Stopped grammar from parsing child traversals spawned from g

This was already disallowed in Java, so it follows that it should be prevented even earlier by the parser. CTR

CHANGELOG.asciidoc

@@ -23,8 +23,9 @@ image::https://raw.githubusercontent.com/apache/tinkerpop/master/docs/static/ima
 [[release-3-7-4]]
 === TinkerPop 3.7.4 (NOT OFFICIALLY RELEASED YET)
 
-* Add log entry in WsAndHttpChannelizerHandler.
-* IdentityRemovalStrategy does not omit IdentityStep if only with RepeatEndStep under RepeatStep.
+* Add log entry in `WsAndHttpChannelizerHandler`.
+* Changed `IdentityRemovalStrategy` to omit `IdentityStep` if only with `RepeatEndStep` under `RepeatStep`.
+* Changed Gremlin grammar to make use of `g` to spawn child traversals a syntax error.
 
 [[release-3-7-3]]
 === TinkerPop 3.7.3 (October 23, 2024)

gremlin-core/src/test/java/org/apache/tinkerpop/gremlin/language/grammar/GremlinQueryParserTest.java

@@ -110,4 +110,16 @@ public void shouldParseMultiVariablesWithNoOp() {
         assertEquals(g.V(null, null, null).has("name", P.gt(null)).asAdmin().getBytecode(),
                 t.asAdmin().getBytecode());
     }
+
+    @Test(expected = GremlinParserException.class)
+    public void shouldNotParseChildTraversalsSpawnedFromG() {
+        final GremlinAntlrToJava gremlinAntlrToJava = new GremlinAntlrToJava("g",
+                EmptyGraph.instance(), __::start, g, VariableResolver.NoVariableResolver.instance());
+        try {
+            GremlinQueryParser.parse("g.addE('knows').from(g.V(1))", gremlinAntlrToJava);
+        } catch (Exception ex) {
+            ex.printStackTrace();
+            throw ex;
+        }
+    }
 }

gremlin-language/src/main/antlr4/Gremlin.g4

@@ -167,8 +167,7 @@ chainedParentOfGraphTraversal
     ;
 
 nestedTraversal
-    : rootTraversal
-    | chainedTraversal
+    : chainedTraversal
     | ANON_TRAVERSAL_ROOT DOT chainedTraversal
     ;
 

gremlin-language/src/test/resources/incorrect-traversals.txt

@@ -21,4 +21,6 @@ g.V('3').dedupe()
 g.V().order().bye('code').limit(1)
 g.V().horder().by(id)
 g.mergeE(["weight": 0.5, Direction.out: 1])
-g.mergeE(["weight": 0.5, Direction.in: 1])
+g.mergeE(["weight": 0.5, Direction.in: 1])
+g.addE('knows').from(g.V(1))
+g.addE('knows').from(g.V(1).next())