Building standard library with LLD fails on Windows with "undefined symbol" errors

[michaelwoerister]

Currently it's not possible to cross-compile the standard library for aarch64-pc-windows-msvc. To reproduce, install the MSVC's ARM64 toolchain (I used MSVC 15.8.3) and configure Rust as follows:

./configure --host=x86_64-pc-windows-msvc --target=aarch64-pc-windows-msvc --set rust.lld

Running ./x.py build will abort with linker errors (error log provided by @froydnj):

 rust-lld: error: undefined symbol: _ZN47_$LT$std..fs..File$u20$as$u20$std..io..Read$GT$4read17h278f0b774c14e76aE
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.11.rcgu.o:(_ZN71_$LT$std..io..buffered..BufReader$LT$R$GT$$u20$as$u20$std..io..Read$GT$4read17he17302c0375fd14cE)
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.11.rcgu.o:(_ZN71_$LT$std..io..buffered..BufReader$LT$R$GT$$u20$as$u20$std..io..Read$GT$4read17he17302c0375fd14cE)

complete error log

error: linking with `rust-lld` failed: exit code: 1
  |
  = note: "rust-lld" "-flavor" "link" "/LIBPATH:C:\\Users\\froyd\\rust\\build\\x86_64-pc-windows-msvc\\stage2\\lib\\rustlib\\aarch64-pc-windows-msvc\\lib" "C:\\Users\\froyd\\rust\\build\\x86_64-pc-windows-msvc\\stage2-test\\aarch64-pc-windows-msvc\\release\\deps\\term-2c32649037e8f914.term.brlane49-cgu.0.rcgu.o" "C:\\Users\\froyd\\rust\\build\\x86_64-pc-windows-msvc\\stage2-test\\aarch64-pc-windows-msvc\\release\\deps\\term-2c32649037e8f914.term.brlane49-cgu.1.rcgu.o" "C:\\Users\\froyd\\rust\\build\\x86_64-pc-windows-msvc\\stage2-test\\aarch64-pc-windows-msvc\\release\\deps\\term-2c32649037e8f914.term.brlane49-cgu.10.rcgu.o" "C:\\Users\\froyd\\rust\\build\\x86_64-pc-windows-msvc\\stage2-test\\aarch64-pc-windows-msvc\\release\\deps\\term-2c32649037e8f914.term.brlane49-cgu.11.rcgu.o" "C:\\Users\\froyd\\rust\\build\\x86_64-pc-windows-msvc\\stage2-test\\aarch64-pc-windows-msvc\\release\\deps\\term-2c32649037e8f914.term.brlane49-cgu.12.rcgu.o" "C:\\Users\\froyd\\rust\\build\\x86_64-pc-windows-msvc\\stage2-test\\aarch64-pc-windows-msvc\\release\\deps\\term-2c32649037e8f914.term.brlane49-cgu.13.rcgu.o" "C:\\Users\\froyd\\rust\\build\\x86_64-pc-windows-msvc\\stage2-test\\aarch64-pc-windows-msvc\\release\\deps\\term-2c32649037e8f914.term.brlane49-cgu.14.rcgu.o" "C:\\Users\\froyd\\rust\\build\\x86_64-pc-windows-msvc\\stage2-test\\aarch64-pc-windows-msvc\\release\\deps\\term-2c32649037e8f914.term.brlane49-cgu.15.rcgu.o" "C:\\Users\\froyd\\rust\\build\\x86_64-pc-windows-msvc\\stage2-test\\aarch64-pc-windows-msvc\\release\\deps\\term-2c32649037e8f914.term.brlane49-cgu.2.rcgu.o" "C:\\Users\\froyd\\rust\\build\\x86_64-pc-windows-msvc\\stage2-test\\aarch64-pc-windows-msvc\\release\\deps\\term-2c32649037e8f914.term.brlane49-cgu.3.rcgu.o" "C:\\Users\\froyd\\rust\\build\\x86_64-pc-windows-msvc\\stage2-test\\aarch64-pc-windows-msvc\\release\\deps\\term-2c32649037e8f914.term.brlane49-cgu.4.rcgu.o" "C:\\Users\\froyd\\rust\\build\\x86_64-pc-windows-msvc\\stage2-test\\aarch64-pc-windows-msvc\\release\\deps\\term-2c32649037e8f914.term.brlane49-cgu.5.rcgu.o" "C:\\Users\\froyd\\rust\\build\\x86_64-pc-windows-msvc\\stage2-test\\aarch64-pc-windows-msvc\\release\\deps\\term-2c32649037e8f914.term.brlane49-cgu.6.rcgu.o" "C:\\Users\\froyd\\rust\\build\\x86_64-pc-windows-msvc\\stage2-test\\aarch64-pc-windows-msvc\\release\\deps\\term-2c32649037e8f914.term.brlane49-cgu.7.rcgu.o" "C:\\Users\\froyd\\rust\\build\\x86_64-pc-windows-msvc\\stage2-test\\aarch64-pc-windows-msvc\\release\\deps\\term-2c32649037e8f914.term.brlane49-cgu.8.rcgu.o" "C:\\Users\\froyd\\rust\\build\\x86_64-pc-windows-msvc\\stage2-test\\aarch64-pc-windows-msvc\\release\\deps\\term-2c32649037e8f914.term.brlane49-cgu.9.rcgu.o" "/OUT:C:\\Users\\froyd\\rust\\build\\x86_64-pc-windows-msvc\\stage2-test\\aarch64-pc-windows-msvc\\release\\deps\\term-2c32649037e8f914.dll" "/DEF:C:\\Users\\froyd\\AppData\\Local\\Temp\\rustcr7cV5j\\lib.def" "C:\\Users\\froyd\\rust\\build\\x86_64-pc-windows-msvc\\stage2-test\\aarch64-pc-windows-msvc\\release\\deps\\term-2c32649037e8f914.2ubmzgze4ttlfqh0.rcgu.o" "/OPT:REF,ICF" "/DEBUG" "/LIBPATH:C:\\Users\\froyd\\rust\\build\\x86_64-pc-windows-msvc\\stage2-test\\aarch64-pc-windows-msvc\\release\\deps" "/LIBPATH:C:\\Users\\froyd\\rust\\build\\x86_64-pc-windows-msvc\\stage2-test\\release\\deps" "/LIBPATH:C:\\Users\\froyd\\rust\\build\\x86_64-pc-windows-msvc\\stage2\\lib\\rustlib\\aarch64-pc-windows-msvc\\lib" "kernel32.lib" "/LIBPATH:C:\\Users\\froyd\\rust\\build\\x86_64-pc-windows-msvc\\stage2\\lib\\rustlib\\aarch64-pc-windows-msvc\\lib" "std-9e897034a22da8f8.dll.lib" "C:\\Users\\froyd\\AppData\\Local\\Temp\\rustcr7cV5j\\libcompiler_builtins-aa78be22f43afdbb.rlib" "advapi32.lib" "ws2_32.lib" "userenv.lib" "shell32.lib" "libcmt.lib" "/DLL" "/IMPLIB:C:\\Users\\froyd\\rust\\build\\x86_64-pc-windows-msvc\\stage2-test\\aarch64-pc-windows-msvc\\release\\deps\\term-2c32649037e8f914.dll.lib"
  = note: rust-lld: error: undefined symbol: _ZN73_$LT$core..fmt..Arguments$LT$$u27$a$GT$$u20$as$u20$core..fmt..Display$GT$3fmt17h2a972b9cd14c0b34E
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.10.rcgu.o:(_ZN4core5slice29_$LT$impl$u20$$u5b$T$u5d$$GT$15copy_from_slice17h84c3d20285d3797dE)
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.10.rcgu.o:(_ZN4core5slice29_$LT$impl$u20$$u5b$T$u5d$$GT$15copy_from_slice17h84c3d20285d3797dE)

