rustdoc beta linking trouble in MinGW

[tspiteri]

I have a crate rugflo which depends on a crate gmp-mpfr-sys. The gmp-mpfr-sys crate includes three C libraries that are compiled during crate compilation. One of the C libraries apparently makes use of __emutls_get_address, and the rugflo crate makes use of this library.

If I run

cargo +beta test -p rugflo

the #[test] tests succeed, but the inline documentation tests fail. On stable, both #[test] and inline documentation tests succeed. I'm including part of the error message below.

This is on the beta-x86_64-pc-windows-gnu toolchain, with beta version 1.18.0-beta.1 (4dce672 2017-04-25).

failures:

---- src\float.rs - float::Float::assign_str (line 1566) stdout ----
	error: linking with `gcc` failed: exit code: 1
  |
  = note: "gcc" "-Wl,--enable-long-section-names" "-fno-use-linker-plugin" "-Wl,--nxcompat" "-nostdlib" "-m64" "C:\\Users\\Trevor\\.rustup\\toolchains\\beta-x86_64-pc-windows-gnu\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib\\crt2.o" "C:\\Users\\Trevor\\.rustup\\toolchains\\beta-x86_64-pc-windows-gnu\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib\\rsbegin.o" "-L" "C:\\Users\\Trevor\\.rustup\\toolchains\\beta-x86_64-pc-windows-gnu\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "C:\\Users\\Trevor\\AppData\\Local\\Temp\\rustdoctest.SrhC8rnnvQEZ\\rust_out.0.o" "-o" "C:\\Users\\Trevor\\AppData\\Local\\Temp\\rustdoctest.SrhC8rnnvQEZ\\rust_out.exe" "-Wl,--gc-sections" "-nodefaultlibs" "-L" "c:\\Users\\Trevor\\projects\\t\\target\\debug\\deps" "-L" "c:\\Users\\Trevor\\projects\\t\\target\\debug\\build\\gmp-mpfr-sys-0cc9b17adf0b6ee9\\out\\lib" "-L" "C:\\Users\\Trevor\\.rustup\\toolchains\\beta-x86_64-pc-windows-gnu\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-Wl,-Bstatic" "C:\\Users\\Trevor\\projects\\t\\target\\debug\\deps\\librugflo-b0b353c1d0de4acc.rlib" "C:\\Users\\Trevor\\projects\\t\\target\\debug\\deps\\librugrat-06b8c4776c6f6356.rlib" "C:\\Users\\Trevor\\projects\\t\\target\\debug\\deps\\librugint-0f0e67a952d13d05.rlib" "C:\\Users\\Trevor\\projects\\t\\target\\debug\\deps\\libgmp_mpfr_sys-ec78d94836c71bdb.rlib" "C:\\Users\\Trevor\\projects\\t\\target\\debug\\deps\\librand-76456d761c2cb637.rlib" "-L" "C:\\Users\\Trevor\\.rustup\\toolchains\\beta-x86_64-pc-windows-gnu\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-Wl,-Bdynamic" "-l" "std-e2451a256f66ac19" "-Wl,-Bstatic" "C:\\Users\\Trevor\\.rustup\\toolchains\\beta-x86_64-pc-windows-gnu\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib\\libcompiler_builtins-91b619d34dd1f5aa.rlib" "-Wl,-Bdynamic" "-l" "advapi32" "-l" "advapi32" "-l" "ws2_32" "-l" "userenv" "-l" "shell32" "-lmingwex" "-lmingw32" "-lgcc" "-lmsvcrt" "-luser32" "-lkernel32" "C:\\Users\\Trevor\\.rustup\\toolchains\\beta-x86_64-pc-windows-gnu\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib\\rsend.o"
  = note: C:\Users\Trevor\projects\t\target\debug\deps\libgmp_mpfr_sys-ec78d94836c71bdb.rlib(exceptions.o):exceptions.c:(.text+0xc): undefined reference to `__emutls_get_address'
          C:\Users\Trevor\projects\t\target\debug\deps\libgmp_mpfr_sys-ec78d94836c71bdb.rlib(exceptions.o):exceptions.c:(.text+0x42): undefined reference to `__emutls_get_address'
          C:\Users\Trevor\projects\t\target\debug\deps\libgmp_mpfr_sys-ec78d94836c71bdb.rlib(exceptions.o):exceptions.c:(.text+0x7c): undefined reference to `__emutls_get_address'
          C:\Users\Trevor\projects\t\target\debug\deps\libgmp_mpfr_sys-ec78d94836c71bdb.rlib(exceptions.o):exceptions.c:(.text+0xb2): undefined reference to `__emutls_get_address'
          C:\Users\Trevor\projects\t\target\debug\deps\libgmp_mpfr_sys-ec78d94836c71bdb.rlib(exceptions.o):exceptions.c:(.text+0xec): undefined reference to `__emutls_get_address'
          C:\Users\Trevor\projects\t\target\debug\deps\libgmp_mpfr_sys-ec78d94836c71bdb.rlib(exceptions.o):exceptions.c:(.text+0x10c): more undefined references to `__emutls_get_address' follow
          

