Support dynamically-linked and/or native musl targets

[smaeul]

These changes allow native compilation on musl-based distributions and the use of dynamic libraries on linux-musl targets. This is intended to remove limitations based on past assumptions about musl targets, while maintaining existing behavior by default.

A minor related bugfix is included.

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @eddyb (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

Please see the contribution instructions for more information.

[eddyb]

r? @alexcrichton

[alexcrichton]

Looks great to me! Just some minor comments but otherwise I think this is good to go.

[alexcrichton]

Looks great to me! Just some minor comments but otherwise I think this is good to go.

[alexcrichton]

As an idea actually, I think we can leverage this for MSVC as well. The bin/rustc.rs script above has a hard-coded branch for MSVC but I think we could change that here. Could this code be updated with something like:

.or_else(|| {
    if target.contains("msvc") {
        Some(true)
    } else {
        None
    }
})

[smaeul]

Since +crt-static was previously unconditional for msvc, I left it that way when moving the check over.

[alexcrichton]

Could you add a comment her to what this block is doing?

[smaeul]

While working on getting these two details sorted out, I tried to use the stage2 rustc to bootstrap from again. However, it was getting immediately SIGKILL'd even with --help or --version. readelf told me it had no .text section.

Because src/librustc_back/target/linux_musl_base.rs adds -nostdlib to the linker arguments (to support building on glibc-targeting toolchains), the crt*.o startup files are not getting added, ld does not find the _start symbol, and -Wl,-O1 causes it to optimize out the entire binary.

We need to conditionally pass -nostdlib to the linker, just like we conditionally provide the startup files. However, pre_link_args is used by several other targets, so I'm not sure what to change.

I will rebase and take care of the other issues, though.

[alexcrichton]

Ouch yeah that sounds like a bad issue. That's not fixed up in this PR, right? If so, did you want to include it here or postpone for a future PR? (I'm fine with either)

[alexcrichton]

Ouch yeah that sounds like a bad issue. That's not fixed up in this PR, right? If so, did you want to include it here or postpone for a future PR? (I'm fine with either)

[alexcrichton]

Oh I thought we were replacing the contains("mips") annotations with a different one? Otherwise this may end up breaking the mips-musl build :(

[smaeul]

It was my understanding that we wanted to support both +crt-static and -crt-static for user code with any build of rustc. The crt_static option in config.toml only controls if rustc itself is statically or dynamically linked.

If we want to support static linking (especially with a glibc-based toolchain) on a target, we need musl-root and the startup files for that target.

[alexcrichton]

Like above, the mips check being removed here may break that build

[smaeul]

As above, mips would be dynamic-only without this change

[alexcrichton]

@bors: r+

Hm ok, makes sense. Let's see if mips builds break

[bors]

📌 Commit 706fc55 has been approved by alexcrichton

[smaeul]

In regards to -nostdlib completely breaking stage2, there are three different situations I see we're trying to support here:

1. Dynamic linking with a musl toolchain
2. Static linking with a musl toolchain
3. Static linking with a glibc toolchain

Cases 1 and 2 can use the toolchain-provided crt*.o, libc, and libgcc_s/libunwind, so they do not need any files copied over, and they do not need any extra linker arguments. Case 3 requires providing our own crt*.o, libc.a, and libunwind.a, and it requires -nostdlib to suppress the default toolchain versions.

We can make case 2 look like case 3, since static linking is self-contained, but it is a bit of a hack (e.g. using /usr for musl-root will lock libc version to the one we copied into the sysroot when building rustc). Making case 1 look like case 3 is even more difficult and fragile. Sharing the same TargetOptions among all three is just not going to work.

I see three ways to resolve this. I don't know which is most preferable.

1. More completely distinguish between cases 1 and {2,3}. This PR makes manually providing the startup files to the linker conditional on +crt-static. It might work to make -nostdlib also conditional on +crt-static.
2. Distinguish between cases {1,2} and 3. If we have a way to know if we are linking with a foreign toolchain, we can drop all of the linker flags/files for case 2. Then musl-root would only be used for case 3.
3. Drop built-in support for case 3, and require the user to have an appropriate linker (musl-gcc or a cross toolchain) to cross-link. Then we can remove the special-casing and musl-root entirely.

If I completely remove -nostdlib and the target files (unconditionally), I can build a complete stage2 with crt_static=true in config.toml. Building a stage1 with crt_static=false in config.toml also works, but fails in stage2-std trying to link shared libraries against a static libunwind. I have not investigated this yet, but it seems like a separate issue.