          rust-lld: error: undefined symbol: _ZN3std5error221_$LT$impl$u20$core..convert..From$LT$$RF$$u27$b$u20$str$GT$$u20$for$u20$alloc..boxed..Box$LT$$LP$dyn$u20$std..error..Error$u20$$u2b$$u20$core..marker..Sync$u20$$u2b$$u20$core..marker..Send$u20$$u2b$$u20$$u27$a$RP$$GT$$GT$4from17h9eeab4eb33fac824E
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.11.rcgu.o:(_ZN3std2io4Read10read_exact17h54ee1715c74e9886E)
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.11.rcgu.o:(_ZN79_$LT$std..io..buffered..BufWriter$LT$W$GT$$u20$as$u20$core..ops..drop..Drop$GT$4drop17h0a2a4eb954c6a297E)

          rust-lld: error: undefined symbol: _ZN47_$LT$std..fs..File$u20$as$u20$std..io..Read$GT$4read17h278f0b774c14e76aE
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.11.rcgu.o:(_ZN71_$LT$std..io..buffered..BufReader$LT$R$GT$$u20$as$u20$std..io..Read$GT$4read17he17302c0375fd14cE)
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.11.rcgu.o:(_ZN71_$LT$std..io..buffered..BufReader$LT$R$GT$$u20$as$u20$std..io..Read$GT$4read17he17302c0375fd14cE)

