVersionError](err)
+	return ok
 }
 
 // isNoSuchPackageVersion reports whether err indicates that the requested
@@ -2075,8 +2076,11 @@
 // that could contain it exists at that version, or because every such module
 // that does exist does not actually contain the package.
 func isNoSuchPackageVersion(err error) bool {
-	var noPackage *modload.PackageNotInModuleError
-	return isNoSuchModuleVersion(err) || errors.As(err, &noPackage)
+	if isNoSuchModuleVersion(err) {
+		return true
+	}
+	_, ok := errors.AsType[*modload.PackageNotInModuleError](err)
+	return ok
 }
 
 // workspace represents the set of modules in a workspace.
diff --git a/src/cmd/go/internal/modget/query.go b/src/cmd/go/internal/modget/query.go
index 05872d5..a7ea863 100644
--- a/src/cmd/go/internal/modget/query.go
+++ b/src/cmd/go/internal/modget/query.go
@@ -283,7 +283,7 @@
 	// If err already mentions all of the relevant parts of q, just log err to
 	// reduce stutter. Otherwise, log both q and err.
 	//
-	// TODO(bcmills): Use errors.As to unpack these errors instead of parsing
+	// TODO(bcmills): Use errors.AsType to unpack these errors instead of parsing
 	// strings with regular expressions.
 
 	if !utf8.ValidString(q.pattern) || !utf8.ValidString(q.version) {
diff --git a/src/cmd/go/internal/modload/build.go b/src/cmd/go/internal/modload/build.go
index 6e30afd..568019f 100644
--- a/src/cmd/go/internal/modload/build.go
+++ b/src/cmd/go/internal/modload/build.go
@@ -129,11 +129,10 @@
 	}
 
 	info, err := Query(ctx, m.Path, "upgrade", m.Version, CheckAllowed)
-	var noVersionErr *NoMatchingVersionError
-	if errors.Is(err, ErrDisallowed) ||
+	if _, ok := errors.AsType[*NoMatchingVersionError](err); ok ||
 		errors.Is(err, fs.ErrNotExist) ||
-		errors.As(err, &noVersionErr) {
-		// Ignore "not found" and "no matching version" errors.
+		errors.Is(err, ErrDisallowed) {
+		// Ignore "no matching version" and "not found" errors.
 		// This means the proxy has no matching version or no versions at all.
 		//
 		// Ignore "disallowed" errors. This means the current version is
@@ -238,10 +237,10 @@
 	}
 
 	err := CheckRetractions(ctx, module.Version{Path: m.Path, Version: m.Version})
-	var noVersionErr *NoMatchingVersionError
-	var retractErr *ModuleRetractedError
-	if err == nil || errors.Is(err, fs.ErrNotExist) || errors.As(err, &noVersionErr) {
-		// Ignore "not found" and "no matching version" errors.
+	if err == nil {
+		return
+	} else if _, ok := errors.AsType[*NoMatchingVersionError](err); ok || errors.Is(err, fs.ErrNotExist) {
+		// Ignore "no matching version" and "not found" errors.
 		// This means the proxy has no matching version or no versions at all.
 		//
 		// We should report other errors though. An attacker that controls the
@@ -250,7 +249,7 @@
 		// hide versions, since the "list" and "latest" endpoints are not
 		// authenticated.
 		return
-	} else if errors.As(err, &retractErr) {
+	} else if retractErr, ok := errors.AsType[*ModuleRetractedError](err); ok {
 		if len(retractErr.Rationale) == 0 {
 			m.Retracted = []string{"retracted by module author"}
 		} else {
@@ -265,9 +264,8 @@
 // author. m.Error is set if there's an error loading deprecation information.
 func addDeprecation(ctx context.Context, m *modinfo.ModulePublic) {
 	deprecation, err := CheckDeprecation(ctx, module.Version{Path: m.Path, Version: m.Version})
-	var noVersionErr *NoMatchingVersionError
-	if errors.Is(err, fs.ErrNotExist) || errors.As(err, &noVersionErr) {
-		// Ignore "not found" and "no matching version" errors.
+	if _, ok := errors.AsType[*NoMatchingVersionError](err); ok || errors.Is(err, fs.ErrNotExist) {
+		// Ignore "no matching version" and "not found" errors.
 		// This means the proxy has no matching version or no versions at all.
 		//
 		// We should report other errors though. An attacker that controls the
diff --git a/src/cmd/go/internal/modload/buildlist.go b/src/cmd/go/internal/modload/buildlist.go
index 2ba04f7..0b2264d 100644
--- a/src/cmd/go/internal/modload/buildlist.go
+++ b/src/cmd/go/internal/modload/buildlist.go
@@ -932,7 +932,7 @@
 			q.Add(func() {
 				skipModFile := true
 				_, _, _, _, err := importFromModules(ctx, pkg.path, tidy, nil, skipModFile)
-				if aie := (*AmbiguousImportError)(nil); errors.As(err, &aie) {
+				if _, ok := errors.AsType[*AmbiguousImportError](err); ok {
 					disambiguateRoot.Store(pkg.mod, true)
 				}
 			})
diff --git a/src/cmd/go/internal/modload/edit.go b/src/cmd/go/internal/modload/edit.go
index b406193..d127194 100644
--- a/src/cmd/go/internal/modload/edit.go
+++ b/src/cmd/go/internal/modload/edit.go
@@ -226,8 +226,10 @@
 		// conflict we discover from one or more of the original roots.
 		mg, upgradedRoots, err := extendGraph(ctx, rootPruning, roots, selectedRoot)
 		if err != nil {
-			var tooNew *gover.TooNewError
-			if mg == nil || errors.As(err, &tooNew) {
+			if mg == nil {
+				return orig, false, err
+			}
+			if _, ok := errors.AsType[*gover.TooNewError](err); ok {
 				return orig, false, err
 			}
 			// We're about to walk the entire extended module graph, so we will find
diff --git a/src/cmd/go/internal/modload/import.go b/src/cmd/go/internal/modload/import.go
index 171d9d6..3d4cfca 100644
--- a/src/cmd/go/internal/modload/import.go
+++ b/src/cmd/go/internal/modload/import.go
@@ -410,7 +410,7 @@
 
 			root, isLocal, err := fetch(ctx, m)
 			if err != nil {
-				if sumErr := (*sumMissingError)(nil); errors.As(err, &sumErr) {
+				if _, ok := errors.AsType[*sumMissingError](err); ok {
 					// We are missing a sum needed to fetch a module in the build list.
 					// We can't verify that the package is unique, and we may not find
 					// the package at all. Keep checking other modules to decide which
@@ -549,7 +549,7 @@
 	for _, m := range mods {
 		root, isLocal, err := fetch(ctx, m)
 		if err != nil {
-			if sumErr := (*sumMissingError)(nil); errors.As(err, &sumErr) {
+			if _, ok := errors.AsType[*sumMissingError](err); ok {
 				return module.Version{}, &ImportMissingSumError{importPath: path}
 			}
 			return module.Version{}, err
diff --git a/src/cmd/go/internal/modload/list.go b/src/cmd/go/internal/modload/list.go
index 53cb6c2..555804d 100644
--- a/src/cmd/go/internal/modload/list.go
+++ b/src/cmd/go/internal/modload/list.go
@@ -305,13 +305,11 @@
 // modinfoError wraps an error to create an error message in
 // modinfo.ModuleError with minimal redundancy.
 func modinfoError(path, vers string, err error) *modinfo.ModuleError {
-	var nerr *NoMatchingVersionError
-	var merr *module.ModuleError
-	if errors.As(err, &nerr) {
+	if _, ok := errors.AsType[*NoMatchingVersionError](err); ok {
 		// NoMatchingVersionError contains the query, so we don't mention the
 		// query again in ModuleError.
 		err = &module.ModuleError{Path: path, Err: err}
-	} else if !errors.As(err, &merr) {
+	} else if _, ok := errors.AsType[*module.ModuleError](err); !ok {
 		// If the error does not contain path and version, wrap it in a
 		// module.ModuleError.
 		err = &module.ModuleError{Path: path, Version: vers, Err: err}
diff --git a/src/cmd/go/internal/modload/load.go b/src/cmd/go/internal/modload/load.go
index 8b2be3b..6380e1c 100644
--- a/src/cmd/go/internal/modload/load.go
+++ b/src/cmd/go/internal/modload/load.go
@@ -1304,7 +1304,7 @@
 		}
 
