Extensions for parallelism, version 2

From cppreference.net

C++并行性扩展版本2，ISO/IEC TS 19570:2018为C++标准库定义了以下新组件：

定义于头文件 `<experimental/task_block>`
__cpp_lib_experimental_parallel_task_block	值至少为 201711 表示支持任务块功能 (宏常量)
定义于头文件 `<experimental/execution>`
__cpp_lib_experimental_execution_vector_policy	值至少为 201711 表示支持向量和波前策略 (宏常量)
定义于头文件 `<experimental/algorithm>`
__cpp_lib_experimental_parallel_for_loop	值至少为 201711 表示支持 `for_loop` 类算法 (宏常量)
定义于头文件 `<experimental/simd>`
__cpp_lib_experimental_parallel_simd	值至少为 201803 表示支持数据并行类型库 (宏常量)

Compiler support
Freestanding and hosted
Language
Standard library
Standard library headers
Named requirements
Feature test macros (C++20)
Language support library
Concepts library (C++20)
Diagnostics library
Memory management library
Metaprogramming library (C++11)
General utilities library
Containers library
Iterators library
Ranges library (C++20)
Algorithms library
Strings library
Text processing library
Numerics library
Date and time library
Input/output library
Filesystem library (C++17)
Concurrency support library (C++11)
Execution control library (C++26)
Technical specifications
Symbols index
External libraries

Technical Specification
Filesystem library (filesystem TS)
Library fundamentals (library fundamentals TS)
Library fundamentals 2 (library fundamentals TS v2)
Library fundamentals 3 (library fundamentals TS v3)
Extensions for parallelism (parallelism TS)
Extensions for parallelism 2 (parallelism TS v2)
Extensions for concurrency (concurrency TS)
Extensions for concurrency 2 (concurrency TS v2)
Concepts (concepts TS)
Ranges (ranges TS)
Reflection (reflection TS)
Mathematical special functions (special functions TR)
Experimental Non-TS
Pattern Matching
Linear Algebra
std::execution
Contracts
2D Graphics

定义于头文件 `<experimental/execution_policy>`
unsequenced_policy vector_policy	执行策略类型 (类)
unseq vec	全局执行策略对象 (常量)

simd (并行技术规范 v2)	数据并行向量类型 (类模板)
simd_mask (并行技术规范 v2)	元素类型为 bool 的数据并行类型 (类模板)

目录

定义于头文件 `<experimental/exception_list>`
exception_list	并行执行期间引发的异常 (类)