[commit: ghc] master: Include the instances of associated types in the "extras" of a class (3bf0520)

[Simon Peyton Jones]

Repository : ssh://darcs.haskell.org//srv/darcs/ghc

On branch  : master

http://hackage.haskell.org/trac/ghc/changeset/3bf0520aea5acbecb83dcc0fc722c79ce9f5723c

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

commit 3bf0520aea5acbecb83dcc0fc722c79ce9f5723c
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Wed Aug 3 07:46:50 2011 +0100

    Include the instances of associated types in the "extras" of a class
    
    This fixes Trac #5147, which was going wrong because
    the class ABI fingerprint wasn't changing when we added
    or removed a Show instance to the associated type.

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

 compiler/iface/IfaceSyn.lhs |    8 ++++++++
 compiler/iface/MkIface.lhs  |   24 ++++++++++++++++++++----
 2 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/compiler/iface/IfaceSyn.lhs b/compiler/iface/IfaceSyn.lhs
index 8ca6b39..b5da626 100644
--- a/compiler/iface/IfaceSyn.lhs
+++ b/compiler/iface/IfaceSyn.lhs
@@ -282,6 +282,14 @@ Note [Orphans]: the ifInstOrph and ifRuleOrph fields
 If a module contains any "orphans", then its interface file is read
 regardless, so that its instances are not missed.
 
+ - If an instance is an orphan its ifInstOprh field is Nothing
+   Otherwise ifInstOrph is (Just n) where n is the Name of a
+   local class or tycon that witnesses its non-orphan-hood.
+   This computation is done by MkIface.instanceToIfaceInst
+
+ - Similarly for ifRuleOrph
+   The computation is done by MkIface.coreRuleToIfaceRule
+
 Roughly speaking, an instance is an orphan if its head (after the =>)
 mentions nothing defined in this module.  Functional dependencies
 complicate the situation though. Consider
diff --git a/compiler/iface/MkIface.lhs b/compiler/iface/MkIface.lhs
index a72ed4e..fcf7c31 100644
--- a/compiler/iface/MkIface.lhs
+++ b/compiler/iface/MkIface.lhs
@@ -650,9 +650,22 @@ type IfaceDeclABI = (Module, IfaceDecl, IfaceDeclExtras)
 
 data IfaceDeclExtras 
   = IfaceIdExtras    Fixity [IfaceRule]
-  | IfaceDataExtras  Fixity [IfaceInstABI] [(Fixity,[IfaceRule])]
-  | IfaceClassExtras Fixity [IfaceInstABI] [(Fixity,[IfaceRule])]
+
+  | IfaceDataExtras  
+       Fixity			-- Fixity of the tycon itself
+       [IfaceInstABI]		-- Local instances of this tycon
+       				-- See Note [Orphans] in IfaceSyn
+       [(Fixity,[IfaceRule])]	-- For each construcotr, fixity and RULES
+
+  | IfaceClassExtras 
+       Fixity			-- Fixity of the class itself
+       [IfaceInstABI] 		-- Local instances of this class *or*
+       				--   of its associated data types
+       				-- See Note [Orphans] in IfaceSyn
+       [(Fixity,[IfaceRule])]	-- For each class method, fixity and RULES
+
   | IfaceSynExtras   Fixity
+
   | IfaceOtherDeclExtras
 
 abiDecl :: IfaceDeclABI -> IfaceDecl
@@ -727,9 +740,12 @@ declExtras fix_fn rule_env inst_env decl
                      IfaceDataExtras (fix_fn n)
                         (map ifDFun $ lookupOccEnvL inst_env n)
                         (map (id_extras . ifConOcc) (visibleIfConDecls cons))
-      IfaceClass{ifSigs=sigs} -> 
+      IfaceClass{ifSigs=sigs, ifATs=ats} -> 
                      IfaceClassExtras (fix_fn n)
-                        (map ifDFun $ lookupOccEnvL inst_env n)
+                        (map ifDFun $ (concatMap (lookupOccEnvL inst_env . ifName) ats)
+                                    ++ lookupOccEnvL inst_env n)
+		           -- Include instances of the associated types
+			   -- as well as instances of the class (Trac #5147)
                         [id_extras op | IfaceClassOp op _ _ <- sigs]
       IfaceSyn{} -> IfaceSynExtras (fix_fn n)
       _other -> IfaceOtherDeclExtras