tbv2: use std::decay_t in make_field

CodeGen v2 permits template parameters to be qualified. This means that if we
call `make_field` with a template parameter it will be qualified. However, we
don't qualify the types when generating meta functions such as `NameProvider`
and `TypeHandler`. This means these qualified types don't match up with the
expected type.

Use `std::decay_t` when forwarding the type to `NameProvider` and `TypeHandler`
so they're always the base type that they were generated with.

Test Plan:
- CI
- Added a test for `std::unique_ptr<const Foo>` to exercise this. Failed
  before, passes after.

oi/CodeGen.cpp

@@ -1060,7 +1060,7 @@ void addStandardTypeHandlers(TypeGraph& typeGraph,
     getSizeType(Ctx& ctx, const T &t, typename TypeHandler<Ctx, T>::type returnArg) {
       JLOG("obj @");
       JLOGPTR(&t);
-      return TypeHandler<Ctx, T>::getSizeType(ctx, t, returnArg);
+      return TypeHandler<Ctx, std::decay_t<T>>::getSizeType(ctx, t, returnArg);
     }
 )";
 
@@ -1072,9 +1072,9 @@ constexpr inst::Field make_field(std::string_view name) {
     sizeof(T),
     ExclusiveSizeProvider<T>::size,
     name,
-    NameProvider<T>::names,
-    TypeHandler<Ctx, T>::fields,
-    TypeHandler<Ctx, T>::processors,
+    NameProvider<std::decay_t<T>>::names,
+    TypeHandler<Ctx, std::decay_t<T>>::fields,
+    TypeHandler<Ctx, std::decay_t<T>>::processors,
   };
 }
 )";

test/integration/std_smart_ptr.toml

@@ -31,6 +31,31 @@ definitions = '''
       }
     ]
     '''
+  [cases.unique_ptr_const_uint64_empty]
+    param_types = ["std::unique_ptr<const std::uint64_t>&"]
+    setup = "return {nullptr};"
+    expect_json = '''
+    [
+      {
+        "staticSize": 8,
+        "dynamicSize": 0,
+        "exclusiveSize": 8,
+        "length": 0,
+        "capacity": 1,
+        "elementStaticSize": 8
+      }
+    ]
+    '''
+    expect_json_v2 = '''
+    [
+      {
+        "staticSize": 8,
+        "exclusiveSize": 8,
+        "length": 0,
+        "capacity": 1
+      }
+    ]
+    '''
   [cases.unique_ptr_uint64_present]
     param_types = ["std::unique_ptr<std::uint64_t>&"]
     setup = "return {std::make_unique<std::uint64_t>(64)};"
@@ -79,6 +104,30 @@ definitions = '''
       }
     ]
     '''
+  [cases.unique_ptr_const_vector_empty]
+    param_types = ["std::unique_ptr<const std::vector<std::uint64_t>>&"]
+    setup = "return {nullptr};"
+    expect_json = '''
+    [
+      {
+        "staticSize": 8,
+        "dynamicSize": 0,
+        "length": 0,
+        "capacity": 1,
+        "elementStaticSize": 24
+      }
+    ]
+    '''
+    expect_json_v2 = '''
+    [
+      {
+        "staticSize": 8,
+        "exclusiveSize": 8,
+        "length": 0,
+        "capacity": 1
+      }
+    ]
+    '''
   [cases.unique_ptr_vector_present]
     param_types = ["std::unique_ptr<std::vector<std::uint64_t>>&"]
     setup = "return {std::make_unique<std::vector<std::uint64_t>>(std::initializer_list<std::uint64_t>({1,2,3,4,5}))};"
@@ -181,6 +230,30 @@ definitions = '''
       }
     ]
     '''
+  [cases.shared_ptr_const_uint64_empty]
+    param_types = ["std::shared_ptr<const std::uint64_t>&"]
+    setup = "return {nullptr};"
+    expect_json = '''
+    [
+      {
+        "staticSize": 16,
+        "dynamicSize": 0,
+        "length": 0,
+        "capacity": 1,
+        "elementStaticSize": 8
+      }
+    ]
+    '''
+    expect_json_v2 = '''
+    [
+      {
+        "staticSize": 16,
+        "exclusiveSize": 16,
+        "length": 0,
+        "capacity": 1
+      }
+    ]
+    '''
   [cases.shared_ptr_uint64_present]
     param_types = ["std::shared_ptr<std::uint64_t>&"]
     setup = "return std::make_shared<std::uint64_t>(64);"
@@ -232,6 +305,30 @@ definitions = '''
       }
     ]
     '''
+  [cases.shared_ptr_const_vector_empty]
+    param_types = ["std::shared_ptr<const std::vector<std::uint64_t>>&"]
+    setup = "return {nullptr};"
+    expect_json = '''
+    [
+      {
+        "staticSize": 16,
+        "dynamicSize": 0,
+        "length": 0,
+        "capacity": 1,
+        "elementStaticSize": 24
+      }
+    ]
+    '''
+    expect_json_v2 = '''
+    [
+      {
+        "staticSize": 16,
+        "exclusiveSize": 16,
+        "length": 0,
+        "capacity": 1
+      }
+    ]
+    '''
   [cases.shared_ptr_vector_present]
     param_types = ["std::shared_ptr<std::vector<std::uint64_t>>&"]
     setup = "return std::make_shared<std::vector<std::uint64_t>>(std::initializer_list<std::uint64_t>({1,2,3,4,5}));"

types/shrd_ptr_type.toml

@@ -60,7 +60,7 @@ el.pointer = std::get<ParsedData::VarInt>(d.val).value;
 type = """
 types::st::Sum<DB,
   types::st::Unit<DB>,
-  typename TypeHandler<Ctx, T0>::type>
+  typename TypeHandler<Ctx, std::decay_t<T0>>::type>
 """
 func = """
 #ifdef __GLIBCXX__

types/uniq_ptr_type.toml

@@ -61,7 +61,7 @@ el.pointer = std::get<ParsedData::VarInt>(d.val).value;
 type = """
 types::st::Sum<DB,
   types::st::Unit<DB>,
-  typename TypeHandler<Ctx, T0>::type>
+  typename TypeHandler<Ctx, std::decay_t<T0>>::type>
 """
 func = """
 auto sum = std::get<ParsedData::Sum>(d.val);