Usage of Template Haskell quotes in GHC source tree vs. usage of GHC as a library

A recent commit 983ce558 starts using TemplateHaskellQuotes in the GHC codebase. It seems this is at odds with using GHC as a library, a la ghc-lib.

The ghc-lib approach is to basically take the module hierarchy from the compiler/ subtree, and compile it as a completely vanilla Haskell library, with no direct attachment to the host GHC version. This enables using e.g. GHC 9.4 to compile a program using the GHC 9.6 API, and so on. In particular, it also makes it very easy to apply patches to the version of GHC used as a library, since in this setup it doesn't need to be able to bootstrap.

So what is the problem with using TemplateHaskellQuotes? The problem is the dependency on the template-haskell package. When a module inside GHC-as-a-library containing TH quotes is compiled, the quotes are translated into applications of the constructors defined by the host GHC's TH package. But because GHC is tightly coupled to the TH support library, GHC-as-a-library needs to ship with its own internal version of the library. So the code that tries to process the results of these quotes is using the target GHC's TH definitions. And that leads to a conflict: code like

leftName :: Namel
leftName = 'Left

is now a type mismatch between the type of 'Left being template-haskell-2.19.0.0:Language.Haskell.TH.Syntax.Name (example when using GHC 9.4.5 as the host) and the type of leftName being ghc-lib-9.9.20230712:Language.Haskell.TH.Syntax.Name (example when the target version is built from recent master).

Currently, ghc-lib-gen has a pre-processing step on the GHC source tree that replaces these quotations with applications containing direct references to the target TH constructors: https://github.com/digital-asset/ghc-lib/blob/ab01fb2b4d1e3a9338390e9c10ccd769bbf37aeb/ghc-lib-gen/src/Ghclibgen.hs#L419-L467 but I am worried that this is very fragile.

So any ideas on how to tackle this situation better?