Monitor also ghc.shim file on Windows

Author: jasagredo

cabal-install/src/Distribution/Client/ProjectPlanning.hs

@@ -989,6 +989,9 @@ programsMonitorFiles progdb =
       monitorFileSearchPath
         (programMonitorFiles prog)
         (programPath prog)
+        ++ if programId prog == "ghc" && buildOS == Windows
+          then [monitorFile $ programPath prog -<.> "shim"]
+          else []
   ]
 
 -- | Select the bits of a 'ProgramDb' to monitor for value changes.

changelog.d/pr-10853

@@ -0,0 +1,13 @@
+synopsis: Monitor `ghc.shim` on Windows
+packages: cabal-install
+prs: #10853
+issues: #10850
+
+description: {
+
+- On Linux it is the `ghc` executable that changes when changing compiler
+  version in GHCup (the symlink points to a new location) but on Windows it is
+  the companion `ghc.shim` file that changes. This file is now also monitored
+  for changes to trigger rebuilds.
+
+}