| ======================================== |
| Clang 12.0.0 (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 12 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 12.0.0. 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 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/>`_. |
| |
| What's New in Clang 12.0.0? |
| =========================== |
| |
| 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 |
| ------------------ |
| |
| - ... |
| |
| Improvements to Clang's diagnostics |
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |
| |
| - ... |
| |
| Non-comprehensive list of changes in this release |
| ------------------------------------------------- |
| |
| - ... |
| |
| New Compiler Flags |
| ------------------ |
| |
| - ... |
| |
| - -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). |
| |
| Deprecated Compiler Flags |
| ------------------------- |
| |
| The following options are deprecated and ignored. They will be removed in |
| future versions of Clang. |
| |
| - ... |
| |
| Modified Compiler Flags |
| ----------------------- |
| |
| - 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. |
| |
| New Pragmas in Clang |
| -------------------- |
| |
| - ... |
| |
| Attribute Changes in Clang |
| -------------------------- |
| |
| - ... |
| |
| Windows Support |
| --------------- |
| |
| C Language Changes in Clang |
| --------------------------- |
| |
| - ... |
| |
| 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 |
| -------------------- |
| |
| OpenMP Support in Clang |
| ----------------------- |
| |
| - ... |
| |
| CUDA Support in Clang |
| --------------------- |
| |
| - ... |
| |
| Internal API Changes |
| -------------------- |
| |
| These are major API changes that have happened since the 11.0.0 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. |
| |
| - ... |
| |
| Build System Changes |
| -------------------- |
| |
| These are major changes to the build system that have happened since the 11.0.0 |
| release of Clang. Users of the build system should adjust accordingly. |
| |
| - ... |
| |
| AST Matchers |
| ------------ |
| |
| - ... |
| |
| clang-format |
| ------------ |
| |
| - 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; |
| }; |
| |
| |
| 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 |
| API documentation which are up-to-date with the Git 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>`_. |
