[TTG: Handling Source Locations] Foundation and Pat

Trac Issues #15495

This patch removes the ping-pong style from HsPat (only, for now), using the plan laid out at https://ghc.haskell.org/trac/ghc/wiki/ImplementingTreesThatGrow/HandlingSourceLocations (solution A).
- the class `HasSrcSpan`, and its functions (e.g., `cL` and `dL`), are introduced
- some instances of `HasSrcSpan` are introduced
- some constructors `L` are replaced with `cL`
- some patterns `L` are replaced with `dL->L` view pattern
- some type annotation are necessarily updated (e.g., `Pat p` --> `Pat (GhcPass p)`)

1 files changed, 2 insertions, 0 deletions

diff --git a/haddock-api/src/Haddock/Backends/LaTeX.hs b/haddock-api/src/Haddock/Backends/LaTeX.hs
index 22cb247f..b66116bb 100644
--- a/haddock-api/src/Haddock/Backends/LaTeX.hs
+++ b/haddock-api/src/Haddock/Backends/LaTeX.hs
@@ -1,5 +1,7 @@
 {-# OPTIONS_GHC -fno-warn-name-shadowing #-}
 {-# LANGUAGE RecordWildCards #-}
+{-# LANGUAGE TypeFamilies #-}
+
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Haddock.Backends.LaTeX