[commit: testsuite] master: Add a type signature for a function with an ambiguous type (0b8ea97)

[Simon Peyton Jones]

Repository : ssh://darcs.haskell.org//srv/darcs/testsuite

On branch  : master

http://hackage.haskell.org/trac/ghc/changeset/0b8ea972714f7f368a3b1884477fdf4e24cc1bf4

>---------------------------------------------------------------

commit 0b8ea972714f7f368a3b1884477fdf4e24cc1bf4
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Sat Jul 21 19:10:48 2012 +0100

    Add a type signature for a function with an ambiguous type
    
    There's a comment with visit_PPSArgs to explain.  GHC was rightfully
    rejecting visit_PPS as having an ambiguous type.  And it does!  It
    worked before because the ambiguity involved only standard classes
    and hence was resolved.
    
    (I suppose this could be a warning instead.  But I'm fixing the test
    anyway.)

>---------------------------------------------------------------

 tests/programs/joao-circular/Visfun_Lazy.hs |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/tests/programs/joao-circular/Visfun_Lazy.hs b/tests/programs/joao-circular/Visfun_Lazy.hs
index fa76899..494604e 100644
--- a/tests/programs/joao-circular/Visfun_Lazy.hs
+++ b/tests/programs/joao-circular/Visfun_Lazy.hs
@@ -854,6 +854,20 @@ visit_PPCArgs (C_NilPPCArgs_1 ) x_ifillerrs x_ifillfmts x_ifillmins x_ireqs = (x
       x_fmts = ([] )
       x_fillmins = ([] )
       x_error = ([] )
+
+
+visit_PPSArgs :: PPSArgs -> [T_Frame] -> (T_Errs, T_Fmts, Integer, T_Mins)
+-- This function's most general type is
+-- visit_PPSArgs :: forall a. (Integral a, Show a)
+--               => PPSArgs -> [T_Frame] -> (T_Errs, T_Fmts, a, T_Mins)
+-- But in the same mutually recusive group is visit_PPS whose type becomes
+-- visit_PPS :: forall a. (Integral a, Show a)
+--           => PPS -> T_Frame -> (Bool, T_Formats, INT, INT, INT)
+-- which GHC now (rightfully) rejects that as ambiguous, even though
+-- acutally default resolution will allow it at call sites,
+-- So I've added a type signature 
+-- SLPJ July 2012
+
 visit_PPSArgs (C_ConsArgs_1 t_PPS t_PPSArgs_2 ) x_reqs = (x_error , x_fmts , x_len , x_mins )
   where
       x_reqs_2 = (tail_T_Reqs x_reqs)