error: aborting due to previous error

thread 'rustc' panicked at 'Box<Any>', src\librustc_errors\lib.rs:453
note: Run with `RUST_BACKTRACE=1` for a backtrace.
thread 'rustc' panicked at 'couldn't compile the test', src\librustdoc\test.rs:273

---- src\float.rs - float::Constant (line 130) stdout ----
	error: linking with `gcc` failed: exit code: 1
  |

...
(repetitions)
...

thread 'rustc' panicked at 'Box<Any>', src\librustc_errors\lib.rs:453
thread 'rustc' panicked at 'couldn't compile the test', src\librustdoc\test.rs:273


failures:
    src\float.rs - float::Constant (line 130)
    src\float.rs - float::Float::assign_random_bits_round (line 1237)
    src\float.rs - float::Float::assign_random_cont_round (line 1344)
    src\float.rs - float::Float::assign_str (line 1566)
    src\float.rs - float::Float::assign_str_radix (line 1583)
    src\float.rs - float::Float::assign_str_radix_round (line 1625)
    src\float.rs - float::Float::assign_str_round (line 1605)
    src\float.rs - float::Float::to_integer_exp (line 344)
    src\float.rs - float::Float::to_string_radix (line 1463)
    src\float.rs - float::Rational::assign (line 2090)
    src\float.rs - float::Rational::from (line 2033)
    src\float.rs - float::Round::Nearest (line 92)
    src\lib.rs -  (line 51)

test result: FAILED. 0 passed; 13 failed; 0 ignored; 0 measured

error: test failed, to rerun pass '--doc'

[alexcrichton]

cc @vadimcn @brson

I wonder if this is related to the pthread business on beta? Or maybe this is just related to updating the MinGW compiler we're bundling?

@tspiteri do you have MinGW and/or MSYS installed? Or do you know if you're using the bundled version of gcc that comes with Rust itself?

[tspiteri]

I have MinGW and MSYS installed from the msys2.org (msys2.github.io) page. That is needed to build the copies of the GNU libraries GMP, MPFR and MPC in gmp-mpfr-sys.

[vadimcn]

@tspiteri: what does gcc --version -v say?

[tspiteri]

The gcc version is

gcc.exe (Rev2, Built by MSYS2 project) 6.3.0
Copyright (C) 2016 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.


