[Reflection] Accept BuiltinTypeDescriptors with zero size.

rdar://problem/56784375

Author: mikeash

stdlib/public/Reflection/TypeRefBuilder.cpp

@@ -253,8 +253,6 @@ TypeRefBuilder::getBuiltinTypeInfo(const TypeRef *TR) {
 
   for (auto Info : ReflectionInfos) {
     for (auto BuiltinTypeDescriptor : Info.Builtin) {
-      if (BuiltinTypeDescriptor->Size <= 0)
-        continue;
       if (BuiltinTypeDescriptor->getAlignment() <= 0)
         continue;
       if (BuiltinTypeDescriptor->Stride <= 0)

validation-test/Reflection/reflect_empty_struct.swift

@@ -2,7 +2,7 @@
 // RUN: %target-build-swift -lswiftSwiftReflectionTest -I %S/Inputs/EmptyStruct/ %s -o %t/reflect_empty_struct
 // RUN: %target-codesign %t/reflect_empty_struct
 
-// RUN: %target-run %target-swift-reflection-test %t/reflect_empty_struct | %FileCheck %s --check-prefix=CHECK-%target-ptrsize
+// RUN: %target-run %target-swift-reflection-test %t/reflect_empty_struct | %FileCheck %s --check-prefix=CHECK-%target-ptrsize --dump-input fail
 
 // REQUIRES: objc_interop
 // REQUIRES: executable_test
@@ -31,15 +31,13 @@ reflect(object: obj)
 // CHECK-64: Type info:
 // CHECK-64: (class_instance size=80 alignment=8 stride=80 num_extra_inhabitants=0 bitwise_takable=1
 // CHECK-64:   (field name=a offset=16
-// CHECK-64:     (struct size=0 alignment=1 stride=1 num_extra_inhabitants=0 bitwise_takable=1))
+// CHECK-64:     (builtin size=0 alignment=1 stride=1 num_extra_inhabitants=0 bitwise_takable=1))
 // CHECK-64:   (field name=b offset=16
 // CHECK-64:     (opaque_existential size=32 alignment=8 stride=32 num_extra_inhabitants=2147483647 bitwise_takable=1
 // CHECK-64:       (field name=metadata offset=24
 // CHECK-64:         (builtin size=8 alignment=8 stride=8 num_extra_inhabitants=2147483647 bitwise_takable=1))))
 // CHECK-64:   (field name=c offset=48
-// CHECK-64:     (struct size=0 alignment=1 stride=1 num_extra_inhabitants=0 bitwise_takable=1
-// CHECK-64:       (field name=trailing offset=0
-// CHECK-64:         (tuple size=0 alignment=1 stride=1 num_extra_inhabitants=0 bitwise_takable=1))))
+// CHECK-64:     (builtin size=0 alignment=4 stride=1 num_extra_inhabitants=0 bitwise_takable=1))
 // CHECK-64:   (field name=d offset=48
 // CHECK-64:     (opaque_existential size=32 alignment=8 stride=32 num_extra_inhabitants=2147483647 bitwise_takable=1
 // CHECK-64:       (field name=metadata offset=24
@@ -53,15 +51,13 @@ reflect(object: obj)
 // CHECK-32: Type info:
 // CHECK-32: (class_instance size=40 alignment=4 stride=40 num_extra_inhabitants=0 bitwise_takable=1
 // CHECK-32:   (field name=a offset=8
-// CHECK-32:     (struct size=0 alignment=1 stride=1 num_extra_inhabitants=0 bitwise_takable=1))
+// CHECK-32:     (builtin size=0 alignment=1 stride=1 num_extra_inhabitants=0 bitwise_takable=1))
 // CHECK-32:   (field name=b offset=8
 // CHECK-32:     (opaque_existential size=16 alignment=4 stride=16 num_extra_inhabitants=4096 bitwise_takable=1
 // CHECK-32:       (field name=metadata offset=12
 // CHECK-32:         (builtin size=4 alignment=4 stride=4 num_extra_inhabitants=4096 bitwise_takable=1))))
 // CHECK-32:   (field name=c offset=24
-// CHECK-32:     (struct size=0 alignment=1 stride=1 num_extra_inhabitants=0 bitwise_takable=1
-// CHECK-32:       (field name=trailing offset=0
-// CHECK-32:         (tuple size=0 alignment=1 stride=1 num_extra_inhabitants=0 bitwise_takable=1))))
+// CHECK-32:     (builtin size=0 alignment=4 stride=1 num_extra_inhabitants=0 bitwise_takable=1))
 // CHECK-32:   (field name=d offset=24
 // CHECK-32:     (opaque_existential size=16 alignment=4 stride=16 num_extra_inhabitants=4096 bitwise_takable=1
 // CHECK-32:       (field name=metadata offset=12