[frewsxcv]

Looks like there's a failure here:

https://travis-ci.org/rust-lang/rust/jobs/209064374

@bors r-

[alexcrichton]

@smaeul oh AFAIK we don't support static linking with glibc at all today (or at least if it looks like we do it wasn't intended)

[jmesmon]

@alexcrichton IIUC, "Static linking with a glibc toolchain" means, in this context "using a glibc toolchain to statically link to musl" (which, again IIUC, is the only currently supported mode prior to this PR)

[smaeul]

@alexcrichton I could have been more clear there. I meant (for case 3 above) statically linking to musl with a toolchain that targets glibc, i.e. where musl-gcc or ${ARCH}-linux-musl-gcc is not available. As far as I can tell, that's the only case where musl-root or -nostdlib is necessary.

[alexcrichton]

Oh right yeah that makes sense.

In reality we don't need a glibc toolchain at all, the intention is that we can produce a musl binary at any time. All we need is a linker really. But yeah I think the best solution is not passing -nostdlib if we're compiling with -C target-feature=-crt-static

[smaeul]

The build failures here look to be because the tests for mips are not expecting a musl-root, so the default (/usr/local) is being used. The configure script and test infrastructure will need to be updated to add an option for this and generate the appropriate libraries.

[alexcrichton]

@smaeul the configuration is in tree actually, mind updating that to pass the right configure args?

[alexcrichton]

ping @smaeul, any updates here?

[smaeul]

About figuring out when to pass -nostdlib and crt*, I found the easiest way to get things working both shared and static was to remove them entirely. In other words, if we just let the linker find libc and the startup files, we don't need any overriding at all (no linker flags, no musl root), as long as the linker knows where to find the files. And if the compiler is native, an appropriate cross linker exists, or musl-gcc exists, that is a valid assumption. Unfortunately, it breaks current behavior -- I don't know what's acceptable here.

Otherwise, we'll need to add some sort of conditional expression to src/librustc_back/target/linux_musl_base.rs, and I don't know how to do that.

I haven't worked on the CI/configure issue because I'm not sure how good of an idea it is to get this "working" but at the same time completely broken. I'd like to try to get the linking issue fixed first.

[alexcrichton]

Yeah the purpose of the musl target today is that you don't need to have musl-gcc or a similar wrapper installed, so we'll need to preserve the capability somehow.

[jirutka]

I’ve tried to build rustc in Alpine Linux with this patch and I hit few issues.

At first, there’s a relevant part of the build script:

pkgver=1.16.0
_stage0dir="$srcdir/stage0"

# Don't set wrong LD_LIBRARY_PATH, we will rather set it manually when
# invoking make.
sed -i /LD_LIBRARY_PATH/d src/bootstrap/bootstrap.py

# Precompiled rustc and rust-std from VoidLinux.
cp -flr "$srcdir"/rustc-$pkgver-*/rustc/* \
        "$srcdir"/rust-std-$pkgver-*/rust-std-*/* \
        "$srcdir"/cargo-*-*/cargo/* \
        "$_stage0dir"/  

# Note: We use llvm 3.8.1 for now.
./configure \
        --build="$_ctarget" \
        --host="$_ctarget" \
        --prefix="/usr" \
        --release-channel="stable" \
        --enable-local-rust \
        --local-rust-root="$_stage0dir" \
        --llvm-root="/usr" \
        --musl-root="/usr" \
        --enable-rustbuild \
        --enable-vendor \
        --disable-docs \
        --disable-jemalloc \
        --disable-rpath

# Set LD_LIBRARY_PATH, so rustc in stage0 can find correct libs.
LD_LIBRARY_PATH="$_stage0dir/lib" \
        make RUST_BACKTRACE=1 RUST_CRT_STATIC="false" VERBOSE=1

LD_LIBRARY_PATH="$_stage0dir/lib" \
        make install DESTDIR="$pkgdir"

I’ve removed -nostdlib from src/librustc_back/target/linux_musl_base.rs:

-    // Make sure that the linker/gcc really don't pull in anything, including
-    // default objects, libs, etc.
-    base.pre_link_args.push("-nostdlib".to_string());

The build succeeds, but rustc fails when trying to compile anything:

