Give ntConstant an end position

A constant declaration produced a node with no end position at all, so a
consumer working in line ranges could not tell how far the declaration
reached. That silently truncates any constant whose value spans lines:

  const
    Banner = 'first part ' +
             'second part';

reported only the first line, and a tool slicing that range dropped the
continuation.

ntConstant was built with FStack.Push, so it was a plain TSyntaxNode with
nowhere to record an end. Two changes are needed, because the node the
caller finally sees is not the node that was parsed:

  ConstantDeclaration now pushes a compound node and records its end, the
  same way TypeDeclaration already does. This gives the intermediate
  ConstList an accurate extent.

  ConstSection rebuilds each constant from that ConstList, so it also has
  to push a compound node and inherit the end from it. The start still
  comes from the name, which is what a caller looking for the constant
  expects; only the end is new.

TCompoundSyntaxNode.AssignEndPositionFrom is the counterpart to the
existing AssignPositionFrom, for exactly this rebuild case.

Single-line constants keep ending on their own line - the new test asserts
both directions, since an end that ran on to the next declaration would be
no more useful than one that stopped short.

Verified against the existing suite: 42 passing, with the one pre-existing
Serialization.BinaryRoundTrip failure unchanged (line_seq holds a pointer
value that does not survive a round trip, unrelated to this change).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: Patrick Quist

Source/DelphiAST.Classes.pas

@@ -104,6 +104,8 @@   TCompoundSyntaxNode = class(TSyntaxNode)
     FEndLine: Integer;
   public
     function Clone: TSyntaxNode; override;
+    //counterpart to AssignPositionFrom, for a node rebuilt from a parsed one
+    procedure AssignEndPositionFrom(const Node: TCompoundSyntaxNode);
 
     property EndCol: Integer read FEndCol write FEndCol;
     property EndLine: Integer read FEndLine write FEndLine;
@@ -629,6 +631,12 @@ procedure TSyntaxNode.AssignPositionFrom(const Node: TSyntaxNode);
 
 { TCompoundSyntaxNode }
 
+procedure TCompoundSyntaxNode.AssignEndPositionFrom(const Node: TCompoundSyntaxNode);
+begin
+  FEndCol := Node.EndCol;
+  FEndLine := Node.EndLine;
+end;
+
 function TCompoundSyntaxNode.Clone: TSyntaxNode;
 begin
   Result := inherited;

Source/DelphiAST.pas

@@ -1195,9 +1195,11 @@ procedure TPasSyntaxTreeBuilder.CompoundStatement;
 
 procedure TPasSyntaxTreeBuilder.ConstantDeclaration;
 begin
-  FStack.Push(ntConstant);
+  //compound: a constant's value can span lines, so record where it ends. as TypeDeclaration.
+  FStack.PushCompoundSyntaxNode(ntConstant);
   try
     inherited;
+    SetCurrentCompoundNodesEndPosition;
   finally
     FStack.Pop;
   end;
@@ -1329,9 +1331,12 @@ procedure TPasSyntaxTreeBuilder.ConstSection;
         if Constant.Typ <> ntName then
           Continue;
 
-        Temp := FStack.Push(ConstList.Typ);
+        //compound: start from the name, end from the ConstList that measured the value.
+        Temp := FStack.PushCompoundSyntaxNode(ConstList.Typ);
         try
           Temp.AssignPositionFrom(Constant);
+          if ConstList is TCompoundSyntaxNode then
+            TCompoundSyntaxNode(Temp).AssignEndPositionFrom(TCompoundSyntaxNode(ConstList));
 
           FStack.AddChild(Constant.Clone);
           if Assigned(TypeInfo) then

Test/UnitTests/DelphiAST.Tests.pas

@@ -177,6 +177,39 @@ procedure TestSourcePositions;
   end;
 end;
 
+procedure TestConstantEndPosition;
+var
+  Root, ConstsNode, Node, Spanning, Single: TSyntaxNode;
+begin
+  Root := ParseSource('unit Consts;' + sLineBreak + 'interface' + sLineBreak + 'const' +
+    sLineBreak + '  Spanning = ''first part '' +' + sLineBreak + '    ''second part'';' +
+    sLineBreak + '  Single = 42;' + sLineBreak + 'implementation' + sLineBreak + 'end.');
+  try
+    ConstsNode := FindDescendant(Root, ntConstants);
+    AssertNotNil(ConstsNode, 'No const section was produced');
+    Spanning := nil;
+    Single := nil;
+    for Node in ConstsNode.ChildNodes do
+      if Node.Typ = ntConstant then
+        if Node.Line = 4 then
+          Spanning := Node
+        else if Node.Line = 6 then
+          Single := Node;
+
+    AssertNotNil(Spanning, 'No constant starting on line 4');
+    AssertTrue(Spanning is TCompoundSyntaxNode,
+      'Constant node must be compound so it can carry an end position');
+    AssertEquals(5, TCompoundSyntaxNode(Spanning).EndLine,
+      'A multi-line constant must reach the last line of its value');
+
+    AssertNotNil(Single, 'No constant starting on line 6');
+    AssertEquals(6, TCompoundSyntaxNode(Single).EndLine,
+      'A single-line constant must end on its own line, not run on to what follows');
+  finally
+    Root.Free;
+  end;
+end;
+
 procedure TestInvalidSyntax;
 var
   Root: TSyntaxNode;
@@ -229,6 +262,7 @@ procedure RunAllTests;
   RunTest('AST.GenericRecordAndProperty', TestGenericRecordAndProperty);
   RunTest('Writer.LiteralsUnicodeAndXmlEscaping', TestLiteralsAndUnicode);
   RunTest('AST.SourcePositions', TestSourcePositions);
+  RunTest('AST.ConstantEndPosition', TestConstantEndPosition);
   RunTest('Parser.InvalidSyntax', TestInvalidSyntax);
   {$IFNDEF FPC}
   RunTest('Serialization.BinaryRoundTrip', TestBinarySerializationRoundTrip);