 		// Add importer information to checksum errors.
-		if sumErr := (*ImportMissingSumError)(nil); errors.As(pkg.err, &sumErr) {
+		if sumErr, ok := errors.AsType[*ImportMissingSumError](pkg.err); ok {
 			if importer := pkg.stack; importer != nil {
 				sumErr.importer = importer.path
 				sumErr.importerVersion = importer.mod.Version
@@ -1312,7 +1312,7 @@
 			}
 		}
 
-		if stdErr := (*ImportMissingError)(nil); errors.As(pkg.err, &stdErr) && stdErr.isStd {
+		if stdErr, ok := errors.AsType[*ImportMissingError](pkg.err); ok && stdErr.isStd {
 			// Add importer go version information to import errors of standard
 			// library packages arising from newer releases.
 			if importer := pkg.stack; importer != nil {
@@ -1384,7 +1384,7 @@
 	var maxTooNew *gover.TooNewError
 	for _, pkg := range ld.pkgs {
 		if pkg.err != nil {
-			if tooNew := (*gover.TooNewError)(nil); errors.As(pkg.err, &tooNew) {
+			if tooNew, ok := errors.AsType[*gover.TooNewError](pkg.err); ok {
 				if maxTooNew == nil || gover.Compare(tooNew.GoVersion, maxTooNew.GoVersion) > 0 {
 					maxTooNew = tooNew
 				}
@@ -1573,7 +1573,7 @@
 			// we should only add the missing import once.
 			continue
 		}
-		if !errors.As(pkg.err, new(*ImportMissingError)) {
+		if _, ok := errors.AsType[*ImportMissingError](pkg.err); !ok {
 			// Leave other errors for Import or load.Packages to report.
 			continue
 		}
@@ -1584,8 +1584,7 @@
 			var err error
 			mod, err = queryImport(ctx, pkg.path, ld.requirements)
 			if err != nil {
-				var ime *ImportMissingError
-				if errors.As(err, &ime) {
+				if ime, ok := errors.AsType[*ImportMissingError](err); ok {
 					for curstack := pkg.stack; curstack != nil; curstack = curstack.stack {
 						if MainModules.Contains(curstack.mod.Path) {
 							ime.ImportingMainModule = curstack.mod
@@ -1625,7 +1624,7 @@
 		maxTooNewPkg *loadPkg
 	)
 	for _, pm := range pkgMods {
-		if tooNew := (*gover.TooNewError)(nil); errors.As(pm.pkg.err, &tooNew) {
+		if tooNew, ok := errors.AsType[*gover.TooNewError](pm.pkg.err); ok {
 			if maxTooNew == nil || gover.Compare(tooNew.GoVersion, maxTooNew.GoVersion) > 0 {
 				maxTooNew = tooNew
 				maxTooNewPkg = pm.pkg
@@ -1771,8 +1770,7 @@
 			// full module graph.
 			m, _, _, _, err := importFromModules(ctx, path, ld.requirements, nil, ld.skipImportModFiles)
 			if err != nil {
-				var missing *ImportMissingError
-				if errors.As(err, &missing) && ld.ResolveMissingImports {
+				if _, ok := errors.AsType[*ImportMissingError](err); ok && ld.ResolveMissingImports {
 					// This package isn't provided by any selected module.
 					// If we can find it, it will be a new root dependency.
 					m, err = queryImport(ctx, path, ld.requirements)
@@ -2196,14 +2194,14 @@
 			// module that previously provided the package to a version that no
 			// longer does, or to a version for which the module source code (but
 			// not the go.mod file in isolation) has a checksum error.
-			if missing := (*ImportMissingError)(nil); errors.As(mismatch.err, &missing) {
+			if _, ok := errors.AsType[*ImportMissingError](mismatch.err); ok {
 				selected := module.Version{
 					Path:    pkg.mod.Path,
 					Version: mg.Selected(pkg.mod.Path),
 				}
 				ld.error(fmt.Errorf("%s loaded from %v,\n\tbut go %s would fail to locate it in %s", pkg.stackText(), pkg.mod, compatVersion, selected))
 			} else {
-				if ambiguous := (*AmbiguousImportError)(nil); errors.As(mismatch.err, &ambiguous) {
+				if _, ok := errors.AsType[*AmbiguousImportError](mismatch.err); ok {
 					// TODO: Is this check needed?
 				}
 				ld.error(fmt.Errorf("%s loaded from %v,\n\tbut go %s would fail to locate it:\n\t%v", pkg.stackText(), pkg.mod, compatVersion, mismatch.err))
diff --git a/src/cmd/go/internal/modload/modfile.go b/src/cmd/go/internal/modload/modfile.go
index 04e204c..42a38aa 100644
--- a/src/cmd/go/internal/modload/modfile.go
+++ b/src/cmd/go/internal/modload/modfile.go
@@ -76,8 +76,7 @@
 }
 
 func shortPathErrorList(err error) error {
-	var el modfile.ErrorList
-	if errors.As(err, &el) {
+	if el, ok := errors.AsType[modfile.ErrorList](err); ok {
 		for i := range el {
 			el[i].Filename = base.ShortPath(el[i].Filename)
 		}
@@ -175,12 +174,15 @@
 // its author.
 func CheckRetractions(ctx context.Context, m module.Version) (err error) {
 	defer func() {
-		if retractErr := (*ModuleRetractedError)(nil); err == nil || errors.As(err, &retractErr) {
+		if err == nil {
+			return
+		}
+		if _, ok := errors.AsType[*ModuleRetractedError](err); ok {
 			return
 		}
 		// Attribute the error to the version being checked, not the version from
 		// which the retractions were to be loaded.
-		if mErr := (*module.ModuleError)(nil); errors.As(err, &mErr) {
+		if mErr, ok := errors.AsType[*module.ModuleError](err); ok {
 			err = mErr.Err
 		}
 		err = &retractionLoadingError{m: m, err: err}
diff --git a/src/cmd/go/internal/modload/query.go b/src/cmd/go/internal/modload/query.go
index c4cf554..145a8de 100644
--- a/src/cmd/go/internal/modload/query.go
+++ b/src/cmd/go/internal/modload/query.go
@@ -932,7 +932,7 @@
 				if notExistErr == nil {
 					notExistErr = rErr
 				}
-			} else if iv := (*module.InvalidVersionError)(nil); errors.As(rErr, &iv) {
+			} else if _, ok := errors.AsType[*module.InvalidVersionError](rErr); ok {
 				if invalidVersion == nil {
 					invalidVersion = rErr
 				}
diff --git a/src/cmd/go/internal/test/test.go b/src/cmd/go/internal/test/test.go
index 8bfb3c1..611cf7e 100644
--- a/src/cmd/go/internal/test/test.go
+++ b/src/cmd/go/internal/test/test.go
@@ -1735,8 +1735,7 @@
 		} else if errors.Is(err, exec.ErrWaitDelay) {
 			fmt.Fprintf(cmd.Stdout, "*** Test I/O incomplete %v after exiting.\n", cmd.WaitDelay)
 		}
-		var ee *exec.ExitError
-		if len(out) == 0 || !errors.As(err, &ee) || !ee.Exited() {
+		if ee, ok := errors.AsType[*exec.ExitError](err); !ok || !ee.Exited() || len(out) == 0 {
 			// If there was no test output, print the exit status so that the reason
 			// for failure is clear.
 			fmt.Fprintf(cmd.Stdout, "%s\n", err)
diff --git a/src/cmd/go/internal/test/testflag.go b/src/cmd/go/internal/test/testflag.go
index 983e8f5..ba64720 100644
--- a/src/cmd/go/internal/test/testflag.go
+++ b/src/cmd/go/internal/test/testflag.go
@@ -260,7 +260,7 @@
 			break
 		}
 
