IRGen: Skip lowering unavailable types nested in extensions.

Part of rdar://107425181

Author: tshortli

lib/IRGen/GenDecl.cpp

@@ -5489,6 +5489,9 @@ Address IRGenModule::getAddrOfEnumCase(EnumElementDecl *Case,
 
 void IRGenModule::emitNestedTypeDecls(DeclRange members) {
   for (Decl *member : members) {
+    if (Lowering::shouldSkipLowering(member))
+      continue;
+
     member->visitAuxiliaryDecls([&](Decl *decl) {
       emitNestedTypeDecls({decl, nullptr});
     });

test/IRGen/unavailable_decl_optimization.swift

@@ -158,16 +158,6 @@ extension S: P {
   public func requirement() {}
 }
 
-// CHECK-NO-STRIP: s4Test29unavailableFuncWithNestedTypeyyF
-// CHECK-STRIP-NOT: s4Test29unavailableFuncWithNestedTypeyyF
-@available(*, unavailable)
-public func unavailableFuncWithNestedType() {
-  struct Nested {
-    // s4Test29unavailableFuncWithNestedTypeyyF0E0L_V6methodyyF
-    public func method() {}
-  }
-}
-
 // MARK: -
 
 // MARK: UnavailableEnum
@@ -187,8 +177,3 @@ public func unavailableFuncWithNestedType() {
 
 // CHECK: s4Test1EOwug
 // CHECK: s4Test1EOMa
-
-// MARK: unavailableFuncWithNestedType().Nested
-
-// CHECK-NO-STRIP: s4Test29unavailableFuncWithNestedTypeyyF0E0L_VMa
-// CHECK-STRIP-NOT: s4Test29unavailableFuncWithNestedTypeyyF0E0L_VMa

test/IRGen/unavailable_decl_optimization_nested_type.swift

@@ -0,0 +1,35 @@
+// RUN: %target-swift-frontend -parse-as-library -module-name Test -validate-tbd-against-ir=missing %s -emit-ir | %FileCheck %s --check-prefixes=CHECK,CHECK-NO-STRIP
+
+// RUN: %target-swift-frontend -parse-as-library -module-name Test -validate-tbd-against-ir=missing -unavailable-decl-optimization=complete %s -emit-ir | %FileCheck %s --check-prefixes=CHECK,CHECK-STRIP
+
+// CHECK-NO-STRIP: s4Test29unavailableFuncWithNestedTypeyyF
+// CHECK-STRIP-NOT: s4Test29unavailableFuncWithNestedTypeyyF
+@available(*, unavailable)
+public func unavailableFuncWithNestedType() {
+  struct NestedInFunction {
+    // s4Test29unavailableFuncWithNestedTypeyyF0E10InFunctionL_VADycfC
+    init() {}
+  }
+
+  _ = NestedInFunction()
+}
+
+// CHECK-NO-STRIP: s4Test29unavailableFuncWithNestedTypeyyF0E10InFunctionL_VADycfC
+// CHECK-STRIP-NOT: s4Test29unavailableFuncWithNestedTypeyyF0E10InFunctionL_VADycfC
+
+public struct S {}
+
+extension S {
+  @available(*, unavailable)
+  public struct NestedInExtension {
+    // CHECK-NO-STRIP: s4Test1SV17NestedInExtensionV6methodyyF
+    // CHECK-STRIP-NOT: s4Test1SV17NestedInExtensionV6methodyyF
+    public func method() {}
+  }
+}
+
+// CHECK-NO-STRIP: s4Test1SV17NestedInExtensionVMa
+// CHECK-STRIP-NOT: s4Test1SV17NestedInExtensionVMa
+
+// CHECK-NO-STRIP: s4Test29unavailableFuncWithNestedTypeyyF0E10InFunctionL_VMa
+// CHECK-STRIP-NOT: s4Test29unavailableFuncWithNestedTypeyyF0E10InFunctionL_VMa