Avoding linker scripts in MinGW libraries

[mati865]

LLD doesn't and won't support linker scripts in COFF mode. That creates a problem since winapi has following linker scripts:

winapi-x86_64-pc-windows-gnu-0.4.0/lib/libwinapi_mincore.a
winapi-x86_64-pc-windows-gnu-0.4.0/lib/libwinapi_mincore_downlevel.a
winapi-x86_64-pc-windows-gnu-0.4.0/lib/libwinapi_nanosrv.a
winapi-x86_64-pc-windows-gnu-0.4.0/lib/libwinapi_onecore.a
winapi-x86_64-pc-windows-gnu-0.4.0/lib/libwinapi_onecoreuap.a
winapi-x86_64-pc-windows-gnu-0.4.0/lib/libwinapi_onecoreuap_downlevel.a
winapi-x86_64-pc-windows-gnu-0.4.0/lib/libwinapi_onecore_downlevel.a
winapi-x86_64-pc-windows-gnu-0.4.0/lib/libwinapi_runtimeobject.a
winapi-x86_64-pc-windows-gnu-0.4.0/lib/libwinapi_shcore.a
winapi-x86_64-pc-windows-gnu-0.4.0/lib/libwinapi_vfw32.a
winapi-x86_64-pc-windows-gnu-0.4.0/lib/libwinapi_windowsapp.a
winapi-x86_64-pc-windows-gnu-0.4.0/lib/libwinapi_windowsapp_downlevel.a

Maybe the they could be consolidated into single objects (just like mingw-w64 does) or replaced with response files?

For now I've set WINAPI_NO_BUNDLED_LIBRARIES=1.

[retep998]

Feel free to improve how they are generated. https://github.com/retep998/windump-rs/blob/master/src/bin/exports.rs

Ideally I'd like raw-dylib to be implemented so I don't need these import libraries.

[mati865]

We actually don't need these import libs any more when not using self-contained mode. Maybe Rust should somehow tell if it's using native or self-contained mode so crates like winapi can avoid hacks like this one?

[retep998]

If there is some way to detect whether Rust is not using self-contained mode, then sure I could have winapi automatically disable the bundled import libraries. raw-dylib is still better though.

[mati865]

Raw-dylib is great but latest PR seems stuck: rust-lang/rust#71497

cc @petrochenkov Do you think Rust could somehow notify crates it is using native linkage mode so winapi could avoid forcing bundled libraries?

[petrochenkov]

@mati865

Do you think Rust could somehow notify crates it is using native linkage mode so winapi could avoid forcing bundled libraries?

This seems more complex than setting WINAPI_NO_BUNDLED_LIBRARIES.

winapi needs to decide whether self-contained mode is enabled or not in a build script, right?
If -C link-self-contained is used then it will supposedly be set through RUSTFLAGS or .cargo/config, does cargo provide build scripts access to this configuration somehow?
I'm not even sure cargo applies RUSTFLAGS to build scripts, so even if we set a cfg predicate in rustc when -C link-self-contained is passed, then the build script may not see it.

[mati865]

Cargo docs don't mention RUSTFLAGS but RUSTC_LINKER seems available. Soon using linker from outside sysroot will be the same as native link mode. I'll experiment with that.

[mati865]

RUSTC_LINKER is set only when manually configured in ~/.cargo/config. So avoiding bundled libs will probably have to wait until raw-dylib becomes a thing.
retep998/windump-rs#1 fixes the original issue reported here so avoiding bundled libs can wait.