-		if nf := (cmdflag.NonFlagError{}); errors.As(err, &nf) {
+		if nf, ok := errors.AsType[cmdflag.NonFlagError](err); ok {
 			if !inPkgList && packageNames != nil {
 				// We already saw the package list previously, and this argument is not
 				// a flag, so it — and everything after it — must be either a value for
@@ -295,7 +295,7 @@
 			inPkgList = false
 		}
 
-		if nd := (cmdflag.FlagNotDefinedError{}); errors.As(err, &nd) {
+		if nd, ok := errors.AsType[cmdflag.FlagNotDefinedError](err); ok {
 			// This is a flag we do not know. We must assume that any args we see
 			// after this might be flag arguments, not package names, so make
 			// packageNames non-nil to indicate that the package list is complete.
diff --git a/src/cmd/go/internal/vcweb/vcstest/vcstest_test.go b/src/cmd/go/internal/vcweb/vcstest/vcstest_test.go
index 67234ac..6a6a0ee 100644
--- a/src/cmd/go/internal/vcweb/vcstest/vcstest_test.go
+++ b/src/cmd/go/internal/vcweb/vcstest/vcstest_test.go
@@ -155,10 +155,10 @@
 				t.Log(buf)
 			}
 			if err != nil {
-				if notInstalled := (vcweb.ServerNotInstalledError{}); errors.As(err, &notInstalled) || errors.Is(err, exec.ErrNotFound) {
+				if _, ok := errors.AsType[vcweb.ServerNotInstalledError](err); ok || errors.Is(err, exec.ErrNotFound) {
 					t.Skip(err)
 				}
-				if skip := (vcweb.SkipError{}); errors.As(err, &skip) {
+				if skip, ok := errors.AsType[vcweb.SkipError](err); ok {
 					if skip.Msg == "" {
 						t.Skip("SKIP")
 					} else {
diff --git a/src/cmd/go/internal/vcweb/vcweb.go b/src/cmd/go/internal/vcweb/vcweb.go
index b81ff5e..4b4e127 100644
--- a/src/cmd/go/internal/vcweb/vcweb.go
+++ b/src/cmd/go/internal/vcweb/vcweb.go
@@ -244,9 +244,9 @@
 	})
 	if err != nil {
 		s.logger.Print(err)
-		if notFound := (ScriptNotFoundError{}); errors.As(err, &notFound) {
+		if _, ok := errors.AsType[ScriptNotFoundError](err); ok {
 			http.NotFound(w, req)
-		} else if notInstalled := (ServerNotInstalledError{}); errors.As(err, &notInstalled) || errors.Is(err, exec.ErrNotFound) {
+		} else if _, ok := errors.AsType[ServerNotInstalledError](err); ok || errors.Is(err, exec.ErrNotFound) {
 			http.Error(w, err.Error(), http.StatusNotImplemented)
 		} else {
 			http.Error(w, err.Error(), http.StatusInternalServerError)
diff --git a/src/cmd/go/internal/version/version.go b/src/cmd/go/internal/version/version.go
index c26dd42..781bc08 100644
--- a/src/cmd/go/internal/version/version.go
+++ b/src/cmd/go/internal/version/version.go
@@ -168,7 +168,7 @@
 	bi, err := buildinfo.ReadFile(file)
 	if err != nil {
 		if mustPrint {
-			if pathErr := (*os.PathError)(nil); errors.As(err, &pathErr) && filepath.Clean(pathErr.Path) == filepath.Clean(file) {
+			if pathErr, ok := errors.AsType[*os.PathError](err); ok && filepath.Clean(pathErr.Path) == filepath.Clean(file) {
 				fmt.Fprintf(os.Stderr, "%v\n", file)
 			} else {
 				// Skip errors for non-Go binaries.
diff --git a/src/cmd/go/internal/vet/vetflag.go b/src/cmd/go/internal/vet/vetflag.go
index d0bdb58..f5454e2 100644
--- a/src/cmd/go/internal/vet/vetflag.go
+++ b/src/cmd/go/internal/vet/vetflag.go
@@ -142,7 +142,7 @@
 			break
 		}
 
-		if nf := (cmdflag.NonFlagError{}); errors.As(err, &nf) {
+		if _, ok := errors.AsType[cmdflag.NonFlagError](err); ok {
 			// Everything from here on out — including the argument we just consumed —
 			// must be a package name.
 			packageNames = args
diff --git a/src/cmd/go/internal/work/build.go b/src/cmd/go/internal/work/build.go
index 6741b39..a7d9f3a 100644
--- a/src/cmd/go/internal/work/build.go
+++ b/src/cmd/go/internal/work/build.go
@@ -705,7 +705,7 @@
 				continue
 			}
 			haveErrors = true
-			if missingErr := (*modload.ImportMissingError)(nil); !errors.As(pkg.Error, &missingErr) {
+			if _, ok := errors.AsType[*modload.ImportMissingError](pkg.Error); !ok {
 				allMissingErrors = false
 				break
 			}
diff --git a/src/cmd/go/internal/work/exec.go b/src/cmd/go/internal/work/exec.go
index 72b9177..f12aed7 100644
--- a/src/cmd/go/internal/work/exec.go
+++ b/src/cmd/go/internal/work/exec.go
@@ -169,9 +169,10 @@
 					a.Package.Incomplete = true
 				}
 			} else {
-				var ipe load.ImportPathError
-				if a.Package != nil && (!errors.As(err, &ipe) || ipe.ImportPath() != a.Package.ImportPath) {
-					err = fmt.Errorf("%s: %v", a.Package.ImportPath, err)
+				if a.Package != nil {
+					if ipe, ok := errors.AsType[load.ImportPathError](err); !ok || ipe.ImportPath() != a.Package.ImportPath {
+						err = fmt.Errorf("%s: %v", a.Package.ImportPath, err)
+					}
 				}
 				sh := b.Shell(a)
 				sh.Errorf("%s", err)
diff --git a/src/cmd/internal/bootstrap_test/experiment_toolid_test.go b/src/cmd/internal/bootstrap_test/experiment_toolid_test.go
index ff2379c..ca292b7 100644
--- a/src/cmd/internal/bootstrap_test/experiment_toolid_test.go
+++ b/src/cmd/internal/bootstrap_test/experiment_toolid_test.go
@@ -97,7 +97,7 @@
 	cmd.Env = env
 	out, err := cmd.Output()
 	if err != nil {
-		if ee := (*exec.ExitError)(nil); errors.As(err, &ee) {
+		if ee, ok := errors.AsType[*exec.ExitError](err); ok {
 			out = append(out, ee.Stderr...)
 		}
 		t.Fatalf("%s failed:\n%s\n%s", cmd, out, err)
diff --git a/src/cmd/internal/robustio/robustio_darwin.go b/src/cmd/internal/robustio/robustio_darwin.go
index 99fd8eb..69ea247 100644
--- a/src/cmd/internal/robustio/robustio_darwin.go
+++ b/src/cmd/internal/robustio/robustio_darwin.go
@@ -13,9 +13,6 @@
 
