[project @ 2003-09-23 16:52:44 by sof]

[ghc-hetmet.git] / ghc / compiler / typecheck / TcRnTypes.lhs

diff --git a/ghc/compiler/typecheck/TcRnTypes.lhs b/ghc/compiler/typecheck/TcRnTypes.lhs
index 1408eda..47a9ed8 100644 (file)
--- a/ghc/compiler/typecheck/TcRnTypes.lhs
+++ b/ghc/compiler/typecheck/TcRnTypes.lhs
@@ -595,10 +595,16 @@ data ImportAvails
                -- combine stuff coming from different (unqualified) 
                -- imports of the same module
 
-       imp_mods :: ModuleEnv (Module, Bool),
+       imp_mods :: ModuleEnv (Module, Maybe Bool),
                -- Domain is all directly-imported modules
-               -- Bool is True if there was an unrestricted import
-               --      (i.e. not a selective list)
+               -- Maybe value answers the question "is the import restricted?"
+               --   Nothing    => unrestricted import (e.g., "import Foo")
+               --   Just True  => restricted import, at least one entity (e.g., "import Foo(x)")
+               --   Just False => fully restricted import (e.g., "import Foo ()")
+               --
+               --  A distinction is made between the first and the third in order
+               --  to more precisely emit warnings about unused imports.
+               --
                -- We need the Module in the range because we can't get
                --      the keys of a ModuleEnv
                -- Used