From: sof <unknown>
Date: Thu, 21 Jan 1999 20:02:45 +0000 (+0000)
Subject: [project @ 1999-01-21 20:02:43 by sof]
X-Git-Tag: Approx_2487_patches~26
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;h=718754ae4f9230b9ecb2e0e47e25e1e101bfe41b;p=ghc-hetmet.git

[project @ 1999-01-21 20:02:43 by sof]
Robustified derived toEnum methods; gives better error message when
passed enum tags < 0.
---

diff --git a/ghc/compiler/prelude/PrelInfo.lhs b/ghc/compiler/prelude/PrelInfo.lhs
index 6c4049e..830247a 100644
--- a/ghc/compiler/prelude/PrelInfo.lhs
+++ b/ghc/compiler/prelude/PrelInfo.lhs
@@ -606,7 +606,7 @@ deriving_occ_info
     , (ordClassKey, 	[intTyCon_RDR, compose_RDR, eqTag_RDR])
 				-- EQ (from Ordering) is needed to force in the constructors
 				-- as well as the type constructor.
-    , (enumClassKey, 	[intTyCon_RDR, map_RDR, plus_RDR, showsPrec_RDR, append_RDR]) 
+    , (enumClassKey, 	[intTyCon_RDR, and_RDR, map_RDR, plus_RDR, showsPrec_RDR, append_RDR]) 
 				-- The last two Enum deps are only used to produce better
 				-- error msgs for derived toEnum methods.
     , (boundedClassKey,	[intTyCon_RDR])
diff --git a/ghc/compiler/typecheck/TcGenDeriv.lhs b/ghc/compiler/typecheck/TcGenDeriv.lhs
index cab4e7c..09e4992 100644
--- a/ghc/compiler/typecheck/TcGenDeriv.lhs
+++ b/ghc/compiler/typecheck/TcGenDeriv.lhs
@@ -483,11 +483,16 @@ gen_Enum_binds tycon
 
     to_enum
       = mk_easy_FunMonoBind tycon_loc toEnum_RDR [a_Pat] [] $
-	HsIf (HsApp (HsApp (HsVar gt_RDR) 
-			   (HsVar a_RDR))
-			   (HsVar (maxtag_RDR tycon)))
-	     (illegal_toEnum_tag occ_nm (maxtag_RDR tycon))
+	HsIf (HsApp (HsApp 
+	            (HsVar and_RDR)
+		    (HsApp (HsApp (HsVar ge_RDR)
+				  (HsVar a_RDR))
+				  (HsLit (HsInt 0))))
+                    (HsApp (HsApp (HsVar le_RDR)
+				  (HsVar a_RDR))
+				  (HsVar (maxtag_RDR tycon))))
              (mk_easy_App (tag2con_RDR tycon) [a_RDR])
+	     (illegal_toEnum_tag occ_nm (maxtag_RDR tycon))
 	     tycon_loc
 
     enum_from