 // isEphemeralError returns true if err may be resolved by waiting.
 func isEphemeralError(err error) bool {
-	var errno syscall.Errno
-	if errors.As(err, &errno) {
-		return errno == errFileNotFound
-	}
-	return false
+	errno, ok := errors.AsType[syscall.Errno](err)
+	return ok && errno == errFileNotFound
 }
diff --git a/src/cmd/internal/robustio/robustio_flaky.go b/src/cmd/internal/robustio/robustio_flaky.go
index c56e36c..ec1a2da 100644
--- a/src/cmd/internal/robustio/robustio_flaky.go
+++ b/src/cmd/internal/robustio/robustio_flaky.go
@@ -31,8 +31,7 @@
 			return err
 		}
 
-		var errno syscall.Errno
-		if errors.As(err, &errno) && (lowestErrno == 0 || errno < lowestErrno) {
+		if errno, ok := errors.AsType[syscall.Errno](err); ok && (lowestErrno == 0 || errno < lowestErrno) {
 			bestErr = err
 			lowestErrno = errno
 		} else if bestErr == nil {
diff --git a/src/cmd/internal/robustio/robustio_windows.go b/src/cmd/internal/robustio/robustio_windows.go
index 687dcb6..ad46ec5 100644
--- a/src/cmd/internal/robustio/robustio_windows.go
+++ b/src/cmd/internal/robustio/robustio_windows.go
@@ -14,8 +14,7 @@
 
 // isEphemeralError returns true if err may be resolved by waiting.
 func isEphemeralError(err error) bool {
-	var errno syscall.Errno
-	if errors.As(err, &errno) {
+	if errno, ok := errors.AsType[syscall.Errno](err); ok {
 		switch errno {
 		case syscall.ERROR_ACCESS_DENIED,
 			syscall.ERROR_FILE_NOT_FOUND,
diff --git a/src/cmd/internal/script/engine.go b/src/cmd/internal/script/engine.go
index eb9344f..4607868 100644
--- a/src/cmd/internal/script/engine.go
+++ b/src/cmd/internal/script/engine.go
@@ -185,7 +185,7 @@
 
 	var lineno int
 	lineErr := func(err error) error {
-		if errors.As(err, new(*CommandError)) {
+		if _, ok := errors.AsType[*CommandError](err); ok {
 			return err
 		}
 		return fmt.Errorf("%s:%d: %w", file, lineno, err)
@@ -283,7 +283,7 @@
 		// Run the command.
 		err = e.runCommand(s, cmd, impl)
 		if err != nil {
-			if stop := (stopError{}); errors.As(err, &stop) {
+			if stop, ok := errors.AsType[stopError](err); ok {
 				// Since the 'stop' command halts execution of the entire script,
 				// log its message separately from the section in which it appears.
 				err = endSection(true)
@@ -607,13 +607,13 @@
 		return nil
 	}
 
-	if s := (stopError{}); errors.As(err, &s) {
+	if _, ok := errors.AsType[stopError](err); ok {
 		// This error originated in the Stop command.
 		// Propagate it as-is.
 		return cmdError(cmd, err)
 	}
 
-	if w := (waitError{}); errors.As(err, &w) {
+	if _, ok := errors.AsType[waitError](err); ok {
 		// This error was surfaced from a background process by a call to Wait.
 		// Add a call frame for Wait itself, but ignore its "want" field.
 		// (Wait itself cannot fail to wait on commands or else it would leak
diff --git a/src/cmd/internal/script/scripttest/scripttest.go b/src/cmd/internal/script/scripttest/scripttest.go
index bace662..349201f 100644
--- a/src/cmd/internal/script/scripttest/scripttest.go
+++ b/src/cmd/internal/script/scripttest/scripttest.go
@@ -89,7 +89,7 @@
 		return e.Execute(s, filename, bufio.NewReader(testScript), log)
 	}()
 
-	if skip := (skipError{}); errors.As(err, &skip) {
+	if skip, ok := errors.AsType[skipError](err); ok {
 		if skip.msg == "" {
 			t.Skip("SKIP")
 		} else {
diff --git a/src/cmd/link/link_test.go b/src/cmd/link/link_test.go
index 0125ba8..31822d2 100644
--- a/src/cmd/link/link_test.go
+++ b/src/cmd/link/link_test.go
@@ -1532,11 +1532,13 @@
 		}
 		cmd = testenv.Command(t, testenv.GoToolPath(t), "tool", "nm", exe)
 		out, err = cmd.CombinedOutput()
-		if err != nil && !errors.As(err, new(*exec.ExitError)) {
-			// Error exit is fine as it may have no symbols.
-			// On darwin we need to emit dynamic symbol references so it
-			// actually has some symbols, and nm succeeds.
-			t.Errorf("(mode=%s) go tool nm failed: %v\n%s", mode, err, out)
+		if err != nil {
+			if _, ok := errors.AsType[*exec.ExitError](err); !ok {
+				// Error exit is fine as it may have no symbols.
+				// On darwin we need to emit dynamic symbol references so it
+				// actually has some symbols, and nm succeeds.
+				t.Errorf("(mode=%s) go tool nm failed: %v\n%s", mode, err, out)
+			}
 		}
 		for _, s := range syms {
 			if bytes.Contains(out, []byte(s)) {
diff --git a/src/crypto/tls/conn.go b/src/crypto/tls/conn.go
index 09dc9ea..2de120a 100644
--- a/src/crypto/tls/conn.go
+++ b/src/crypto/tls/conn.go
@@ -1578,9 +1578,9 @@
 			// the handshake (RFC 9001, Section 5.7).
 			c.quicSetReadSecret(QUICEncryptionLevelApplication, c.cipherSuite, c.in.trafficSecret)
 		} else {
-			var a alert
 			c.out.Lock()
-			if !errors.As(c.out.err, &a) {
+			a, ok := errors.AsType[alert](c.out.err)
+			if !ok {
 				a = alertInternalError
 			}
 			c.out.Unlock()
diff --git a/src/crypto/tls/handshake_server.go b/src/crypto/tls/handshake_server.go
index 088c66f..a2cf176 100644
--- a/src/crypto/tls/handshake_server.go
+++ b/src/crypto/tls/handshake_server.go
@@ -965,10 +965,9 @@
 
