2. We make them *shadow* the outer bindings. If we don't do that,
we'll get a complaint when extending the GlobalRdrEnv, saying that
- there are two bindings for 'f'.
-
- This shadowing applies even if the binding for 'f' is in a
- where-clause, and hence is in the *local* RdrEnv not the *global*
- RdrEnv.
-
-We find out whether we are inside a [d| ... |] by testing the TH
-stage. This is a slight hack, because the stage field was really meant for
-the type checker, and here we are not interested in the fields of Brack,
-hence the error thunks in thRnBrack.
+ there are two bindings for 'f'. There are several tricky points:
+
+ * This shadowing applies even if the binding for 'f' is in a
+ where-clause, and hence is in the *local* RdrEnv not the *global*
+ RdrEnv.
+
+ * The *qualified* name M.f from the enclosing module must certainly
+ still be available. So we don't nuke it entirely; we just make
+ it seem like qualified import.
+
+ * We only shadow *External* names (which come from the main module)
+ Do not shadow *Inernal* names because in the bracket
+ [d| class C a where f :: a
+ f = 4 |]
+ rnSrcDecls will first call extendGlobalRdrEnvRn with C[f] from the
+ class decl, and *separately* extend the envt with the value binding.
+
+3. We find out whether we are inside a [d| ... |] by testing the TH
+ stage. This is a slight hack, because the stage field was really
+ meant for the type checker, and here we are not interested in the
+ fields of Brack, hence the error thunks in thRnBrack.
\begin{code}
extendGlobalRdrEnvRn :: [AvailInfo]
-> MiniFixityEnv
-> RnM (TcGblEnv, TcLclEnv)
-- Updates both the GlobalRdrEnv and the FixityEnv
- -- We return a new TcLclEnv only becuase we might have to
+ -- We return a new TcLclEnv only because we might have to
-- delete some bindings from it;
-- see Note [Top-level Names in Template Haskell decl quotes]
-- See Note [Top-level Names in Template Haskell decl quotes]
shadowP = isBrackStage stage
new_occs = map (nameOccName . gre_name) gres
- rdr_env1 = hideSomeUnquals rdr_env new_occs
+ rdr_env1 = transformGREs qual_gre new_occs rdr_env
lcl_env1 = lcl_env { tcl_rdr = delListFromOccEnv (tcl_rdr lcl_env) new_occs }
(rdr_env2, lcl_env2) | shadowP = (rdr_env1, lcl_env1)
| otherwise = (rdr_env, lcl_env)
where
name = gre_name gre
occ = nameOccName name
+
+ qual_gre :: GlobalRdrElt -> GlobalRdrElt
+ -- Transform top-level GREs from the module being compiled
+ -- so that they are out of the way of new definitions in a Template
+ -- Haskell bracket
+ -- See Note [Top-level Names in Template Haskell decl quotes]
+ -- Seems like 5 times as much work as it deserves!
+ --
+ -- For a LocalDef we make a (fake) qualified imported GRE for a
+ -- local GRE so that the original *qualified* name is still in scope
+ -- but the *unqualified* one no longer is. What a hack!
+
+ qual_gre gre@(GRE { gre_prov = LocalDef, gre_name = name })
+ | isExternalName name = gre { gre_prov = Imported [imp_spec] }
+ | otherwise = gre
+ -- Do not shadow Internal (ie Template Haskell) Names
+ -- See Note [Top-level Names in Template Haskell decl quotes]
+ where
+ mod = ASSERT2( isExternalName name, ppr name) moduleName (nameModule name)
+ imp_spec = ImpSpec { is_item = ImpAll, is_decl = decl_spec }
+ decl_spec = ImpDeclSpec { is_mod = mod, is_as = mod,
+ is_qual = True, -- Qualified only!
+ is_dloc = srcLocSpan (nameSrcLoc name) }
+
+ qual_gre gre@(GRE { gre_prov = Imported specs })
+ = gre { gre_prov = Imported (map qual_spec specs) }
+
+ qual_spec spec@(ImpSpec { is_decl = decl_spec })
+ = spec { is_decl = decl_spec { is_qual = True } }
\end{code}
@getLocalDeclBinders@ returns the names for an @HsDecl@. It's
-- Get all the top-level binders bound the group *except*
-- for value bindings, which are treated separately
-- Specificaly we return AvailInfo for
--- type decls
--- class decls
+-- type decls (incl constructors and record selectors)
+-- class decls (including class ops)
-- associated types
-- foreign imports
-- (in hs-boot files) value signatures