Merge pull request swiftlang#77285 from xymus/recover-under-loadObjCMethods

Serialization: Recover from errors under `loadObjCMethods`

Author: xymus

lib/Serialization/ModuleFile.cpp

@@ -713,8 +713,15 @@ void ModuleFile::loadObjCMethods(
       continue;
 
     // Deserialize the method and add it to the list.
+    // Drop methods with errors.
+    auto funcOrError = getDeclChecked(std::get<2>(result));
+    if (!funcOrError) {
+      diagnoseAndConsumeError(funcOrError.takeError());
+      continue;
+    }
+
     if (auto func = dyn_cast_or_null<AbstractFunctionDecl>(
-                      getDecl(std::get<2>(result)))) {
+                      funcOrError.get())) {
       methods.push_back(func);
     }
   }

test/Serialization/Recovery/objc_report_method_override.swift

@@ -0,0 +1,38 @@
+/// Recover under diagnoseUnintendedObjCMethodOverrides.
+/// rdar://138764733
+
+// RUN: %empty-directory(%t)
+// RUN: split-file %s %t
+// REQUIRES: objc_interop
+
+// RUN: %target-swift-frontend -emit-module %t/HiddenDep.swift -I %t \
+// RUN:   -o %t/HiddenDep.swiftmodule \
+// RUN:   -disable-objc-attr-requires-foundation-module
+
+// RUN: %target-swift-frontend -emit-module %t/Lib.swift -I %t \
+// RUN:   -o %t/Lib.swiftmodule \
+// RUN:   -swift-version 6 -enable-library-evolution \
+// RUN:   -disable-objc-attr-requires-foundation-module
+
+// RUN: %target-swift-frontend -typecheck %t/Client.swift -I %t \
+// RUN:   -disable-objc-attr-requires-foundation-module
+
+//--- HiddenDep.swift
+@objc
+public class HiddenType {}
+
+//--- Lib.swift
+internal import HiddenDep
+
+@objc public class Redecl {
+  @objc
+  func methodWithXref() -> HiddenType { fatalError() }
+}
+
+//--- Client.swift
+import Lib
+
+extension Redecl {
+  @objc(methodWithXref)
+  func methodWithXref_alias() { }
+}