 		chains, err := certs[0].Verify(opts)
 		if err != nil {
-			var errCertificateInvalid x509.CertificateInvalidError
-			if errors.As(err, &x509.UnknownAuthorityError{}) {
+			if _, ok := errors.AsType[x509.UnknownAuthorityError](err); ok {
 				c.sendAlert(alertUnknownCA)
-			} else if errors.As(err, &errCertificateInvalid) && errCertificateInvalid.Reason == x509.Expired {
+			} else if errCertificateInvalid, ok := errors.AsType[x509.CertificateInvalidError](err); ok && errCertificateInvalid.Reason == x509.Expired {
 				c.sendAlert(alertCertificateExpired)
 			} else {
 				c.sendAlert(alertBadCertificate)
diff --git a/src/crypto/tls/handshake_server_test.go b/src/crypto/tls/handshake_server_test.go
index 941f2a3..43183db 100644
--- a/src/crypto/tls/handshake_server_test.go
+++ b/src/crypto/tls/handshake_server_test.go
@@ -403,8 +403,7 @@
 
 	err := Server(s, testConfig).Handshake()
 	s.Close()
-	var opErr *net.OpError
-	if !errors.As(err, &opErr) || opErr.Err != error(alertUnknownCA) {
+	if opErr, ok := errors.AsType[*net.OpError](err); !ok || opErr.Err != error(alertUnknownCA) {
 		t.Errorf("Got error: %s; expected: %s", err, error(alertUnknownCA))
 	}
 }
diff --git a/src/crypto/tls/quic.go b/src/crypto/tls/quic.go
index 3be479e..2ba2242 100644
--- a/src/crypto/tls/quic.go
+++ b/src/crypto/tls/quic.go
@@ -362,12 +362,11 @@
 	if err == nil {
 		return nil
 	}
-	var ae AlertError
-	if errors.As(err, &ae) {
+	if _, ok := errors.AsType[AlertError](err); ok {
 		return err
 	}
-	var a alert
-	if !errors.As(err, &a) {
+	a, ok := errors.AsType[alert](err)
+	if !ok {
 		a = alertInternalError
 	}
 	// Return an error wrapping the original error and an AlertError.
diff --git a/src/crypto/tls/quic_test.go b/src/crypto/tls/quic_test.go
index f6e8c55..5f4b2b7 100644
--- a/src/crypto/tls/quic_test.go
+++ b/src/crypto/tls/quic_test.go
@@ -368,8 +368,7 @@
 	if !errors.Is(err, AlertError(alertBadCertificate)) {
 		t.Errorf("connection handshake terminated with error %q, want alertBadCertificate", err)
 	}
-	var e *CertificateVerificationError
-	if !errors.As(err, &e) {
+	if _, ok := errors.AsType[*CertificateVerificationError](err); !ok {
 		t.Errorf("connection handshake terminated with error %q, want CertificateVerificationError", err)
 	}
 }
diff --git a/src/debug/buildinfo/buildinfo.go b/src/debug/buildinfo/buildinfo.go
index 12e3b75..d202d50 100644
--- a/src/debug/buildinfo/buildinfo.go
+++ b/src/debug/buildinfo/buildinfo.go
@@ -67,7 +67,7 @@
 // with module support.
 func ReadFile(name string) (info *BuildInfo, err error) {
 	defer func() {
-		if pathErr := (*fs.PathError)(nil); errors.As(err, &pathErr) {
+		if _, ok := errors.AsType[*fs.PathError](err); ok {
 			err = fmt.Errorf("could not read Go build info: %w", err)
 		} else if err != nil {
 			err = fmt.Errorf("could not read Go build info from %s: %w", name, err)
diff --git a/src/encoding/json/jsontext/coder_test.go b/src/encoding/json/jsontext/coder_test.go
index 4a9efb3..8602e3e 100644
--- a/src/encoding/json/jsontext/coder_test.go
+++ b/src/encoding/json/jsontext/coder_test.go
@@ -486,7 +486,7 @@
 				// Retry as a ReadToken call.
 				expectError := dec.PeekKind() == '}' || dec.PeekKind() == ']'
 				if expectError {
-					if !errors.As(err, new(*SyntacticError)) {
+					if _, ok := errors.AsType[*SyntacticError](err); !ok {
 						t.Fatalf("%s: Decoder.ReadToken error is %T, want %T", where, err, new(SyntacticError))
 					}
 					tickTock = !tickTock
diff --git a/src/encoding/json/jsontext/fuzz_test.go b/src/encoding/json/jsontext/fuzz_test.go
index 60d16b9..3ad181d 100644
--- a/src/encoding/json/jsontext/fuzz_test.go
+++ b/src/encoding/json/jsontext/fuzz_test.go
@@ -53,9 +53,10 @@
 			} else {
 				val, err := dec.ReadValue()
 				if err != nil {
-					expectError := dec.PeekKind() == '}' || dec.PeekKind() == ']'
-					if expectError && errors.As(err, new(*SyntacticError)) {
-						continue
+					if expectError := dec.PeekKind() == '}' || dec.PeekKind() == ']'; expectError {
+						if _, ok := errors.AsType[*SyntacticError](err); ok {
+							continue
+						}
 					}
 					if err == io.EOF {
 						break
diff --git a/src/encoding/json/jsontext/state.go b/src/encoding/json/jsontext/state.go
index d214fd5..538dfe3 100644
--- a/src/encoding/json/jsontext/state.go
+++ b/src/encoding/json/jsontext/state.go
@@ -24,8 +24,7 @@
 // The name of a duplicate JSON object member can be extracted as:
 //
 //	err := ...
-//	var serr jsontext.SyntacticError
-//	if errors.As(err, &serr) && serr.Err == jsontext.ErrDuplicateName {
+//	if serr, ok := errors.AsType[jsontext.SyntacticError](err); ok && serr.Err == jsontext.ErrDuplicateName {
 //		ptr := serr.JSONPointer // JSON pointer to duplicate name
 //		name := ptr.LastToken() // duplicate name itself
 //		...
diff --git a/src/encoding/json/v2/errors.go b/src/encoding/json/v2/errors.go
index 9485d7b..0f50d60 100644
--- a/src/encoding/json/v2/errors.go
+++ b/src/encoding/json/v2/errors.go
@@ -28,8 +28,7 @@
 // The name of an unknown JSON object member can be extracted as:
 //
 //	err := ...
-//	var serr json.SemanticError
-//	if errors.As(err, &serr) && serr.Err == json.ErrUnknownName {
+//	if serr, ok := errors.AsType[json.SemanticError](err); ok && serr.Err == json.ErrUnknownName {
 //		ptr := serr.JSONPointer // JSON pointer to unknown name
 //		name := ptr.LastToken() // unknown name itself
 //		...
diff --git a/src/encoding/json/v2/example_test.go b/src/encoding/json/v2/example_test.go
index c6bf0a8..6d539bb 100644
--- a/src/encoding/json/v2/example_test.go
+++ b/src/encoding/json/v2/example_test.go
@@ -371,8 +371,7 @@
 	// Specifying RejectUnknownMembers causes Unmarshal
 	// to reject the presence of any unknown members.
 	err = json.Unmarshal([]byte(input), new(Color), json.RejectUnknownMembers(true))
-	var serr *json.SemanticError
-	if errors.As(err, &serr) && serr.Err == json.ErrUnknownName {
+	if serr, ok := errors.AsType[*json.SemanticError](err); ok && serr.Err == json.ErrUnknownName {
 		fmt.Println("Unmarshal error:", serr.Err, strconv.Quote(serr.JSONPointer.LastToken()))
 	}
 
diff --git a/src/go/types/api_test.go b/src/go/types/api_test.go
index f7a98ae..2798b9e 100644
--- a/src/go/types/api_test.go
+++ b/src/go/types/api_test.go
@@ -2480,8 +2480,8 @@
 			t.Fatalf("Instantiate(%v, %v) returned nil error, want non-nil", T, test.targs)
 		}
 