          rust-lld: error: undefined symbol: _ZN79_$LT$std..path..Path$u20$as$u20$core..convert..AsRef$LT$std..path..Path$GT$$GT$6as_ref17he945222ff32fd726E
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.12.rcgu.o:(_ZN3std2fs4File4open17h17da0bceedbdeefbE)
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.12.rcgu.o:(_ZN3std2fs4File4open17h17da0bceedbdeefbE)

          rust-lld: error: undefined symbol: _ZN82_$LT$std..path..PathBuf$u20$as$u20$core..convert..AsRef$LT$std..path..Path$GT$$GT$6as_ref17he10fff899ec3ba9aE
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.12.rcgu.o:(_ZN3std2fs8metadata17h0fa7f67ccea52baeE)

          rust-lld: error: undefined symbol: _ZN3std3ffi6os_str85_$LT$impl$u20$core..convert..AsRef$LT$std..ffi..os_str..OsStr$GT$$u20$for$u20$str$GT$6as_ref17h4fff6be7d583afb5E
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.12.rcgu.o:(_ZN3std3env3var17h443aa255a44023c3E)
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.12.rcgu.o:(_ZN3std3env6var_os17hdf78d67fb86bc31aE)

          rust-lld: error: undefined symbol: _ZN60_$LT$alloc..string..String$u20$as$u20$core..clone..Clone$GT$5clone17h4b24dcf27e218542E
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.12.rcgu.o:(_ZN44_$LT$T$u20$as$u20$alloc..borrow..ToOwned$GT$8to_owned17he1b1c763f42eb1b9E)

          rust-lld: error: undefined symbol: _ZN3std5error229_$LT$impl$u20$core..convert..From$LT$alloc..string..String$GT$$u20$for$u20$alloc..boxed..Box$LT$$LP$dyn$u20$std..error..Error$u20$$u2b$$u20$core..marker..Sync$u20$$u2b$$u20$core..marker..Send$u20$$u2b$$u20$$u27$static$RP$$GT$$GT$4from17h6a7d84947f47f853E
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.12.rcgu.o:(_ZN50_$LT$T$u20$as$u20$core..convert..Into$LT$U$GT$$GT$4into17had9622a930073bdcE)

          rust-lld: error: undefined symbol: _ZN40_$LT$str$u20$as$u20$core..fmt..Debug$GT$3fmt17hbe61a3430dd2168dE
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.12.rcgu.o:(_ZN53_$LT$$RF$$u27$a$u20$T$u20$as$u20$core..fmt..Debug$GT$3fmt17h19e4b58322a0debfE)

          rust-lld: error: undefined symbol: _ZN60_$LT$std..io..stdio..StdoutRaw$u20$as$u20$std..io..Write$GT$5write17hf039c99cc25f3872E
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.12.rcgu.o:(_ZN65_$LT$std..io..stdio..Maybe$LT$W$GT$$u20$as$u20$std..io..Write$GT$5write17h36c941d8633c1a65E)

          rust-lld: error: undefined symbol: _ZN3std4path95_$LT$impl$u20$core..convert..AsRef$LT$std..path..Path$GT$$u20$for$u20$alloc..string..String$GT$6as_ref17hb5273f3d4d5c62ceE
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.12.rcgu.o:(_ZN66_$LT$$RF$$u27$a$u20$T$u20$as$u20$core..convert..AsRef$LT$U$GT$$GT$6as_ref17h88469db36cd005bbE)

          rust-lld: error: undefined symbol: _ZN3std3ffi6os_str85_$LT$impl$u20$core..convert..AsRef$LT$std..ffi..os_str..OsStr$GT$$u20$for$u20$str$GT$6as_ref17h4fff6be7d583afb5E
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.13.rcgu.o:(_ZN4term8terminfo8searcher19get_dbpath_for_term17hf8fd73e6c94258f3E)
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.13.rcgu.o:(_ZN4term8terminfo8searcher19get_dbpath_for_term17hf8fd73e6c94258f3E)
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.13.rcgu.o:(_ZN4term8terminfo8searcher19get_dbpath_for_term17hf8fd73e6c94258f3E)
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.13.rcgu.o:(_ZN4term8terminfo8searcher19get_dbpath_for_term17hf8fd73e6c94258f3E)
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.13.rcgu.o:(_ZN4term8terminfo8searcher19get_dbpath_for_term17hf8fd73e6c94258f3E)
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.13.rcgu.o:(_ZN4term8terminfo8searcher19get_dbpath_for_term17hf8fd73e6c94258f3E)
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.13.rcgu.o:(_ZN4term8terminfo8searcher19get_dbpath_for_term17hf8fd73e6c94258f3E)

