[commit: ghc] master: Stable name type role (2287257)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/228725747c3e493c36d6b6ad1034ca56581cb758/ghc

>---------------------------------------------------------------

commit 228725747c3e493c36d6b6ad1034ca56581cb758
Author: David Feuer <david.feuer at gmail.com>
Date:   Thu Oct 4 13:52:23 2018 -0400

    Stable name type role
    
    Make the `StableName#` parameter phantom:
    
    There is actually never any reason to care about the type of
    the underlying object of a `StableName#`. The underlying object
    type shouldn't really even *be* a parameter. But at least we
    can mark it as phantom.
    
    Reviewers: hvr, bgamari, erikd, simonmar
    
    Reviewed By: simonmar
    
    Subscribers: ekmett, rwbarton, carter
    
    Differential Revision: https://phabricator.haskell.org/D5117


>---------------------------------------------------------------

228725747c3e493c36d6b6ad1034ca56581cb758
 compiler/prelude/TysPrim.hs      | 2 +-
 docs/users_guide/8.8.1-notes.rst | 8 ++++++++
 libraries/base/changelog.md      | 4 ++++
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/compiler/prelude/TysPrim.hs b/compiler/prelude/TysPrim.hs
index c5af4a5..4a69df8 100644
--- a/compiler/prelude/TysPrim.hs
+++ b/compiler/prelude/TysPrim.hs
@@ -943,7 +943,7 @@ mkStablePtrPrimTy ty = TyConApp stablePtrPrimTyCon [ty]
 -}
 
 stableNamePrimTyCon :: TyCon
-stableNamePrimTyCon = pcPrimTyCon stableNamePrimTyConName [Representational] UnliftedRep
+stableNamePrimTyCon = pcPrimTyCon stableNamePrimTyConName [Phantom] UnliftedRep
 
 mkStableNamePrimTy :: Type -> Type
 mkStableNamePrimTy ty = TyConApp stableNamePrimTyCon [ty]
diff --git a/docs/users_guide/8.8.1-notes.rst b/docs/users_guide/8.8.1-notes.rst
index 6bdde40..a27aee7 100644
--- a/docs/users_guide/8.8.1-notes.rst
+++ b/docs/users_guide/8.8.1-notes.rst
@@ -104,6 +104,10 @@ Template Haskell
   eventlog events similar to ``traceBinaryEvent#`` but allows the user to pass
   the event payload as a binary blob instead of a ``String``.
 
+- The ``StableName#`` type parameter now has a phantom role instead of
+  a representational one. There is really no reason to care about the
+  type of the underlying object.
+
 ``ghc`` library
 ~~~~~~~~~~~~~~~
 
@@ -114,6 +118,10 @@ Template Haskell
 - Support the characters from recent versions of Unicode (up to v. 12) in literals
     (see :ghc-ticket:`5518`).
 
+- The ``StableName`` type parameter now has a phantom role instead of
+  a representational one. There is really no reason to care about the
+  type of the underlying object.
+
 Build system
 ~~~~~~~~~~~~
 
diff --git a/libraries/base/changelog.md b/libraries/base/changelog.md
index 8964edd..3709a0a 100644
--- a/libraries/base/changelog.md
+++ b/libraries/base/changelog.md
@@ -6,6 +6,10 @@
   * Support the characters from recent versions of Unicode (up to v. 12) in
     literals (#5518).
 
+  * The `StableName` type parameter now has a phantom role instead of
+    a representational one. There is really no reason to care about the
+    type of the underlying object.
+
 ## 4.12.0.0 *TBA*
   * Bundled with GHC *TBA*