From 4e84810eca640220a333f104d25412399b6c0d31 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn-Egil=20Dahlberg?= <egil@erlang.org>
Date: Mon, 18 Aug 2014 18:45:26 +0200
Subject: compiler: Reintroduce binary limit for Map keys

---
 lib/compiler/src/v3_core.erl | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

(limited to 'lib/compiler/src/v3_core.erl')

diff --git a/lib/compiler/src/v3_core.erl b/lib/compiler/src/v3_core.erl
index 9f1f3b635c..348ef9051d 100644
--- a/lib/compiler/src/v3_core.erl
+++ b/lib/compiler/src/v3_core.erl
@@ -1609,7 +1609,8 @@ pattern_map_pairs(Ps, St) ->
 
 %% remove cluddering annotations
 pattern_map_clean_key(#c_literal{val=V}) -> {literal,V};
-pattern_map_clean_key(#c_var{name=V}) -> {var,V}.
+pattern_map_clean_key(#c_var{name=V}) -> {var,V};
+pattern_map_clean_key(_) -> erlang:throw(nomatch).
 
 pattern_alias_map_pairs([],_,_,_) -> [];
 pattern_alias_map_pairs([#c_map_pair{key=Ck}=Pair|Pairs],Kdb,Kset,St) ->
@@ -1630,11 +1631,17 @@ pattern_alias_map_pair_patterns([Cv1,Cv2|Cvs]) ->
     pattern_alias_map_pair_patterns([pat_alias(Cv1,Cv2)|Cvs]).
 
 pattern_map_pair({map_field_exact,L,K,V}, St) ->
-    {Ck,[],_} = expr(K,St),
-    #c_map_pair{anno=lineno_anno(L,St),
-		op=#c_literal{val=exact},
-		key=Ck,
-		val=pattern(V,St)}.
+    %% guard against pre-expressions
+    %% i.e. keys like {atom, <<0:300>>} where
+    %% <<0:300>> becomes a pre-expression
+    case expr(K,St) of
+	{Ck,[],_} ->
+	    #c_map_pair{anno=lineno_anno(L,St),
+			op=#c_literal{val=exact},
+			key=Ck,
+			val=pattern(V,St)};
+	_ -> erlang:throw(nomatch)
+    end.
 
 %% pat_bin([BinElement], State) -> [BinSeg].
 
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