$ rustc hello_world.rs
error: linking with `cc` failed: exit code: 1
  |
  = note: "cc" "-Wl,--as-needed" "-Wl,-z,noexecstack" "-Wl,--eh-frame-hdr" "-Wl,-(" "-m64" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib/crt1.o" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib/crti.o" "-L" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib" "hello_world.0.o" "-o" "hello_world" "-Wl,--gc-sections" "-pie" "-nodefaultlibs" "-L" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib" "-Wl,-Bstatic" "-Wl,-Bdynamic" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-d73d432e81fd8b19.rlib" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib/librand-709b996bacb8eb07.rlib" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libcollections-df1635bc25c3e592.rlib" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd_unicode-00ee5191e548d906.rlib" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libpanic_unwind-85f96f5a1caa812c.rlib" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libunwind-1e0a4dc78495337e.rlib" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib/liballoc-a1562f522536bd3b.rlib" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib/liballoc_system-bde4c172625df17f.rlib" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib/liblibc-bf68330d3f5e10dd.rlib" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libcore-963774836b754896.rlib" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libcompiler_builtins-9802cab648d12028.rlib" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib/crtn.o" "-Wl,-)"
  = note: /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/crt1.o: In function `_start':
          crt1.c:(.text+0x0): multiple definition of `_start'
          /usr/lib/gcc/x86_64-alpine-linux-musl/6.3.0/../../../../lib/Scrt1.o:Scrt1.c:(.text+0x0): first defined here
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/crt1.o: In function `_start_c':
          crt1.c:(.text._start_c+0x0): multiple definition of `_start_c'
          /usr/lib/gcc/x86_64-alpine-linux-musl/6.3.0/../../../../lib/Scrt1.o:Scrt1.c:(.text._start_c+0x0): first defined here
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/crti.o: In function `_init':
          /home/buildozer/aports/main/musl/src/musl-1.1.16/crt/x86_64/crti.s:4: multiple definition of `_init'
          /usr/lib/gcc/x86_64-alpine-linux-musl/6.3.0/../../../../lib/crti.o:/home/buildozer/aports/main/musl/src/musl-1.1.16/crt/x86_64/crti.s:4: first defined here
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/crti.o: In function `_fini':
          /home/buildozer/aports/main/musl/src/musl-1.1.16/crt/x86_64/crti.s:4: multiple definition of `_fini'
          /usr/lib/gcc/x86_64-alpine-linux-musl/6.3.0/../../../../lib/crti.o:/home/buildozer/aports/main/musl/src/musl-1.1.16/crt/x86_64/crti.s:4: first defined here
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-d73d432e81fd8b19.rlib(std-d73d432e81fd8b19.0.o): In function `collections::vec::{{impl}}::into_boxed_slice<u8>':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/liballoc/raw_vec.rs:517: undefined reference to `_Unwind_Resume'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-d73d432e81fd8b19.rlib(std-d73d432e81fd8b19.0.o): In function `alloc::heap::deallocate':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/liballoc/heap.rs:113: undefined reference to `_Unwind_Resume'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-d73d432e81fd8b19.rlib(std-d73d432e81fd8b19.0.o): In function `std::sys::imp::mutex::{{impl}}::unlock':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libstd/sys/unix/mutex.rs:72: undefined reference to `_Unwind_Resume'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-d73d432e81fd8b19.rlib(std-d73d432e81fd8b19.0.o): In function `core::result::unwrap_failed<std::ffi::c_str::NulError>':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/liballoc/heap.rs:113: undefined reference to `_Unwind_Resume'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-d73d432e81fd8b19.rlib(std-d73d432e81fd8b19.0.o): In function `drop':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/liballoc/heap.rs:113: undefined reference to `_Unwind_Resume'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-d73d432e81fd8b19.rlib(std-d73d432e81fd8b19.0.o):/home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/liballoc/heap.rs:113: more undefined references to `_Unwind_Resume' follow
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-d73d432e81fd8b19.rlib(std-d73d432e81fd8b19.0.o): In function `std::sys::imp::backtrace::tracing::imp::write':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:42: undefined reference to `_Unwind_Backtrace'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-d73d432e81fd8b19.rlib(std-d73d432e81fd8b19.0.o): In function `std::sys::imp::backtrace::tracing::imp::write::trace_fn':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:62: undefined reference to `_Unwind_GetIPInfo'
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:83: undefined reference to `_Unwind_FindEnclosingFunction'
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:93: undefined reference to `_Unwind_Resume'
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:103: undefined reference to `_Unwind_Resume'
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:103: undefined reference to `_Unwind_Resume'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-d73d432e81fd8b19.rlib(std-d73d432e81fd8b19.0.o): In function `alloc::heap::deallocate':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/liballoc/heap.rs:113: undefined reference to `_Unwind_Resume'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-d73d432e81fd8b19.rlib(std-d73d432e81fd8b19.0.o): In function `std::sys::imp::os_str::{{impl}}::fmt':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/liballoc/heap.rs:113: undefined reference to `_Unwind_Resume'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-d73d432e81fd8b19.rlib(std-d73d432e81fd8b19.0.o):/home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/liballoc/arc.rs:768: more undefined references to `_Unwind_Resume' follow
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libpanic_unwind-85f96f5a1caa812c.rlib(panic_unwind-85f96f5a1caa812c.0.o): In function `panic_unwind::imp::find_eh_action':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libpanic_unwind/gcc.rs:264: undefined reference to `_Unwind_GetLanguageSpecificData'
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libpanic_unwind/gcc.rs:266: undefined reference to `_Unwind_GetIPInfo'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libpanic_unwind-85f96f5a1caa812c.rlib(panic_unwind-85f96f5a1caa812c.0.o): In function `panic_unwind::dwarf::eh::find_eh_action':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libpanic_unwind/dwarf/eh.rs:69: undefined reference to `_Unwind_GetRegionStart'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libpanic_unwind-85f96f5a1caa812c.rlib(panic_unwind-85f96f5a1caa812c.0.o): In function `panic_unwind::imp::rust_eh_personality':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libpanic_unwind/gcc.rs:172: undefined reference to `_Unwind_SetGR'
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libpanic_unwind/gcc.rs:173: undefined reference to `_Unwind_SetGR'
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libpanic_unwind/gcc.rs:174: undefined reference to `_Unwind_SetIP'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libpanic_unwind-85f96f5a1caa812c.rlib(panic_unwind-85f96f5a1caa812c.0.o): In function `panic_unwind::imp::find_eh_action::{{closure}}':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libpanic_unwind/gcc.rs:272: undefined reference to `_Unwind_GetTextRelBase'
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libpanic_unwind/gcc.rs:273: undefined reference to `_Unwind_GetDataRelBase'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libpanic_unwind-85f96f5a1caa812c.rlib(panic_unwind-85f96f5a1caa812c.0.o): In function `panic_unwind::imp::cleanup':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libpanic_unwind/gcc.rs:100: undefined reference to `_Unwind_DeleteException'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libpanic_unwind-85f96f5a1caa812c.rlib(panic_unwind-85f96f5a1caa812c.0.o): In function `panic_unwind::imp::panic':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libpanic_unwind/gcc.rs:83: undefined reference to `_Unwind_RaiseException'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libpanic_unwind-85f96f5a1caa812c.rlib(panic_unwind-85f96f5a1caa812c.0.o): In function `core::ops::FnOnce::call_once':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libpanic_unwind/gcc.rs:272: undefined reference to `_Unwind_GetTextRelBase'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libpanic_unwind-85f96f5a1caa812c.rlib(panic_unwind-85f96f5a1caa812c.0.o): In function `core::ops::FnOnce::call_once':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libpanic_unwind/gcc.rs:273: undefined reference to `_Unwind_GetDataRelBase'
          collect2: error: ld returned 1 exit status

