From 8a8f67816c3f8423be566b7885745f3b45b43505 Mon Sep 17 00:00:00 2001
From: Simon Hengel <sol@typeful.net>
Date: Sat, 25 Jan 2025 20:24:01 +0700
Subject: [PATCH] Add tests for more GHC errors

---
 src/GHC/Diagnostic.hs                          | 14 ++++++++++----
 test/GHC/DiagnosticSpec.hs                     |  1 +
 test/assets/use-BlockArguments/Foo.hs          |  2 +-
 test/assets/use-TemplateHaskellQuotes/Foo.hs   |  2 ++
 test/assets/use-TemplateHaskellQuotes/err.json |  1 +
 test/assets/use-TemplateHaskellQuotes/err.out  |  6 ++++++
 6 files changed, 21 insertions(+), 5 deletions(-)
 create mode 100644 test/assets/use-TemplateHaskellQuotes/Foo.hs
 create mode 100644 test/assets/use-TemplateHaskellQuotes/err.json
 create mode 100644 test/assets/use-TemplateHaskellQuotes/err.out

diff --git a/src/GHC/Diagnostic.hs b/src/GHC/Diagnostic.hs
index 5caebf6c..af91e190 100644
--- a/src/GHC/Diagnostic.hs
+++ b/src/GHC/Diagnostic.hs
@@ -92,9 +92,15 @@ format diagnostic = encodeUtf8 . render $ unlines [
     unlines = foldr ($+$) empty
 
 removeGhciSpecificHints :: Diagnostic -> Diagnostic
-removeGhciSpecificHints diagnostic = diagnostic { hints = map f diagnostic.hints }
+removeGhciSpecificHints diagnostic = diagnostic { hints = map processHint diagnostic.hints }
   where
-    f :: String -> String
-    f input = case lines input of
-      [hint, "You may enable this language extension in GHCi with:", ghciHint] | "  :set -X" `isPrefixOf` ghciHint -> hint
+    isSetLanguageExtension :: String -> Bool
+    isSetLanguageExtension = isPrefixOf "  :set -X"
+
+    processHint :: String -> String
+    processHint input = case lines input of
+      [hint, "You may enable this language extension in GHCi with:", ghciHint]
+        | isSetLanguageExtension ghciHint -> hint
+      hint : "You may enable these language extensions in GHCi with:" : ghciHints
+        | all isSetLanguageExtension ghciHints -> hint
       _ -> input
diff --git a/test/GHC/DiagnosticSpec.hs b/test/GHC/DiagnosticSpec.hs
index 68813449..2e160966 100644
--- a/test/GHC/DiagnosticSpec.hs
+++ b/test/GHC/DiagnosticSpec.hs
@@ -50,6 +50,7 @@ spec = do
     test "variable-not-in-scope"
     test "variable-not-in-scope-perhaps-use"
     test "use-BlockArguments"
+    test "use-TemplateHaskellQuotes"
     test "non-existing"
     test "parse-error"
     test "lex-error"
diff --git a/test/assets/use-BlockArguments/Foo.hs b/test/assets/use-BlockArguments/Foo.hs
index de194c98..b8c2caa4 100644
--- a/test/assets/use-BlockArguments/Foo.hs
+++ b/test/assets/use-BlockArguments/Foo.hs
@@ -1,5 +1,5 @@
 {-# LANGUAGE NoBlockArguments #-}
-module BlockArguments.Foo where
+module Foo where
 
 foo :: IO ()
 foo = id do return ()
diff --git a/test/assets/use-TemplateHaskellQuotes/Foo.hs b/test/assets/use-TemplateHaskellQuotes/Foo.hs
new file mode 100644
index 00000000..03b2235b
--- /dev/null
+++ b/test/assets/use-TemplateHaskellQuotes/Foo.hs
@@ -0,0 +1,2 @@
+module Foo where
+foo = [|23|]
diff --git a/test/assets/use-TemplateHaskellQuotes/err.json b/test/assets/use-TemplateHaskellQuotes/err.json
new file mode 100644
index 00000000..ef59c116
--- /dev/null
+++ b/test/assets/use-TemplateHaskellQuotes/err.json
@@ -0,0 +1 @@
+{"version":"1.0","ghcVersion":"ghc-9.10.1","span":{"file":"test/assets/use-TemplateHaskellQuotes/Foo.hs","start":{"line":2,"column":7},"end":{"line":2,"column":13}},"severity":"Error","code":62558,"message":["Syntax error on [| 23 |]","In the Template Haskell quotation [| 23 |]"],"hints":["Enable any of the following extensions: TemplateHaskell, TemplateHaskellQuotes\nYou may enable these language extensions in GHCi with:\n  :set -XTemplateHaskell\n  :set -XTemplateHaskellQuotes"]}
diff --git a/test/assets/use-TemplateHaskellQuotes/err.out b/test/assets/use-TemplateHaskellQuotes/err.out
new file mode 100644
index 00000000..a794148d
--- /dev/null
+++ b/test/assets/use-TemplateHaskellQuotes/err.out
@@ -0,0 +1,6 @@
+test/assets/use-TemplateHaskellQuotes/Foo.hs:2:7: error: [GHC-62558]
+    • Syntax error on [| 23 |]
+    • In the Template Haskell quotation [| 23 |]
+    Suggested fix:
+      Enable any of the following extensions: TemplateHaskell, TemplateHaskellQuotes
+