tests: Ghc9 shows TH-errors after the dollar sign

Instead of including it like older versions did

$(foo)
  ~~~~
  some TH error/warning

Author: anka-213

ghcide/test/exe/Main.hs

@@ -3660,7 +3660,7 @@ thReloadingTest unboxed = testCase name $ runWithExtraFiles dir $ \dir -> do
     bdoc <- createDoc bPath "haskell" bSource
     cdoc <- createDoc cPath "haskell" cSource
 
-    expectDiagnostics [("THB.hs", [(DsWarning, (4,0), "Top-level binding")])]
+    expectDiagnostics [("THB.hs", [(DsWarning, (4,thDollarIdx), "Top-level binding")])]
 
     -- Change th from () to Bool
     let aSource' = T.unlines $ init (T.lines aSource) ++ ["th_a = [d| a = False|]"]
@@ -3672,7 +3672,7 @@ thReloadingTest unboxed = testCase name $ runWithExtraFiles dir $ \dir -> do
     expectDiagnostics
         [("THC.hs", [(DsError, (4, 4), "Couldn't match expected type '()' with actual type 'Bool'")])
         ,("THC.hs", [(DsWarning, (6,0), "Top-level binding")])
-        ,("THB.hs", [(DsWarning, (4,0), "Top-level binding")])
+        ,("THB.hs", [(DsWarning, (4,thDollarIdx), "Top-level bindin")])
         ]
 
     closeDoc adoc
@@ -3695,7 +3695,7 @@ thLinkingTest unboxed = testCase name $ runWithExtraFiles dir $ \dir -> do
     adoc <- createDoc aPath "haskell" aSource
     bdoc <- createDoc bPath "haskell" bSource
 
-    expectDiagnostics [("THB.hs", [(DsWarning, (4,0), "Top-level binding")])]
+    expectDiagnostics [("THB.hs", [(DsWarning, (4,thDollarIdx), "Top-level binding")])]
 
     let aSource' = T.unlines $ init (init (T.lines aSource)) ++ ["th :: DecsQ", "th = [d| a = False|]"]
     changeDoc adoc [TextDocumentContentChangeEvent Nothing Nothing aSource']
@@ -3704,7 +3704,7 @@ thLinkingTest unboxed = testCase name $ runWithExtraFiles dir $ \dir -> do
     let bSource' = T.unlines $ init (T.lines bSource) ++ ["$th"]
     changeDoc bdoc [TextDocumentContentChangeEvent Nothing Nothing bSource']
 
-    expectDiagnostics [("THB.hs", [(DsWarning, (4,0), "Top-level binding")])]
+    expectDiagnostics [("THB.hs", [(DsWarning, (4,thDollarIdx), "Top-level binding")])]
 
     closeDoc adoc
     closeDoc bdoc
@@ -4698,7 +4698,7 @@ ifaceTHTest = testCase "iface-th-test" $ runWithExtraFiles "TH" $ \dir -> do
     changeDoc cdoc [TextDocumentContentChangeEvent Nothing Nothing cSource]
     expectDiagnostics
       [("THC.hs", [(DsError, (4, 4), "Couldn't match expected type '()' with actual type 'Bool'")])
-      ,("THB.hs", [(DsWarning, (4,0), "Top-level binding")])]
+      ,("THB.hs", [(DsWarning, (4,thDollarIdx), "Top-level binding")])]
     closeDoc cdoc
 
 ifaceErrorTest :: TestTree
@@ -5515,3 +5515,11 @@ listOfChar = "String"
 #else
 listOfChar = "[Char]"
 #endif
+
+-- | Ghc 9 doesn't include the $-sign in TH warnings like earlier versions did
+thDollarIdx :: Int
+#if MIN_GHC_API_VERSION(9,0,1)
+thDollarIdx = 1
+#else
+thDollarIdx = 0
+#endif