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3217. <memory> and <execution> should define __cpp_lib_parallel_algorithm

Section: 17.3.1 [support.limits.general] Status: Resolved Submitter: Jonathan Wakely Opened: 2019-06-12 Last modified: 2026-06-10

Priority: 3

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Discussion:

There are parallel overloads of algorithms in <memory>, so it should define the macro. Also, <execution> defines the exec policies for use with the algos, so that should define the macro too.

[2019-07 Issue Prioritization]

Priority to 3 after discussion on the reflector.

[Brno 2026-06-10; Status changed: New → Resolved by P3179R9.]

Proposed resolution:

This wording is relative to N4810.

1. Modify 17.3.1 [support.limits.general], Table 36 — "Standard library feature-test macros", as indicated:

   Table 36 — Standard library feature-test macros

   Macro name	Value	Header(s)
   […]
   __cpp_lib_parallel_algorithm	201603L	<algorithm> <execution> <memory> <numeric>
   […]