We can see three problems here:

1. Wrong absolute paths coming from build environment into the stack trace. This is an unrelated error, I’ll create a separate issue for it.
2. crt1.c:(.text+0x0): multiple definition of '_start'
3. undefined reference to '_Unwind_Resume'

I’ve fixed the second problem by removing the following snippet from src/librustc_back/target/linux_musl_base.rs:

-    // When generating a statically linked executable there's generally some
-    // small setup needed which is listed in these files. These are provided by
-    // a musl toolchain and are linked by default by the `musl-gcc` script. Note
-    // that `gcc` also does this by default, it just uses some different files.
-    //
-    // Each target directory for musl has these object files included in it so
-    // they'll be included from there.
-    base.pre_link_objects_exe.push("crt1.o".to_string());
-    base.pre_link_objects_exe.push("crti.o".to_string());
-    base.post_link_objects.push("crtn.o".to_string());

And the third problem by removing this: (This actually hasn’t fixed it, removing base.crt_static_default = true; and so linking dynamically by default did)

-    base.pre_link_args.push("-Wl,-(".to_string());
-    base.post_link_args.push("-Wl,-)".to_string());

After these changes we end up just with base.pre_link_args.push("-Wl,--eh-frame-hdr".to_string()); (which is maybe not even needed), otherwise it’s the same as linux_base. And rustc finally works!

