1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
|
=======================================
Clang 8.0.0 (In-Progress) Release Notes
=======================================
.. contents::
:local:
:depth: 2
Written by the `LLVM Team <https://llvm.org/>`_
.. warning::
These are in-progress notes for the upcoming Clang 8 release.
Release notes for previous releases can be found on
`the Download Page <https://releases.llvm.org/download.html>`_.
Introduction
============
This document contains the release notes for the Clang C/C++/Objective-C
frontend, part of the LLVM Compiler Infrastructure, release 8.0.0. Here we
describe the status of Clang in some detail, including major
improvements from the previous release and new feature work. For the
general LLVM release notes, see `the LLVM
documentation <https://llvm.org/docs/ReleaseNotes.html>`_. All LLVM
releases may be downloaded from the `LLVM releases web
site <https://llvm.org/releases/>`_.
For more information about Clang or LLVM, including information about the
latest release, please see the `Clang Web Site <https://clang.llvm.org>`_ or the
`LLVM Web Site <https://llvm.org>`_.
Note that if you are reading this file from a Subversion checkout or the
main Clang web page, this document applies to the *next* release, not
the current one. To see the release notes for a specific release, please
see the `releases page <https://llvm.org/releases/>`_.
What's New in Clang 8.0.0?
==========================
Some of the major new features and improvements to Clang are listed
here. Generic improvements to Clang as a whole or to its underlying
infrastructure are described first, followed by language-specific
sections with improvements to Clang's support for those languages.
Major New Features
------------------
- Clang supports use of a profile remapping file, which permits
profile data captured for one version of a program to be applied
when building another version where symbols have changed (for
example, due to renaming a class or namespace).
See the :doc:`UsersManual` for details.
Improvements to Clang's diagnostics
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Non-comprehensive list of changes in this release
-------------------------------------------------
- ...
New Compiler Flags
------------------
- ...
Deprecated Compiler Flags
-------------------------
The following options are deprecated and ignored. They will be removed in
future versions of Clang.
- ...
Modified Compiler Flags
-----------------------
- As of clang 8, `alignof` and `_Alignof` return the ABI alignment of a type,
as opposed to the preferred alignment. `__alignof` still returns the
preferred alignment. `-fclang-abi-compat=7` (and previous) will make
`alignof` and `_Alignof` return preferred alignment again.
New Pragmas in Clang
--------------------
- Clang now supports adding multiple `#pragma clang attribute` attributes into
a scope of pushed attributes.
Attribute Changes in Clang
--------------------------
- ...
Windows Support
---------------
- clang-cl now supports the use of the precompiled header options /Yc and /Yu
without the filename argument. When these options are used without the
filename, a `#pragma hdrstop` inside the source marks the end of the
precompiled code.
- clang-cl has a new command-line option, ``/Zc:dllexportInlines-``, similar to
``-fvisibility-inlines-hidden`` on non-Windows, that makes class-level
`dllexport` and `dllimport` attributes not apply to inline member functions.
This can significantly reduce compile and link times. See the `User's Manual
<UsersManual.html#the-zc-dllexportinlines-option>`_ for more info.
- ...
C Language Changes in Clang
---------------------------
- ...
...
C11 Feature Support
^^^^^^^^^^^^^^^^^^^
...
C++ Language Changes in Clang
-----------------------------
- ...
C++1z Feature Support
^^^^^^^^^^^^^^^^^^^^^
...
Objective-C Language Changes in Clang
-------------------------------------
...
OpenCL C Language Changes in Clang
----------------------------------
...
ABI Changes in Clang
--------------------
- `_Alignof` and `alignof` now return the ABI alignment of a type, as opposed
to the preferred alignment.
- This is more in keeping with the language of the standards, as well as
being compatible with gcc
- `__alignof` and `__alignof__` still return the preferred alignment of
a type
- This shouldn't break any ABI except for things that explicitly ask for
`alignas(alignof(T))`.
- If you have interfaces that break with this change, you may wish to switch
to `alignas(__alignof(T))`, instead of using the `-fclang-abi-compat`
switch.
OpenMP Support in Clang
----------------------------------
CUDA Support in Clang
---------------------
Internal API Changes
--------------------
These are major API changes that have happened since the 7.0.0 release of
Clang. If upgrading an external codebase that uses Clang as a library,
this section should help get you past the largest hurdles of upgrading.
- ...
AST Matchers
------------
- ...
clang-format
------------
- ...
libclang
--------
...
Static Analyzer
---------------
- ...
...
.. _release-notes-ubsan:
Undefined Behavior Sanitizer (UBSan)
------------------------------------
* The Implicit Conversion Sanitizer (``-fsanitize=implicit-conversion``) group
was extended. One more type of issues is caught - implicit integer sign change.
(``-fsanitize=implicit-integer-sign-change``).
This makes the Implicit Conversion Sanitizer feature-complete,
with only missing piece being bitfield handling.
While there is a ``-Wsign-conversion`` diagnostic group that catches this kind
of issues, it is both noisy, and does not catch **all** the cases.
.. code-block:: c++
bool consume(unsigned int val);
void test(int val) {
(void)consume(val); // If the value was negative, it is now large positive.
(void)consume((unsigned int)val); // OK, the conversion is explicit.
}
Like some other ``-fsanitize=integer`` checks, these issues are **not**
undefined behaviour. But they are not *always* intentional, and are somewhat
hard to track down. This group is **not** enabled by ``-fsanitize=undefined``,
but the ``-fsanitize=implicit-integer-sign-change`` check
is enabled by ``-fsanitize=integer``.
(as is ``-fsanitize=implicit-integer-truncation`` check)
Core Analysis Improvements
==========================
- ...
New Issues Found
================
- ...
Python Binding Changes
----------------------
The following methods have been added:
- ...
Significant Known Problems
==========================
Additional Information
======================
A wide variety of additional information is available on the `Clang web
page <https://clang.llvm.org/>`_. The web page contains versions of the
API documentation which are up-to-date with the Subversion version of
the source code. You can access versions of these documents specific to
this release by going into the "``clang/docs/``" directory in the Clang
tree.
If you have any questions or comments about Clang, please feel free to
contact us via the `mailing
list <https://lists.llvm.org/mailman/listinfo/cfe-dev>`_.
|
