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Hui Xie 20869c5ba0 [libc++] fix views::all hard error on lvalue move only views instead of SFINAE
For an lvalue reference to a move only view x, views::all(x) gives hard error because the expression inside noexcept is not well formed and it is not SFINAE friendly.

Given a move only view type `V`, and a concept

```
template <class R>
concept can_all = requires {
    std::views::all(std::declval<R>());
};
```

The expression `can_all<V&>` returns
libstdc++: false
msvc stl : false
libc++   : error: static_cast from 'V' to 'typename decay<decltype((std::forward<V &>(__t)))>::type' (aka 'V') uses deleted function
      noexcept(noexcept(_LIBCPP_AUTO_CAST(std::forward<_Tp>(__t))))

The standard spec has its own problem, the spec says it is expression equivalent to `decay-copy(E)` but the spec of `decay-copy` does not have any constraint, which means the expression `decay-copy(declval<V&>())` is well-formed and the concept `can_all<V&>` should return true and should error when instantiating the function body of decay-copy. This is clearly wrong behaviour in the spec and we will probably create an LWG issue. But the libc++'s behaviour is clearly not correct. The `noexcept` is an "extension" in libc++ which is not in the spec, but the expression inside `noexpect` triggers hard error, which is not right.

Reviewed By: #libc, ldionne, var-const

Differential Revision: https://reviews.llvm.org/D128281
2022-06-22 09:50:16 +01:00
.github [github] format and refactor GitHub workflows 2022-06-11 11:31:21 +04:30
bolt [BOLT][TEST] Fix stack alignment in section-reloc-with-addend.s 2022-06-20 14:47:37 -07:00
clang Fix interaction of pragma FENV_ACCESS with other pragmas 2022-06-22 15:13:54 +07:00
clang-tools-extra [clang-tidy][docs] Fix wrong sphinx link after d9afb8c3e8 2022-06-21 11:42:09 +02:00
cmake [CMake] Make FindLibEdit.cmake more robust 2022-05-27 13:06:45 -07:00
compiler-rt [ORC-RT] Make the ORC runtime C API public. 2022-06-16 19:02:23 -07:00
cross-project-tests [Dexter] Remove debugger-dependent test from windows 2022-06-13 19:27:34 +01:00
flang [flang] Cleanup code and add test from fir-dev 2022-06-22 09:39:11 +02:00
libc [libc] Fix bug in UInt comparison operators. 2022-06-22 05:41:07 +00:00
libclc libclc: Add clspv64 target 2022-01-13 09:28:19 +00:00
libcxx [libc++] fix views::all hard error on lvalue move only views instead of SFINAE 2022-06-22 09:50:16 +01:00
libcxxabi [libc++abi][AIX] Use _LIBCXXABI_FUNC_VIS for exported routines 2022-06-21 16:18:17 -04:00
libunwind [libunwind] Ensure test/libunwind_01.pass is not completely inlined 2022-06-20 09:05:49 +00:00
lld [lld-macho] Work around odr-use of const non-inline static data member to fix -O0 build after D128298 2022-06-21 19:22:28 -07:00
lldb [lldb] [test] Mark TestNonStop as LLGS-specific 2022-06-22 05:36:30 +02:00
llvm [SCCP] Don't mark edges feasible when resolving undefs 2022-06-22 10:28:27 +02:00
llvm-libgcc [llvm-libgcc] initial commit 2022-02-16 17:06:45 +00:00
mlir [mlir][Transform] NFC - Pass TransformState as an argument to applyToOne methods 2022-06-22 01:19:13 -07:00
openmp [Libomptarget] Remove duplicate data environment exit 2022-06-21 22:35:32 -04:00
polly [polly] #include <algorithm> 2022-06-21 13:27:55 -07:00
pstl [libc++] Use _LIBCPP_ASSERT by default for _PSTL_ASSERTions 2022-05-20 16:58:21 +02:00
runtimes Restore missing runtimes-test-depends target that causes build failures when LLVM_INCLUDE_TESTS is ON 2022-06-13 15:47:38 -05:00
third-party Ensure newlines at the end of files (NFC) 2021-12-26 08:51:06 -08:00
utils [mlir][TilingInterface] Enable tile and fuse using TilingInterface. 2022-06-21 17:22:58 +00:00
.arcconfig Add modern arc config for default "onto" branch 2021-02-22 11:58:13 -08:00
.arclint
.clang-format Revert "Title: [RISCV] Add missing part of instruction vmsge {u}. VX Review By: craig.topper Differential Revision : https://reviews.llvm.org/D100115" 2021-04-14 08:04:37 +01:00
.clang-tidy [clangd] Cleanup of readability-identifier-naming 2022-02-01 13:31:52 +00:00
.git-blame-ignore-revs Add __config formatting to .git-blame-ignore-revs 2022-06-14 09:52:49 -04:00
.gitignore [llvm] Ignore .rej files in .gitignore 2022-04-28 08:44:51 -07:00
.mailmap .mailmap: remove stray space in comment 2022-02-24 18:50:08 -05:00
CONTRIBUTING.md docs: update some bug tracker references (NFC) 2022-01-10 15:59:08 -08:00
README.md Fix grammar and punctuation across several docs; NFC 2022-04-07 07:11:11 -04:00
SECURITY.md [docs] Describe reporting security issues on the chromium tracker. 2021-05-19 15:21:50 -07:00

README.md

The LLVM Compiler Infrastructure

This directory and its sub-directories contain the source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and run-time environments.

