<no location info> for shadowing warnings in TH-generated code

[byorgey]

See attached test case, which causes this warning to be printed when THShadowSplice.hs is compiled with -Wall:

<no location info>:
    Warning: This binding for `x' shadows the existing binding
               bound at THShadowSplice.hs:7:3

There ought to be some location info. I have also seen warnings of the form

<no location info>:
    Warning: This binding for `x' shadows the existing binding
               bound at <no location info>

although I have not yet been able to construct a small test case which exhibits this behavior.

[simonpj@…]

commit 68bcb1399c8cd17f6db641a68fd4d20fff08c01a

Author: Simon Peyton Jones <simonpj@microsoft.com>
Date:   Fri Sep 2 09:11:24 2011 +0100

    Make Convert.thRdrName give a decent source locations (fixes Trac #5434)
    
    thRdrName is used to construct *binders*, and some of them are
    Exact RdrNames, so we need to give them a decent source location.

 compiler/hsSyn/Convert.lhs |   26 ++++++++++++++++++--------
 1 files changed, 18 insertions(+), 8 deletions(-)

[simonpj]

Thanks. Fixed and test added.