[project @ 2002-09-16 12:45:59 by simonpj]

Silly bug in plusImportAvails [HEAD only]

diff --git a/ghc/compiler/typecheck/TcRnTypes.lhs b/ghc/compiler/typecheck/TcRnTypes.lhs
index db4e7f8..8babf69 100644 (file)
--- a/ghc/compiler/typecheck/TcRnTypes.lhs
+++ b/ghc/compiler/typecheck/TcRnTypes.lhs
@@ -478,6 +478,9 @@ data ImportAvails
                -- Used to figure out "module M" export specifiers
                -- Domain is only modules with *unqualified* imports
                -- (see 1.4 Report Section 5.1.1)
+               -- The list of Avails is cumulative, not necessarily
+               -- nicely uniquified. For example, we might have Maybe(Nothing)
+               -- and Maybe(Just) in the list, separately.
 
        imp_mods :: ModuleEnv (Module, Bool)
                -- Domain is all directly-imported modules
@@ -502,7 +505,7 @@ plusImportAvails
   (ImportAvails { imp_env = env1, imp_unqual = unqual1, imp_mods = mods1 })
   (ImportAvails { imp_env = env2, imp_unqual = unqual2, imp_mods = mods2 })
   = ImportAvails { imp_env    = env1 `plusAvailEnv` env2, 
-                  imp_unqual = unqual1 `plusModuleEnv` unqual2, 
+                  imp_unqual = plusModuleEnv_C (++) unqual1 unqual2, 
                   imp_mods   = mods1 `plusModuleEnv` mods2 }
 
 mkImportAvails :: ModuleName -> Bool