From 6b086be8e3184c68764c5a320b064cca01ffc5fc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20Skytt=C3=A4?= <ville.skytta@upcloud.com>
Date: Sun, 20 Aug 2023 19:03:02 +0300
Subject: [PATCH] Suggest strings.ContainsFunc instead of strings.IndexFunc
 with Go 1.21+

---
 simple/lint.go                                         | 10 +++++++++-
 simple/lint_test.go                                    |  6 +++++-
 .../example.com/CheckStringsContains_go120/contains.go |  9 +++++++++
 .../example.com/CheckStringsContains_go121/contains.go |  9 +++++++++
 .../CheckStringsContains_go121/contains.go.golden      |  9 +++++++++
 5 files changed, 41 insertions(+), 2 deletions(-)
 create mode 100644 simple/testdata/src/example.com/CheckStringsContains_go120/contains.go
 create mode 100644 simple/testdata/src/example.com/CheckStringsContains_go121/contains.go
 create mode 100644 simple/testdata/src/example.com/CheckStringsContains_go121/contains.go.golden

diff --git a/simple/lint.go b/simple/lint.go
index 433caa172..c99031533 100644
--- a/simple/lint.go
+++ b/simple/lint.go
@@ -349,6 +349,7 @@ func CheckStringsContains(pass *analysis.Pass) (interface{}, error) {
 			return
 		}
 
+		opts := []report.Option{}
 		var r ast.Expr
 		switch funIdent.Name {
 		case "IndexRune":
@@ -366,6 +367,12 @@ func CheckStringsContains(pass *analysis.Pass) (interface{}, error) {
 				X:   pkgIdent,
 				Sel: &ast.Ident{Name: "Contains"},
 			}
+		case "IndexFunc":
+			r = &ast.SelectorExpr{
+				X:   pkgIdent,
+				Sel: &ast.Ident{Name: "ContainsFunc"},
+			}
+			opts = append(opts, report.MinimumStdlibVersion(21))
 		default:
 			return
 		}
@@ -381,9 +388,10 @@ func CheckStringsContains(pass *analysis.Pass) (interface{}, error) {
 			}
 		}
 
-		report.Report(pass, node, fmt.Sprintf("should use %s instead", report.Render(pass, r)),
+		opts = append(opts,
 			report.FilterGenerated(),
 			report.Fixes(edit.Fix(fmt.Sprintf("simplify use of %s", report.Render(pass, call.Fun)), edit.ReplaceWithNode(pass.Fset, node, r))))
+		report.Report(pass, node, fmt.Sprintf("should use %s instead", report.Render(pass, r)), opts...)
 	}
 	code.Preorder(pass, fn, (*ast.BinaryExpr)(nil))
 	return nil, nil
diff --git a/simple/lint_test.go b/simple/lint_test.go
index 2d3f98baa..d9acc2598 100644
--- a/simple/lint_test.go
+++ b/simple/lint_test.go
@@ -11,7 +11,11 @@ func TestAll(t *testing.T) {
 		"S1000": {{Dir: "example.com/CheckSingleCaseSelect"}},
 		"S1001": {{Dir: "example.com/CheckLoopCopy"}},
 		"S1002": {{Dir: "example.com/CheckIfBoolCmp"}},
-		"S1003": {{Dir: "example.com/CheckStringsContains"}},
+		"S1003": {
+			{Dir: "example.com/CheckStringsContains"},
+			{Dir: "example.com/CheckStringsContains_go120", Version: "1.20"},
+			{Dir: "example.com/CheckStringsContains_go121", Version: "1.21"},
+		},
 		"S1004": {{Dir: "example.com/CheckBytesCompare"}},
 		"S1005": {
 			{Dir: "example.com/CheckUnnecessaryBlank"},
diff --git a/simple/testdata/src/example.com/CheckStringsContains_go120/contains.go b/simple/testdata/src/example.com/CheckStringsContains_go120/contains.go
new file mode 100644
index 000000000..8d5789dc3
--- /dev/null
+++ b/simple/testdata/src/example.com/CheckStringsContains_go120/contains.go
@@ -0,0 +1,9 @@
+package pkg
+
+import (
+	"strings"
+)
+
+func fn() {
+	_ = strings.IndexFunc("", func(r rune) bool { return false }) != -1
+}
diff --git a/simple/testdata/src/example.com/CheckStringsContains_go121/contains.go b/simple/testdata/src/example.com/CheckStringsContains_go121/contains.go
new file mode 100644
index 000000000..ebedc9c71
--- /dev/null
+++ b/simple/testdata/src/example.com/CheckStringsContains_go121/contains.go
@@ -0,0 +1,9 @@
+package pkg
+
+import (
+	"strings"
+)
+
+func fn() {
+	_ = strings.IndexFunc("", func(r rune) bool { return false }) != -1 //@ diag(`strings.ContainsFunc`)
+}
diff --git a/simple/testdata/src/example.com/CheckStringsContains_go121/contains.go.golden b/simple/testdata/src/example.com/CheckStringsContains_go121/contains.go.golden
new file mode 100644
index 000000000..8f7da2d98
--- /dev/null
+++ b/simple/testdata/src/example.com/CheckStringsContains_go121/contains.go.golden
@@ -0,0 +1,9 @@
+package pkg
+
+import (
+	"strings"
+)
+
+func fn() {
+	_ = strings.ContainsFunc("", func(r rune) bool { return false }) //@ diag(`strings.ContainsFunc`)
+}