From 24e61aad37355fa3a5503b11a60ab7b314a3f405 Mon Sep 17 00:00:00 2001
From: Ben Price <ben@brprice.uk>
Date: Mon, 27 Jan 2020 13:53:32 +0000
Subject: [PATCH] Lint should say when it is checking a rule
It is rather confusing that when lint finds an error in a rule attached
to a binder, it reports the error as in the RHS, not the rule:
...
In the RHS of foo
We add a clarifying line:
...
In the RHS of foo
In a rule attached to foo
The implication that the rule lives inside the RHS is a bit odd, but
this niggle is already present for unfoldings, whose pattern we are
following.
---
compiler/GHC/Core/Lint.hs | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/compiler/GHC/Core/Lint.hs b/compiler/GHC/Core/Lint.hs
index 872a081f471..f0222ec6322 100644
--- a/compiler/GHC/Core/Lint.hs
+++ b/compiler/GHC/Core/Lint.hs
@@ -659,7 +659,7 @@ lintLetBind top_lvl rec_flag binder rhs rhs_ty
ppr binder)
_ -> return ()
- ; mapM_ (lintCoreRule binder binder_ty) (idCoreRules binder)
+ ; addLoc (RuleOf binder) $ mapM_ (lintCoreRule binder binder_ty) (idCoreRules binder)
; addLoc (UnfoldingOf binder) $
lintIdUnfolding binder binder_ty (idUnfolding binder) }
@@ -2293,6 +2293,7 @@ data LintLocInfo
= RhsOf Id -- The variable bound
| OccOf Id -- Occurrence of id
| LambdaBodyOf Id -- The lambda-binder
+ | RuleOf Id -- Rules attached to a binder
| UnfoldingOf Id -- Unfolding of a binder
| BodyOfLetRec [Id] -- One of the binders
| CaseAlt CoreAlt -- Case alternative
@@ -2511,6 +2512,9 @@ dumpLoc (OccOf v)
dumpLoc (LambdaBodyOf b)
= (getSrcLoc b, text "In the body of lambda with binder" <+> pp_binder b)
+dumpLoc (RuleOf b)
+ = (getSrcLoc b, text "In a rule attached to" <+> pp_binder b)
+
dumpLoc (UnfoldingOf b)
= (getSrcLoc b, text "In the unfolding of" <+> pp_binder b)
--
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