[PATCH] D81554: [ADT] Allow IsSizeLessThanThresholdT for incomplete types. NFC
Yevgeny Rouban via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Wed Jun 10 05:25:42 PDT 2020
yrouban created this revision.
yrouban added reviewers: chandlerc, fedor.sergeev, vvereschaka.
Herald added a subscriber: dexonsmith.
Herald added a project: LLVM.
yrouban added a reviewer: DaniilSuchkov.
If the type T is incomplete then sizeof(T) results in C++ compilation error at line:
static constexpr bool value = sizeof(T) <= (2 * sizeof(void *));
This patch allows incomplete types in parameters of function. Example:
using SomeFunc = void(SomeIncompleteType &);
llvm::unique_function<SomeFuncType> SomeFunc;
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D81554
Files:
llvm/include/llvm/ADT/FunctionExtras.h
Index: llvm/include/llvm/ADT/FunctionExtras.h
===================================================================
--- llvm/include/llvm/ADT/FunctionExtras.h
+++ llvm/include/llvm/ADT/FunctionExtras.h
@@ -46,12 +46,12 @@
class unique_function<ReturnT(ParamTs...)> {
static constexpr size_t InlineStorageSize = sizeof(void *) * 3;
- // MSVC has a bug and ICEs if we give it a particular dependent value
- // expression as part of the `std::conditional` below. To work around this,
- // we build that into a template struct's constexpr bool.
- template <typename T> struct IsSizeLessThanThresholdT {
- static constexpr bool value = sizeof(T) <= (2 * sizeof(void *));
- };
+ template <typename T, class = void>
+ struct IsSizeLessThanThresholdT : std::false_type {};
+
+ template <typename T>
+ struct IsSizeLessThanThresholdT<
+ T, std::enable_if_t<sizeof(T) <= 2 * sizeof(void *)>> : std::true_type {};
// Provide a type function to map parameters that won't observe extra copies
// or moves and which are small enough to likely pass in register to values
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