diff --git a/include/swift/AST/DiagnosticsCommon.def b/include/swift/AST/DiagnosticsCommon.def
index a000471..678d17f 100644
--- a/include/swift/AST/DiagnosticsCommon.def
+++ b/include/swift/AST/DiagnosticsCommon.def
@@ -58,8 +58,6 @@
 // Generic disambiguation
 NOTE(while_parsing_as_left_angle_bracket,none,
      "while parsing this '<' as a type parameter bracket", ())
-NOTE(while_parsing_as_less_operator,none,
-     "while parsing this '<' as an operator", ())
 
 
 // FIXME: This is used both as a parse error (a literal "super" outside a
diff --git a/include/swift/AST/DiagnosticsParse.def b/include/swift/AST/DiagnosticsParse.def
index 7adedf4..0cc1062 100644
--- a/include/swift/AST/DiagnosticsParse.def
+++ b/include/swift/AST/DiagnosticsParse.def
@@ -755,8 +755,6 @@
       "default arguments are not allowed in subscripts", ())
 ERROR(no_default_arg_curried,none,
       "default arguments are not allowed in curried parameter lists", ())
-WARNING(let_on_param_is_redundant, none,
-      "'let' keyword is unnecessary; function parameters are immutable by default", (unsigned))
 ERROR(var_pattern_in_var,none,
       "'%select{var|let}0' cannot appear nested inside another 'var' or "
       "'let' pattern", (unsigned))
diff --git a/include/swift/AST/DiagnosticsSema.def b/include/swift/AST/DiagnosticsSema.def
index 42e442f..221461d 100644
--- a/include/swift/AST/DiagnosticsSema.def
+++ b/include/swift/AST/DiagnosticsSema.def
@@ -45,11 +45,6 @@
 NOTE(extended_type_declared_here,none,
      "extended type declared here", ())
 
-NOTE(while_converting_default_tuple_value,none,
-     "while converting default tuple value to element type %0", (Type))
-NOTE(while_converting_subscript_index,none,
-     "while converting subscript index to expected type %0", (Type))
-
 //------------------------------------------------------------------------------
 // Constraint solver diagnostics
 //------------------------------------------------------------------------------
@@ -915,8 +910,6 @@
       "%select{local function|closure}0 that captures "
       "%select{context|generic parameters|dynamic Self type}1",
       (bool, unsigned))
-NOTE(c_function_pointer_captures_here,none,
-     "%0 captured here", (Identifier))
 
 //------------------------------------------------------------------------------
 // Type Check Declarations
@@ -1508,8 +1501,6 @@
 
 ERROR(redundant_conformance,none,
       "redundant conformance of %0 to protocol %1", (Type, DeclName))
-NOTE(protocol_conformance_implied_here,none,
-     "implied protocol conformance %0 here can be made explicit", (Identifier))
 
 // "Near matches"
 WARNING(optional_req_near_match,none,
@@ -1517,9 +1508,6 @@
         (DescriptiveDeclKind, DeclName, DeclName, DeclName))
 NOTE(optional_req_nonobjc_near_match_add_objc,none,
      "add '@objc' to provide an Objective-C entrypoint", ())
-NOTE(optional_req_nonobjc_to_objc,none,
-     "rename to %0 to satisfy this requirement",
-     (DeclName))
 NOTE(optional_req_near_match_move,none,
      "move %0 to %select{an|another}1 extension to silence this warning",
      (DeclName, unsigned))
@@ -1775,8 +1763,6 @@
       "static declarations are already final", ())
 ERROR(open_decl_cannot_be_final,none,
       "%0 cannot be declared both 'final' and 'open'", (DescriptiveDeclKind))
-NOTE(decl_init_here,none,
-     "initial value is here", ())
 
 
 // Inheritance
@@ -2069,9 +2055,6 @@
 #define SELECT_APPLICATION_MAIN "select{'UIApplicationMain'|'NSApplicationMain'}"
 #define SELECT_APPLICATION_DELEGATE "select{'UIApplicationDelegate'|'NSApplicationDelegate'}"
 
-ERROR(attr_ApplicationMain_not_class,none,
-      "%" SELECT_APPLICATION_MAIN "0 attribute may only be used on classes",
-      (unsigned))
 ERROR(attr_ApplicationMain_not_ApplicationDelegate,none,
       "%" SELECT_APPLICATION_MAIN "0 class must conform to the %" SELECT_APPLICATION_DELEGATE "0 protocol",
       (unsigned))
@@ -2125,17 +2108,7 @@
      "found this candidate", ())
 NOTE(found_candidate_type,none,
      "found candidate with type %0", (Type))
-NOTE(first_declaration,none,
-     "first declaration", ())
-NOTE(second_declaration,none,
-     "second declaration", ())
 
-ERROR(no_IntegerLiteralType_found,none,
-      "standard library error: IntegerLiteralType not defined", ())
-ERROR(no_FloatLiteralType_found,none,
-      "standard library error: FloatLiteralType not defined", ())
-ERROR(no_StringLiteralType_found,none,
-      "standard library error: StringLiteralType not defined", ())
 ERROR(no_MaxBuiltinIntegerType_found,none,
    "standard library error: _MaxBuiltinIntegerType is not properly defined", ())
 ERROR(no_MaxBuiltinFloatType_found,none,
@@ -2241,9 +2214,6 @@
       "'" TRY_KIND_SELECT(0) "' following assignment operator does not cover "
       "everything to its right", (unsigned))
 
-NOTE(subscript_decl_here,none,
-     "subscript operator declared here", ())
-
 ERROR(broken_bool,none, "type 'Bool' is broken", ())
 
 WARNING(inject_forced_downcast,none,
@@ -3465,10 +3435,6 @@
         "%select{variable|parameter}1 %0 was written to, but never read",
         (Identifier, unsigned))
 
-WARNING(extraneous_default_args_in_call, none,
-        "call to %0 has extraneous arguments that could use defaults",
-        (DeclName))
-
 //------------------------------------------------------------------------------
 // Circular reference diagnostics
 //------------------------------------------------------------------------------
diff --git a/lib/SIL/SILVerifier.cpp b/lib/SIL/SILVerifier.cpp
index 8c008fa..49d7170 100644
--- a/lib/SIL/SILVerifier.cpp
+++ b/lib/SIL/SILVerifier.cpp
@@ -1664,7 +1664,7 @@
     }
 
     // Metatypes preserve their instance type through lowering.
-    if (auto loweredMT = loweredType.getAs<MetatypeType>()) {
+    if (loweredType.is<MetatypeType>()) {
       if (auto formalMT = dyn_cast<MetatypeType>(formalType)) {
         return isLoweringOf(loweredType.getMetatypeInstanceType(F.getModule()),
                             formalMT.getInstanceType());
@@ -3010,7 +3010,7 @@
   void checkSwitchValueInst(SwitchValueInst *SVI) {
     // TODO: Type should be either integer or function
     auto Ty = SVI->getOperand()->getType();
-    require(Ty.getAs<BuiltinIntegerType>() || Ty.getAs<SILFunctionType>(),
+    require(Ty.is<BuiltinIntegerType>() || Ty.is<SILFunctionType>(),
             "switch_value operand should be either of an integer "
             "or function type");