Stop using dlltool for generating import libraries on MinGW

[bjorn3]

Proposal

Older versions of ld.bfd didn't properly support short import libraries as archive members like the builtin implementation of rustc generates. So we worked around this by using binutils dlltool, which produces the old import library format. We have now bumped the minimum supported ld.bfd version to one which properly handles them, so we can drop the dlltool usage. This makes cross-compilation a bit easier and removes a bunch of code in rustc.

So far, rustc used to pick whatever dlltool it could find in PATH, and fail if couldn't find it. The related argument -Cdlltool allows explicit choice of the dlltool binary.
For now -Cdlltool will still be respected if passed, but if not passed, no implicit dlltool will be used anymore.

This has been implemented in rust-lang/rust#161050.

Mentors or Reviewers

@mati865

Process

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Note

Concerns (0 active)

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[rustbot]

Important

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cc @rust-lang/compiler

[mati865]

@rustbot second

[RalfJung]

@rustbot concern flag
Apparently there's also a -C flag affected by this change. The MCP should be amended to explain which flag is affected how and why.

[mati865]

@rustbot resolve flag

The MCP was updated to address the concerns.

[rustbot]

The final comment period is now complete, this major change is now accepted. 🎉

As the automated representative, I want to express gratitude to the author for their work and everyone else who contributed to this major change proposal.

If you think this major change shouldn't have been accepted, feel free to remove the major-change-accepted label and reopen this issue.

Note

Further progress is now tracked over at rust-lang/rust#161671.