[project @ 2002-05-29 13:09:24 by simonpj]

Wibble to previous commit on negative literals in patterns (fixes crash in GHC/Real.lhs)

diff --git a/ghc/compiler/typecheck/TcPat.lhs b/ghc/compiler/typecheck/TcPat.lhs
index e4decd0..548f710 100644 (file)
--- a/ghc/compiler/typecheck/TcPat.lhs
+++ b/ghc/compiler/typecheck/TcPat.lhs
@@ -323,9 +323,15 @@ tcPat tc_bndr pat@(NPatIn over_lit mb_neg) pat_ty
              emptyBag, emptyBag, emptyLIE)
   where
     origin = PatOrigin pat
-    lit' = case over_lit of
-               HsIntegral i _   -> HsInteger i
-               HsFractional f _ -> HsRat f pat_ty
+
+       -- The literal in an NPatIn is always positive...
+       -- But in NPat, the literal is used to find identical patterns
+       --      so we must negate the literal when necessary!
+    lit' = case (over_lit, mb_neg) of
+            (HsIntegral i _, Nothing)   -> HsInteger i
+            (HsIntegral i _, Just _)    -> HsInteger (-i)
+            (HsFractional f _, Nothing) -> HsRat f pat_ty
+            (HsFractional f _, Just _)  -> HsRat (-f) pat_ty
 \end{code}
 
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