[wasm][debugger] Implement support for null-conditional operators in simple expressions

src/mono/wasm/debugger/BrowserDebugProxy/MemberReferenceResolver.cs

@@ -77,18 +77,17 @@ public async Task<JObject> GetValueFromObject(JToken objRet, CancellationToken t
  return null;
  }
 
- public async Task<(JObject containerObject, string remaining)> ResolveStaticMembersInStaticTypes(string varName, CancellationToken token)
+ public async Task<(JObject containerObject, ArraySegment<string> remaining)> ResolveStaticMembersInStaticTypes(ArraySegment<string> parts, CancellationToken token)
  {
  string classNameToFind = "";
- string[] parts = varName.Split(".", StringSplitOptions.TrimEntries);
  var store = await proxy.LoadStore(sessionId, token);
  var methodInfo = context.CallStack.FirstOrDefault(s => s.Id == scopeId)?.Method?.Info;
 
  if (methodInfo == null)
  return (null, null);
 
  int typeId = -1;
- for (int i = 0; i < parts.Length; i++)
+ for (int i = 0; i < parts.Count; i++)
  {
  string part = parts[i];
 
@@ -97,9 +96,9 @@ public async Task<JObject> GetValueFromObject(JToken objRet, CancellationToken t
  JObject memberObject = await FindStaticMemberInType(classNameToFind, part, typeId);
  if (memberObject != null)
  {
- string remaining = null;
- if (i < parts.Length - 1)
- remaining = string.Join('.', parts[(i + 1)..]);
+ ArraySegment<string> remaining = null;
+ if (i < parts.Count - 1)
+ remaining = parts[i..];
 
  return (memberObject, remaining);
  }
@@ -177,6 +176,10 @@ async Task<int> FindStaticTypeId(string typeName)
  // Checks Locals, followed by `this`
  public async Task<JObject> Resolve(string varName, CancellationToken token)
  {
+ // question mark at the end of expression is invalid
+ if (varName[^1] == '?')
+ throw new ReturnAsErrorException($"Expected expression.", "ReferenceError");
+
  //has method calls
  if (varName.Contains('('))
  return null;
@@ -187,18 +190,19 @@ public async Task<JObject> Resolve(string varName, CancellationToken token)
  if (scopeCache.ObjectFields.TryGetValue(varName, out JObject valueRet))
  return await GetValueFromObject(valueRet, token);
 
- string[] parts = varName.Split(".");
- if (parts.Length == 0)
- return null;
+ string[] parts = varName.Split(".", StringSplitOptions.TrimEntries);
+ if (parts.Length == 0 || string.IsNullOrEmpty(parts[0]))
+ throw new ReturnAsErrorException($"Failed to resolve expression: {varName}", "ReferenceError");
 
  JObject retObject = await ResolveAsLocalOrThisMember(parts[0]);
+ bool throwOnNullReference = parts[0][^1] != '?';
  if (retObject != null && parts.Length > 1)
- retObject = await ResolveAsInstanceMember(string.Join('.', parts[1..]), retObject);
+ retObject = await ResolveAsInstanceMember(parts, retObject, throwOnNullReference);
 
  if (retObject == null)
  {
- (retObject, string remaining) = await ResolveStaticMembersInStaticTypes(varName, token);
- if (!string.IsNullOrEmpty(remaining))
+ (retObject, ArraySegment<string> remaining) = await ResolveStaticMembersInStaticTypes(parts, token);
+ if (remaining != null && remaining.Count != 0)
  {
  if (retObject.IsNullValuedObject())
  {
@@ -207,7 +211,7 @@ public async Task<JObject> Resolve(string varName, CancellationToken token)
  }
  else
  {
- retObject = await ResolveAsInstanceMember(remaining, retObject);
+ retObject = await ResolveAsInstanceMember(remaining, retObject, throwOnNullReference);
  }
  }
  }
@@ -217,7 +221,6 @@ public async Task<JObject> Resolve(string varName, CancellationToken token)
 
  async Task<JObject> ResolveAsLocalOrThisMember(string name)
  {
- var nameTrimmed = name.Trim();
  if (scopeCache.Locals.Count == 0 && !localsFetched)
  {
  Result scope_res = await proxy.GetScopeProperties(sessionId, scopeId, token);
@@ -226,7 +229,11 @@ async Task<JObject> ResolveAsLocalOrThisMember(string name)
  localsFetched = true;
  }
 
