[PoC] qt, depends: Add wayland support without build-time nor fixed run-time deps

[laanwj]

Built on PR #29923.
Loosely based on PR #22708.

This is a proof-of-concept of using the same methodology as in #29923 to support both Wayland and X11 windowing backends, for the Linux release binary, without any extra build-time nor fixed run-time dependencies. It results in a bitcoin-qt binary that "just works" on systems that have only one of them installed, or both.

Everything (including libEGL) is loaded dynamically at run time if needed.

$ readelf -a src/qt/bitcoin-qt |grep '(NEEDED)'

 0x0000000000000001 (NEEDED)             Shared library: [libm.so.6]
 0x0000000000000001 (NEEDED)             Shared library: [libstdc++.so.6]
 0x0000000000000001 (NEEDED)             Shared library: [libgcc_s.so.1]
 0x0000000000000001 (NEEDED)             Shared library: [libc.so.6]
 0x0000000000000001 (NEEDED)             Shared library: [ld-linux-x86-64.so.2]

(libdl.so.1 also when building with older GLIBC, as for guix)

When launching with WAYLAND_DISPLAY=... (takes priority):

2024-04-25T07:13:54Z Bitcoin Core version v27.99.0-4d5957ddc638-dirty (release build)
2024-04-25T07:13:54Z Qt 5.15.13 (static), plugin=wayland (static)
2024-04-25T07:16:43Z Static plugins:
2024-04-25T07:16:43Z  QXcbIntegrationPlugin, version 331520
2024-04-25T07:16:43Z  QWaylandIntegrationPlugin, version 331520
2024-04-25T07:16:43Z  QWaylandEglClientBufferPlugin, version 331520
2024-04-25T07:16:43Z  QWaylandBradientDecorationPlugin, version 331520
2024-04-25T07:16:43Z  QWaylandXdgShellIntegrationPlugin, version 3315202

When launching with DISPLAY=...:

2024-04-25T07:16:43Z Bitcoin Core version v27.99.0-4d5957ddc638-dirty (release build)
2024-04-25T07:16:43Z Qt 5.15.13 (static), plugin=xcb (static)

Will make this a draft. This is not ready for review: the Qt patch can potentially be cleaned up a lot with regard to generated wayland code. But it works. Please review #29923 instead, which needs to go in first anyway.

Closes #19950.

• qtsowrap wayland branch: https://github.com/laanwj/qtsowrap/tree/wayland

Co-authored-by: Hennadii Stepanov

Notes

• If you get an error that a qtwayland-... is missing while running make in depends, remove the depends/sources/.download-stamps/.*qt* files to make sure it re-attempts to download missing files.

[DrahtBot]

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Type	Reviewers
Concept ACK	hebasto

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Conflicts

Reviewers, this pull request conflicts with the following ones:

• #29985 (depends: Fix build of Qt for 32-bit platforms with recent glibc by laanwj)
• #29923 (depends: Remove Qt build-time dependencies by laanwj)
• #29895 (guix: remove bzip2 from deps by fanquake)
• #29880 (depends: build FreeType with CMake by fanquake)
• #29878 (depends: build expat with CMake by fanquake)

If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

[hebasto]

This is a proof-of-concept of using the same methodology as in #29923 to support both Wayland and X11 windowing backends, for the Linux release binary, without any extra build-time nor fixed run-time dependencies.

Concept ACK on this.

Obviously :)

[DrahtBot]

🐙 This pull request conflicts with the target branch and needs rebase.