Cabal: Disable GHCi libraries on Windows with GHC >=9.4 #8062
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As noted in GHC #21068, the lld linker used on Windows by GHC 9.4 and later does not support object merging. Consequently, --enable-library-for-ghci can no longer be supported on this platform.
bgamari
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This flag is needed for efficiency, but everything should still work, somehow. There seems to be no replacement for this speedup on Windows. |
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We have concluded that we should disable this flag by default on Windows. |
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By the way, this is the breakage that we previously encountered last time we tried to disable GHCi libraries: #1968 |
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Let's remember to close #1968 before we merge this, rather than after. |
As of 9.4, GHC on Windows may produce .o files that are in fact archive files due to the lack of object merging support in the lld linker (see GHC #21068). Consequently, we must ensure that `ar` merges input archives' members, not add them as a single entry.
well maybe we could let it open, as disabling libraries for ghci in other os's would trigger the bug, but given the package is barely buildable with windows nowadays, i would merge it anyways |
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Looks good to me, it would need a changelog entry mentioning the windows change but also the arDashLSupported addition which does not seem rdirectly related with and affects all os's
No additional test needed for the windows change imo, no sure about the other one
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Whoops, it looks like GitHub closed the MR as a result of my renaming the branch. I'll open a new MR addressing @jneira's comments shortly. |
As noted in GHC #21068, the lld linker used on Windows by GHC 9.4 and later does not support object merging. Consequently,
--enable-library-for-ghcican no longer be supported on this platform.Please include the following checklist in your PR:
Please also shortly describe how you tested your change. Bonus points for added tests!