From 0d3f812938c0d9c70fbf16975f79ebffd6cc5db5 Mon Sep 17 00:00:00 2001 From: "simonpj@microsoft.com" Date: Wed, 21 Jul 2010 14:42:48 +0000 Subject: [PATCH] Fix inlining for default methods This was discombobulated by a patch a week ago; now fixed, quite straightforwardly. See Note [Default methods and instances] --- compiler/typecheck/TcInstDcls.lhs | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) diff --git a/compiler/typecheck/TcInstDcls.lhs b/compiler/typecheck/TcInstDcls.lhs index d4100d0..c04f4a2 100644 --- a/compiler/typecheck/TcInstDcls.lhs +++ b/compiler/typecheck/TcInstDcls.lhs @@ -531,13 +531,17 @@ tcInstDecls2 tycl_decls inst_decls = do { -- (a) Default methods from class decls let class_decls = filter (isClassDecl . unLoc) tycl_decls ; dm_binds_s <- mapM tcClassDecl2 class_decls + ; let dm_binds = unionManyBags dm_binds_s -- (b) instance declarations - ; inst_binds_s <- mapM tcInstDecl2 inst_decls + ; let dm_ids = collectHsBindsBinders dm_binds + -- Add the default method Ids (again) + -- See Note [Default methods and instances] + ; inst_binds_s <- tcExtendIdEnv dm_ids $ + mapM tcInstDecl2 inst_decls -- Done - ; return (unionManyBags dm_binds_s `unionBags` - unionManyBags inst_binds_s) } + ; return (dm_binds `unionBags` unionManyBags inst_binds_s) } tcInstDecl2 :: InstInfo Name -> TcM (LHsBinds Id) tcInstDecl2 (InstInfo { iSpec = ispec, iBinds = ibinds }) @@ -550,6 +554,18 @@ tcInstDecl2 (InstInfo { iSpec = ispec, iBinds = ibinds }) loc = getSrcSpan dfun_id \end{code} +See Note [Default methods and instances] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +The default method Ids are already in the type environment (see Note +[Default method Ids and Template Haskell] in TcTyClsDcls), BUT they +don't have their InlinePragmas yet. Usually that would not matter, +because the simplifier propagates information from binding site to +use. But, unusually, when compiling instance decls we *copy* the +INLINE pragma from the default method to the method for that +particular operation (see Note [INLINE and default methods] below). + +So right here in tcInstDecl2 we must re-extend the type envt with +the default method Ids replete with their INLINE pragmas. Urk. \begin{code} tc_inst_decl2 :: Id -> InstBindings Name -> TcM (LHsBinds Id) -- 1.7.10.4