From: simonpj <unknown>
Date: Mon, 30 Apr 2001 10:49:21 +0000 (+0000)
Subject: [project @ 2001-04-30 10:48:57 by simonpj]
X-Git-Tag: Approximately_9120_patches~2065
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;h=39068cf49bf3553f90ec316569619c310a6be8de;hp=c481ebb0eca85885e22e526ea5de43573e725199;p=ghc-hetmet.git

[project @ 2001-04-30 10:48:57 by simonpj]
Improve error message
---

diff --git a/ghc/compiler/typecheck/TcBinds.lhs b/ghc/compiler/typecheck/TcBinds.lhs
index 5bd9cae..a50bc50 100644
--- a/ghc/compiler/typecheck/TcBinds.lhs
+++ b/ghc/compiler/typecheck/TcBinds.lhs
@@ -473,8 +473,7 @@ generalise binder_names mbind tau_tvs lie_req sigs
 
     tysig_names = [name | (TySigInfo name _ _ _ _ _ _ _) <- sigs]
 
-    doc | null sigs = ptext SLIT("banding(s) for")        <+> pprBinders binder_names
-	| otherwise = ptext SLIT("type signature(s) for") <+> pprBinders binder_names
+    doc = ptext SLIT("type signature(s) for") <+> pprBinders binder_names
 
 -----------------------
 	-- CHECK THAT ALL THE SIGNATURE CONTEXTS ARE UNIFIABLE
@@ -827,5 +826,5 @@ restrictedBindCtxtErr binder_names
 		ptext SLIT("that falls under the monomorphism restriction")])
 
 -- Used in error messages
-pprBinders bndrs = braces (pprWithCommas ppr bndrs)
+pprBinders bndrs = pprWithCommas ppr bndrs
 \end{code}
diff --git a/ghc/compiler/typecheck/TcInstDcls.lhs b/ghc/compiler/typecheck/TcInstDcls.lhs
index 1a38a13..95add91 100644
--- a/ghc/compiler/typecheck/TcInstDcls.lhs
+++ b/ghc/compiler/typecheck/TcInstDcls.lhs
@@ -729,7 +729,8 @@ check_tyvars dflags clas inst_taus
   | otherwise 				      = [the_err]
   where
     the_err = instTypeErr clas inst_taus msg
-    msg     = ptext SLIT("There must be at least one non-type-variable in the instance head")
+    msg     =  ptext SLIT("There must be at least one non-type-variable in the instance head")
+	    $$ ptext SLIT("Use -fallow-undecidable-instances to lift this restriction")
 
 check_fundeps dflags theta clas inst_taus
   | checkInstFDs theta clas inst_taus = []