Response files created by "swift-frontend.exe" on Windows include "/LIB" which causes linking failures

[sienkewits]

Description

On Windows, when compiling/linking many files, the swiftc compiler ends up putting the command line parameters for the link step into a temporary response file. The first linker parameter in the response file is "/LIB", which (according to the linker) is supposed to be the first parameter of the linker command. However, because "/LIB" is in the response file, it is not interpreted properly by the linker as the first parameter, and the link step fails. If "/LIB" is taken out of the response file, and put onto the linker command line, then the link step works as expected.

Reproduction

A reproducible testcase can be found at:
https://github.com/sienkewits/swiftc-link-issue

Expected behavior

The provided testcase should compile and link successfully.

Environment

This issue has been reproduced with swiftc version 5.8.1 and 5.10.1 on Windows.

Additional information

No response

[cgweeder]

Greetings -

I have seen this incorrect behavior as well, on Windows. Hopefully someone from the Swift team can take a look at this ticket and triage.

Regards,
C

[compnerd]

What version of swift are you using? This shouldn't be happening on the development snapshots at the very least if it didn't already make it into 6.0.