From 89a11db9f553737c653e7c1996d0e5c368496608 Mon Sep 17 00:00:00 2001
From: Paul King <paulk@asert.com.au>
Date: Sat, 8 Sep 2018 10:22:37 +1000
Subject: [PATCH] GROOVY-8778: Cast short-hand breaks for empty map

---
 src/antlr/GroovyParser.g4                       |  2 +-
 src/test/groovy/GroovyTruthTest.groovy          |  4 +++-
 .../apache/groovy/parser/antlr4/AstBuilder.java | 17 ++++++++---------
 3 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/src/antlr/GroovyParser.g4 b/src/antlr/GroovyParser.g4
index f2a3e2fd6ed..72d6fab6e5a 100644
--- a/src/antlr/GroovyParser.g4
+++ b/src/antlr/GroovyParser.g4
@@ -1013,7 +1013,7 @@ indexPropertyArgs
     ;
 
 namedPropertyArgs
-    :   LBRACK mapEntryList RBRACK
+    :   LBRACK (mapEntryList | COLON) RBRACK
     ;
 
 primary
diff --git a/src/test/groovy/GroovyTruthTest.groovy b/src/test/groovy/GroovyTruthTest.groovy
index 8034e59fb91..e602125a43e 100644
--- a/src/test/groovy/GroovyTruthTest.groovy
+++ b/src/test/groovy/GroovyTruthTest.groovy
@@ -43,8 +43,10 @@ class GroovyTruthTest extends GroovyTestCase {
         testTrue([1])
         testFalse([].toArray())
 
-        testFalse [:]
+        testFalse Collections.EMPTY_MAP
+        testFalse([:])
         testTrue([bla: 'some value'])
+
         testTrue 1234
         testFalse 0
         testTrue 0.3f
diff --git a/subprojects/parser-antlr4/src/main/java/org/apache/groovy/parser/antlr4/AstBuilder.java b/subprojects/parser-antlr4/src/main/java/org/apache/groovy/parser/antlr4/AstBuilder.java
index ce8ee318b76..16bda16ce62 100644
--- a/subprojects/parser-antlr4/src/main/java/org/apache/groovy/parser/antlr4/AstBuilder.java
+++ b/subprojects/parser-antlr4/src/main/java/org/apache/groovy/parser/antlr4/AstBuilder.java
@@ -2332,19 +2332,18 @@ public Expression visitPathElement(PathElementContext ctx) {
             return configureAST(
                     new BinaryExpression(baseExpr, createGroovyToken(tuple.getFirst()), tuple.getSecond(), isSafeChain || asBoolean(ctx.indexPropertyArgs().QUESTION())),
                     ctx);
-        } else if (asBoolean(ctx.namedPropertyArgs())) { // this is a special way to new instance, e.g. Person[name: 'Daniel.Sun', location: 'Shanghai']
+        } else if (asBoolean(ctx.namedPropertyArgs())) { // this is a special way to signify a cast, e.g. Person[name: 'Daniel.Sun', location: 'Shanghai']
             List<MapEntryExpression> mapEntryExpressionList =
                     this.visitNamedPropertyArgs(ctx.namedPropertyArgs());
 
             Expression right;
-            if (mapEntryExpressionList.size() == 1) {
-                MapEntryExpression mapEntryExpression = mapEntryExpressionList.get(0);
-
-                if (mapEntryExpression.getKeyExpression() instanceof SpreadMapExpression) {
-                    right = mapEntryExpression.getKeyExpression();
-                } else {
-                    right = mapEntryExpression;
-                }
+            if (mapEntryExpressionList.size() == 0) {
+                // expecting list of MapEntryExpressions later so use SpreadMap to smuggle empty MapExpression to later stages
+                right = configureAST(
+                        new SpreadMapExpression(configureAST(new MapExpression(), ctx.namedPropertyArgs())),
+                        ctx.namedPropertyArgs());
+            } else if (mapEntryExpressionList.size() == 1 && mapEntryExpressionList.get(0).getKeyExpression() instanceof SpreadMapExpression) {
+                right = mapEntryExpressionList.get(0).getKeyExpression();
             } else {
                 ListExpression listExpression =
                         configureAST(