$ rustc -C target-feature=-crt-static hello_world.rs
$ ./hello_world
Hello, world!
$ ldd hello_world
        /lib/ld-musl-x86_64.so.1 (0x2ecbf67a000)
        libgcc_s.so.1 => /usr/lib/libgcc_s.so.1 (0x2ecbf240000)
        libc.musl-x86_64.so.1 => /lib/ld-musl-x86_64.so.1 (0x2ecbf67a000)

I’m not sure if it’s really intentional that it links dynamically by default now, but I don’t mind this. (Pardon, I also removed base.crt_static_default = true; and forgot about it.)

However, statical linking is now broken:

$ rustc -C target-feature=+crt-static hello_world.rs
error: linking with `cc` failed: exit code: 1
  |
  = note: "cc" "-Wl,--as-needed" "-Wl,-z,noexecstack" "-Wl,--eh-frame-hdr" "-m64" "-L" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib" "hello_world.0.o" "-o" "hello_world" "-Wl,--gc-sections" "-pie" "-nodefaultlibs" "-L" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib" "-Wl,-Bstatic" "-Wl,-Bdynamic" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-86059d53218552f5.rlib" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib/librand-36efc09e6c3aa7b6.rlib" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libcollections-64ae13b816203712.rlib" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd_unicode-a6dea33a6a8b7481.rlib" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libpanic_unwind-12770ed0830004c4.rlib" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libunwind-52493d6bc7a4edfb.rlib" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib/liballoc-8ffb79da497eb47f.rlib" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib/liballoc_system-35e8b7ebb64c18bd.rlib" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib/liblibc-2b2567c2ae2ad7d0.rlib" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libcore-6588f2833738184c.rlib" "/usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libcompiler_builtins-5ef8fa488c4b9f32.rlib"
  = note: /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-86059d53218552f5.rlib(std-86059d53218552f5.0.o): In function `collections::vec::{{impl}}::into_boxed_slice<u8>':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/liballoc/raw_vec.rs:517: undefined reference to `_Unwind_Resume'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-86059d53218552f5.rlib(std-86059d53218552f5.0.o): In function `alloc::heap::deallocate':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/liballoc/heap.rs:113: undefined reference to `_Unwind_Resume'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-86059d53218552f5.rlib(std-86059d53218552f5.0.o): In function `core::result::unwrap_failed<std::ffi::c_str::NulError>':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/liballoc/heap.rs:113: undefined reference to `_Unwind_Resume'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-86059d53218552f5.rlib(std-86059d53218552f5.0.o): In function `std::sys::imp::mutex::{{impl}}::unlock':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libstd/sys/unix/mutex.rs:72: undefined reference to `_Unwind_Resume'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-86059d53218552f5.rlib(std-86059d53218552f5.0.o): In function `drop':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/liballoc/heap.rs:113: undefined reference to `_Unwind_Resume'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-86059d53218552f5.rlib(std-86059d53218552f5.0.o):/home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/liballoc/heap.rs:113: more undefined references to `_Unwind_Resume' follow
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-86059d53218552f5.rlib(std-86059d53218552f5.0.o): In function `std::sys::imp::backtrace::tracing::imp::write':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:42: undefined reference to `_Unwind_Backtrace'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-86059d53218552f5.rlib(std-86059d53218552f5.0.o): In function `std::sys::imp::backtrace::tracing::imp::write::trace_fn':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:62: undefined reference to `_Unwind_GetIPInfo'
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:83: undefined reference to `_Unwind_FindEnclosingFunction'
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:93: undefined reference to `_Unwind_Resume'
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:103: undefined reference to `_Unwind_Resume'
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:103: undefined reference to `_Unwind_Resume'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-86059d53218552f5.rlib(std-86059d53218552f5.0.o): In function `alloc::heap::deallocate':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/liballoc/heap.rs:113: undefined reference to `_Unwind_Resume'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-86059d53218552f5.rlib(std-86059d53218552f5.0.o): In function `std::sys::imp::os_str::{{impl}}::fmt':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/liballoc/heap.rs:113: undefined reference to `_Unwind_Resume'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libstd-86059d53218552f5.rlib(std-86059d53218552f5.0.o):/home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/liballoc/arc.rs:768: more undefined references to `_Unwind_Resume' follow
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libpanic_unwind-12770ed0830004c4.rlib(panic_unwind-12770ed0830004c4.0.o): In function `panic_unwind::imp::find_eh_action':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libpanic_unwind/gcc.rs:264: undefined reference to `_Unwind_GetLanguageSpecificData'
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libpanic_unwind/gcc.rs:266: undefined reference to `_Unwind_GetIPInfo'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libpanic_unwind-12770ed0830004c4.rlib(panic_unwind-12770ed0830004c4.0.o): In function `panic_unwind::dwarf::eh::find_eh_action':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libpanic_unwind/dwarf/eh.rs:69: undefined reference to `_Unwind_GetRegionStart'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libpanic_unwind-12770ed0830004c4.rlib(panic_unwind-12770ed0830004c4.0.o): In function `panic_unwind::imp::rust_eh_personality':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libpanic_unwind/gcc.rs:172: undefined reference to `_Unwind_SetGR'
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libpanic_unwind/gcc.rs:173: undefined reference to `_Unwind_SetGR'
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libpanic_unwind/gcc.rs:174: undefined reference to `_Unwind_SetIP'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libpanic_unwind-12770ed0830004c4.rlib(panic_unwind-12770ed0830004c4.0.o): In function `panic_unwind::imp::find_eh_action::{{closure}}':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libpanic_unwind/gcc.rs:272: undefined reference to `_Unwind_GetTextRelBase'
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libpanic_unwind/gcc.rs:273: undefined reference to `_Unwind_GetDataRelBase'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libpanic_unwind-12770ed0830004c4.rlib(panic_unwind-12770ed0830004c4.0.o): In function `panic_unwind::imp::cleanup':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libpanic_unwind/gcc.rs:100: undefined reference to `_Unwind_DeleteException'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libpanic_unwind-12770ed0830004c4.rlib(panic_unwind-12770ed0830004c4.0.o): In function `panic_unwind::imp::panic':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libpanic_unwind/gcc.rs:83: undefined reference to `_Unwind_RaiseException'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libpanic_unwind-12770ed0830004c4.rlib(panic_unwind-12770ed0830004c4.0.o): In function `core::ops::FnOnce::call_once':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libpanic_unwind/gcc.rs:272: undefined reference to `_Unwind_GetTextRelBase'
          /usr/lib/rustlib/x86_64-unknown-linux-musl/lib/libpanic_unwind-12770ed0830004c4.rlib(panic_unwind-12770ed0830004c4.0.o): In function `core::ops::FnOnce::call_once':
          /home/jirutjak/aports/testing/rust/src/rustc-1.16.0-src/src/libpanic_unwind/gcc.rs:273: undefined reference to `_Unwind_GetDataRelBase'
          collect2: error: ld returned 1 exit status