-		var argErr *ArgumentError
-		if !errors.As(err, &argErr) {
+		argErr, ok := errors.AsType[*ArgumentError](err)
+		if !ok {
 			t.Fatalf("Instantiate(%v, %v): error is not an *ArgumentError", T, test.targs)
 		}
 
@@ -2496,8 +2496,8 @@
 		Index: 1,
 		Err:   Error{Msg: "test"},
 	}
-	var e Error
-	if !errors.As(err, &e) {
+	e, ok := errors.AsType[Error](err)
+	if !ok {
 		t.Fatalf("error %v does not wrap types.Error", err)
 	}
 	if e.Msg != "test" {
diff --git a/src/internal/runtime/wasitest/testdata/tcpecho.go b/src/internal/runtime/wasitest/testdata/tcpecho.go
index 819e352..6da56ac 100644
--- a/src/internal/runtime/wasitest/testdata/tcpecho.go
+++ b/src/internal/runtime/wasitest/testdata/tcpecho.go
@@ -62,8 +62,7 @@
 		l, err := net.FileListener(f)
 		f.Close()
 
-		var se syscall.Errno
-		switch errors.As(err, &se); se {
+		switch se, _ := errors.AsType[syscall.Errno](err); se {
 		case syscall.ENOTSOCK:
 			continue
 		case syscall.EBADF:
diff --git a/src/internal/testenv/testenv_unix.go b/src/internal/testenv/testenv_unix.go
index a629078..22eeca2 100644
--- a/src/internal/testenv/testenv_unix.go
+++ b/src/internal/testenv/testenv_unix.go
@@ -21,8 +21,7 @@
 		return false
 	}
 
-	var errno syscall.Errno
-	if errors.As(err, &errno) {
+	if errno, ok := errors.AsType[syscall.Errno](err); ok {
 		switch errno {
 		case syscall.EPERM, syscall.EROFS:
 			// User lacks permission: either the call requires root permission and the
diff --git a/src/io/fs/readdir_test.go b/src/io/fs/readdir_test.go
index 4c409ae..30f5ad0 100644
--- a/src/io/fs/readdir_test.go
+++ b/src/io/fs/readdir_test.go
@@ -94,8 +94,8 @@
 }
 
 func errorPath(err error) string {
-	var perr *PathError
-	if !errors.As(err, &perr) {
+	perr, ok := errors.AsType[*PathError](err)
+	if !ok {
 		return ""
 	}
 	return perr.Path
diff --git a/src/log/log_test.go b/src/log/log_test.go
index 8cc05c5..5d5d38c 100644
--- a/src/log/log_test.go
+++ b/src/log/log_test.go
@@ -272,8 +272,7 @@
 			cmd.Env = append(cmd.Environ(), envVar+"=1")
 
 			out, err := cmd.CombinedOutput()
-			var exitErr *exec.ExitError
-			if !errors.As(err, &exitErr) {
+			if _, ok := errors.AsType[*exec.ExitError](err); !ok {
 				t.Fatalf("expected exec.ExitError: %v", err)
 			}
 
diff --git a/src/log/slog/logger_test.go b/src/log/slog/logger_test.go
index bf645d9..edacef1 100644
--- a/src/log/slog/logger_test.go
+++ b/src/log/slog/logger_test.go
@@ -303,8 +303,7 @@
 			cmd.Env = append(cmd.Environ(), envVar+"=1")
 
 			out, err := cmd.CombinedOutput()
-			var exitErr *exec.ExitError
-			if !errors.As(err, &exitErr) {
+			if _, ok := errors.AsType[*exec.ExitError](err); !ok {
 				t.Fatalf("expected exec.ExitError: %v", err)
 			}
 
diff --git a/src/net/dnsclient_unix.go b/src/net/dnsclient_unix.go
index 5e060a6..940fccc 100644
--- a/src/net/dnsclient_unix.go
+++ b/src/net/dnsclient_unix.go
@@ -842,8 +842,7 @@
 	}
 	p, server, err := r.lookup(ctx, arpa, dnsmessage.TypePTR, conf)
 	if err != nil {
-		var dnsErr *DNSError
-		if errors.As(err, &dnsErr) && dnsErr.IsNotFound {
+		if dnsErr, ok := errors.AsType[*DNSError](err); ok && dnsErr.IsNotFound {
 			if order == hostLookupDNSFiles {
 				names := lookupStaticAddr(addr)
 				if len(names) > 0 {
diff --git a/src/net/dnsclient_unix_test.go b/src/net/dnsclient_unix_test.go
index 826b4da..fc1d40f 100644
--- a/src/net/dnsclient_unix_test.go
+++ b/src/net/dnsclient_unix_test.go
@@ -2627,8 +2627,7 @@
 				}
 
 				expectedErr := DNSError{Err: errNoSuchHost.Error(), Name: v.req, IsNotFound: true}
-				var dnsErr *DNSError
-				errors.As(err, &dnsErr)
+				dnsErr, _ := errors.AsType[*DNSError](err)
 				if dnsErr == nil || *dnsErr != expectedErr {
 					t.Errorf("%v: Lookup%v: unexpected error: %v", i, testName, err)
 				}
@@ -2820,8 +2819,7 @@
 		}
 
 		expectedErr := DNSError{Err: errNoSuchHost.Error(), Name: testName, IsNotFound: true}
-		var dnsErr *DNSError
-		errors.As(err, &dnsErr)
+		dnsErr, _ := errors.AsType[*DNSError](err)
 		if dnsErr == nil || *dnsErr != expectedErr {
 			t.Errorf("Lookup%v: unexpected error: %v", v.name, err)
 		}
@@ -2853,8 +2851,7 @@
 
 	r := &Resolver{PreferGo: true, Dial: fake.DialContext}
 	_, _, err := r.tryOneName(context.Background(), getSystemDNSConfig(), "go.dev.", dnsmessage.TypeA)
-	var dnsErr *DNSError
-	if !(errors.As(err, &dnsErr) && dnsErr.Err == errServerMisbehaving.Error()) {
+	if dnsErr, ok := errors.AsType[*DNSError](err); !ok || dnsErr.Err != errServerMisbehaving.Error() {
 		t.Fatalf("r.tryOneName(): unexpected error: %v", err)
 	}
 }
diff --git a/src/net/http/h2_error_test.go b/src/net/http/h2_error_test.go
index 5e40068..e718254 100644
--- a/src/net/http/h2_error_test.go
+++ b/src/net/http/h2_error_test.go
@@ -25,19 +25,18 @@
 }
 
