Windows/VS Code/Stack/HLS 2.12.0.0, regression from HLS 2.11.0.0? #4752
Description
On Windows 11/VS Code/Stack, I am experiencing regression with a small 'toy' single-package project if I switch GHC 9.10.2 (LTS 24.11)/HLS 2.11.0.0 with GHC 9.10.3 (LTS 24.18)/HLS 2.12.0.0 (both HLS are GHCup-supplied).
Evaluate... does not trigger an evaluation.
The last lines of the 'OUTPUT' pane are:
Hidden: no
Range: 1:1-2:1
Source: compiler
Severity: DiagnosticSeverity_Error
Code: <none>
Message:
�[0;91m(NeedsCompilation,NormalizedFilePath
"D:\\Users\\mike\\Code\\Haskell\\lambertW\\.stack-work\\dist\\1a191874\\build\\lambertW-exe\\autogen\\Paths_lambertW.hs")user
error (Failed to get the immediate reverse dependencies of NormalizedFilePath
"D:\\Users\\mike\\Code\\Haskell\\lambertW\\.stack-work\\dist\\1a191874\\build\\lambertW-exe\\autogen\\Paths_lambertW.hs")�[0m
2025-11-02T18:24:51.669918Z | Info | Live bytes: 26.04MB Heap size: 599.79MB
haskell-language-server-9.10.3~2.12.0.0.exe: internal error: ARR_WORDS object (00007ff404efb060) entered!
(GHC version 9.10.3 for x86_64_unknown_mingw32)
Please report this as a GHC bug: https://www.haskell.org/ghc/reportabug
haskell-language-server-wrapper-2.12.0.0.exe: callProcess: C:\ghcup\bin\haskell-language-server-9.10.3.exe "--lsp" (exit -1073740791): failed
[Error - 6:25:07 PM] The Haskell (lambertW) server crashed 5 times in the last 3 minutes. The server will not be restarted. See the output for more information.
[Error - 6:25:07 PM] Server process exited with code 1.
EDIT: A GitHub repository with my 'toy' project is here:
I am trying to add:
-- >>> lambertW0 1.0
to the Haddock comment for lambertW0. That works with GHC 9.10.2/HLS 2.11.0.0 but fails with GHC 9.10.3/HLS 2.12.0.0.
(The library builds fine with GHC 9.10.2 and GHC 9.10.3 and lambertW0 1.0 evaluates fine in stack ghci.)