go/analysis/internal/checker: fix panic due to nil Pass

adonovan · gopherbot · commit d49da96b8023 · 2025-09-10T07:57:49.000-07:00
This CL documents that that internal.Pass backdoor accessor function (renamed to ActionPass for clarity) may return nil if the action was never executed, and adds defensive checks. Also, remove go1.22 transitional iterator. Thanks to cuishang for reporting and investigating. Fixes golang/go#75358 Change-Id: I59a8ce5bfb6e3a25ba129c35f321930d6786f611 Reviewed-on: https://go-review.googlesource.com/c/tools/+/702375 Reviewed-by: Robert Findley <rfindley@google.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Auto-Submit: Alan Donovan <adonovan@google.com>
diff --git a/go/analysis/analysistest/analysistest.go b/go/analysis/analysistest/analysistest.go
@@ -425,7 +425,7 @@ func Run(t Testing, dir string, a *analysis.Analyzer, patterns ...string) []*Res
 
 		// Construct the legacy result.
 		results = append(results, &Result{
-			Pass:        internal.Pass(act),
+			Pass:        internal.ActionPass(act), // may be nil
 			Diagnostics: act.Diagnostics,
 			Facts:       facts,
 			Result:      act.Result,
@@ -448,12 +448,12 @@ func Run(t Testing, dir string, a *analysis.Analyzer, patterns ...string) []*Res
 type Result struct {
 	Action *checker.Action
 
-	// legacy fields
+	// legacy fields (do not use)
 	Facts       map[types.Object][]analysis.Fact // nil key => package fact
-	Pass        *analysis.Pass
-	Diagnostics []analysis.Diagnostic // see Action.Diagnostics
-	Result      any                   // see Action.Result
-	Err         error                 // see Action.Err
+	Pass        *analysis.Pass                   // nil => action not executed
+	Diagnostics []analysis.Diagnostic            // see Action.Diagnostics
+	Result      any                              // see Action.Result
+	Err         error                            // see Action.Err
 }
 
 // loadPackages uses go/packages to load a specified packages (from source, with
diff --git a/go/analysis/checker/checker.go b/go/analysis/checker/checker.go
@@ -34,6 +34,7 @@ import (
 	"fmt"
 	"go/types"
 	"io"
+	"iter"
 	"log"
 	"os"
 	"reflect"
@@ -94,14 +95,7 @@ type Graph struct {
 //	for act := range graph.All() {
 //		...
 //	}
-//
-// Clients using go1.22 should iterate using the code below and may
-// not assume anything else about the result:
-//
-//	graph.All()(func (act *Action) bool {
-//		...
-//	})
-func (g *Graph) All() actionSeq {
+func (g *Graph) All() iter.Seq[*Action] {
 	return func(yield func(*Action) bool) {
 		forEach(g.Roots, func(act *Action) error {
 			if !yield(act) {
@@ -231,8 +225,9 @@ func Analyze(analyzers []*analysis.Analyzer, pkgs []*packages.Package, opts *Opt
 
 func init() {
 	// Allow analysistest to access Action.pass,
-	// for its legacy Result data type.
-	internal.Pass = func(x any) *analysis.Pass { return x.(*Action).pass }
+	// for the legacy analysistest.Result data type,
+	// and for internal/checker.ApplyFixes to access pass.ReadFile.
+	internal.ActionPass = func(x any) *analysis.Pass { return x.(*Action).pass }
 }
 
 type objectFactKey struct {
diff --git a/go/analysis/checker/iter_go122.go b/go/analysis/checker/iter_go122.go
diff --git a/go/analysis/checker/iter_go123.go b/go/analysis/checker/iter_go123.go
diff --git a/go/analysis/internal/checker/checker.go b/go/analysis/internal/checker/checker.go
@@ -193,11 +193,13 @@ func Run(args []string, analyzers []*analysis.Analyzer) (exitcode int) {
 	if analysisflags.Fix {
 		fixActions := make([]analysisflags.FixAction, len(graph.Roots))
 		for i, act := range graph.Roots {
-			fixActions[i] = analysisflags.FixAction{
-				Name:         act.String(),
-				FileSet:      act.Package.Fset,
-				ReadFileFunc: internal.Pass(act).ReadFile,
-				Diagnostics:  act.Diagnostics,
+			if pass := internal.ActionPass(act); pass != nil {
+				fixActions[i] = analysisflags.FixAction{
+					Name:         act.String(),
+					FileSet:      act.Package.Fset,
+					ReadFileFunc: pass.ReadFile,
+					Diagnostics:  act.Diagnostics,
+				}
 			}
 		}
 		if err := analysisflags.ApplyFixes(fixActions, dbg('v')); err != nil {
diff --git a/go/analysis/internal/internal.go b/go/analysis/internal/internal.go
@@ -8,5 +8,8 @@ import "golang.org/x/tools/go/analysis"
 
 // This function is set by the checker package to provide
 // backdoor access to the private Pass field
-// of the checker.Action type, for use by analysistest.
-var Pass func(any) *analysis.Pass
+// of the *checker.Action type, for use by analysistest.
+//
+// It may return nil, for example if the action was not
+// executed because of a failed dependent.
+var ActionPass func(action any) *analysis.Pass
