From aa708f4b8a2eba0dadc87e82ec74caa862f3661a Mon Sep 17 00:00:00 2001
From: Teo Camarasu <teofil.camarasu@circuithub.com>
Date: Fri, 18 Oct 2024 11:42:45 +0100
Subject: [PATCH] Set NOINLINE pragmas on Generics derived default
 implementations of Rel8able (#346)

This is an easy change that should speed up compilation for end-users without having to make any changes to their code.

See Note [Generics and Inlining]
---
 .../20241018_112157_teofilcamarasu_try_noinline.md   |  5 +++++
 src/Rel8/Generic/Rel8able.hs                         | 12 ++++++++++++
 2 files changed, 17 insertions(+)
 create mode 100644 changelog.d/20241018_112157_teofilcamarasu_try_noinline.md

diff --git a/changelog.d/20241018_112157_teofilcamarasu_try_noinline.md b/changelog.d/20241018_112157_teofilcamarasu_try_noinline.md
new file mode 100644
index 00000000..5a30feaa
--- /dev/null
+++ b/changelog.d/20241018_112157_teofilcamarasu_try_noinline.md
@@ -0,0 +1,5 @@
+### Added
+
+- Add `NOINLINE` pragmas to `Generic` derived default methods of `Rel8able`. This should speed up
+  compilation times. If users wish for these methods to be `INLINE`d, they can override with a
+  pragma in their own code.
diff --git a/src/Rel8/Generic/Rel8able.hs b/src/Rel8/Generic/Rel8able.hs
index 25faaead..365c17cb 100644
--- a/src/Rel8/Generic/Rel8able.hs
+++ b/src/Rel8/Generic/Rel8able.hs
@@ -168,6 +168,7 @@ class HTable (GColumns t) => Rel8able t where
   type GColumns t = G.GColumns TColumns (GRep t Expr)
   type GFromExprs t = t Result
 
+  {-# NOINLINE gfromColumns #-} -- See Note [Generics and Inlining]
   default gfromColumns :: forall context.
     ( SRel8able t Expr
     , forall table. SRel8able t (Field table)
@@ -181,6 +182,7 @@ class HTable (GColumns t) => Rel8able t where
     SName -> sfromColumns
     SResult -> sfromResult
 
+  {-# NOINLINE gtoColumns #-} -- See Note [Generics and Inlining]
   default gtoColumns :: forall context.
     ( SRel8able t Expr
     , forall table. SRel8able t (Field table)
@@ -194,10 +196,12 @@ class HTable (GColumns t) => Rel8able t where
     SName -> stoColumns
     SResult -> stoResult
 
+  {-# NOINLINE gfromResult #-} -- See Note [Generics and Inlining]
   default gfromResult :: (SSerialize t, GFromExprs t ~ t Result)
     => GColumns t Result -> GFromExprs t
   gfromResult = sfromResult
 
+  {-# NOINLINE gtoResult #-} -- See Note [Generics and Inlining]
   default gtoResult :: (SSerialize t, GFromExprs t ~ t Result)
     => GFromExprs t -> GColumns t Result
   gtoResult = stoResult
@@ -274,3 +278,11 @@ stoResult =
     (\(_ :: proxy x) -> serialize @_ @x) .
   from .
   Record
+
+-- Note [Generics and Inlining]
+-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+-- We want to make sure that Generics derived functions (by default)
+-- do not expose their unfoldings. These are always unoptimised code and can
+-- therefore be quite large, and bloat our interfaces.
+-- By marking these as NOINLINE we can considerably speed up our compile times.
+-- If users do want these INLINEd, they can locally override the default using a pragma.