[tools] go/analysis/passes/modernize: fix stringsseq panic

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Gopher Robot (Gerrit)

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Jul 24, 2026, 12:34:58 PM (2 days ago) Jul 24

to Madeline Kalil, goph...@pubsubhelper.golang.org, golang-...@googlegroups.com, golang...@luci-project-accounts.iam.gserviceaccount.com, Alan Donovan, golang-co...@googlegroups.com

Gopher Robot submitted the change with unreviewed changes

Unreviewed changes

3 is the latest approved patch-set.
The change was submitted with unreviewed changes in the following files:

```
The name of the file: go/analysis/passes/modernize/stringsseq.go
Insertions: 18, Deletions: 18.

@@ -116,24 +116,24 @@
 					continue
 				}
 
-				if obj := typeutil.Callee(info, call); obj != nil {
-					switch obj {
-					case stringsSplit, stringsFields, bytesSplit, bytesFields:
-						oldFnName := obj.Name()
-						seqFnName := fmt.Sprintf("%sSeq", oldFnName)
-						pass.Report(analysis.Diagnostic{
-							Pos:     sel.Pos(),
-							End:     sel.End(),
-							Message: fmt.Sprintf("Ranging over %s is more efficient", seqFnName),
-							SuggestedFixes: []analysis.SuggestedFix{{
-								Message: fmt.Sprintf("Replace %s with %s", oldFnName, seqFnName),
-								TextEdits: append(edits, analysis.TextEdit{
-									Pos:     sel.Sel.Pos(),
-									End:     sel.Sel.End(),
-									NewText: []byte(seqFnName)}),
-							}},
-						})
-					}
+				switch obj := typeutil.Callee(info, call); obj {
+				case nil:
+					// a conversion, not a call
+				case stringsSplit, stringsFields, bytesSplit, bytesFields:
+					oldFnName := obj.Name()
+					seqFnName := fmt.Sprintf("%sSeq", oldFnName)
+					pass.Report(analysis.Diagnostic{
+						Pos:     sel.Pos(),
+						End:     sel.End(),
+						Message: fmt.Sprintf("Ranging over %s is more efficient", seqFnName),
+						SuggestedFixes: []analysis.SuggestedFix{{
+							Message: fmt.Sprintf("Replace %s with %s", oldFnName, seqFnName),
+							TextEdits: append(edits, analysis.TextEdit{
+								Pos:     sel.Sel.Pos(),
+								End:     sel.Sel.End(),
+								NewText: []byte(seqFnName)}),
+						}},
+					})
 				}
 			}
 		}
```

Change information

Commit message:

go/analysis/passes/modernize: fix stringsseq panic

The stringsseq modernizer matches the call operand
of a range statement against strings.Split,
strings.Fields, bytes.Split, or bytes.Fields. If the
call operand is a conversion, typeutil.Callee(call)
will return nil. If the current package does not import
"bytes", the index.Object for bytes.Fields and bytes.Split
will also be nil, so it will match one of these cases and
create a nil panic on obj.Name().

Add a switch case for nil so that we don't enter the
wrong case when the CallExpr is a conversion.

Fixes golang/go#80554

Change-Id: Ie4608a4103ca0d820cdef7450a8612a53a2e0ed9

Reviewed-on: https://go-review.googlesource.com/c/tools/+/805280

Reviewed-by: Alan Donovan <adon...@google.com>

Auto-Submit: Madeline Kalil <mka...@google.com>

LUCI-TryBot-Result: golang...@luci-project-accounts.iam.gserviceaccount.com <golang...@luci-project-accounts.iam.gserviceaccount.com>

Files: