Changed OverLit warnings to work with negative literals (#13257)

Test Plan: Validate, check generated warnings

Reviewers: austin, bgamari, dfeuer

Reviewed By: bgamari, dfeuer

Subscribers: dfeuer, thomie

Differential Revision: https://phabricator.haskell.org/D3281

2 files changed, 12 insertions, 2 deletions

diff --git a/compiler/deSugar/DsExpr.hs b/compiler/deSugar/DsExpr.hs
index 28254c93b4..faf562e428 100644
--- a/compiler/deSugar/DsExpr.hs
+++ b/compiler/deSugar/DsExpr.hs
@@ -271,6 +271,15 @@ dsExpr (HsWrap co_fn e)
        ; warnAboutIdentities dflags e' (exprType wrapped_e)
        ; return wrapped_e }
 
+dsExpr (NegApp (L loc (HsOverLit lit@(OverLit { ol_val = HsIntegral src i })))
+                neg_expr)
+  = do { expr' <- putSrcSpanDs loc $ do
+          { dflags <- getDynFlags
+          ; warnAboutOverflowedLiterals dflags
+                                        (lit { ol_val = HsIntegral src (-i) })
+          ; dsOverLit' dflags lit }
+       ; dsSyntaxExpr neg_expr [expr'] }
+
 dsExpr (NegApp expr neg_expr)
   = do { expr' <- dsLExpr expr
        ; dsSyntaxExpr neg_expr [expr'] }
diff --git a/compiler/deSugar/MatchLit.hs b/compiler/deSugar/MatchLit.hs
index 2e9a5235bf..6ed34f42db 100644
--- a/compiler/deSugar/MatchLit.hs
+++ b/compiler/deSugar/MatchLit.hs
@@ -8,10 +8,11 @@ Pattern-matching literal patterns
 
 {-# LANGUAGE CPP, ScopedTypeVariables #-}
 
-module MatchLit ( dsLit, dsOverLit, hsLitKey
+module MatchLit ( dsLit, dsOverLit, dsOverLit', hsLitKey
                 , tidyLitPat, tidyNPat
                 , matchLiterals, matchNPlusKPats, matchNPats
-                , warnAboutIdentities, warnAboutEmptyEnumerations
+                , warnAboutIdentities, warnAboutOverflowedLiterals
+                , warnAboutEmptyEnumerations
                 ) where
 
 #include "HsVersions.h"