Class layout info (#19623)

Updates the haddock submodule.

6 files changed, 70 insertions, 28 deletions

diff --git a/compiler/Language/Haskell/Syntax/Concrete.hs b/compiler/Language/Haskell/Syntax/Concrete.hs
new file mode 100644
index 0000000000..982eac3216
--- /dev/null
+++ b/compiler/Language/Haskell/Syntax/Concrete.hs
@@ -0,0 +1,63 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE KindSignatures #-}
+{-# LANGUAGE StandaloneDeriving #-}
+{-# LANGUAGE DeriveDataTypeable #-}
+
+-- | Bits of concrete syntax (tokens, layout).
+
+module Language.Haskell.Syntax.Concrete
+  ( LHsToken, LHsUniToken,
+    HsToken(HsTok),
+    HsUniToken(HsNormalTok, HsUnicodeTok),
+    LayoutInfo(ExplicitBraces, VirtualBraces, NoLayoutInfo)
+  ) where
+
+import GHC.Prelude
+import GHC.TypeLits (Symbol, KnownSymbol)
+import Data.Data
+import Language.Haskell.Syntax.Extension
+
+type LHsToken tok p = XRec p (HsToken tok)
+type LHsUniToken tok utok p = XRec p (HsUniToken tok utok)
+
+-- | A token stored in the syntax tree. For example, when parsing a
+-- let-expression, we store @HsToken "let"@ and @HsToken "in"@.
+-- The locations of those tokens can be used to faithfully reproduce
+-- (exactprint) the original program text.
+data HsToken (tok :: Symbol) = HsTok
+
+-- | With @UnicodeSyntax@, there might be multiple ways to write the same
+-- token. For example an arrow could be either @->@ or @→@. This choice must be
+-- recorded in order to exactprint such tokens, so instead of @HsToken "->"@ we
+-- introduce @HsUniToken "->" "→"@.
+--
+-- See also @IsUnicodeSyntax@ in @GHC.Parser.Annotation@; we do not use here to
+-- avoid a dependency.
+data HsUniToken (tok :: Symbol) (utok :: Symbol) = HsNormalTok | HsUnicodeTok
+
+deriving instance KnownSymbol tok => Data (HsToken tok)
+deriving instance (KnownSymbol tok, KnownSymbol utok) => Data (HsUniToken tok utok)
+
+-- | Layout information for declarations.
+data LayoutInfo pass =
+
+    -- | Explicit braces written by the user.
+    --
+    -- @
+    -- class C a where { foo :: a; bar :: a }
+    -- @
+    ExplicitBraces !(LHsToken "{" pass) !(LHsToken "}" pass)
+  |
+    -- | Virtual braces inserted by the layout algorithm.
+    --
+    -- @
+    -- class C a where
+    --   foo :: a
+    --   bar :: a
+    -- @
+    VirtualBraces
+      !Int -- ^ Layout column (indentation level, begins at 1)
+  |
+    -- | Empty or compiler-generated blocks do not have layout information
+    -- associated with them.
+    NoLayoutInfo
diff --git a/compiler/Language/Haskell/Syntax/Decls.hs b/compiler/Language/Haskell/Syntax/Decls.hs
index af8c0bb1e9..012304edf4 100644
--- a/compiler/Language/Haskell/Syntax/Decls.hs
+++ b/compiler/Language/Haskell/Syntax/Decls.hs
@@ -97,8 +97,9 @@ import {-# SOURCE #-} Language.Haskell.Syntax.Expr
         -- Because Expr imports Decls via HsBracket
 
 import Language.Haskell.Syntax.Binds
-import Language.Haskell.Syntax.Type
+import Language.Haskell.Syntax.Concrete
 import Language.Haskell.Syntax.Extension
+import Language.Haskell.Syntax.Type
 import Language.Haskell.Syntax.Basic (Role)
 
