Move the Linux runner into a subdirectory

[robert-ancell]

Fixes #60213

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[robert-ancell]

I'm trying to work out what is failing in the plugin_test_linux - any hints as to how to run this locally would help!

[christopherfujino]

The failure I'm seeing on Linux plugin_test_linux is:

[2024-08-20 21:55:02.546347] [STDOUT] stderr: [   +6 ms] CMake Error at flutter/generated_plugins.cmake:16 (target_link_libraries):
[2024-08-20 21:55:02.546404] [STDOUT] stderr: [        ]   Attempt to add link library "plugintest_plugin" to target
[2024-08-20 21:55:02.546422] [STDOUT] stderr: [        ]   "plugintest_example" which is not built in this directory.
[2024-08-20 21:55:02.546483] [STDOUT] stderr: [        ]   This is allowed only when policy CMP0079 is set to NEW.

https://logs.chromium.org/logs/flutter/buildbucket/cr-buildbucket/8739022238067392529/+/u/run_plugin_test_linux/stdout

[robert-ancell]

It should be good now with the CMake fixes for plugins. I think the Windows test failure is not related from reading the log.

The CMake code is the bit I am most unsure about, especially which parts go in the root CMakeLists.txt and which goes in runner/CMakeLists.txt. I tried to copy as much from the Windows implementation that I could.

[loic-sharma]

This looks reasonable to me, but I'm a total CMake novice. @stuartmorgan will be able to give a much better review :)

[stuartmorgan]

Sorry, I completely lost track of this review somehow. Mostly looks good, but the version change and mismatch are odd.

What's the plan for updating docs? We have docs that refer to these file paths but if we just change all of them we'll have docs that are wrong for everyone with existing projects. Do we list both (forever, in each location)? But we can't auto-migrate, because they are user-editable files.

This is unfortunately a change that would have been much easier if I'd done it shortly after filing, instead of letting it stable support go out without fixing it :(

[stuartmorgan]

test-exempt: code refactor with no semantic change

[robert-ancell]

I propose we update the docs to the new location, with a footnote about it having been different in the past if required.

I'm not familiar with the auto-migration code but this should be possible to do, shouldn't it? If a developer has not modified the original files then we could move them without any issues.

[robert-ancell]

For context - I was motivated to fix this due to the new FlApplication class - if we're going to change the template we might as well do this migration at the same time.

[robert-ancell]

@stuartmorgan anything else required before landing this?

[cbracken]

[stuartmorgan]

Sorry, LGTM

Is there an issue tracking the docs audit/update that will need to happen when this reaches stable?

[robert-ancell]

The only reference to main.cc and my_application.cc on the website is in https://docs.flutter.dev/platform-integration/platform-channels. Do you think there's anywhere else this should be mentioned?

[stuartmorgan]

I figured there would be references to some part of the runner code or build files in the general docs about building an app too, but if it's just that one page that's easy!