The README briefly describes how to get started with building LLVM. For more information on how to contribute to the LLVM project, please take a look at the Contributing to LLVM guide.

Getting Started with the LLVM System

Taken from here.

Overview

Welcome to the LLVM project!

The LLVM project has multiple components. The core of the project is itself called "LLVM". This contains all of the tools, libraries, and header files needed to process intermediate representations and convert them into object files. Tools include an assembler, disassembler, bitcode analyzer, and bitcode optimizer. It also contains basic regression tests.

C-like languages use the Clang frontend. This component compiles C, C++, Objective-C, and Objective-C++ code into LLVM bitcode -- and from there into object files, using LLVM.

Other components include: the libc++ C++ standard library, the LLD linker, and more.

Getting the Source Code and Building LLVM

The LLVM Getting Started documentation may be out of date. The Clang Getting Started page might have more accurate information.

This is an example work-flow and configuration to get and build the LLVM source:

  1. Checkout LLVM (including related sub-projects like Clang):

    • git clone https://github.com/llvm/llvm-project.git

    • Or, on windows, git clone --config core.autocrlf=false https://github.com/llvm/llvm-project.git

  2. Configure and build LLVM and Clang:

    • cd llvm-project

    • cmake -S llvm -B build -G <generator> [options]

      Some common build system generators are:

      • Ninja --- for generating Ninja build files. Most llvm developers use Ninja.
      • Unix Makefiles --- for generating make-compatible parallel makefiles.
      • Visual Studio --- for generating Visual Studio projects and solutions.
      • Xcode --- for generating Xcode projects.

      Some common options:

      • -DLLVM_ENABLE_PROJECTS='...' and -DLLVM_ENABLE_RUNTIMES='...' --- semicolon-separated list of the LLVM sub-projects and runtimes you'd like to additionally build. LLVM_ENABLE_PROJECTS can include any of: clang, clang-tools-extra, cross-project-tests, flang, libc, libclc, lld, lldb, mlir, openmp, polly, or pstl. LLVM_ENABLE_RUNTIMES can include any of libcxx, libcxxabi, libunwind, compiler-rt, libc or openmp. Some runtime projects can be specified either in LLVM_ENABLE_PROJECTS or in LLVM_ENABLE_RUNTIMES.

        For example, to build LLVM, Clang, libcxx, and libcxxabi, use -DLLVM_ENABLE_PROJECTS="clang" -DLLVM_ENABLE_RUNTIMES="libcxx;libcxxabi".

      • -DCMAKE_INSTALL_PREFIX=directory --- Specify for directory the full path name of where you want the LLVM tools and libraries to be installed (default /usr/local). Be careful if you install runtime libraries: if your system uses those provided by LLVM (like libc++ or libc++abi), you must not overwrite your system's copy of those libraries, since that could render your system unusable. In general, using something like /usr is not advised, but /usr/local is fine.

      • -DCMAKE_BUILD_TYPE=type --- Valid options for type are Debug, Release, RelWithDebInfo, and MinSizeRel. Default is Debug.

      • -DLLVM_ENABLE_ASSERTIONS=On --- Compile with assertion checks enabled (default is Yes for Debug builds, No for all other build types).

    • cmake --build build [-- [options] <target>] or your build system specified above directly.

      • The default target (i.e. ninja or make) will build all of LLVM.

      • The check-all target (i.e. ninja check-all) will run the regression tests to ensure everything is in working order.

      • CMake will generate targets for each tool and library, and most LLVM sub-projects generate their own check-<project> target.

      • Running a serial build will be slow. To improve speed, try running a parallel build. That's done by default in Ninja; for make, use the option -j NNN, where NNN is the number of parallel jobs to run. In most cases, you get the best performance if you specify the number of CPU threads you have. On some Unix systems, you can specify this with -j$(nproc).

    • For more information see CMake.

Consult the Getting Started with LLVM page for detailed information on configuring and compiling LLVM. You can visit Directory Layout to learn about the layout of the source code tree.

Getting in touch

Join LLVM Discourse forums, discord chat or #llvm IRC channel on OFTC.

The LLVM project has adopted a code of conduct for participants to all modes of communication within the project.