- if (scopeCache.Locals.TryGetValue(nameTrimmed, out JObject obj))
+ // remove null-condition, otherwise TryGet by name fails
+ if (name[^1] == '?' || name[^1] == '!')
+ name = name.Remove(name.Length - 1);
+
+ if (scopeCache.Locals.TryGetValue(name, out JObject obj))
  return obj["value"]?.Value<JObject>();
 
  if (!scopeCache.Locals.TryGetValue("this", out JObject objThis))
@@ -242,54 +249,76 @@ async Task<JObject> ResolveAsLocalOrThisMember(string name)
  return null;
  }
 
- JToken objRet = valueOrError.Value.FirstOrDefault(objPropAttr => objPropAttr["name"].Value<string>() == nameTrimmed);
+ JToken objRet = valueOrError.Value.FirstOrDefault(objPropAttr => objPropAttr["name"].Value<string>() == name);
  if (objRet != null)
  return await GetValueFromObject(objRet, token);
 
  return null;
  }
 
- async Task<JObject> ResolveAsInstanceMember(string expr, JObject baseObject)
+ async Task<JObject> ResolveAsInstanceMember(ArraySegment<string> parts, JObject baseObject, bool throwOnNullReference)
  {
  JObject resolvedObject = baseObject;
- string[] parts = expr.Split('.');
- for (int i = 0; i < parts.Length; i++)
+ // parts[0] - name of baseObject
+ for (int i = 1; i < parts.Count; i++)
  {
- string partTrimmed = parts[i].Trim();
- if (partTrimmed.Length == 0)
+ string part = parts[i];
+ if (part.Length == 0)
  return null;
 
+ if (part[^1] == '!')
+ part = part.Remove(part.Length - 1);
+
+ bool hasCurrentPartNullCondition = part[^1] == '?';
+
+ // current value of resolvedObject is on parts[i - 1]
+ if (resolvedObject.IsNullValuedObject())
+ {
+ // trying null.$member
+ if (throwOnNullReference)
+ throw new ReturnAsErrorException($"Expression threw NullReferenceException trying to access \"{part}\" on a null-valued object.", "ReferenceError");
+
+ if (i == parts.Count - 1)
+ {
+ // this is not ideal, it returns the last object
+ // that had objectId and was null-valued,
+ // so the class/description of object are not of the last part
+ return resolvedObject;
+ }
+
+ // check if null condition is correctly applied: should we throw or return null-object
+ throwOnNullReference = !hasCurrentPartNullCondition;
+ continue;
+ }
+
  if (!DotnetObjectId.TryParse(resolvedObject?["objectId"]?.Value<string>(), out DotnetObjectId objectId))
- return null;
+ {
+ if (resolvedObject["type"].Value<string>() == "string")
+ throw new ReturnAsErrorException($"String properties evaluation is not supported yet.", "ReferenceError"); // Issue #66823
+ if (!throwOnNullReference)
+ throw new ReturnAsErrorException($"Operation '?' not allowed on primitive type - '{parts[i - 1]}'", "ReferenceError");
+ throw new ReturnAsErrorException($"Cannot find member '{part}' on a primitive type", "ReferenceError");
+ }
 
- ValueOrError<GetMembersResult> valueOrError = await proxy.RuntimeGetObjectMembers(sessionId, objectId, null, token);
+ var args = JObject.FromObject(new { forDebuggerDisplayAttribute = true });
+ ValueOrError<GetMembersResult> valueOrError = await proxy.RuntimeGetObjectMembers(sessionId, objectId, args, token);
  if (valueOrError.IsError)
  {
  logger.LogDebug($"ResolveAsInstanceMember failed with : {valueOrError.Error}");
  return null;
  }
 
- JToken objRet = valueOrError.Value.FirstOrDefault(objPropAttr => objPropAttr["name"]?.Value<string>() == partTrimmed);
+ if (hasCurrentPartNullCondition)
+ part = part.Remove(part.Length - 1);
+ JToken objRet = valueOrError.Value.FirstOrDefault(objPropAttr => objPropAttr["name"]?.Value<string>() == part);
  if (objRet == null)
  return null;
 
  resolvedObject = await GetValueFromObject(objRet, token);
  if (resolvedObject == null)
  return null;
-
- if (resolvedObject.IsNullValuedObject())
- {
- if (i < parts.Length - 1)
- {
- // there is some parts remaining, and can't
- // do null.$remaining
- return null;
- }
-
- return resolvedObject;
- }
+ throwOnNullReference = !hasCurrentPartNullCondition;
  }
-
  return resolvedObject;
  }
  }

