From: simonpj@microsoft.com <unknown>
Date: Thu, 23 Sep 2010 10:58:20 +0000 (+0000)
Subject: Avoid ASSERT black hole
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;h=528db2ad98caf5067ebdadf424c6c816c3927dd4;p=ghc-hetmet.git

Avoid ASSERT black hole

When this ASSERT tripped in CoreToStg it tried to print out
too much, which tripped the asssertion again.  Result: an
infinite loop with no output at all.  Hard to debug!
---

diff --git a/compiler/stgSyn/CoreToStg.lhs b/compiler/stgSyn/CoreToStg.lhs
index 3b004c1..9ddac59 100644
--- a/compiler/stgSyn/CoreToStg.lhs
+++ b/compiler/stgSyn/CoreToStg.lhs
@@ -184,7 +184,11 @@ coreTopBindToStg this_pkg env body_fvs (NonRec id rhs)
 	
 	bind = StgNonRec id stg_rhs
     in
-    ASSERT2(consistentCafInfo id bind, ppr id {- $$ ppr rhs $$ ppr bind -} )
+    ASSERT2(consistentCafInfo id bind, ppr id )
+      -- NB: previously the assertion printed 'rhs' and 'bind'
+      --     as well as 'id', but that led to a black hole
+      --     where printing the assertion error tripped the
+      --     assertion again!
     (env', fvs' `unionFVInfo` body_fvs, bind)
 
 coreTopBindToStg this_pkg env body_fvs (Rec pairs)