Issue on Debian 7 (wheezy).

[mingwandroid]

I ran into this when trying to run my own build of alacritty. I verified that my /usr/lib/x86_64-linux-gnu/libXrandr.so.2.2.0 does not export XRRChangeProviderProperty.

thread 'main' panicked at 'Failed to initialize any backend!
    Wayland status: NoWaylandLib
    X11 status: LibraryOpenError(
    OpenError {
        kind: Symbol,
        detail: "XRRChangeProviderProperty - /usr/lib/x86_64-linux-gnu/libXrandr.so.2.2.0: undefined symbol: XRRChangeProviderProperty"
    }
)
', /opt/rust/.cargo.Linux/registry/src/gh.neting.cc-1ecc6299db9ec823/winit-0.15.0/src/platform/linux/mod.rs:418:9
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
             at libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1: std::panicking::default_hook::{{closure}}
             at libstd/sys_common/backtrace.rs:71
   2: std::panicking::rust_panic_with_hook
             at libstd/panicking.rs:227
             at libstd/panicking.rs:463
   3: std::panicking::begin_panic
             at /checkout/src/libstd/panicking.rs:397
   4: alacritty::display::Display::new
             at /opt/rust/.cargo.Linux/registry/src/gh.neting.cc-1ecc6299db9ec823/winit-0.15.0/src/platform/linux/mod.rs:418
   5: alacritty::main
             at src/main.rs:104
             at src/main.rs:62
   6: std::rt::lang_start::{{closure}}
             at /checkout/src/libstd/rt.rs:74
   7: main
   8: __libc_start_main
   9: <unknown>

Can this symbol being missing be marked as non-fatal somehow?

[ghost]

Something similar to this has occurred before. The solution we used was to provide an alternate struct that only included symbols available in an older version. If I ever get around to getting the v3 branch up and running, I'll stop encouraging x11-dl in favor of generated bindings, similar to how the gl_generator crate is used.

In the meantime, can you post the output you get from running:

readelf -Ws /usr/lib/x86_64-linux-gnu/libXrandr.so.2.2.0

I'll add a struct, probably called XrandrWheezy or something, that only includes the functions listed from readelf output. Thanks!

[mingwandroid]

Thanks a lot! Here you go:

Symbol table '.dynsym' contains 87 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND 
     1: 0000000000001870     0 SECTION LOCAL  DEFAULT   10 
     2: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND free@GLIBC_2.2.5 (2)
     3: 0000000000000000     0 NOTYPE  WEAK   DEFAULT  UND _ITM_deregisterTMCloneTable
     4: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND _XData32
     5: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND _XReply
     6: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND XextFindDisplay
     7: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND strlen@GLIBC_2.2.5 (2)
     8: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND XFree
     9: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND _XSend
    10: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND XextRemoveDisplay
    11: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND _XDeqAsyncHandler
    12: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND memcpy@GLIBC_2.2.5 (2)
    13: 0000000000000000     0 NOTYPE  WEAK   DEFAULT  UND __gmon_start__
    14: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND XMissingExtension
    15: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND XRenderSetSubpixelOrder
    16: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND _XGetRequest
    17: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND malloc@GLIBC_2.2.5 (2)
    18: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND _XRead32
    19: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND _XGetAsyncReply
    20: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND _XRead
    21: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND _XSetLastRequestRead
    22: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND memmove@GLIBC_2.2.5 (2)
    23: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND _XReadPad
    24: 0000000000000000     0 NOTYPE  WEAK   DEFAULT  UND _Jv_RegisterClasses
    25: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND _XEatData
    26: 0000000000000000     0 NOTYPE  WEAK   DEFAULT  UND _ITM_registerTMCloneTable
    27: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND XextAddDisplay
    28: 0000000000000000     0 FUNC    WEAK   DEFAULT  UND __cxa_finalize@GLIBC_2.2.5 (2)
    29: 00000000000045a0   217 FUNC    GLOBAL DEFAULT   12 XRRDestroyMode
    30: 0000000000002b40    12 FUNC    GLOBAL DEFAULT   12 XRRConfigTimes
    31: 0000000000002af0    73 FUNC    GLOBAL DEFAULT   12 XRRConfigRates
    32: 0000000000004220   316 FUNC    GLOBAL DEFAULT   12 XRRSetPanning
    33: 0000000000002ed0   486 FUNC    GLOBAL DEFAULT   12 XRRSetScreenConfigAndRate
    34: 0000000000004210     5 FUNC    GLOBAL DEFAULT   12 XRRFreePanning
    35: 00000000000061a0     5 FUNC    GLOBAL DEFAULT   12 XRRFreeScreenResources
    36: 0000000000002b70   172 FUNC    GLOBAL DEFAULT   12 XRRRotations
    37: 0000000000006444     0 FUNC    GLOBAL DEFAULT   13 _fini
    38: 0000000000004880     5 FUNC    GLOBAL DEFAULT   12 XRRFreeModeInfo
    39: 0000000000005170   403 FUNC    GLOBAL DEFAULT   12 XRRConfigureOutputProperty
    40: 0000000000004360   135 FUNC    GLOBAL DEFAULT   12 XRRAllocModeInfo
    41: 0000000000004ce0   294 FUNC    GLOBAL DEFAULT   12 XRRGetOutputPrimary
    42: 00000000000057c0   860 FUNC    GLOBAL DEFAULT   12 XRRGetOutputProperty
    43: 00000000000021f0   404 FUNC    GLOBAL DEFAULT   12 XRRQueryVersion
    44: 0000000000006180    10 FUNC    GLOBAL DEFAULT   12 XRRGetScreenResources
    45: 0000000000004fd0   414 FUNC    GLOBAL DEFAULT   12 XRRQueryOutputProperty
    46: 0000000000003320     5 FUNC    GLOBAL DEFAULT   12 XRRFreeCrtcInfo
    47: 0000000000004060   422 FUNC    GLOBAL DEFAULT   12 XRRGetPanning
    48: 00000000000056c0   255 FUNC    GLOBAL DEFAULT   12 XRRDeleteOutputProperty
    49: 0000000000002c20   166 FUNC    GLOBAL DEFAULT   12 XRRSizes
    50: 0000000000006300   321 FUNC    GLOBAL DEFAULT   12 XRRSetScreenSize
    51: 0000000000003760   351 FUNC    GLOBAL DEFAULT   12 XRRSetCrtcGamma
    52: 0000000000004890   804 FUNC    GLOBAL DEFAULT   12 XRRGetOutputInfo
    53: 0000000000002ec0     5 FUNC    GLOBAL DEFAULT   12 XRRFreeScreenConfigInfo
    54: 00000000000038c0     5 FUNC    GLOBAL DEFAULT   12 XRRFreeGamma
    55: 0000000000002e30   137 FUNC    GLOBAL DEFAULT   12 XRRGetScreenInfo
    56: 00000000000043f0   431 FUNC    GLOBAL DEFAULT   12 XRRCreateMode
    57: 0000000000003330   355 FUNC    GLOBAL DEFAULT   12 XRRSetCrtcConfig
    58: 00000000000061b0   323 FUNC    GLOBAL DEFAULT   12 XRRGetScreenSizeRange
    59: 00000000000038d0   497 FUNC    GLOBAL DEFAULT   12 XRRSetCrtcTransform
    60: 0000000000006190     7 FUNC    GLOBAL DEFAULT   12 XRRGetScreenResourcesCurrent
    61: 0000000000004780   255 FUNC    GLOBAL DEFAULT   12 XRRDeleteOutputMode
    62: 0000000000002ad0    12 FUNC    GLOBAL DEFAULT   12 XRRConfigRotations
    63: 0000000000005310   940 FUNC    GLOBAL DEFAULT   12 XRRChangeOutputProperty
    64: 0000000000002d90   158 FUNC    GLOBAL DEFAULT   12 XRRTimes
    65: 0000000000004e10   438 FUNC    GLOBAL DEFAULT   12 XRRListOutputProperties
    66: 0000000000002cd0   190 FUNC    GLOBAL DEFAULT   12 XRRRates
    67: 0000000000002510   430 FUNC    GLOBAL DEFAULT   12 XRRUpdateConfiguration
    68: 00000000002074b8     0 NOTYPE  GLOBAL DEFAULT  ABS __bss_start
    69: 00000000002074e8     0 NOTYPE  GLOBAL DEFAULT  ABS _end
    70: 0000000000002400   263 FUNC    GLOBAL DEFAULT   12 XRRSelectInput
    71: 0000000000002110    66 FUNC    GLOBAL DEFAULT   12 XRRRootToScreen
    72: 0000000000004bc0     5 FUNC    GLOBAL DEFAULT   12 XRRFreeOutputInfo
    73: 0000000000002ae0    10 FUNC    GLOBAL DEFAULT   12 XRRConfigSizes
    74: 0000000000002b60     5 FUNC    GLOBAL DEFAULT   12 XRRConfigCurrentRate
    75: 00000000000030c0    25 FUNC    GLOBAL DEFAULT   12 XRRSetScreenConfig
    76: 0000000000002160    97 FUNC    GLOBAL DEFAULT   12 XRRQueryExtension
    77: 0000000000004bd0   263 FUNC    GLOBAL DEFAULT   12 XRRSetOutputPrimary
    78: 00000000000035d0   399 FUNC    GLOBAL DEFAULT   12 XRRGetCrtcGamma
    79: 00000000002074b8     0 NOTYPE  GLOBAL DEFAULT  ABS _edata
    80: 00000000000030e0   569 FUNC    GLOBAL DEFAULT   12 XRRGetCrtcInfo
    81: 00000000000034a0   210 FUNC    GLOBAL DEFAULT   12 XRRGetCrtcGammaSize
    82: 0000000000003ad0  1424 FUNC    GLOBAL DEFAULT   12 XRRGetCrtcTransform
    83: 0000000000003580    79 FUNC    GLOBAL DEFAULT   12 XRRAllocGamma
    84: 0000000000002b50    11 FUNC    GLOBAL DEFAULT   12 XRRConfigCurrentConfiguration
    85: 0000000000004680   255 FUNC    GLOBAL DEFAULT   12 XRRAddOutputMode
    86: 0000000000001870     0 FUNC    GLOBAL DEFAULT   10 _init

