Closed
Description
On investigating rust-lang/wg-cargo-std-aware#32 I've managed to reduce this down to:
$ cat foo.rs
pub fn foo() {
bar::<usize>();
}
pub fn bar<T>() {
baz();
}
fn baz() {}
$ cat bar.rs
extern crate foo;
pub fn bar() {
foo::foo();
}
$ rustc --crate-type rlib foo.rs
$ rustc --crate-type dylib bar.rs -L .
$ rustc --crate-type dylib bar.rs -L . -C opt-level=2
error: linking with `link.exe` failed: exit code: 1120
|
= note: "C:\\Program Files (x86)\\Microsoft Visual Studio\\2019\\Community\\VC\\Tools\\MSVC\\14.22.27905\\bin\\HostX64\\x64\\link.exe" "/NOLOGO" "/NXCOMPAT" "/LIBPATH:C:\\Users\\alex\\.rustup\\toolchains\\stable-x86_64-pc-windows-msvc\\lib\\rustlib\\x86_64-pc-windows-msvc\\lib" "bar.bar.3a1fbbbh-cgu.0.rcgu.o" "/OUT:bar.dll" "/DEF:C:\\Users\\alex\\AppData\\Local\\Temp\\rustcAYUABK\\lib.def" "bar.13x131manznmlae2.rcgu.o" "bar.4hnz5vh12lvh2qha.rcgu.o" "/OPT:REF,ICF" "/DEBUG" "/NATVIS:C:\\Users\\alex\\.rustup\\toolchains\\stable-x86_64-pc-windows-msvc\\lib\\rustlib\\etc\\intrinsic.natvis" "/NATVIS:C:\\Users\\alex\\.rustup\\toolchains\\stable-x86_64-pc-windows-msvc\\lib\\rustlib\\etc\\liballoc.natvis" "/NATVIS:C:\\Users\\alex\\.rustup\\toolchains\\stable-x86_64-pc-windows-msvc\\lib\\rustlib\\etc\\libcore.natvis" "/LIBPATH:." "/LIBPATH:C:\\Users\\alex\\.rustup\\toolchains\\stable-x86_64-pc-windows-msvc\\lib\\rustlib\\x86_64-pc-windows-msvc\\lib" "C:\\Users\\alex\\AppData\\Local\\Temp\\rustcAYUABK\\libfoo.rlib" "C:\\Users\\alex\\AppData\\Local\\Temp\\rustcAYUABK\\libstd-b2f27b8d08c4688f.rlib" "C:\\Users\\alex\\AppData\\Local\\Temp\\rustcAYUABK\\libpanic_unwind-9c73c9c2e052b2f1.rlib" "C:\\Users\\alex\\AppData\\Local\\Temp\\rustcAYUABK\\libbacktrace-7a588e8fa018f6bc.rlib" "C:\\Users\\alex\\AppData\\Local\\Temp\\rustcAYUABK\\librustc_demangle-74b71f441b8acffe.rlib" "C:\\Users\\alex\\AppData\\Local\\Temp\\rustcAYUABK\\libhashbrown-42efce06651eab9c.rlib" "C:\\Users\\alex\\AppData\\Local\\Temp\\rustcAYUABK\\librustc_std_workspace_alloc-7518db6030684168.rlib" "C:\\Users\\alex\\AppData\\Local\\Temp\\rustcAYUABK\\libunwind-f7edde5930d50b47.rlib" "C:\\Users\\alex\\AppData\\Local\\Temp\\rustcAYUABK\\libcfg_if-30189c8e78e151e8.rlib" "C:\\Users\\alex\\AppData\\Local\\Temp\\rustcAYUABK\\liblibc-5f5719f1cab83a12.rlib" "C:\\Users\\alex\\AppData\\Local\\Temp\\rustcAYUABK\\liballoc-f297c401e81b90c6.rlib" "C:\\Users\\alex\\AppData\\Local\\Temp\\rustcAYUABK\\librustc_std_workspace_core-f8c80c1aefab6a32.rlib" "C:\\Users\\alex\\AppData\\Local\\Temp\\rustcAYUABK\\libcore-6d66b6e58725d3ed.rlib" "C:\\Users\\alex\\AppData\\Local\\Temp\\rustcAYUABK\\libcompiler_builtins-1f6a73e107798f53.rlib" "advapi32.lib" "ws2_32.lib" "userenv.lib" "msvcrt.lib" "/DLL" "/IMPLIB:bar.dll.lib"
= note: lib.def : error LNK2001: unresolved external symbol _ZN3foo3bar17h95b7da637b923d2cE
bar.dll.lib : fatal error LNK1120: 1 unresolved externals
error: aborting due to previous error
The platform used here to reproduce the error is x86_64-pc-windows-msvc, but it looks like macOS also generates the same error. The error doesn't appear to manifest on Linux, presumably because the linker options just ignore non-defined symbols.
Here you can see that when both crates are compiled with the same optimization level the link succeeds, but with different optimization levels the wrong symbol name is generated, so the wrong symbol is asked to be exported which causes an error.
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