[TypeChecker] TypeWrappers: Inject _storage variable into initializer body

Author: xedin

lib/Sema/TypeCheckStmt.cpp

@@ -2129,19 +2129,35 @@ TypeCheckFunctionBodyRequest::evaluate(Evaluator &evaluator,
       // what the type of the expression is.  Take the inserted return back out.
       body->setLastElement(func->getSingleExpressionBody());
     }
-  } else if (isa<ConstructorDecl>(AFD) &&
-             (body->empty() ||
-                !isKnownEndOfConstructor(body->getLastElement()))) {
-    // For constructors, we make sure that the body ends with a "return" stmt,
-    // which we either implicitly synthesize, or the user can write.  This
-    // simplifies SILGen.
-    SmallVector<ASTNode, 8> Elts(body->getElements().begin(),
-                                 body->getElements().end());
-    Elts.push_back(new (ctx) ReturnStmt(body->getRBraceLoc(),
-                                        /*value*/nullptr,
-                                        /*implicit*/true));
-    body = BraceStmt::create(ctx, body->getLBraceLoc(), Elts,
-                             body->getRBraceLoc(), body->isImplicit());
+  } else if (auto *ctor = dyn_cast<ConstructorDecl>(AFD)) {
+    // If this is user-defined constructor that requires `_storage`
+    // variable injection, do so now so now.
+    if (auto *storageVar = ctor->getLocalTypeWrapperStorageVar()) {
+      SmallVector<ASTNode, 8> Elts;
+
+      Elts.push_back(storageVar->getParentPatternBinding());
+      Elts.push_back(storageVar);
+
+      Elts.append(body->getElements().begin(),
+                  body->getElements().end());
+
+      body = BraceStmt::create(ctx, body->getLBraceLoc(), Elts,
+                               body->getRBraceLoc(), body->isImplicit());
+    }
+
+    if (body->empty() ||
+        !isKnownEndOfConstructor(body->getLastElement())) {
+      // For constructors, we make sure that the body ends with a "return" stmt,
+      // which we either implicitly synthesize, or the user can write.  This
+      // simplifies SILGen.
+      SmallVector<ASTNode, 8> Elts(body->getElements().begin(),
+                                   body->getElements().end());
+      Elts.push_back(new (ctx) ReturnStmt(body->getRBraceLoc(),
+                                          /*value*/nullptr,
+                                          /*implicit*/true));
+      body = BraceStmt::create(ctx, body->getLBraceLoc(), Elts,
+                               body->getRBraceLoc(), body->isImplicit());
+    }
   }
 
   // Typechecking, in particular ApplySolution is going to replace closures