From 83639a0d9c24df99eb6cc1f2695a9c6bcc6cbca6 Mon Sep 17 00:00:00 2001
From: Hans Wennborg <hans@hanshq.net>
Date: Fri, 15 Feb 2019 12:20:33 +0000
Subject: [PATCH] Speculatively revert r354051 "Recommit Optional
 specialization for trivially copyable types" and r354055 "Optional
 specialization for trivially copyable types, part2"

These are suspected to cause Clang to get miscompiled on Ubuntu 14.04
(Trusty) which uses GCC 4.8.4. Reverting for an hour to see if this
helps. See llvm-commits thread.

> Recommit Optional specialization for trivially copyable types
>
> Unfortunately the original code gets misscompiled by GCC (at least 8.1),
> this is a tentative workaround using std::memcpy instead of inplace new
> for trivially copyable types. I'll revert if it breaks.
>
> Original revision: https://reviews.llvm.org/D57097

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@354126 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/ADT/Optional.h    | 45 ----------------------------------
 unittests/ADT/OptionalTest.cpp | 20 ---------------
 2 files changed, 65 deletions(-)

diff --git a/include/llvm/ADT/Optional.h b/include/llvm/ADT/Optional.h
index f7d35c745fb..25a3185064f 100644
--- a/include/llvm/ADT/Optional.h
+++ b/include/llvm/ADT/Optional.h
@@ -21,7 +21,6 @@
 #include "llvm/Support/type_traits.h"
 #include <algorithm>
 #include <cassert>
-#include <cstring>
 #include <new>
 #include <utility>
 
@@ -110,50 +109,6 @@ template <typename T, bool = is_trivially_copyable<T>::value> struct OptionalSto
   }
 };
 
-template <typename T> struct OptionalStorage<T, true> {
-  AlignedCharArrayUnion<T> storage;
-  bool hasVal = false;
-
-  OptionalStorage() = default;
-
-  OptionalStorage(const T &y) : hasVal(true) {
-    std::memcpy(storage.buffer, reinterpret_cast<char const *>(&y), sizeof(T));
-  }
-  OptionalStorage(const OptionalStorage &O) = default;
-  OptionalStorage(T &&y) : hasVal(true) {
-    std::memcpy(storage.buffer, reinterpret_cast<char*>(&y), sizeof(T));
-  }
-
-  OptionalStorage(OptionalStorage &&O) = default;
-
-  OptionalStorage &operator=(T &&y) {
-    hasVal = true;
-    std::memcpy(storage.buffer, reinterpret_cast<char*>(&y), sizeof(T));
-    return *this;
-  }
-  OptionalStorage &operator=(OptionalStorage &&O) = default;
-
-  OptionalStorage &operator=(const T &y) {
-    hasVal = true;
-    std::memcpy(storage.buffer, reinterpret_cast<char const*>(&y), sizeof(T));
-    return *this;
-  }
-  OptionalStorage &operator=(const OptionalStorage &O) = default;
-
-  ~OptionalStorage() = default;
-
-  T *getPointer() {
-    assert(hasVal);
-    return reinterpret_cast<T *>(storage.buffer);
-  }
-  const T *getPointer() const {
-    assert(hasVal);
-    return reinterpret_cast<const T *>(storage.buffer);
-  }
-
-  void reset() { hasVal = false; }
-};
-
 } // namespace optional_detail
 
 template <typename T> class Optional {
diff --git a/unittests/ADT/OptionalTest.cpp b/unittests/ADT/OptionalTest.cpp
index c39b6727cd5..98adaccca96 100644
--- a/unittests/ADT/OptionalTest.cpp
+++ b/unittests/ADT/OptionalTest.cpp
@@ -18,12 +18,6 @@ using namespace llvm;
 
 namespace {
 
-static_assert(llvm::is_trivially_copyable<Optional<int>>::value,
-              "trivially copyable");
-
-static_assert(llvm::is_trivially_copyable<Optional<std::array<int, 3>>>::value,
-              "trivially copyable");
-
 struct NonDefaultConstructible {
   static unsigned CopyConstructions;
   static unsigned Destructions;
@@ -51,10 +45,6 @@ unsigned NonDefaultConstructible::CopyConstructions = 0;
 unsigned NonDefaultConstructible::Destructions = 0;
 unsigned NonDefaultConstructible::CopyAssignments = 0;
 
-static_assert(
-    !llvm::is_trivially_copyable<Optional<NonDefaultConstructible>>::value,
-    "not trivially copyable");
-
 // Test fixture
 class OptionalTest : public testing::Test {
 };
@@ -213,10 +203,6 @@ struct MultiArgConstructor {
 };
 unsigned MultiArgConstructor::Destructions = 0;
 
-static_assert(
-    !llvm::is_trivially_copyable<Optional<MultiArgConstructor>>::value,
-    "not trivially copyable");
-
 TEST_F(OptionalTest, Emplace) {
   MultiArgConstructor::ResetCounts();
   Optional<MultiArgConstructor> A;
@@ -264,9 +250,6 @@ unsigned MoveOnly::MoveConstructions = 0;
 unsigned MoveOnly::Destructions = 0;
 unsigned MoveOnly::MoveAssignments = 0;
 
-static_assert(!llvm::is_trivially_copyable<Optional<MoveOnly>>::value,
-              "not trivially copyable");
-
 TEST_F(OptionalTest, MoveOnlyNull) {
   MoveOnly::ResetCounts();
   Optional<MoveOnly> O;
@@ -368,9 +351,6 @@ private:
 unsigned Immovable::Constructions = 0;
 unsigned Immovable::Destructions = 0;
 
-static_assert(!llvm::is_trivially_copyable<Optional<Immovable>>::value,
-              "not trivially copyable");
-
 TEST_F(OptionalTest, ImmovableEmplace) {
   Optional<Immovable> A;
   Immovable::ResetCounts();
-- 
2.50.1