feat: detect potential nested contexts in function declarations

pkg/analyzer/analyzer.go

@@ -30,6 +30,7 @@ func run(pass *analysis.Pass) (interface{}, error) {
 		(*ast.ForStmt)(nil),
 		(*ast.RangeStmt)(nil),
 		(*ast.FuncLit)(nil),
+		(*ast.FuncDecl)(nil),
 	}
 
 	inspctr.Preorder(nodeFilter, func(node ast.Node) {
@@ -81,25 +82,23 @@ func getReportMessage(node ast.Node) string {
 		return "nested context in loop"
 	case *ast.FuncLit:
 		return "nested context in function literal"
+	case *ast.FuncDecl:
+		return "potential nested context in function declaration"
 	default:
 		return "unsupported nested context type"
 	}
 }
 
 func getBody(node ast.Node) (*ast.BlockStmt, error) {
-	forStmt, ok := node.(*ast.ForStmt)
-	if ok {
-		return forStmt.Body, nil
-	}
-
-	rangeStmt, ok := node.(*ast.RangeStmt)
-	if ok {
-		return rangeStmt.Body, nil
-	}
-
-	funcLit, ok := node.(*ast.FuncLit)
-	if ok {
-		return funcLit.Body, nil
+	switch typedNode := node.(type) {
+	case *ast.ForStmt:
+		return typedNode.Body, nil
+	case *ast.RangeStmt:
+		return typedNode.Body, nil
+	case *ast.FuncLit:
+		return typedNode.Body, nil
+	case *ast.FuncDecl:
+		return typedNode.Body, nil
 	}
 
 	return nil, errUnknown

testdata/src/example.go

@@ -249,3 +249,25 @@ func testCasesInit(t *testing.T) {
 		})
 	}
 }
+
+type Container struct {
+	Ctx context.Context
+}
+
+func something() func(*Container) {
+	return func(r *Container) {
+		ctx := r.Ctx
+		ctx = context.WithValue(ctx, "key", "val")
+		r.Ctx = ctx // want "nested context in function literal"
+	}
+}
+
+func other() func(*Container) {
+	return blah
+}
+
+func blah(r *Container) {
+	ctx := r.Ctx
+	ctx = context.WithValue(ctx, "key", "val")
+	r.Ctx = ctx // want "potential nested context in function declaration"
+}