Build type checked bodies for more synthesized declarations

lib/AST/Decl.cpp

@@ -6856,7 +6856,13 @@ Type ConstructorDecl::getInitializerInterfaceType() {
     return InitializerInterfaceType;
 
   // Lazily calculate initializer type.
-  auto funcTy = getInterfaceType()->castTo<AnyFunctionType>()->getResult();
+  auto allocatorTy = getInterfaceType();
+  if (!allocatorTy->is<AnyFunctionType>()) {
+    InitializerInterfaceType = ErrorType::get(getASTContext());
+    return InitializerInterfaceType;
+  }
+
+  auto funcTy = allocatorTy->castTo<AnyFunctionType>()->getResult();
   assert(funcTy->is<FunctionType>());
 
   // Constructors have an initializer type that takes an instance

lib/SILGen/SILGenExpr.cpp

@@ -931,6 +931,25 @@ RValue RValueEmitter::visitOtherConstructorDeclRefExpr(
 }
 
 RValue RValueEmitter::visitNilLiteralExpr(NilLiteralExpr *E, SGFContext C) {
+  // Peephole away the call to Optional<T>(nilLiteral: ()).
+  if (E->getType()->getOptionalObjectType()) {
+    auto *noneDecl = SGF.getASTContext().getOptionalNoneDecl();
+    auto enumTy = SGF.getLoweredType(E->getType());
+
+    ManagedValue noneValue;
+    if (enumTy.isLoadable(SGF.F) || !SGF.silConv.useLoweredAddresses()) {
+      noneValue = ManagedValue::forUnmanaged(
+        SGF.B.createEnum(E, SILValue(), noneDecl, enumTy));
+    } else {
+      noneValue =
+          SGF.B.bufferForExpr(E, enumTy, SGF.getTypeLowering(enumTy), C,
+                              [&](SILValue newAddr) {
+                                SGF.B.createInjectEnumAddr(E, newAddr, noneDecl);
+                              });
+    }
+    return RValue(SGF, E, noneValue);
+  }
+
   return SGF.emitLiteral(E, C);
 }
 

lib/Sema/CSApply.cpp

@@ -1912,57 +1912,27 @@ namespace {
     }
 
     Expr *visitNilLiteralExpr(NilLiteralExpr *expr) {
+      auto type = simplifyType(cs.getType(expr));
+
+      // By far the most common 'nil' literal is for Optional<T>.none.
+      // We don't have to look up the witness in this case since SILGen
+      // knows how to lower it directly.
+      if (auto objectType = type->getOptionalObjectType()) {
+        cs.setType(expr, type);
+        return expr;
+      }
+
       auto &tc = cs.getTypeChecker();
       auto *protocol = tc.getProtocol(expr->getLoc(),
                                       KnownProtocolKind::ExpressibleByNilLiteral);
 
       // For type-sugar reasons, prefer the spelling of the default literal
       // type.
-      auto type = simplifyType(cs.getType(expr));
       if (auto defaultType = tc.getDefaultType(protocol, dc)) {
         if (defaultType->isEqual(type))
           type = defaultType;
       }
 
-      // By far the most common 'nil' literal is for Optional<T>.none.
-      //
-      // Emit this case directly instead of calling Optional.init(nilLiteral:),
-      // since this generates more efficient SIL.
-      if (auto objectType = type->getOptionalObjectType()) {
-        auto *nilDecl = tc.Context.getOptionalNoneDecl();
-        tc.validateDecl(nilDecl);
-        if (!nilDecl->hasInterfaceType())
-          return nullptr;
-
-        auto genericSig =
-          nilDecl->getDeclContext()->getGenericSignatureOfContext();
-        SubstitutionMap subs =
-          SubstitutionMap::get(genericSig, llvm::makeArrayRef(objectType),
-                               { });
-        ConcreteDeclRef concreteDeclRef(nilDecl, subs);
-
-        auto nilType = FunctionType::get(
-            {FunctionType::Param(MetatypeType::get(type))}, type);
-        auto *nilRefExpr = new (tc.Context) DeclRefExpr(
-            concreteDeclRef, DeclNameLoc(expr->getLoc()),
-              /*implicit=*/true, AccessSemantics::Ordinary,
-            nilType);
-        cs.cacheType(nilRefExpr);
-
-        auto *typeExpr = TypeExpr::createImplicitHack(
-            expr->getLoc(),
-            type,
-            tc.Context);
-        cs.cacheType(typeExpr);
-
-        auto *callExpr = new (tc.Context) DotSyntaxCallExpr(
-            nilRefExpr, expr->getLoc(), typeExpr, type);
-        callExpr->setImplicit(true);
-        cs.cacheType(callExpr);
-
-        return callExpr;
-      }
-
       DeclName initName(tc.Context, DeclBaseName::createConstructor(),
                         { tc.Context.Id_nilLiteral });
       return convertLiteralInPlace(expr, type, protocol,