From: Ian Lynagh <igloo@earth.li>
Date: Tue, 26 Oct 2010 21:15:46 +0000 (+0000)
Subject: Use removeDups to find top-level duplicate names
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;h=116134b1319e60ff38fc3710bd764cff34554837;p=ghc-hetmet.git

Use removeDups to find top-level duplicate names
findDupsEq is quadratic, whereas removeDups is n log n.
Fixes T1969 regression.
---

diff --git a/compiler/coreSyn/CoreLint.lhs b/compiler/coreSyn/CoreLint.lhs
index c347ed2..0ca5c43 100644
--- a/compiler/coreSyn/CoreLint.lhs
+++ b/compiler/coreSyn/CoreLint.lhs
@@ -117,11 +117,11 @@ lintCoreBindings binds
     --    M.n{r3}  = ...
     --    M.n{r29} = ...
     -- becuase they both get the same linker symbol
-    ext_dups = findDupsEq eq_ext (map Var.varName binders)
-    eq_ext n1 n2 | Just m1 <- nameModule_maybe n1
-                 , Just m2 <- nameModule_maybe n2
-                 = m1==m2 && nameOccName n1 == nameOccName n2
-                 | otherwise = False
+    ext_dups = snd (removeDups ord_ext (map Var.varName binders))
+    ord_ext n1 n2 | Just m1 <- nameModule_maybe n1
+                  , Just m2 <- nameModule_maybe n2
+                  = compare (m1, nameOccName n1) (m2, nameOccName n2)
+                  | otherwise = LT
 
     lint_bind (Rec prs)		= mapM_ (lintSingleBinding TopLevel Recursive) prs
     lint_bind (NonRec bndr rhs) = lintSingleBinding TopLevel NonRecursive (bndr,rhs)