2020-02-14 05:46:33 +08:00
|
|
|
========================================
|
2020-07-15 17:40:53 +08:00
|
|
|
Clang 12.0.0 (In-Progress) Release Notes
|
2020-02-14 05:46:33 +08:00
|
|
|
========================================
|
|
|
|
|
|
|
|
|
|
.. contents::
|
|
|
|
|
:local:
|
|
|
|
|
:depth: 2
|
|
|
|
|
|
|
|
|
|
Written by the `LLVM Team <https://llvm.org/>`_
|
|
|
|
|
|
|
|
|
|
.. warning::
|
|
|
|
|
|
2020-07-15 17:40:53 +08:00
|
|
|
These are in-progress notes for the upcoming Clang 12 release.
|
2020-02-14 05:46:33 +08:00
|
|
|
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
|
2020-07-15 17:40:53 +08:00
|
|
|
frontend, part of the LLVM Compiler Infrastructure, release 12.0.0. Here we
|
2020-02-14 05:46:33 +08:00
|
|
|
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 Git 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/>`_.
|
|
|
|
|
|
2020-07-15 17:40:53 +08:00
|
|
|
What's New in Clang 12.0.0?
|
2020-02-14 05:46:33 +08:00
|
|
|
===========================
|
|
|
|
|
|
|
|
|
|
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
|
|
|
|
|
------------------
|
|
|
|
|
|
|
|
|
|
- ...
|
|
|
|
|
|
|
|
|
|
Improvements to Clang's diagnostics
|
|
|
|
|
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
|
|
2020-07-15 17:40:53 +08:00
|
|
|
- ...
|
2020-06-05 00:45:04 +08:00
|
|
|
|
2020-02-14 05:46:33 +08:00
|
|
|
Non-comprehensive list of changes in this release
|
|
|
|
|
-------------------------------------------------
|
|
|
|
|
|
2020-07-15 17:40:53 +08:00
|
|
|
- ...
|
2020-05-26 02:44:35 +08:00
|
|
|
|
2020-02-14 05:46:33 +08:00
|
|
|
New Compiler Flags
|
|
|
|
|
------------------
|
|
|
|
|
|
2020-07-15 17:40:53 +08:00
|
|
|
- ...
|
2020-07-11 21:07:27 +08:00
|
|
|
|
2020-07-11 20:53:50 +08:00
|
|
|
- -fpch-codegen and -fpch-debuginfo generate shared code and/or debuginfo
|
|
|
|
|
for contents of a precompiled header in a separate object file. This object
|
|
|
|
|
file needs to be linked in, but its contents do not need to be generated
|
|
|
|
|
for other objects using the precompiled header. This should usually save
|
|
|
|
|
compile time. If not using clang-cl, the separate object file needs to
|
|
|
|
|
be created explicitly from the precompiled header.
|
|
|
|
|
Example of use:
|
|
|
|
|
|
|
|
|
|
.. code-block:: console
|
|
|
|
|
|
|
|
|
|
$ clang++ -x c++-header header.h -o header.pch -fpch-codegen -fpch-debuginfo
|
|
|
|
|
$ clang++ -c header.pch -o shared.o
|
|
|
|
|
$ clang++ -c source.cpp -o source.o -include-pch header.pch
|
|
|
|
|
$ clang++ -o binary source.o shared.o
|
|
|
|
|
|
|
|
|
|
- Using -fpch-instantiate-templates when generating the precompiled header
|
|
|
|
|
usually increases the amount of code/debuginfo that can be shared.
|
|
|
|
|
- In some cases, especially when building with optimizations enabled, using
|
|
|
|
|
-fpch-codegen may generate so much code in the shared object that compiling
|
|
|
|
|
it may be a net loss in build time.
|
|
|
|
|
- Since headers may bring in private symbols of other libraries, it may be
|
|
|
|
|
sometimes necessary to discard unused symbols (such as by adding
|
|
|
|
|
-Wl,--gc-sections on ELF platforms to the linking command, and possibly
|
|
|
|
|
adding -fdata-sections -ffunction-sections to the command generating
|
|
|
|
|
the shared object).