src/mono/wasm/debugger/BrowserDebugProxy/MonoProxy.cs

@@ -752,14 +752,14 @@ internal async Task<ValueOrError<GetMembersResult>> RuntimeGetObjectMembers(Sess
  GetObjectCommandOptions getObjectOptions = GetObjectCommandOptions.WithProperties;
  if (args != null)
  {
- if (args["accessorPropertiesOnly"] != null && args["accessorPropertiesOnly"].Value<bool>())
- {
+ if (args["accessorPropertiesOnly"]?.Value<bool>() == true)
  getObjectOptions |= GetObjectCommandOptions.AccessorPropertiesOnly;
- }
- if (args["ownProperties"] != null && args["ownProperties"].Value<bool>())
- {
+
+ if (args["ownProperties"]?.Value<bool>() == true)
  getObjectOptions |= GetObjectCommandOptions.OwnProperties;
- }
+
+ if (args["forDebuggerDisplayAttribute"]?.Value<bool>() == true)
+ getObjectOptions |= GetObjectCommandOptions.ForDebuggerDisplayAttribute;
  }
  try
  {

src/mono/wasm/debugger/DebuggerTestSuite/EvaluateOnCallFrameTests.cs

@@ -507,13 +507,13 @@ public async Task EvaluateSimpleMethodCallsError() => await CheckInspectLocalsAt
 
  var (_, res) = await EvaluateOnCallFrame(id, "this.objToTest.MyMethodWrong()", expect_ok: false );
  Assert.Equal(
- $"Method 'MyMethodWrong' not found in type 'DebuggerTests.EvaluateMethodTestsClass.ParmToTest'", 
+ $"Method 'MyMethodWrong' not found in type 'DebuggerTests.EvaluateMethodTestsClass.ParmToTest'",
  res.Error["result"]?["description"]?.Value<string>());
 
  (_, res) = await EvaluateOnCallFrame(id, "this.objToTest.MyMethod(1)", expect_ok: false);
-  Assert.Equal(
-  "Unable to evaluate method 'MyMethod'. Too many arguments passed.", 
-  res.Error["result"]?["description"]?.Value<string>());
+ Assert.Equal(
+ "Unable to evaluate method 'MyMethod'. Too many arguments passed.",
+ res.Error["result"]?["description"]?.Value<string>());
 
  (_, res) = await EvaluateOnCallFrame(id, "this.CallMethodWithParm(\"1\")", expect_ok: false );
  Assert.Contains("Unable to evaluate method 'this.CallMethodWithParm(\"1\")'", res.Error["message"]?.Value<string>());
@@ -523,7 +523,7 @@ public async Task EvaluateSimpleMethodCallsError() => await CheckInspectLocalsAt
 
  (_, res) = await EvaluateOnCallFrame(id, "this.ParmToTestObjException.MyMethod()", expect_ok: false );
  Assert.Contains(
- "Cannot evaluate '(this.ParmToTestObjException.MyMethod()\n)'", 
+ "Cannot evaluate '(this.ParmToTestObjException.MyMethod()\n)'",
  res.Error["result"]?["description"]?.Value<string>());
  });
 
@@ -1147,8 +1147,64 @@ await EvaluateOnCallFrameAndCheck(id,
  );
  });
 
