[outcome] Add option single_header

[jeremy-coulon]

Summary

Changes to recipe: outcome/*

Motivation

Add single_header option. Default is True for backward compatibility.

Details

I need single_header=False for my own recipe of LLFIO
I found a duplicate PR which is closed here #15995
My solution seems much simpler.

---

• Read the contributing guidelines
• Checked that this PR is not a duplicate: list of PRs by recipe
• Tested locally with at least one configuration using a recent version of Conan

[jeremy-coulon]

outcome also depends on a recent version of status-code when single_header=False

Waiting for this PR to be merged: #24728

[conan-center-bot]

Conan v1 pipeline ✔️

All green in build 4 (641357f16dcea7b71c05551065879276ee209a1a):

• outcome/2.2.8:
  All packages built successfully! (All logs)

• outcome/2.2.9:
  All packages built successfully! (All logs)

• outcome/2.2.7:
  All packages built successfully! (All logs)

• outcome/2.2.4:
  All packages built successfully! (All logs)

• outcome/2.1.5:
  All packages built successfully! (All logs)

---

Conan v2 pipeline ✔️

Note: Conan v2 builds are now mandatory. Please read our discussion about it.

All green in build 4 (641357f16dcea7b71c05551065879276ee209a1a):

• outcome/2.2.8:
  All packages built successfully! (All logs)

• outcome/2.2.9:
  All packages built successfully! (All logs)

• outcome/2.2.7:
  All packages built successfully! (All logs)

• outcome/2.2.4:
  All packages built successfully! (All logs)

• outcome/2.1.5:
  All packages built successfully! (All logs)

[uilianries]

@jeremy-coulon Hello! Thank you for your PR, and sorry for the delay in reviewing it.

Some comments about your PR:

The upstream indeed documents about using single-header or multiple headers for Outcome:
https://github.com/ned14/outcome#usage-as-a-single-header-file

When consuming external status-code from a package manager, a definition should be exported as well: https://github.com/ned14/outcome/blob/develop/CMakeLists.txt#L172C34-L172C64. It should be added to package_info.

The non-packaged project llfio is consuming outcome as pointed: https://github.com/ned14/llfio/blob/06ea607de0346a1d77a807fd37efc2fdfb005de5/programs/CMakeLists.txt#L15C26-L15C33 And requires non single-header variant: https://github.com/ned14/llfio/blob/06ea607de0346a1d77a807fd37efc2fdfb005de5/include/llfio/v2.0/multiplex.hpp#L30

This PR makes sense in terms of supporting llfio, but it will not work when adding llfio in ConanCenterIndex, because the package Outcome with the single_header=False will not exist in Conan Center, resulting in the missing headers.

[github-actions]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.