From ce2a33e35d87bb317bcd526328efd39ec6671405 Mon Sep 17 00:00:00 2001
From: Chiawen Chen <golopot@gmail.com>
Date: Wed, 2 Oct 2024 15:58:39 +0800
Subject: [PATCH] gopls/internal: fix extract refactor for cases with anonymous
 functions

This fix ignores return statements inside anonymous functions. These
return statements can be ignored because they does not meddle with
the control flow of the outer function.

Fixes golang/go#64821

Change-Id: I21f82f8663bf3343412d5b537802a56efc34495f
Reviewed-on: https://go-review.googlesource.com/c/tools/+/617335
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>
Reviewed-by: Alan Donovan <adonovan@google.com>
Auto-Submit: Robert Findley <rfindley@google.com>
---
 gopls/internal/golang/extract.go              |  4 +++
 .../codeaction/functionextraction.txt         | 33 +++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/gopls/internal/golang/extract.go b/gopls/internal/golang/extract.go
index d1092d85409..6ea011e220e 100644
--- a/gopls/internal/golang/extract.go
+++ b/gopls/internal/golang/extract.go
@@ -246,6 +246,10 @@ func extractFunctionMethod(fset *token.FileSet, start, end token.Pos, src []byte
 		if n.Pos() < start || n.End() > end {
 			return n.Pos() <= end
 		}
+		// exclude return statements in function literals because they don't affect the refactor.
+		if _, ok := n.(*ast.FuncLit); ok {
+			return false
+		}
 		ret, ok := n.(*ast.ReturnStmt)
 		if !ok {
 			return true
diff --git a/gopls/internal/test/marker/testdata/codeaction/functionextraction.txt b/gopls/internal/test/marker/testdata/codeaction/functionextraction.txt
index 1c65fcd2329..1b9f487c49d 100644
--- a/gopls/internal/test/marker/testdata/codeaction/functionextraction.txt
+++ b/gopls/internal/test/marker/testdata/codeaction/functionextraction.txt
@@ -581,3 +581,36 @@ func newFunction() (int, error) {
 	return u, err
 }
 
+-- anonymousfunc.go --
+package extract
+import "cmp"
+import "slices"
+
+// issue go#64821
+func _() {
+	var s []string //@codeaction("var", anonEnd, "refactor.extract.function", anon1)
+	slices.SortFunc(s, func(a, b string) int {
+		return cmp.Compare(a, b)
+	})
+	println(s) //@loc(anonEnd, ")")
+}
+
+-- @anon1/anonymousfunc.go --
+package extract
+import "cmp"
+import "slices"
+
+// issue go#64821
+func _() {
+	//@codeaction("var", anonEnd, "refactor.extract.function", anon1)
+	newFunction() //@loc(anonEnd, ")")
+}
+
+func newFunction() {
+	var s []string
+	slices.SortFunc(s, func(a, b string) int {
+		return cmp.Compare(a, b)
+	})
+	println(s)
+}
+