 func TestStreamError(t *testing.T) {
-	var target externalStreamError
 	streamErr := http2streamError(42, http2ErrCodeProtocol)
-	ok := errors.As(streamErr, &target)
+	extStreamErr, ok := errors.AsType[externalStreamError](streamErr)
 	if !ok {
-		t.Fatalf("errors.As failed")
+		t.Fatalf("errors.AsType failed")
 	}
-	if target.StreamID != streamErr.StreamID {
-		t.Errorf("got StreamID %v, expected %v", target.StreamID, streamErr.StreamID)
+	if extStreamErr.StreamID != streamErr.StreamID {
+		t.Errorf("got StreamID %v, expected %v", extStreamErr.StreamID, streamErr.StreamID)
 	}
-	if target.Cause != streamErr.Cause {
-		t.Errorf("got Cause %v, expected %v", target.Cause, streamErr.Cause)
+	if extStreamErr.Cause != streamErr.Cause {
+		t.Errorf("got Cause %v, expected %v", extStreamErr.Cause, streamErr.Cause)
 	}
-	if uint32(target.Code) != uint32(streamErr.Code) {
-		t.Errorf("got Code %v, expected %v", target.Code, streamErr.Code)
+	if uint32(extStreamErr.Code) != uint32(streamErr.Code) {
+		t.Errorf("got Code %v, expected %v", extStreamErr.Code, streamErr.Code)
 	}
 }
diff --git a/src/net/lookup_test.go b/src/net/lookup_test.go
index 514cbd0..2a77410 100644
--- a/src/net/lookup_test.go
+++ b/src/net/lookup_test.go
@@ -1420,8 +1420,8 @@
 			return
 		}
 
-		var dnsErr *DNSError
-		if errors.As(err, &dnsErr) {
+		dnsErr, ok := errors.AsType[*DNSError](err)
+		if ok {
 			succeeded := true
 			if !dnsErr.IsNotFound {
 				succeeded = false
@@ -1455,8 +1455,7 @@
 func TestLookupPortNotFound(t *testing.T) {
 	allResolvers(t, func(t *testing.T) {
 		_, err := LookupPort("udp", "_-unknown-service-")
-		var dnsErr *DNSError
-		if !errors.As(err, &dnsErr) || !dnsErr.IsNotFound {
+		if dnsErr, ok := errors.AsType[*DNSError](err); !ok || !dnsErr.IsNotFound {
 			t.Fatalf("unexpected error: %v", err)
 		}
 	})
@@ -1475,8 +1474,7 @@
 func TestLookupPortDifferentNetwork(t *testing.T) {
 	allResolvers(t, func(t *testing.T) {
 		_, err := LookupPort("udp", tcpOnlyService)
-		var dnsErr *DNSError
-		if !errors.As(err, &dnsErr) || !dnsErr.IsNotFound {
+		if dnsErr, ok := errors.AsType[*DNSError](err); !ok || !dnsErr.IsNotFound {
 			t.Fatalf("unexpected error: %v", err)
 		}
 	})
diff --git a/src/os/exec/exec_test.go b/src/os/exec/exec_test.go
index 3bded3d..1decebd 100644
--- a/src/os/exec/exec_test.go
+++ b/src/os/exec/exec_test.go
@@ -1378,8 +1378,8 @@
 		// The child process should be reported as failed,
 		// and the grandchild will exit (or die by SIGPIPE) once the
 		// stderr pipe is closed.
-		if ee := new(*exec.ExitError); !errors.As(err, ee) {
-			t.Errorf("Wait error = %v; want %T", err, *ee)
+		if ee, ok := errors.AsType[*exec.ExitError](err); !ok {
+			t.Errorf("Wait error = %v; want %T", err, ee)
 		}
 	})
 
@@ -1423,8 +1423,8 @@
 
 		// This command ignores SIGINT, sleeping until it is killed.
 		// Wait should return the usual error for a killed process.
-		if ee := new(*exec.ExitError); !errors.As(err, ee) {
-			t.Errorf("Wait error = %v; want %T", err, *ee)
+		if ee, ok := errors.AsType[*exec.ExitError](err); !ok {
+			t.Errorf("Wait error = %v; want %T", err, ee)
 		}
 	})
 
@@ -1471,7 +1471,7 @@
 		t.Logf("stderr:\n%s", cmd.Stderr)
 		t.Logf("[%d] %v", cmd.Process.Pid, err)
 
-		if ee := new(*exec.ExitError); !errors.As(err, ee) {
+		if _, ok := errors.AsType[*exec.ExitError](err); !ok {
 			t.Errorf("Wait error = %v; want %v", err, ctx.Err())
 		}
 
diff --git a/src/os/os_test.go b/src/os/os_test.go
index 9f6eb13e..5367349 100644
--- a/src/os/os_test.go
+++ b/src/os/os_test.go
@@ -840,8 +840,7 @@
 	if err == nil {
 		t.Error("Readdirnames succeeded; want non-nil error")
 	}
-	var pe *PathError
-	if !errors.As(err, &pe) || pe.Path != f.Name() {
+	if pe, ok := errors.AsType[*PathError](err); !ok || pe.Path != f.Name() {
 		t.Errorf("Readdirnames returned %q; want a PathError with path %q", err, f.Name())
 	}
 	if len(names) > 0 {
diff --git a/src/runtime/pprof/proto_windows.go b/src/runtime/pprof/proto_windows.go
index f4dc44b..3118e89 100644
--- a/src/runtime/pprof/proto_windows.go
+++ b/src/runtime/pprof/proto_windows.go
@@ -67,8 +67,7 @@
 func createModuleSnapshot() (syscall.Handle, error) {
 	for {
 		snap, err := syscall.CreateToolhelp32Snapshot(windows.TH32CS_SNAPMODULE|windows.TH32CS_SNAPMODULE32, uint32(syscall.Getpid()))
-		var errno syscall.Errno
-		if err != nil && errors.As(err, &errno) && errno == windows.ERROR_BAD_LENGTH {
+		if errno, ok := errors.AsType[syscall.Errno](err); ok && errno == windows.ERROR_BAD_LENGTH {
 			// When CreateToolhelp32Snapshot(SNAPMODULE|SNAPMODULE32, ...) fails
 			// with ERROR_BAD_LENGTH then it should be retried until it succeeds.
 			continue
diff --git a/src/testing/fstest/testfs.go b/src/testing/fstest/testfs.go
index 1fb84b89..72830a0 100644
--- a/src/testing/fstest/testfs.go
+++ b/src/testing/fstest/testfs.go
@@ -29,7 +29,7 @@
 // The contents of fsys must not change concurrently with TestFS.
 //
 // If TestFS finds any misbehaviors, it returns either the first error or a
-// list of errors. Use [errors.Is] or [errors.As] to inspect.
+// list of errors. Use [errors.Is] or [errors.AsType] to inspect.
 //
 // Typical usage inside a test is:
 //
diff --git a/src/testing/fstest/testfs_test.go b/src/testing/fstest/testfs_test.go
index d6d6d89..e3d7f1a 100644
--- a/src/testing/fstest/testfs_test.go
+++ b/src/testing/fstest/testfs_test.go
@@ -105,8 +105,12 @@
 
 	// TestFS is expected to return a list of errors.
 	// Enforce that the list can be extracted for browsing.
-	var errs interface{ Unwrap() []error }
-	if !errors.As(err, &errs) {
+	type wrapper interface{
+		error
+		Unwrap() []error
+	}
+	errs, ok := errors.AsType[wrapper](err)
+	if !ok {
 		t.Errorf("caller should be able to extract the errors as a list: %#v", err)
 	} else {
 		for _, err := range errs.Unwrap() {
diff --git a/src/text/template/exec_test.go b/src/text/template/exec_test.go
index 6544090..8665f3a 100644
--- a/src/text/template/exec_test.go
+++ b/src/text/template/exec_test.go
@@ -1015,8 +1015,7 @@
 	var b bytes.Buffer
 	err := tmpl.Execute(&b, nil)
 