|
|
|
|
|
|
2020-02-14 05:46:33 +08:00
|
|
|
Deprecated Compiler Flags
|
|
|
|
|
-------------------------
|
|
|
|
|
|
|
|
|
|
The following options are deprecated and ignored. They will be removed in
|
|
|
|
|
future versions of Clang.
|
|
|
|
|
|
|
|
|
|
- ...
|
|
|
|
|
|
|
|
|
|
Modified Compiler Flags
|
|
|
|
|
-----------------------
|
|
|
|
|
|
2020-08-04 06:11:28 +08:00
|
|
|
- On ELF, ``-gz`` now defaults to ``-gz=zlib`` with the integrated assembler.
|
|
|
|
|
It produces ``SHF_COMPRESSED`` style compression of debug information. GNU
|
|
|
|
|
binutils 2.26 or newer, or lld is required to link produced object files. Use
|
|
|
|
|
``-gz=zlib-gnu`` to get the old behavior.
|
2020-02-14 05:46:33 +08:00
|
|
|
|
|
|
|
|
New Pragmas in Clang
|
|
|
|
|
--------------------
|
|
|
|
|
|
|
|
|
|
- ...
|
|
|
|
|
|
|
|
|
|
Attribute Changes in Clang
|
|
|
|
|
--------------------------
|
|
|
|
|
|
2020-07-15 17:40:53 +08:00
|
|
|
- ...
|
2020-02-14 05:46:33 +08:00
|
|
|
|
|
|
|
|
Windows Support
|
|
|
|
|
---------------
|
|
|
|
|
|
|
|
|
|
C Language Changes in Clang
|
|
|
|
|
---------------------------
|
|
|
|
|
|
2020-03-03 01:33:14 +08:00
|
|
|
- ...
|
2020-02-14 05:46:33 +08:00
|
|
|
|
|
|
|
|
C++ Language Changes in Clang
|
|
|
|
|
-----------------------------
|
|
|
|
|
|
2020-07-15 17:40:53 +08:00
|
|
|
- ...
|
2020-02-14 05:46:33 +08:00
|
|
|
|
|
|
|
|
C++1z Feature Support
|
|
|
|
|
^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
|
...
|
|
|
|
|
|
|
|
|
|
Objective-C Language Changes in Clang
|
|
|
|
|
-------------------------------------
|
|
|
|
|
|
|
|
|
|
OpenCL C Language Changes in Clang
|
|
|
|
|
----------------------------------
|
|
|
|
|
|
|
|
|
|
...
|
|
|
|
|
|
|
|
|
|
ABI Changes in Clang
|
|
|
|
|
--------------------
|
|
|
|
|
|
|
|
|
|
OpenMP Support in Clang
|
|
|
|
|
-----------------------
|
|
|
|
|
|
|
|
|
|
- ...
|
|
|
|
|
|
|
|
|
|
CUDA Support in Clang
|
|
|
|
|
---------------------
|
|
|
|
|
|
|
|
|
|
- ...
|
|
|
|
|
|
|
|
|
|
Internal API Changes
|
|
|
|
|
--------------------
|
|
|
|
|
|
2020-07-15 17:40:53 +08:00
|
|
|
These are major API changes that have happened since the 11.0.0 release of
|
2020-02-14 05:46:33 +08:00
|
|
|
Clang. If upgrading an external codebase that uses Clang as a library,
|
|
|
|
|
this section should help get you past the largest hurdles of upgrading.
|
|
|
|
|
|
2020-07-15 17:40:53 +08:00
|
|
|
- ...
|
Removed a RecursiveASTVisitor feature to visit operator kinds with different methods
Summary:
This feature was only used in two places, but contributed a non-trivial
amount to the complexity of RecursiveASTVisitor, and was buggy (see my
recent patches where I was fixing the bugs that I noticed). I don't
think the convenience benefit of this feature is worth the complexity.
