Merge pull request swiftlang#28187 from aschwaighofer/fix_metadata_emission_foreign_types

IRGen: We need to emit metadata for types that are emitted with shared linkage

Author: aschwaighofer

lib/IRGen/GenDecl.cpp

@@ -1262,6 +1262,17 @@ void IRGenerator::noteUseOfTypeGlobals(NominalTypeDecl *type,
   if (!hasLazyMetadata(type))
     return;
 
+  // If the type can be generated in several TU with weak linkage we don't know
+  // which one will be picked up so we have to require the metadata. Otherwise,
+  // the situation can arise where one TU contains a type descriptor with a null
+  // metadata access function and the other TU which requires metadata has a
+  // type descriptor with a valid metadata access function but the linker picks
+  // the first one.
+  if (isAccessorLazilyGenerated(getTypeMetadataAccessStrategy(
+          type->getDeclaredType()->getCanonicalType()))) {
+    requireMetadata = RequireMetadata;
+  }
+
   // Try to create a new record of the fact that we used this type.
   auto insertResult = LazyTypeGlobals.try_emplace(type);
   auto &entry = insertResult.first->second;

test/IRGen/foreign_type_metadata.swift

@@ -0,0 +1,22 @@
+// RUN: %target-swift-frontend %s -emit-ir | %FileCheck %s
+
+// REQUIRES: objc_interop
+
+import Foundation
+
+// Make sure we emit a metadata accessor for foreign types even if the type
+// metadata is not required by this TU. Another TU could require it and the
+// linker could choose the less defined one of the two.
+
+// CHECK: @"$sSo8_NSRangeVMn" = linkonce_odr hidden constant <{ {{.*}}sSo8_NSRangeVMa{{.*}} }>, section "__TEXT,__const"
+
+func use(_ closure: @escaping (Int) -> ()) {}
+
+public func captureRange(_ r: NSRange?) {
+  var l = r
+  use {
+    if $0 == 0 {
+      l = NSRange()
+    }
+  }
+}

test/Interpreter/ForeignMetadata.swift

@@ -0,0 +1,11 @@
+// RUN: %empty-directory(%t)
+// RUN: cp %s %t/main.swift
+// RUN: %target-build-swift -o %t/main %S/Inputs/ForeignTypeMetadata1.swift  %S/Inputs/ForeignTypeMetadata2.swift %t/main.swift -swift-version 5
+// RUN: %target-codesign %t/main
+// RUN: %target-run %t/main
+
+
+// REQUIRES: executable_test
+// REQUIRES: objc_interop
+
+useType()

test/Interpreter/Inputs/ForeignTypeMetadata1.swift

@@ -0,0 +1,12 @@
+import Foundation
+
+func use(_ closure: @escaping (Int) -> ()) {}
+
+public func captureRange(_ r: NSRange?) {
+  var l = r
+  use {
+    if $0 == 0 {
+      l = NSRange()
+    }
+  }
+}

test/Interpreter/Inputs/ForeignTypeMetadata2.swift

@@ -0,0 +1,7 @@
+import Foundation
+
+public func useType() {
+  var x = [NSRange]()
+  x.append(NSRange())
+  print(x)
+}