          rust-lld: error: undefined symbol: _ZN92_$LT$std..path..PathBuf$u20$as$u20$core..convert..From$LT$std..ffi..os_str..OsString$GT$$GT$4from17hd32fe85aee6e7f6bE
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.13.rcgu.o:(_ZN4term8terminfo8searcher19get_dbpath_for_term17hf8fd73e6c94258f3E)
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.13.rcgu.o:(_ZN4term8terminfo8searcher19get_dbpath_for_term17hf8fd73e6c94258f3E)
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.13.rcgu.o:(_ZN4term8terminfo8searcher19get_dbpath_for_term17hf8fd73e6c94258f3E)
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.13.rcgu.o:(_ZN4term8terminfo8searcher19get_dbpath_for_term17hf8fd73e6c94258f3E)
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.13.rcgu.o:(_ZN4term8terminfo8searcher19get_dbpath_for_term17hf8fd73e6c94258f3E)
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.13.rcgu.o:(_ZN4term8terminfo8searcher19get_dbpath_for_term17hf8fd73e6c94258f3E)

          rust-lld: error: undefined symbol: _ZN3std4path77_$LT$impl$u20$core..convert..AsRef$LT$std..path..Path$GT$$u20$for$u20$str$GT$6as_ref17h0ca87727d4f1f137E
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.13.rcgu.o:(_ZN4term8terminfo8searcher19get_dbpath_for_term17hf8fd73e6c94258f3E)
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.13.rcgu.o:(_ZN4term8terminfo8searcher19get_dbpath_for_term17hf8fd73e6c94258f3E)
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.13.rcgu.o:(_ZN4term8terminfo8searcher19get_dbpath_for_term17hf8fd73e6c94258f3E)

          rust-lld: error: undefined symbol: _ZN82_$LT$std..path..PathBuf$u20$as$u20$core..convert..AsRef$LT$std..path..Path$GT$$GT$6as_ref17he10fff899ec3ba9aE
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.13.rcgu.o:(_ZN4term8terminfo8searcher19get_dbpath_for_term17hf8fd73e6c94258f3E)
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.13.rcgu.o:(_ZN4term8terminfo8searcher19get_dbpath_for_term17hf8fd73e6c94258f3E)
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.13.rcgu.o:(_ZN4term8terminfo8searcher19get_dbpath_for_term17hf8fd73e6c94258f3E)

          rust-lld: error: undefined symbol: _ZN3std4path95_$LT$impl$u20$core..convert..AsRef$LT$std..path..Path$GT$$u20$for$u20$alloc..string..String$GT$6as_ref17hb5273f3d4d5c62ceE
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.13.rcgu.o:(_ZN4term8terminfo8searcher19get_dbpath_for_term17hf8fd73e6c94258f3E)
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.13.rcgu.o:(_ZN4term8terminfo8searcher19get_dbpath_for_term17hf8fd73e6c94258f3E)

          rust-lld: error: undefined symbol: _ZN4core3fmt3num55_$LT$impl$u20$core..fmt..LowerHex$u20$for$u20$usize$GT$3fmt17h167a3950eded3036E
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.13.rcgu.o:(_ZN4term8terminfo8searcher19get_dbpath_for_term17hf8fd73e6c94258f3E)
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.13.rcgu.o:(_ZN4term8terminfo8searcher19get_dbpath_for_term17hf8fd73e6c94258f3E)

          rust-lld: error: undefined symbol: _ZN3std5error221_$LT$impl$u20$core..convert..From$LT$$RF$$u27$b$u20$str$GT$$u20$for$u20$alloc..boxed..Box$LT$$LP$dyn$u20$std..error..Error$u20$$u2b$$u20$core..marker..Sync$u20$$u2b$$u20$core..marker..Send$u20$$u2b$$u20$$u27$a$RP$$GT$$GT$4from17h9eeab4eb33fac824E
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.15.rcgu.o:(_ZN3std2io5error5Error3new17h2e9937565e5a4accE)
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.15.rcgu.o:(_ZN75_$LT$$RF$$u27$a$u20$mut$u20$I$u20$as$u20$core..iter..iterator..Iterator$GT$4next17h4d0546aa6657129fE)

          rust-lld: error: undefined symbol: _ZN3std5error229_$LT$impl$u20$core..convert..From$LT$alloc..string..String$GT$$u20$for$u20$alloc..boxed..Box$LT$$LP$dyn$u20$std..error..Error$u20$$u2b$$u20$core..marker..Sync$u20$$u2b$$u20$core..marker..Send$u20$$u2b$$u20$$u27$static$RP$$GT$$GT$4from17h6a7d84947f47f853E
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.15.rcgu.o:(_ZN3std2io5error5Error3new17h4abe32e5817d446fE)