[mingwandroid]

I wondered what the difference was between x11-dl and x11. I'm very new to this stuff!

[ghost]

x11 is much cleaner and nicer than x11-dl, but x11-dl is used in situations where it's uncertain whether the system running a program even has libX11.so.6. I don't like the x11-dl situation because it's full of hacks and workarounds, and my previous v3 plans are only slightly better, but it's the best that we have unless I or someone else writes a higher level binding like vberger did with the wayland bindings.

[ghost]

Scratch that. My memory failed me. I was thinking that the last time we added a compatibility struct, it was for Xlib, but looking back at the code, it was Xrandr. This struct is x11_dl::xrandr::Xrandr_2_2_0. See if using this instead of x11_dl::xrandr::Xrandr fixes the problem. Are you using x11-dl directly, or is it a dependency of something else you're using?

[anholt]

Is there a reason you're not having functions available only in newer versions be an Option? You could even assign them only if the server returns the appropriate protocol version.

[ghost]

When I first wrote x11-dl I rushed to get it out so it could be used by glutin and a few other projects. The current behavior expects all function pointers to be non-zero. Checking the protocol version to determine which functions to support is possible, but it would require a major version bump in addition to knowing the minimum protocol versions for every function, and there a lots of functions. This isn't a problem, but it would take some work. As of last year, I don't have the time to do significant work on any programming projects (because school) and have mostly just been checking and merging pull requests. Lately I've been leaning toward safe, high level bindings being better for Rust than directly exposing the C API as both x11 and x11-dl crates currently do. If time permits some day, I may do some work on this, but for now I'm mostly just sitting on x11-rs until somebody else volunteers to take it over.

TLDR: That's a great idea that hadn't occurred to me, but I won't be able to implement it myself in the near future.