-	var e *CustomError
-	if !errors.As(err, &e) {
+	if _, ok := errors.AsType[*CustomError](err); !ok {
 		t.Fatalf("expected custom error; got %s", err)
 	}
 }
diff --git a/src/text/template/funcs.go b/src/text/template/funcs.go
index c28c3ea..30b3243 100644
--- a/src/text/template/funcs.go
+++ b/src/text/template/funcs.go
@@ -22,7 +22,7 @@
 // return value evaluates to non-nil during execution, execution terminates and
 // Execute returns that error.
 //
-// Errors returned by Execute wrap the underlying error; call [errors.As] to
+// Errors returned by Execute wrap the underlying error; call [errors.AsType] to
 // unwrap them.
 //
 // When template execution invokes a function with an argument list, that list

Change information

Files:

M src/cmd/compile/internal/types2/api_test.go
M src/cmd/go/internal/base/path.go
M src/cmd/go/internal/doc/pkgsite.go
M src/cmd/go/internal/fmtcmd/fmt.go
M src/cmd/go/internal/load/pkg.go
M src/cmd/go/internal/modget/get.go
M src/cmd/go/internal/modget/query.go
M src/cmd/go/internal/modload/build.go
M src/cmd/go/internal/modload/buildlist.go
M src/cmd/go/internal/modload/edit.go
M src/cmd/go/internal/modload/import.go
M src/cmd/go/internal/modload/list.go
M src/cmd/go/internal/modload/load.go
M src/cmd/go/internal/modload/modfile.go
M src/cmd/go/internal/modload/query.go
M src/cmd/go/internal/test/test.go
M src/cmd/go/internal/test/testflag.go
M src/cmd/go/internal/vcweb/vcstest/vcstest_test.go
M src/cmd/go/internal/vcweb/vcweb.go
M src/cmd/go/internal/version/version.go
M src/cmd/go/internal/vet/vetflag.go
M src/cmd/go/internal/work/build.go
M src/cmd/go/internal/work/exec.go
M src/cmd/internal/bootstrap_test/experiment_toolid_test.go
M src/cmd/internal/robustio/robustio_darwin.go
M src/cmd/internal/robustio/robustio_flaky.go
M src/cmd/internal/robustio/robustio_windows.go
M src/cmd/internal/script/engine.go
M src/cmd/internal/script/scripttest/scripttest.go
M src/cmd/link/link_test.go
M src/crypto/tls/conn.go
M src/crypto/tls/handshake_server.go
M src/crypto/tls/handshake_server_test.go
M src/crypto/tls/quic.go
M src/crypto/tls/quic_test.go
M src/debug/buildinfo/buildinfo.go
M src/encoding/json/jsontext/coder_test.go
M src/encoding/json/jsontext/fuzz_test.go
M src/encoding/json/jsontext/state.go
M src/encoding/json/v2/errors.go
M src/encoding/json/v2/example_test.go
M src/go/types/api_test.go
M src/internal/runtime/wasitest/testdata/tcpecho.go
M src/internal/testenv/testenv_unix.go
M src/io/fs/readdir_test.go
M src/log/log_test.go
M src/log/slog/logger_test.go
M src/net/dnsclient_unix.go
M src/net/dnsclient_unix_test.go
M src/net/http/h2_error_test.go
M src/net/lookup_test.go
M src/os/exec/exec_test.go
M src/os/os_test.go
M src/runtime/pprof/proto_windows.go
M src/testing/fstest/testfs.go
M src/testing/fstest/testfs_test.go
M src/text/template/exec_test.go
M src/text/template/funcs.go

Change size: L

Delta: 58 files changed, 160 insertions(+), 180 deletions(-)

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Gopher Robot (Gerrit)

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Oct 1, 2025, 4:08:32 PM (12 hours ago) Oct 1

to jub0bs, Gerrit Bot, goph...@pubsubhelper.golang.org, golang-co...@googlegroups.com

Gopher Robot added 1 comment

Patchset-level comments

File-level comment, Patchset 1 (Latest):

Gopher Robot . unresolved

I spotted some possible problems with your PR:

  1. You usually need to reference a bug number for all but trivial or cosmetic fixes. For this repo, the format is usually 'Fixes #12345' or 'Updates #12345' at the end of the commit message. Should you have a bug reference?

Please address any problems by updating the GitHub PR.

When complete, mark this comment as 'Done' and click the [blue 'Reply' button](https://go.dev/wiki/GerritBot#i-left-a-reply-to-a-comment-in-gerrit-but-no-one-but-me-can-see-it) above. These findings are based on heuristics; if a finding does not apply, briefly reply here saying so.

To update the commit title or commit message body shown here in Gerrit, you must edit the GitHub PR title and PR description (the first comment) in the GitHub web interface using the 'Edit' button or 'Edit' menu entry there. Note: pushing a new commit to the PR will not automatically update the commit message used by Gerrit.

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jub0bs (Gerrit)

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Oct 1, 2025, 4:09:48 PM (12 hours ago) Oct 1

to Gerrit Bot, goph...@pubsubhelper.golang.org, Gopher Robot, golang-co...@googlegroups.com

jub0bs added 1 comment

Patchset-level comments

File-level comment, Patchset 1 (Latest):

Gopher Robot . resolved

I spotted some possible problems with your PR:
  1. You usually need to reference a bug number for all but trivial or cosmetic fixes. For this repo, the format is usually 'Fixes #12345' or 'Updates #12345' at the end of the commit message. Should you have a bug reference?
Please address any problems by updating the GitHub PR.
When complete, mark this comment as 'Done' and click the [blue 'Reply' button](https://go.dev/wiki/GerritBot#i-left-a-reply-to-a-comment-in-gerrit-but-no-one-but-me-can-see-it) above. These findings are based on heuristics; if a finding does not apply, briefly reply here saying so.
To update the commit title or commit message body shown here in Gerrit, you must edit the GitHub PR title and PR description (the first comment) in the GitHub web interface using the 'Edit' button or 'Edit' menu entry there. Note: pushing a new commit to the PR will not automatically update the commit message used by Gerrit.
For more details, see:
[how to update commit messages](https://go.dev/wiki/GerritBot/#how-does-gerritbot-determine-the-final-commit-message) for PRs imported into Gerrit.
the Go project's [conventions for commit messages](https://go.dev/doc/contribute#commit_messages) that you should follow.
(In general for Gerrit code reviews, the change author is expected to [log in to Gerrit](https://go-review.googlesource.com/login/) with a Gmail or other Google account and then close out each piece of feedback by marking it as 'Done' if implemented as suggested or otherwise reply to each review comment. See the [Review](https://go.dev/doc/contribute#review) section of the Contributing Guide for details.)

jub0bs

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Jake Bailey (Gerrit)

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Oct 1, 2025, 4:43:02 PM (12 hours ago) Oct 1

to jub0bs, Gerrit Bot, goph...@pubsubhelper.golang.org, Brad Fitzpatrick, Ian Lance Taylor, Russ Cox, Gopher Robot, golang-co...@googlegroups.com

Attention needed from Brad Fitzpatrick, Ian Lance Taylor and Russ Cox

Jake Bailey voted Commit-Queue+1

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