Using built-in specs.
COLLECT_GCC=C:\msys64\mingw64\bin\gcc.exe
COLLECT_LTO_WRAPPER=C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/6.3.0/lto-wrapper.exe
Target: x86_64-w64-mingw32
Configured with: ../gcc-6.3.0/configure --prefix=/mingw64 --with-local-prefix=/mingw64/local --build=x86_64-w64-mingw32 --host=x86_64-w64-mingw32 --target=x86_64-w64-mingw32 --with-native-system-header-dir=/mingw64/x86_64-w64-mingw32/include --libexecdir=/mingw64/lib --enable-bootstrap --with-arch=x86-64 --with-tune=generic --enable-languages=c,lto,c++,objc,obj-c++,fortran,ada --enable-shared --enable-static --enable-libatomic --enable-threads=posix --enable-graphite --enable-fully-dynamic-string --enable-libstdcxx-time=yes --disable-libstdcxx-pch --disable-libstdcxx-debug --disable-isl-version-check --enable-lto --enable-libgomp --disable-multilib --enable-checking=release --disable-rpath --disable-win32-registry --disable-nls --disable-werror --disable-symvers --with-libiconv --with-system-zlib --with-gmp=/mingw64 --with-mpfr=/mingw64 --with-mpc=/mingw64 --with-isl=/mingw64 --with-pkgversion='Rev2, Built by MSYS2 project' --with-bugurl=https://sourceforge.net/projects/msys2 --with-gnu-as --with-gnu-ld
Thread model: posix
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GNU C11 (Rev2, Built by MSYS2 project) version 6.3.0 (x86_64-w64-mingw32)
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GNU assembler (GNU Binutils) 2.28
Copyright (C) 2017 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License version 3 or later.
This program has absolutely no warranty.
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GNU assembler version 2.28 (x86_64-w64-mingw32) using BFD version (GNU Binutils) 2.28
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COLLECT_GCC_OPTIONS='--version' '-v' '-mtune=generic' '-march=x86-64'
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GNU ld (GNU Binutils) 2.28
Copyright (C) 2017 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
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This program has absolutely no warranty.
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[tspiteri]

I've done some narrowing, and the problem is on nightly-2017-04-07-x86_64-pc-windows-gnu, but everything is fine on nightly-2017-04-06-x86_64-pc-windows-gnu. And the problem is only in the testing of inline docs. Other tests, as well as dependent applications, all run fine.

Edit: And the same happens for the i686 toolchain on a 32-bit MSYS shell. Everything works fine on nightly-2017-04-06-i686-pc-windows-gnu, but the issue is there on nightly-2017-04-07-i686-pc-windows-gnu.

[tspiteri]

I'm attaching a reduced test case. cargo +nightly-2017-04-06 test succeeds and cargo +nightly-2017-04-07 test fails on inline docs.

try.zip

[alexcrichton]

Ok thanks for testing @tspiteri! @vadimcn that range of nightlies notably includes #40805 which I suspect is causing problems here.

After some investigation it seems that this is related to the switch to static-nobundle from the previous dylib link kind. The doc test is linking dynamically to libstd whereas the normal unit test is linking statically. This means that the normal doctest is not receiving the -lgcc -lpthread arguments, whereas the test executable is indeed receiving -lgcc -lpthread, explaining why the test executable links correctly but the doctest does not.

Essentially I believe these lines boil down to a regression.

I'm not really sure what to do about this situation. We've gotten ourselves into quite the quagmire with MinGW and the compiler. @vadimcn do you have thoughts?

[alexcrichton]

Ok so drilling more into this regression:

• Win32 toolchains only require -lgcc_eh to be passed to keep working
• Pthread toolchains require both -lgcc_eh and -lpthread
• If you have the rust-mingw package installed, then that's now a pthread toolchain, which means it's basically impossible to get working. Even if you override -C linker it won't work because we bundle the pthread-requiring libs.

I honestly don't know what to do about this regression. @tspiteri my best suggestion to you is to uninstall the x86_64-pc-windows-gnu Rust compilers. Instead you'll typically get much better mileage from an x86_64-pc-windows-msvc compiler cross-compiling to x86_64-pc-windows-gnu. The downside of this approach is that you may need to install the VS build tools to work with plugins and such.

Other than that though the only way I can see to fix this is to switch from static-nobundle for these libs back to dylib. I don't really know if that will have a larger impact or fix this, it's unknown to me.