fix: detect slice type aliases from imported packages

makezero/makezero.go

@@ -199,8 +199,7 @@ func (v *visitor) isSlice(node ast.Node) bool {
 		obj := ident.Obj
 		if obj == nil {
 			if v.info != nil {
-				_, ok := v.info.ObjectOf(ident).Type().(*types.Slice)
-				return ok
+				return v.isSliceType(v.info.ObjectOf(ident).Type())
 			}
 			return false
 		}
@@ -211,12 +210,28 @@ func (v *visitor) isSlice(node ast.Node) bool {
 		node = spec.Type
 	}
 
+	// handle imported types (e.g., types.S)
+	if sel, ok := node.(*ast.SelectorExpr); ok {
+		if v.info != nil {
+			return v.isSliceType(v.info.ObjectOf(sel.Sel).Type())
+		}
+		return false
+	}
+
 	if node, ok := node.(*ast.ArrayType); ok {
 		return node.Len == nil // only slices have zero length
 	}
 	return false
 }
 
+func (v *visitor) isSliceType(t types.Type) bool {
+	if t == nil {
+		return false
+	}
+	_, ok := t.Underlying().(*types.Slice)
+	return ok
+}
+
 func (v *visitor) hasNoLintOnSameLine(node ast.Node) bool {
 	nolint := regexp.MustCompile(`^\s*nozero\b`)
 	nodePos := v.fset.Position(node.Pos())

pkg/analyzer/analyzer_test.go

@@ -10,7 +10,7 @@ import (
 func TestAppend(t *testing.T) {
 	testdata := analysistest.TestData()
 	a := analyzer.NewAnalyzer()
-	analysistest.Run(t, testdata, a, "./append")
+	analysistest.Run(t, testdata, a, "./src/append")
 }
 
 func TestAlways(t *testing.T) {
@@ -20,5 +20,5 @@ func TestAlways(t *testing.T) {
 	if err != nil {
 		t.Fatalf("expected no error but got %q", err)
 	}
-	analysistest.Run(t, testdata, a, "./always")
+	analysistest.Run(t, testdata, a, "./src/always")
 }

pkg/analyzer/testdata/src/always/append.go

@@ -0,0 +1,22 @@
+package always
+
+import (
+	"fmt"
+	"typespkg"
+)
+
+func Foo() {
+	x := make([]int, 5) // want "slice `x` does not have non-zero initial length"
+	fmt.Println(x)
+}
+
+func Bar() {
+	x := make(typespkg.S, 10) // want "slice `x` does not have non-zero initial length"
+	x = append(x, "...")      // want "append to slice `x` with non-zero initialized length"
+	fmt.Println(x)
+}
+
+func Baz() {
+	x := make(typespkg.M, 10)
+	fmt.Println(x)
+}

pkg/analyzer/testdata/src/append/append.go

@@ -0,0 +1,23 @@
+package append
+
+import (
+	"fmt"
+	"typespkg"
+)
+
+func Foo() {
+	x := make([]int, 5)
+	x = append(x, 1) // want "append to slice `x` with non-zero initialized length"
+	fmt.Println(x)
+}
+
+func Bar() {
+	x := make(typespkg.S, 10)
+	x = append(x, "...") // want "append to slice `x` with non-zero initialized length"
+	fmt.Println(x)
+}
+
+func Baz() {
+	x := make(typespkg.M, 10)
+	fmt.Println(x)
+}

pkg/analyzer/testdata/src/typespkg/typespkg.go

@@ -0,0 +1,6 @@
+package typespkg
+
+type (
+	S []string
+	M map[string]int
+)