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Bug 5463 - generated Wayland interfaces are included in the library's ABI
Summary: generated Wayland interfaces are included in the library's ABI
Status: RESOLVED FIXED
Alias: None
Product: SDL
Classification: Unclassified
Component: build (show other bugs)
Version: 2.0.14
Hardware: x86_64 Linux
: P2 normal
Assignee: Sam Lantinga
QA Contact: Sam Lantinga
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2021-01-13 13:27 UTC by Simon McVittie
Modified: 2021-01-23 19:23 UTC (History)
1 user (show)

See Also:

Attachments
build: Prefer to use `wayland-scanner private-code` (4.77 KB, patch)
2021-01-13 13:31 UTC, Simon McVittie 		Details | Diff
waylandtouch: Don't export interface structs (2.09 KB, patch)
2021-01-15 17:49 UTC, Simon McVittie 		Details | Diff
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Description Simon McVittie 2021-01-13 13:27:32 UTC 
If SDL is built with Wayland enabled, the ABI of the library includes generated code for Wayland interfaces. I assume this was not intended to be present? For example:

$ objdump -T -x build/.libs/libSDL2-2.0.so.0
...
0000000000173aa0 g     O .data.rel.ro   0000000000000028              zxdg_shell_v6_interface
...
0000000000172ea0 g     O .data.rel.ro   0000000000000028              wl_data_source_interface
...
0000000000171820 g     O .data.rel.ro   0000000000000028              qt_extended_surface_interface

This seems to be because SDL is using the deprecated form `wayland-scanner code`. In recent versions of wayland-scanner, this produces symbols that are marked with __attribute__((visibility("default")), overriding SDL's -fvisibility=hidden.

A similar report in Qt: https://bugreports.qt.io/browse/QTBUG-73099

I'll attach a patch in a moment.
Comment 1 Simon McVittie 2021-01-13 13:31:06 UTC 
Created attachment 4661 [details]
build: Prefer to use `wayland-scanner private-code`

In versions since 1.15, the `code` mode is a deprecated alias for
`public-code`, which emits symbols with default visibility, overriding
SDL's -fvisibility=hidden option.

Use the `private-code` mode instead. This emits symbols with hidden
visibility, so they do not affect the ABI of libSDL.

See also: https://bugreports.qt.io/browse/QTBUG-73099,
https://lists.freedesktop.org/archives/wayland-devel/2018-February/037097.html
Comment 2 Sam Lantinga 2021-01-14 22:50:56 UTC 
Patch added, thanks!
https://hg.libsdl.org/SDL/rev/0530cf0a871c
Comment 3 Simon McVittie 2021-01-15 17:48:12 UTC 
Sorry, I missed some that are included in the C code rather than being generated at build-time.

It would probably be better if they were generated at build-time like the rest, but for now, I'll just take them out of the ABI...
Comment 4 Simon McVittie 2021-01-15 17:49:02 UTC 
Created attachment 4665 [details]
waylandtouch: Don't export interface structs

These are explicitly written in C code rather than generated at build
time, so they weren't affected by changing how we invoke
wayland-scanner.
Comment 5 Sam Lantinga 2021-01-23 19:23:35 UTC 
Patch added, thanks!
https://hg.libsdl.org/SDL/rev/a3d4219798f6