Merge pull request swiftlang#31409 from hborla/5.3-invalid-decl-ref-expr

[5.3][CSApply] Fix a case where CSApply produced an invalid DeclRefExpr

Author: hborla

lib/Sema/CSApply.cpp

@@ -1080,6 +1080,18 @@ namespace {
       // Build a member reference.
       auto memberRef = resolveConcreteDeclRef(member, memberLocator);
 
+      // If we're referring to a member type, it's just a type
+      // reference.
+      if (auto *TD = dyn_cast<TypeDecl>(member)) {
+        Type refType = simplifyType(openedType);
+        auto ref = TypeExpr::createForDecl(memberLoc, TD, cs.DC, /*isImplicit=*/false);
+        cs.setType(ref, refType);
+        auto *result = new (context) DotSyntaxBaseIgnoredExpr(
+            base, dotLoc, ref, refType);
+        cs.setType(result, refType);
+        return result;
+      }
+
       // If we're referring to the member of a module, it's just a simple
       // reference.
       if (baseTy->is<ModuleType>()) {
@@ -1093,18 +1105,6 @@ namespace {
         return forceUnwrapIfExpected(DSBI, choice, memberLocator);
       }
 
-      // If we're referring to a member type, it's just a type
-      // reference.
-      if (auto *TD = dyn_cast<TypeDecl>(member)) {
-        Type refType = simplifyType(openedType);
-        auto ref = TypeExpr::createForDecl(memberLoc, TD, cs.DC, /*isImplicit=*/false);
-        cs.setType(ref, refType);
-        auto *result = new (context) DotSyntaxBaseIgnoredExpr(
-            base, dotLoc, ref, refType);
-        cs.setType(result, refType);
-        return result;
-      }
-
       bool isUnboundInstanceMember =
         (!baseIsInstance && member->isInstanceMember());
       bool isPartialApplication = shouldBuildCurryThunk(choice, baseIsInstance);

test/Constraints/Inputs/imported_type.h

@@ -0,0 +1,4 @@
+#import <Foundation/Foundation.h>
+
+@interface Data
+@end

test/Constraints/invalid_decl_ref.swift

@@ -0,0 +1,9 @@
+// RUN: %target-swift-frontend -module-name SomeModule -typecheck -verify -dump-ast -import-objc-header %S/Inputs/imported_type.h %s | %FileCheck %s
+
+// REQUIRES: objc_interop
+
+import Foundation
+
+// CHECK: declref_expr type='module<SomeModule>'
+// CHECK-NEXT: type_expr type='Data.Type'
+let type = SomeModule.Data.self