Replace (ptext .. sLit) with `text`

1. `text` is as efficient as `ptext . sLit` thanks to the rewrite rules

2. `text` is visually nicer than `ptext . sLit`

3. `ptext . sLit` encourages using one `ptext` for several `sLit` as in:

    ptext $ case xy of
      ... -> sLit ...
      ... -> sLit ...

  which may allocate SDoc's TextBeside constructors at runtime instead
  of sharing them into CAFs.

1 files changed, 6 insertions, 9 deletions

diff --git a/compiler/GHC/Data/FastString.hs b/compiler/GHC/Data/FastString.hs
index 9ba933f336..590f043d4b 100644
--- a/compiler/GHC/Data/FastString.hs
+++ b/compiler/GHC/Data/FastString.hs
@@ -31,7 +31,8 @@
 --   * Pointer and size of a Latin-1 encoded string.
 --   * Practically no operations.
 --   * Outputting them is fast.
---   * Generated by 'sLit'.
+--   * Generated by 'mkPtrString'.
+--   * Length of string literals (mkPtrString "abc") is computed statically
 --   * Turn into 'GHC.Utils.Outputable.SDoc' with 'GHC.Utils.Outputable.ptext'
 --   * Requires manual memory management.
 --     Improper use may lead to memory leaks or dangling pointers.
@@ -101,7 +102,6 @@ module GHC.Data.FastString
         PtrString (..),
 
         -- ** Construction
-        sLit,
         mkPtrString#,
         mkPtrString,
 
@@ -675,7 +675,7 @@ mkPtrString# a# = PtrString (Ptr a#) (ptrStrLength (Ptr a#))
 -- | Encode a 'String' into a newly allocated 'PtrString' using Latin-1
 -- encoding.  The original string must not contain non-Latin-1 characters
 -- (above codepoint @0xff@).
-{-# INLINE mkPtrString #-}
+{-# NOINLINE[0] mkPtrString #-} -- see rules below
 mkPtrString :: String -> PtrString
 mkPtrString s =
  -- we don't use `unsafeDupablePerformIO` here to avoid potential memory leaks
@@ -693,6 +693,9 @@ mkPtrString s =
    return (PtrString p len)
  )
 
+{-# RULES "mkPtrString"
+    forall x . mkPtrString (unpackCString# x) = mkPtrString#  x #-}
+
 -- | Decode a 'PtrString' back into a 'String' using Latin-1 encoding.
 -- This does not free the memory associated with 'PtrString'.
 unpackPtrString :: PtrString -> String
@@ -714,15 +717,9 @@ ptrStrLength :: Ptr Word8 -> Int
 {-# INLINE ptrStrLength #-}
 ptrStrLength (Ptr a) = I# (cstringLength# a)
 
-{-# NOINLINE sLit #-}
-sLit :: String -> PtrString
-sLit x  = mkPtrString x
-
 {-# NOINLINE fsLit #-}
 fsLit :: String -> FastString
 fsLit x = mkFastString x
 
-{-# RULES "slit"
-    forall x . sLit  (unpackCString# x) = mkPtrString#  x #-}
 {-# RULES "fslit"
     forall x . fsLit (unpackCString# x) = mkFastString# x #-}