+ [ConditionalFact(nameof(RunningOnChrome))]
+ public async Task EvaluateNullObjectPropertiesPositive() => await CheckInspectLocalsAtBreakpointSite(
+ $"DebuggerTests.EvaluateNullableProperties", "Evaluate", 6, "Evaluate",
+ $"window.setTimeout(function() {{ invoke_static_method ('[debugger-test] DebuggerTests.EvaluateNullableProperties:Evaluate'); 1 }})",
+ wait_for_event_fn: async (pause_location) =>
+ {
+ var id = pause_location["callFrames"][0]["callFrameId"].Value<string>();
+
+ // we have no way of returning int? for null values, 
+ // so we return the last non-null class name
+ await EvaluateOnCallFrameAndCheck(id,
+ ("list.Count", TNumber(1)),
+ ("list!.Count", TNumber(1)),
+ ("list?.Count", TNumber(1)),
+ ("listNull", TObject("System.Collections.Generic.List<int>", is_null: true)),
+ ("listNull?.Count", TObject("System.Collections.Generic.List<int>", is_null: true)),
+ ("tc?.MemberList?.Count", TNumber(2)),
+ ("tc!.MemberList?.Count", TNumber(2)),
+ ("tc?.MemberListNull?.Count", TObject("System.Collections.Generic.List<int>", is_null: true)),
+ ("tc.MemberListNull?.Count", TObject("System.Collections.Generic.List<int>", is_null: true)),
+ ("tcNull?.MemberListNull?.Count", TObject("DebuggerTests.EvaluateNullableProperties.TestClass", is_null: true)));
+ });
+
+ [ConditionalFact(nameof(RunningOnChrome))]
+ public async Task EvaluateNullObjectPropertiesNegative() => await CheckInspectLocalsAtBreakpointSite(
+ $"DebuggerTests.EvaluateNullableProperties", "Evaluate", 6, "Evaluate",
+ $"window.setTimeout(function() {{ invoke_static_method ('[debugger-test] DebuggerTests.EvaluateNullableProperties:Evaluate'); 1 }})",
+ wait_for_event_fn: async (pause_location) =>
+ {
+ var id = pause_location["callFrames"][0]["callFrameId"].Value<string>();
+ await CheckEvaluateFail("list.Count.x", "Cannot find member 'x' on a primitive type");
+ await CheckEvaluateFail("listNull.Count", GetNullReferenceErrorOn("\"Count\""));
+ await CheckEvaluateFail("listNull!.Count", GetNullReferenceErrorOn("\"Count\""));
+ await CheckEvaluateFail("tcNull.MemberListNull.Count", GetNullReferenceErrorOn("\"MemberListNull\""));
+ await CheckEvaluateFail("tc.MemberListNull.Count", GetNullReferenceErrorOn("\"Count\""));
+ await CheckEvaluateFail("tcNull?.MemberListNull.Count", GetNullReferenceErrorOn("\"Count\""));
+ await CheckEvaluateFail("listNull?.Count.NonExistingProperty", GetNullReferenceErrorOn("\"NonExistingProperty\""));
+ await CheckEvaluateFail("tc?.MemberListNull! .Count", GetNullReferenceErrorOn("\"Count\""));
+ await CheckEvaluateFail("tc?. MemberListNull!.Count", GetNullReferenceErrorOn("\"Count\""));
+ await CheckEvaluateFail("tc?.MemberListNull.Count", GetNullReferenceErrorOn("\"Count\""));
+ await CheckEvaluateFail("tc! .MemberListNull!.Count", GetNullReferenceErrorOn("\"Count\""));
+ await CheckEvaluateFail("tc!.MemberListNull. Count", GetNullReferenceErrorOn("\"Count\""));
+ await CheckEvaluateFail("tcNull?.Sibling.MemberListNull?.Count", GetNullReferenceErrorOn("\"MemberListNull?\""));
+ await CheckEvaluateFail("listNull?", "Expected expression.");
+ await CheckEvaluateFail("listNull!.Count", GetNullReferenceErrorOn("\"Count\""));
+ await CheckEvaluateFail("x?.p", "Operation '?' not allowed on primitive type - 'x?'");
+
+ string GetNullReferenceErrorOn(string name) => $"Expression threw NullReferenceException trying to access {name} on a null-valued object.";
+
+ async Task CheckEvaluateFail(string expr, string message)
+ {
+ (_, Result _res) = await EvaluateOnCallFrame(id, expr, expect_ok: false);
+ AssertEqual(message, _res.Error["result"]?["description"]?.Value<string>(), $"Expression '{expr}' - wrong error message");
+ }
+ });
+
  [Fact]
- public async Task EvaluateMethodsOnPrimitiveTypesReturningPrimitives() =>  await CheckInspectLocalsAtBreakpointSite(
+ public async Task EvaluateMethodsOnPrimitiveTypesReturningPrimitives() => await CheckInspectLocalsAtBreakpointSite(
  "DebuggerTests.PrimitiveTypeMethods", "Evaluate", 11, "Evaluate",
  "window.setTimeout(function() { invoke_static_method ('[debugger-test] DebuggerTests.PrimitiveTypeMethods:Evaluate'); })",
  wait_for_event_fn: async (pause_location) =>

src/mono/wasm/debugger/tests/debugger-test/debugger-evaluate-test.cs

@@ -1371,7 +1371,7 @@ public static void Evaluate()
  var test = new TestClass();
  }
  }
- 
+
  public static class PrimitiveTypeMethods
  {
  public class TestClass
@@ -1401,6 +1401,30 @@ public static void Evaluate()
  string localString = "S*T*R";
  }
  }
+
+ public static class EvaluateNullableProperties
+ {
+ class TestClass
+ {
+ public List<int> MemberListNull = null;
+ public List<int> MemberList = new List<int>() {1, 2};
+ public TestClass Sibling { get; set; }
+ }
+ static void Evaluate()
+ {
+ #nullable enable
+ List<int>? listNull = null;
+ #nullable disable
+ List<int> list = new List<int>() {1};
+ TestClass tc = new TestClass();
+ TestClass tcNull = null;
+ string str = "str#value";
+ string str_null = null;
+ int x = 5;
+ int? x_null = null;
+ int? x_val = x;
+ }
+ }
 }
 
 namespace DebuggerTestsV2