error: aborting due to previous error

(Yes, I’ve removed that pesky check that rejects +crt-static in stable…)

So we probably need to make some options in linux_musl_base.rs conditional based on crt-static…?

---

@Shizmob tried different approach, he added:

+    // To prevent some nasty linking errors, link in libgcc_s here.
+    base.pre_link_args.push("-lgcc_s".to_string());

This also works, but haven’t tested compiling with +crt-static yet.

/cc @japaric

[japaric]

So we probably need to make some options in linux_musl_base.rs conditional based on crt-static…?

That was my conclusion from #38075 but I'm not too fond of the idea. #40018 already makes the link_args fields conditional wrt to -Z linker-flavor. If we also make it conditional wrt crt-static then we are going to double the number of possible combinations. I can't think of a better option atm.

[smaeul]

@alexcrichton I was able to replace the offending commit and get tests to pass, so everything should be good to go.

[alexcrichton]

@bors: r+

[bors]

📌 Commit e6cd941 has been approved by alexcrichton

[bors]

⌛️ Testing commit e6cd941 with merge a3f0ee9...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: alexcrichton
Pushing a3f0ee9 to master...

[golddranks]

I think this PR broke static musl builds. Posted a new issue and a testcase: #44069

[corbinu]

I don't know if this is the right place to ask but how do I build this on Alpine? I tried cloning master and following the readme and then did this ./x.py --build=x86_64-unknown-linux-musl but it errors out when downloading the assets