c# - 如何使用 Roslyn 检测代码中的闭包？

Question

我能否检测到(使用 roslyn)lambda 主体中的 x 引用是对外部变量 x 的闭包，而不是 lambda 本身的某个局部变量？

var x = "foo";
var a = string[0];
a.Any(i => i == x);

Answer 1

是的。您可以使用 DataFlowAnalysis API。

var tree = CSharpSyntaxTree.ParseText(
    @"
class C{
void M(){
    var x = ""foo"";
    var a = new string[0];
    var testing = a.Any(i => i == x);
}
} 
");
var Mscorlib = PortableExecutableReference.CreateFromAssembly(typeof(object).Assembly);
var compilation = CSharpCompilation.Create("MyCompilation",
    syntaxTrees: new[] { tree }, references: new[] { Mscorlib });
var model = compilation.GetSemanticModel(tree);

var lambda = tree.GetRoot().DescendantNodes().OfType<LocalDeclarationStatementSyntax>().Last();

var dataFlowAnalysis = model.AnalyzeDataFlow(lambda);
var capturedVariables = dataFlowAnalysis.Captured;

foreach(var variable in capturedVariables)
{
    //Do something
}