From 4ca026cee56ba5e01df2e7812f0d1e731e2c1245 Mon Sep 17 00:00:00 2001
From: Tom Stuart <tom.stuart@shopify.com>
Date: Tue, 15 Dec 2020 10:27:25 +0000
Subject: [PATCH] =?UTF-8?q?Raise=20SyntaxError=20on=20pattern=20match=20if?=
 =?UTF-8?q?=20the=20feature=20isn=E2=80=99t=20enabled?=
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The message is “syntax error, unexpected keyword_in” because that’s what
TruffleRuby (without pattern matching support) currently raises.

# Conflicts:
#	src/main/java/org/truffleruby/parser/BodyTranslator.java
---
 .../java/org/truffleruby/parser/BodyTranslator.java    | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/main/java/org/truffleruby/parser/BodyTranslator.java b/src/main/java/org/truffleruby/parser/BodyTranslator.java
index 3df33e33e9af..327e87646acb 100644
--- a/src/main/java/org/truffleruby/parser/BodyTranslator.java
+++ b/src/main/java/org/truffleruby/parser/BodyTranslator.java
@@ -831,6 +831,16 @@ public RubyNode visitCaseNode(CaseParseNode node) {
 
     @Override
     public RubyNode visitCaseInNode(CaseInParseNode node) {
+        if (!language.options.PATTERN_MATCHING) {
+            final RubyContext context = RubyLanguage.getCurrentContext();
+            throw new RaiseException(
+                    context,
+                    context.getCoreExceptions().syntaxError(
+                            "syntax error, unexpected keyword_in",
+                            currentNode,
+                            node.getPosition().toSourceSection(source)));
+        }
+
         final SourceIndexLength sourceSection = node.getPosition();
 
         RubyNode elseNode = translateNodeOrNil(sourceSection, node.getElseNode());