From 884b0a57dde7b1d9556a4c47f6a14a11d39c3c64 Mon Sep 17 00:00:00 2001 From: "simonpj@microsoft.com" Date: Fri, 29 Jun 2007 20:32:19 +0000 Subject: [PATCH] Improve error message (Trac #1446) --- compiler/typecheck/TcSimplify.lhs | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/compiler/typecheck/TcSimplify.lhs b/compiler/typecheck/TcSimplify.lhs index 3f25a4c..773b312 100644 --- a/compiler/typecheck/TcSimplify.lhs +++ b/compiler/typecheck/TcSimplify.lhs @@ -2716,11 +2716,11 @@ report_no_instances tidy_env mb_what insts (clas,tys) = getDictClassTys wanted mk_overlap_msg dict (matches, unifiers) - = vcat [ addInstLoc [dict] ((ptext SLIT("Overlapping instances for") + = ASSERT( not (null matches) ) + vcat [ addInstLoc [dict] ((ptext SLIT("Overlapping instances for") <+> pprPred (dictPred dict))), sep [ptext SLIT("Matching instances") <> colon, nest 2 (vcat [pprInstances ispecs, pprInstances unifiers])], - ASSERT( not (null matches) ) if not (isSingleton matches) then -- Two or more matches empty @@ -2728,7 +2728,8 @@ report_no_instances tidy_env mb_what insts ASSERT( not (null unifiers) ) parens (vcat [ptext SLIT("The choice depends on the instantiation of") <+> quotes (pprWithCommas ppr (varSetElems (tyVarsOfInst dict))), - ptext SLIT("Use -fallow-incoherent-instances to use the first choice above")])] + ptext SLIT("To pick the first instance above, use -fallow-incoherent-instances"), + ptext SLIT("when compiling the other instances")])] where ispecs = [ispec | (ispec, _) <- matches] -- 1.7.10.4