From bafc9fc8ea159e9c0aee95662dde73a035724e64 Mon Sep 17 00:00:00 2001
From: fendor <fendor@posteo.de>
Date: Wed, 26 Nov 2025 09:51:19 +0100
Subject: [PATCH] Disable the hlint plugin for GHC 9.10, for good

---
 docs/support/plugin-support.md                 |  4 +++-
 haskell-language-server.cabal                  | 16 ++++++++++++----
 .../schema/ghc910/default-config.golden.json   |  7 -------
 .../schema/ghc910/markdown-reference.md        |  5 -----
 .../ghc910/vscode-extension-schema.golden.json | 18 ------------------
 5 files changed, 15 insertions(+), 35 deletions(-)

diff --git a/docs/support/plugin-support.md b/docs/support/plugin-support.md
index 724ca99da0..e69c783267 100644
--- a/docs/support/plugin-support.md
+++ b/docs/support/plugin-support.md
@@ -56,7 +56,7 @@ For example, a plugin to provide a formatter which has itself been abandoned has
 | `hls-explicit-record-fields-plugin`  | 2    |                          |
 | `hls-fourmolu-plugin`                | 2    |                          |
 | `hls-gadt-plugin`                    | 2    |                          |
-| `hls-hlint-plugin`                   | 2    |                          |
+| `hls-hlint-plugin`                   | 2    | 9.10 [1]                 |
 | `hls-module-name-plugin`             | 2    |                          |
 | `hls-notes-plugin`                   | 2    |                          |
 | `hls-qualify-imported-names-plugin`  | 2    |                          |
@@ -69,3 +69,5 @@ For example, a plugin to provide a formatter which has itself been abandoned has
 | `hls-stan-plugin`                    | 3    | 9.12.2                   |
 | `hls-retrie-plugin`                  | 3    | 9.10.1, 9.12.2           |
 | `hls-splice-plugin`                  | 3    | 9.10.1, 9.12.2           |
+
+[1]: HLint is incompatible with GHC 9.10 series. See the issue [#4674](https://github.com/haskell/haskell-language-server/issues/4674) for discussion and explanation.
diff --git a/haskell-language-server.cabal b/haskell-language-server.cabal
index c24b1869ba..23260a5393 100644
--- a/haskell-language-server.cabal
+++ b/haskell-language-server.cabal
@@ -709,14 +709,19 @@ flag hlint
   manual:      True
 
 common hlint
-  if flag(hlint)
+  -- Hlint isn't compatible with GHC 9.10, and crashes in subtle ways.
+  -- See https://github.com/haskell/haskell-language-server/issues/4674
+  -- for its wake of destruction.
+  if flag(hlint) && !impl(ghc ==9.10.*)
     build-depends: haskell-language-server:hls-hlint-plugin
     cpp-options: -Dhls_hlint
 
 library hls-hlint-plugin
   import:           defaults, pedantic, warnings
-  -- https://github.com/ndmitchell/hlint/pull/1594
-  if !flag(hlint)
+  -- Hlint isn't compatible with GHC 9.10, and crashes in subtle ways.
+  -- See https://github.com/haskell/haskell-language-server/issues/4674
+  -- for its wake of destruction.
+  if !flag(hlint) || impl(ghc ==9.10.*)
     buildable: False
   exposed-modules:  Ide.Plugin.Hlint
   hs-source-dirs:   plugins/hls-hlint-plugin/src
@@ -763,7 +768,10 @@ library hls-hlint-plugin
 
 test-suite hls-hlint-plugin-tests
   import:           defaults, pedantic, test-defaults, warnings
-  if !flag(hlint)
+  -- Hlint isn't compatible with GHC 9.10, and crashes in subtle ways.
+  -- See https://github.com/haskell/haskell-language-server/issues/4674
+  -- for its wake of destruction.
+  if !flag(hlint) || impl(ghc ==9.10.*)
     buildable: False
   type:             exitcode-stdio-1.0
   hs-source-dirs:   plugins/hls-hlint-plugin/test
diff --git a/test/testdata/schema/ghc910/default-config.golden.json b/test/testdata/schema/ghc910/default-config.golden.json
index 81b63dc6e4..efc5309a4d 100644
--- a/test/testdata/schema/ghc910/default-config.golden.json
+++ b/test/testdata/schema/ghc910/default-config.golden.json
@@ -91,13 +91,6 @@
             },
             "globalOn": true
         },
-        "hlint": {
-            "codeActionsOn": true,
-            "config": {
-                "flags": []
-            },
-            "diagnosticsOn": true
-        },
         "importLens": {
             "codeActionsOn": true,
             "codeLensOn": true,
diff --git a/test/testdata/schema/ghc910/markdown-reference.md b/test/testdata/schema/ghc910/markdown-reference.md
index 668323ce66..af81ddaf3b 100644
--- a/test/testdata/schema/ghc910/markdown-reference.md
+++ b/test/testdata/schema/ghc910/markdown-reference.md
@@ -1,8 +1,3 @@
-## hlint
-| Property | Description | Default | Allowed values |
-| --- | --- | --- | --- |
-| `flags` | Flags used by hlint | `TODO: Array values` |  &nbsp;  |
-
 ## cabal-fmt
 | Property | Description | Default | Allowed values |
 | --- | --- | --- | --- |
diff --git a/test/testdata/schema/ghc910/vscode-extension-schema.golden.json b/test/testdata/schema/ghc910/vscode-extension-schema.golden.json
index ba79ee22c7..a78cb9e147 100644
--- a/test/testdata/schema/ghc910/vscode-extension-schema.golden.json
+++ b/test/testdata/schema/ghc910/vscode-extension-schema.golden.json
@@ -213,24 +213,6 @@
         "scope": "resource",
         "type": "boolean"
     },
-    "haskell.plugin.hlint.codeActionsOn": {
-        "default": true,
-        "description": "Enables hlint code actions",
-        "scope": "resource",
-        "type": "boolean"
-    },
-    "haskell.plugin.hlint.config.flags": {
-        "default": [],
-        "markdownDescription": "Flags used by hlint",
-        "scope": "resource",
-        "type": "array"
-    },
-    "haskell.plugin.hlint.diagnosticsOn": {
-        "default": true,
-        "description": "Enables hlint diagnostics",
-        "scope": "resource",
-        "type": "boolean"
-    },
     "haskell.plugin.importLens.codeActionsOn": {
         "default": true,
         "description": "Enables importLens code actions",