WTF::Vector: Fix primitive types identified as not safe to memcpy.

WTF::Vector: Fix primitive types identified as not safe to memcpy.

The culprit was the implementation of IsAssignable<> traits.

Specifically, "std::declval<T>() = X" is invalid if T is a primitive
type, because the assignment of primitives is not an overloaded
operator and the compilability of this statement for a primitive T is
different from that for a non-primitive T.

The fix is to simply change the left-hand side of the assignment to
"std::declval<T&>".

BUG=624642
Committed: https://crrev.com/757e4b7379983a8760fe8f91e40bb3b34d64bde4
Cr-Commit-Position: refs/heads/master@{#403131}

[Yuta Kitamura, 2016-06-30 08:02:11]

The CQ bit was checked by yutak@chromium.org to run a CQ dry run

[Yuta Kitamura, 2016-06-30 08:02:20]

Description was changed from

==========
WTF::Vector: Fix primitive types identified as not safe to memcpy.

The culprit was the implementation of IsAssignable<> traits.

Specifically, "std::declval<T>() = X" is invalid if T is a primitive
type, because the assignment of primitives is not an overloaded
operator and the compilability of this statement for a primitive T is
different from that for a non-primitive T.

The fix is to simply change the left-hand side of the assignment to
"std::declval<T&>".

BUG=624642
==========

to

==========
WTF::Vector: Fix primitive types identified as not safe to memcpy.

The culprit was the implementation of IsAssignable<> traits.

Specifically, "std::declval<T>() = X" is invalid if T is a primitive
type, because the assignment of primitives is not an overloaded
operator and the compilability of this statement for a primitive T is
different from that for a non-primitive T.

The fix is to simply change the left-hand side of the assignment to
"std::declval<T&>".

BUG=624642
==========

[Yuta Kitamura, 2016-06-30 08:02:20]

yutak@chromium.org changed reviewers:
+ tzik@chromium.org

[Yuta Kitamura, 2016-06-30 08:02:29]

tzik: PTAL?

[commit-bot: I haz the power, 2016-06-30 08:04:03]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[tzik, 2016-06-30 08:06:02]

lgtm

https://codereview.chromium.org/2110183005/diff/1/third_party/WebKit/Source/w...
File third_party/WebKit/Source/wtf/VectorTest.cpp (right):

https://codereview.chromium.org/2110183005/diff/1/third_party/WebKit/Source/w...
third_party/WebKit/Source/wtf/VectorTest.cpp:696:
static_assert(IsAssignable<int, const int&>::value, "aa");
Could you update "aa"?

[Yuta Kitamura, 2016-06-30 08:11:13]

https://codereview.chromium.org/2110183005/diff/1/third_party/WebKit/Source/w...
File third_party/WebKit/Source/wtf/VectorTest.cpp (right):

https://codereview.chromium.org/2110183005/diff/1/third_party/WebKit/Source/w...
third_party/WebKit/Source/wtf/VectorTest.cpp:696:
static_assert(IsAssignable<int, const int&>::value, "aa");
On 2016/06/30 08:06:01, tzik wrote:
> Could you update "aa"?

Whoops, done.

[Yuta Kitamura, 2016-06-30 08:11:13]

https://codereview.chromium.org/2110183005/diff/1/third_party/WebKit/Source/w...
File third_party/WebKit/Source/wtf/VectorTest.cpp (right):

https://codereview.chromium.org/2110183005/diff/1/third_party/WebKit/Source/w...
third_party/WebKit/Source/wtf/VectorTest.cpp:696:
static_assert(IsAssignable<int, const int&>::value, "aa");
On 2016/06/30 08:06:01, tzik wrote:
> Could you update "aa"?

Whoops, done.

[Yuta Kitamura, 2016-06-30 08:11:17]

The CQ bit was checked by yutak@chromium.org

[Yuta Kitamura, 2016-06-30 08:11:17]

The patchset sent to the CQ was uploaded after l-g-t-m from tzik@chromium.org
Link to the patchset: https://codereview.chromium.org/2110183005/#ps20001
(title: "Remove unneeded garbage; add a test for pointers.")

[commit-bot: I haz the power, 2016-06-30 08:11:34]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-06-30 09:47:38]

Description was changed from

==========
WTF::Vector: Fix primitive types identified as not safe to memcpy.

The culprit was the implementation of IsAssignable<> traits.

Specifically, "std::declval<T>() = X" is invalid if T is a primitive
type, because the assignment of primitives is not an overloaded
operator and the compilability of this statement for a primitive T is
different from that for a non-primitive T.

The fix is to simply change the left-hand side of the assignment to
"std::declval<T&>".

BUG=624642
==========

to

==========
WTF::Vector: Fix primitive types identified as not safe to memcpy.

The culprit was the implementation of IsAssignable<> traits.

Specifically, "std::declval<T>() = X" is invalid if T is a primitive
type, because the assignment of primitives is not an overloaded
operator and the compilability of this statement for a primitive T is
different from that for a non-primitive T.

The fix is to simply change the left-hand side of the assignment to
"std::declval<T&>".

BUG=624642
==========

[commit-bot: I haz the power, 2016-06-30 09:47:39]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-06-30 09:47:48]

CQ bit was unchecked.

[commit-bot: I haz the power, 2016-06-30 09:49:43]

Description was changed from

==========
WTF::Vector: Fix primitive types identified as not safe to memcpy.

The culprit was the implementation of IsAssignable<> traits.

Specifically, "std::declval<T>() = X" is invalid if T is a primitive
type, because the assignment of primitives is not an overloaded
operator and the compilability of this statement for a primitive T is
different from that for a non-primitive T.

The fix is to simply change the left-hand side of the assignment to
"std::declval<T&>".

BUG=624642
==========

to

==========
WTF::Vector: Fix primitive types identified as not safe to memcpy.

The culprit was the implementation of IsAssignable<> traits.

Specifically, "std::declval<T>() = X" is invalid if T is a primitive
type, because the assignment of primitives is not an overloaded
operator and the compilability of this statement for a primitive T is
different from that for a non-primitive T.

The fix is to simply change the left-hand side of the assignment to
"std::declval<T&>".

BUG=624642

Committed: https://crrev.com/757e4b7379983a8760fe8f91e40bb3b34d64bde4
Cr-Commit-Position: refs/heads/master@{#403131}
==========

[commit-bot: I haz the power, 2016-06-30 09:49:45]

Patchset 2 (id:??) landed as
https://crrev.com/757e4b7379983a8760fe8f91e40bb3b34d64bde4
Cr-Commit-Position: refs/heads/master@{#403131}