[GHC] #12206: No exposed API to get full text of ErrMsg
GHC
ghc-devs at haskell.org
Sun Jun 19 04:28:50 UTC 2016
#12206: No exposed API to get full text of ErrMsg
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Reporter: bit | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: GHC API | Version: 8.0.1
Keywords: | Operating System: Unknown/Multiple
Architecture: | Type of failure: None/Unknown
Unknown/Multiple |
Test Case: | Blocked By:
Blocking: | Related Tickets:
Differential Rev(s): | Wiki Page:
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In GHC version 7.10.3 it was possible to get the full text of an error
message by using the functions `ErrUtils.errMsgShortDoc` and
`ErrUtils.errMsgExtraInfo`.
But in GHC version 8.0.1 the code has changed. The full text of the error
message is stored in the `ErrMsg` field `ErrUtils.errMsgDoc`, but this
field is hidden, and there doesn't seem to be any API to access its
contents.
The only workaround I can find is to use `ErrUtils.pprLocErrMsg`, and then
strip out the first line containing the location info, and then manually
unindent the 4-space "hang". This is quite ugly.
I suggest exporting `ErrUtils.errMsgDoc`, and then for that to be useful
the fields of `ErrUtils.ErrDoc` will also be needed. Additionally,
`ErrUtils.formatErrDoc` could be a nice bonus to have (and if exported
would lessen the need for the `ErrDoc` fields).
The GHC API changes on every GHC release, so since backwards compatibility
is not an issue, it would seem that there is no need to have a carefully
exposed API, and there is no danger in liberally exporting stuff that
clients could potentially find useful.
Thank you
--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12206>
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