          rust-lld: error: undefined symbol: _ZN3std4path77_$LT$impl$u20$core..convert..AsRef$LT$std..path..Path$GT$$u20$for$u20$str$GT$6as_ref17h0ca87727d4f1f137E
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.15.rcgu.o:(_ZN3std4path7PathBuf4push17h0ae214a74ebc332bE)
          >>> referenced by C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps\term-2c32649037e8f914.term.brlane49-cgu.15.rcgu.o:(_ZN3std4path7PathBuf4push17h401dc332b52f3a78E)

          rust-lld: error: too many errors emitted, stopping now (use /errorlimit:0 to see all errors)


error: aborting due to previous error

error: Could not compile `term`.

Caused by:
  process didn't exit successfully: `C:\Users\froyd\rust\build\bootstrap/debug/rustc --crate-name term libterm\lib.rs --error-format json --crate-type dylib --crate-type rlib --emit=dep-info,link -C prefer-dynamic -C opt-level=2 -C metadata=2c32649037e8f914 -C extra-filename=-2c32649037e8f914 --out-dir C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps --target aarch64-pc-windows-msvc -L dependency=C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\aarch64-pc-windows-msvc\release\deps -L dependency=C:\Users\froyd\rust\build\x86_64-pc-windows-msvc\stage2-test\release\deps` (exit code: 1)
command did not execute successfully: "C:\\Users\\froyd\\rust\\build\\x86_64-pc-windows-msvc\\stage0\\bin\\cargo.exe" "build" "--target" "aarch64-pc-windows-msvc" "-j" "12" "--release" "--manifest-path" "C:\\Users\\froyd\\rust\\src/libtest/Cargo.toml" "--message-format" "json"
expected success, got: exit code: 101
thread 'main' panicked at 'cargo must succeed', bootstrap\compile.rs:1155:9
note: Run with `RUST_BACKTRACE=1` for a backtrace.
failed to run: C:\Users\froyd\rust\build\bootstrap\debug\bootstrap build
Build completed unsuccessfully in 0:39:29

[michaelwoerister]

So it turns out that linking with LLD does not work on Windows in general. At least I get the same linker errors for i686-pc-windows-msvc too. The culprit is the following piece of logic in LLD's handling of .def files:

    // In simple cases, only Name is set. Renamed exports are parsed
    // and set as "ExtName = Name". If Name has the form "OtherDll.Func",
    // it shouldn't be a normal exported function but a forward to another
    // DLL instead. This is supported by both MS and GNU linkers.
    if (E1.ExtName != E1.Name && StringRef(E1.Name).contains('.')) {
      E2.Name = Saver.save(E1.ExtName);
      E2.ForwardTo = Saver.save(E1.Name);
      Config->Exports.push_back(E2);
      continue;
    }

LLD interprets every symbol with a dot in it as a re-export from another DLLs. And it will find plenty of dots in our symbols :)

I don't know yet what the best strategy to solve this is. We'll probably have to avoid dots in our symbol names entirely.

[michaelwoerister]

cc @alexcrichton, who did the initial work for supporting aarch64 in Windows.

[michaelwoerister]

A few thoughts on fixing this:

• Fixing this on the Rust side by not including . in symbol names anymore will break demangling in various external tools like Valgrind (cc @nnethercote). If we have to break tools, we should also clean up symbol name generation at the same time to avoid churn.
• Fixing this in LLD might be possible but somewhat brittle. I experimented with a fix of the logic linked above but then it failed somewhere down the line, where another piece of code worked under the assumption that . has a special meaning in symbol names. I don't think we want to go down that road.

[froydnj]

I cargo-culted the configuration to use lld from @alexcrichton ...is there some reason that Microsoft's linker won't work correctly here?

[michaelwoerister]

The original PR mentions LLD being less buggy than the MSVC linker.

[alexcrichton]

Oh dear, thanks for tracking that down @michaelwoerister! I recall that LLD worked for building MSVC binaries, but I think that must have been simple binaries, I've never bootstrapped with it. It may also be the case now that LLVM and/or link.exe has progressed to being "less buggy" so it may work for aarch64 (haven't check it recently myself)

We could perhaps as a temporary interim measure have different mangling on each platform?

[michaelwoerister]

We could perhaps as a temporary interim measure have different mangling on each platform?

Yeah, Windows might be a good testing ground for a new mangling scheme as there are probably fewer tools that depend on the current scheme.