 import GHC.Types.Basic (TopLevelFlag, OverlapMode, RuleName, Activation)
@@ -457,6 +458,8 @@ data TyClDecl pass
     --                          'GHC.Parser.Annotation.AnnRarrow'
     -- For details on above see Note [exact print annotations] in GHC.Parser.Annotation
   | ClassDecl { tcdCExt    :: XClassDecl pass,         -- ^ Post renamer, FVs
+                tcdLayout  :: !(LayoutInfo pass),      -- ^ Explicit or virtual braces
+                              -- See Note [Class LayoutInfo]
                 tcdCtxt    :: Maybe (LHsContext pass), -- ^ Context...
                 tcdLName   :: LIdP pass,               -- ^ Name of the class
                 tcdTyVars  :: LHsQTyVars pass,         -- ^ Class type variables
diff --git a/compiler/Language/Haskell/Syntax/Expr.hs b/compiler/Language/Haskell/Syntax/Expr.hs
index cc1504a9ea..5a22e35c74 100644
--- a/compiler/Language/Haskell/Syntax/Expr.hs
+++ b/compiler/Language/Haskell/Syntax/Expr.hs
@@ -26,6 +26,7 @@ import Language.Haskell.Syntax.Basic
 import Language.Haskell.Syntax.Decls
 import Language.Haskell.Syntax.Pat
 import Language.Haskell.Syntax.Lit
+import Language.Haskell.Syntax.Concrete
 import Language.Haskell.Syntax.Extension
 import Language.Haskell.Syntax.Type
 import Language.Haskell.Syntax.Binds
diff --git a/compiler/Language/Haskell/Syntax/Extension.hs b/compiler/Language/Haskell/Syntax/Extension.hs
index 4bdb3ce3cb..9ad16c0cd7 100644
--- a/compiler/Language/Haskell/Syntax/Extension.hs
+++ b/compiler/Language/Haskell/Syntax/Extension.hs
@@ -5,7 +5,6 @@
 {-# LANGUAGE DeriveDataTypeable      #-}
 {-# LANGUAGE EmptyCase               #-}
 {-# LANGUAGE EmptyDataDeriving       #-}
-{-# LANGUAGE StandaloneDeriving      #-}
 {-# LANGUAGE FlexibleContexts        #-}
 {-# LANGUAGE FlexibleInstances       #-}
 {-# LANGUAGE GADTs                   #-}
@@ -22,8 +21,6 @@ module Language.Haskell.Syntax.Extension where
 -- This module captures the type families to precisely identify the extension
 -- points for GHC.Hs syntax
 
-import GHC.TypeLits (Symbol, KnownSymbol)
-
 #if MIN_VERSION_GLASGOW_HASKELL(9,3,0,0)
 import Data.Type.Equality (type (~))
 #endif
@@ -731,27 +728,3 @@ type family NoGhcTc (p :: Type)
 -- =====================================================================
 -- End of Type family definitions
 -- =====================================================================
-
-
-
--- =====================================================================
--- Token information
-
-type LHsToken tok p = XRec p (HsToken tok)
-
-data HsToken (tok :: Symbol) = HsTok
-
-deriving instance KnownSymbol tok => Data (HsToken tok)
-
-type LHsUniToken tok utok p = XRec p (HsUniToken tok utok)
-
--- With UnicodeSyntax, there might be multiple ways to write the same token.
--- For example an arrow could be either "->" or "→". This choice must be
--- recorded in order to exactprint such tokens,
--- so instead of HsToken "->" we introduce HsUniToken "->" "→".
---
--- See also IsUnicodeSyntax in GHC.Parser.Annotation; we do not use here to
--- avoid a dependency.
-data HsUniToken (tok :: Symbol) (utok :: Symbol) = HsNormalTok | HsUnicodeTok
-
-deriving instance (KnownSymbol tok, KnownSymbol utok) => Data (HsUniToken tok utok)
diff --git a/compiler/Language/Haskell/Syntax/Pat.hs b/compiler/Language/Haskell/Syntax/Pat.hs
index 95abde9ce0..66b9708bfe 100644
--- a/compiler/Language/Haskell/Syntax/Pat.hs
+++ b/compiler/Language/Haskell/Syntax/Pat.hs
@@ -36,6 +36,7 @@ import {-# SOURCE #-} Language.Haskell.Syntax.Expr (SyntaxExpr, LHsExpr, HsUntyp
 -- friends:
 import Language.Haskell.Syntax.Basic
 import Language.Haskell.Syntax.Lit
+import Language.Haskell.Syntax.Concrete
 import Language.Haskell.Syntax.Extension
 import Language.Haskell.Syntax.Type
 
diff --git a/compiler/Language/Haskell/Syntax/Type.hs b/compiler/Language/Haskell/Syntax/Type.hs
index 4cb8b6ee0f..24e2ceeecc 100644
--- a/compiler/Language/Haskell/Syntax/Type.hs
+++ b/compiler/Language/Haskell/Syntax/Type.hs
@@ -57,6 +57,7 @@ module Language.Haskell.Syntax.Type (
 
 import {-# SOURCE #-} Language.Haskell.Syntax.Expr ( HsUntypedSplice )
 
+import Language.Haskell.Syntax.Concrete
 import Language.Haskell.Syntax.Extension
 
 import GHC.Types.Name.Reader ( RdrName )