[GR-18908] Variable definition with type annotation doesn't require an assignment.

Author: ppisl

graalpython/com.oracle.graal.python.test/src/com/oracle/graal/python/test/parser/AssignmentTests.java

@@ -208,4 +208,9 @@ public void nonLocal01() throws Exception {
                                         "  inner()\n",
                         "SyntaxError: name 'x' is assigned to before nonlocal declaration");
     }
+
+    @Test
+    public void annotationType01() throws Exception {
+        checkTreeResult("j: int");
+    }
 }

graalpython/com.oracle.graal.python.test/testData/goldenFiles/AssignmentTests/annotationType01.tast

@@ -0,0 +1,14 @@
+ModuleRootNode Name: <module 'annotationType01'> SourceSection: [0,6]`j: int`
+  Signature: varArgs=False, varKeywordArgs=False, noArguments=True, positionalOnly=True, requiresKeywordArgs=False
+  FreeVars: None
+  NeedsCellFrame: False
+  FrameDescriptor:  Empty
+  Documentation: None
+  InnerRootNode SourceSection: [0,6]`j: int`
+    ExpressionWithSideEffect SourceSection: [0,6]`j: int`
+      Expression:
+        EmptyNode SourceSection: None
+      SideEffect:
+        WriteNameNodeGen SourceSection: [0,6]`j: int`
+          Identifier: j
+          ObjectLiteralNode SourceSection: None

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/parser/antlr/Python3New.g4

@@ -550,9 +550,15 @@ expr_stmt
 	(
 		':' t=test
 		(
-			'=' test { rhs = $test.result; rhsStopIndex = getStopIndex($test.stop);}
+			'=' test { rhs = $test.result;}
 		)?
-		{ push(new AnnAssignmentSSTNode($lhs.result, $t.result, rhs, getStartIndex($ctx), rhsStopIndex)); }
+		{ 
+                    rhsStopIndex = getStopIndex($test.stop);
+                    if (rhs == null) {
+                        rhs = new SimpleSSTNode(SimpleSSTNode.Type.NONE,  -1, -1);
+                    }
+                    push(new AnnAssignmentSSTNode($lhs.result, $t.result, rhs, getStartIndex($ctx), rhsStopIndex)); 
+                }
 		|
 		augassign
 		(

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/parser/sst/FactorySSTVisitor.java

@@ -997,7 +997,9 @@ public PNode visit(SimpleSSTNode node) {
                 break;
             case NONE:
                 result = nodeFactory.createObjectLiteral(PNone.NONE);
-                result.assignSourceSection(createSourceSection(node.startOffset, node.endOffset));
+                if (node.startOffset < node.endOffset) {
+                    result.assignSourceSection(createSourceSection(node.startOffset, node.endOffset));
+                }
                 break;
             case ELLIPSIS:
                 result = nodeFactory.createObjectLiteral(PEllipsis.INSTANCE);