Fix setting breakpoints in parts of a library.

This fixes the regression caused by
1eaa3dd and reported in #29988.

When picking a class to set a breakpoint, instead of rejecting classes
not defined in the script, we now reject classes which do not belong to
the library to which the script belongs.

[email protected]

Review-Url: https://codereview.chromium.org/2965673004 .

Author: Siva Chandra

runtime/tests/vm/vm.status

@@ -273,6 +273,7 @@ cc/Debug_ScriptGetTokenInfo_MultiLineInterpolation: Fail
 cc/Debugger_PrintBreakpointsToJSONArray: Fail
 cc/Debugger_Rewind_Optimized: SkipSlow
 cc/Debugger_SetBreakpointInFunctionLiteralFieldInitializers: Crash
+cc/Debugger_SetBreakpointInPartOfLibrary: Crash
 cc/ErrorHandleBasics: Fail
 cc/EvalExpression: Crash
 cc/ExternalUint8ClampedArrayAccess: Fail

runtime/vm/debugger.cc

@@ -2710,6 +2710,8 @@ bool Debugger::FindBestFit(const Script& script,
                            Function* best_fit) {
   Zone* zone = Thread::Current()->zone();
   Class& cls = Class::Handle(zone);
+  Library& lib = Library::Handle(zone, script.FindLibrary());
+  ASSERT(!lib.IsNull());
   const GrowableObjectArray& closures = GrowableObjectArray::Handle(
       zone, isolate_->object_store()->closure_functions());
   Array& functions = Array::Handle(zone);
@@ -2740,7 +2742,9 @@ bool Debugger::FindBestFit(const Script& script,
       continue;
     }
     cls = class_table.At(i);
-    if (cls.script() != script.raw()) {
+    // This class is relevant to us only if it belongs to the
+    // library to which |script| belongs.
+    if (cls.library() != lib.raw()) {
       continue;
     }
     // Parse class definition if not done yet.
@@ -2786,6 +2790,11 @@ bool Debugger::FindBestFit(const Script& script,
         TokenPosition end;
         field ^= fields.At(pos);
         ASSERT(!field.IsNull());
+        if (field.Script() != script.raw()) {
+          // The field should be defined in the script we want to set
+          // the breakpoint in.
+          continue;
+        }
         if (Parser::FieldHasFunctionLiteralInitializer(field, &start, &end)) {
           if ((start <= token_pos && token_pos <= end) ||
               (token_pos <= start && start <= last_token_pos)) {

runtime/vm/debugger_test.cc

@@ -80,6 +80,37 @@ static void PausedInClosuresHandler(Dart_IsolateId isolate_id,
   closure_hit_count++;
 }
 
+TEST_CASE(Debugger_SetBreakpointInPartOfLibrary) {
+  const char* kMainScript = "main() {}\n";
+  const char* kLib = "library test_lib;\n";
+  const char* kLibPart =
+      "part of test_lib;\n"
+      "void func(int a, int b) {\n"
+      "  return a + b;\n"
+      "}\n";
+  SetFlagScope<bool> sfs(&FLAG_remove_script_timestamps_for_test, true);
+  Dart_Handle root_lib = TestCase::LoadTestScript(kMainScript, NULL);
+  EXPECT_VALID(root_lib);
+
+  Dart_Handle url = NewString("test_lib_url");
+  Dart_Handle lib_source = NewString(kLib);
+  Dart_Handle lib = Dart_LoadLibrary(url, Dart_Null(), lib_source, 0, 0);
+  EXPECT_VALID(lib);
+  EXPECT(Dart_IsLibrary(lib));
+
+  Dart_Handle part_url = NewString("part_url");
+  Dart_Handle part_source = NewString(kLibPart);
+  Dart_Handle result =
+      Dart_LoadSource(lib, part_url, Dart_Null(), part_source, 0, 0);
+  EXPECT_VALID(result);
+  EXPECT(Dart_IsLibrary(result));
+  EXPECT(Dart_IdentityEquals(lib, result));
+
+  result = Dart_SetBreakpoint(part_url, 3);
+  EXPECT_VALID(result);
+  EXPECT(Dart_IsInteger(result));
+}
+
 TEST_CASE(Debugger_SetBreakpointInFunctionLiteralFieldInitializers) {
   const char* kScriptChars =
       "main() {\n"