Besides complexity, another issue with the current state of
RecursiveASTVisitor is the non-uniformity in how it handles different
AST nodes. All AST nodes follow a regular pattern, but operators are
special -- and this special behavior not documented. Correct usage of
RecursiveASTVisitor relies on shadowing member functions with specific
names and signatures. Near misses don't cause any compile-time errors,
incorrectly named or typed methods are just silently ignored. Therefore,
predictability of RecursiveASTVisitor API is quite important.
This change reduces the size of the `clang` binary by 38 KB (0.2%) in
release mode, and by 7 MB (0.3%) in debug mode. The `clang-tidy` binary
is reduced by 205 KB (0.3%) in release mode, and by 5 MB (0.4%) in debug
mode. I don't think these code size improvements are significant enough
to justify this change on its own (for me, the primary motivation is
reducing code complexity), but they I think are a nice side-effect.
Reviewers: rsmith, sammccall, ymandel, aaron.ballman
Reviewed By: rsmith, sammccall, ymandel, aaron.ballman
Subscribers: cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D82921
2020-07-03 23:01:01 +08:00
|
|
|
|
2020-02-14 05:46:33 +08:00
|
|
|
Build System Changes
|
|
|
|
|
--------------------
|
|
|
|
|
|
2020-07-15 17:40:53 +08:00
|
|
|
These are major changes to the build system that have happened since the 11.0.0
|
2020-02-14 05:46:33 +08:00
|
|
|
release of Clang. Users of the build system should adjust accordingly.
|
|
|
|
|
|
2020-07-15 17:40:53 +08:00
|
|
|
- ...
|
2020-02-14 05:46:33 +08:00
|
|
|
|
|
|
|
|
AST Matchers
|
|
|
|
|
------------
|
|
|
|
|
|
2020-07-03 03:46:27 +08:00
|
|
|
- ...
|
2020-05-27 20:20:05 +08:00
|
|
|
|
2020-02-14 05:46:33 +08:00
|
|
|
clang-format
|
|
|
|
|
------------
|
|
|
|
|
|
2020-07-18 18:35:01 +08:00
|
|
|
- Option ``BitFieldColonSpacing`` has been added that decides how
|
|
|
|
|
space should be added around identifier, colon and bit-width in
|
|
|
|
|
bitfield definitions.
|
|
|
|
|
|
|
|
|
|
.. code-block:: c++
|
|
|
|
|
|
|
|
|
|
// Both (default)
|
|
|
|
|
struct F {
|
|
|
|
|
unsigned dscp : 6;
|
|
|
|
|
unsigned ecn : 2; // AlignConsecutiveBitFields=true
|
|
|
|
|
};
|
|
|
|
|
// None
|
|
|
|
|
struct F {
|
|
|
|
|
unsigned dscp:6;
|
|
|
|
|
unsigned ecn :2;
|
|
|
|
|
};
|
|
|
|
|
// Before
|
|
|
|
|
struct F {
|
|
|
|
|
unsigned dscp :6;
|
|
|
|
|
unsigned ecn :2;
|
|
|
|
|
};
|
|
|
|
|
// After
|
|
|
|
|
struct F {
|
|
|
|
|
unsigned dscp: 6;
|
|
|
|
|
unsigned ecn : 2;
|
|
|
|
|
};
|
|
|
|
|
|
2020-05-20 14:48:45 +08:00
|
|
|
|
2020-02-14 05:46:33 +08:00
|
|
|
libclang
|
|
|
|
|
--------
|
|
|
|
|
|
|
|
|
|
- ...
|
|
|
|
|
|
|
|
|
|
Static Analyzer
|
|
|
|
|
---------------
|
|
|
|
|
|
|
|
|
|
- ...
|
|
|
|
|
|
|
|
|
|
.. _release-notes-ubsan:
|
|
|
|
|
|
|
|
|
|
Undefined Behavior Sanitizer (UBSan)
|
|
|
|
|
------------------------------------
|
|
|
|
|
|
|
|
|
|
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
|
2020-03-23 05:18:40 +08:00
|
|
|
API documentation which are up-to-date with the Git version of
|
2020-02-14 05:46:33 +08:00
|
|
|
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>`_.
|