binaries built in debug mode want to import __CxxFrameHandler3

[Trolldemorted]

I am building windows kernel drivers with rust (no_std and no libc), and debug builds fail because the linker can't find __CxxFrameHandler3 in the kernel libraries (which makes sense).

However, when building with --release the function apparently is optimized out, and linking is successfull.

My target.json:

{
  "_": "Inspired by https://github.com/ryanbreen/breenix/blob/master/x86_64-unknown-none-gnu.json",
  "_note": "`is_like_mcvc` works since #32823, nightly 2016-04-12",
  "_note": "`data-layout` became mandatory since rust-lang/rust#32939, nightly 2016-04-20",

  "llvm-target": "x86_64-pc-windows-msvc",
  "target-endian": "little",
  "target-pointer-width": "64",
  "target-c-int-width": "32",
  "linker-flavor": "msvc",
  "data-layout": "e-m:w-i64:64-f80:128-n8:16:32:64-S128",

  "cpu": "x86-64",
  "features": "-mmx,-sse,-sse2,-sse3,-ssse3,-sse4.1,-sse4.2,-3dnow,-3dnowa,-avx,-avx2,+soft-float",

  "arch": "x86_64",
  "vendor": "pc",
  "os": "windows",
  "env": "msvc",

  "executables": true,
  "dynamic-linking": true,

  "is-like-windows": true,
  "is-like-msvc": true,

  "dll-prefix": "",
  "dll-suffix": ".sys",
  "exe-prefix": "",
  "exe-suffix": ".exe",
  "staticlib-prefix": "lib",
  "staticlib-suffix": ".lib",

  "no-default-libraries":     true,
  "no-compiler-rt":           true,
  "has-rpath":                false,

  "function-sections": true,
  "has-elf-tls":              false,
  "disable-redzone":          true,
  "custom-unwind-resume":     false,
  "eliminate-frame-pointer":  false,
  "position-independent-executables": false,

  "code-model":              "kernel",
  "relocation-model":        "dynamic-no-pic",

  "pre-link-args": ["/NOLOGO", "/NODEFAULTLIB", "/SUBSYSTEM:NATIVE", "/DRIVER", "/RELEASE", "/NXCOMPAT", "/DYNAMICBASE",
    "/INCREMENTAL:NO", "/MANIFEST:NO"],

  "post-link-args": ["/OPT:REF,ICF", "ntoskrnl.lib", "hal.lib",
    "/noimplib", "/ENTRY:DriverEntry", "/DEF:exports.def", "/MERGE:.edata=.rdata", "/MERGE:.rustc=.data"],

  "_end" : false
}

Maybe related: #38641

[alexcrichton]

Fascinating! Out of curiosity, are you compiling with panic=abort or panic=unwind?

[Trolldemorted]

Nothing explicitly, i just added

#[lang = "eh_personality"] extern fn eh_personality() {}
#[lang = "panic_fmt"] extern fn panic_fmt() -> ! { loop {} }

for now.

After adding

[profile.dev]
panic = "abort"

to Cargo.toml it works, thanks for the hint!

Shall i close this issue or is this unwanted behaviour nevertheless? Do non-abort no-std crates make sense?

[alexcrichton]

Ah thanks for testing!

Yeah this is being referenced because of panic = "unwind" referencing panicking machinery (which references this function on MSVC). If it works now I think that's intended behavior so let's close, but we could certainly of course document this better :)

[Trolldemorted]

Imho this is not a documentation issue, but a rustc one: If we build a no_std crate without panic = "abort", the compiler should print a meaningful error message stating that this is impossible.

[alexcrichton]

Perhaps yeah! It's technically not impossible but certainly quite hard to get working

[Trolldemorted]

It would indeed be nice to get it working, but until it does I really recommend a decisive error message.

Should I create a seperate issue for that?

[alexcrichton]

Sure!

[MauriceKayser]

This issue is not resolved by adding panic = "abort" to the crate, because the precompiled libcore is compiled with panic = "unwind". Would it be possible to provide a precompiled libcore with panic = "abort"? That would be really useful for no_std on Windows.

References:
No-std Windows DLL linker error
Missing symbol in no_std application on panic (windows-msvc) #54137
Other modules extern functions can currently be redefined #47449
rustc: assertion failiure in llvm when defining __CxxFrameHandler3 #38641