vala: CodeNode.source_reference is optional, so let the API respect that

38 files changed, 42 insertions, 42 deletions

diff --git a/vala/valaarraycopymethod.vala b/vala/valaarraycopymethod.vala
index 97086cd83..542f108b1 100644
--- a/vala/valaarraycopymethod.vala
+++ b/vala/valaarraycopymethod.vala
@@ -31,7 +31,7 @@ public class Vala.ArrayCopyMethod : Method {
 	 *
 	 * @return newly created method
 	 */
-	public ArrayCopyMethod (SourceReference source_reference) {
+	public ArrayCopyMethod (SourceReference? source_reference = null) {
 		base ("copy", new InvalidType (), source_reference);
 		external = true;
 	}
diff --git a/vala/valaarraycreationexpression.vala b/vala/valaarraycreationexpression.vala
index 60dec766a..8af8fa8fe 100644
--- a/vala/valaarraycreationexpression.vala
+++ b/vala/valaarraycreationexpression.vala
@@ -98,7 +98,7 @@ public class Vala.ArrayCreationExpression : Expression {
 		return sizes;
 	}
 
-	public ArrayCreationExpression (DataType element_type, int rank, InitializerList? initializer_list, SourceReference source_reference) {
+	public ArrayCreationExpression (DataType element_type, int rank, InitializerList? initializer_list, SourceReference? source_reference = null) {
 		this.element_type = element_type;
 		this.rank = rank;
 		this.initializer_list = initializer_list;
diff --git a/vala/valaarraylengthfield.vala b/vala/valaarraylengthfield.vala
index 220718000..791039e1c 100644
--- a/vala/valaarraylengthfield.vala
+++ b/vala/valaarraylengthfield.vala
@@ -31,7 +31,7 @@ public class Vala.ArrayLengthField : Field {
 	 *
 	 * @return newly created field
 	 */
-	public ArrayLengthField (SourceReference source_reference) {
+	public ArrayLengthField (SourceReference? source_reference = null) {
 		base ("length", new InvalidType (), null, source_reference);
 		external = true;
 	}
diff --git a/vala/valaarraymovemethod.vala b/vala/valaarraymovemethod.vala
index 916ae04f2..84ad5f385 100644
--- a/vala/valaarraymovemethod.vala
+++ b/vala/valaarraymovemethod.vala
@@ -31,7 +31,7 @@ public class Vala.ArrayMoveMethod : Method {
 	 *
 	 * @return newly created method
 	 */
-	public ArrayMoveMethod (SourceReference source_reference) {
+	public ArrayMoveMethod (SourceReference? source_reference = null) {
 		base ("move", new VoidType (), source_reference);
 		external = true;
 	}
diff --git a/vala/valaarrayresizemethod.vala b/vala/valaarrayresizemethod.vala
index c1008777e..7a96827a5 100644
--- a/vala/valaarrayresizemethod.vala
+++ b/vala/valaarrayresizemethod.vala
@@ -31,7 +31,7 @@ public class Vala.ArrayResizeMethod : Method {
 	 *
 	 * @return newly created method
 	 */
-	public ArrayResizeMethod (SourceReference source_reference) {
+	public ArrayResizeMethod (SourceReference? source_reference = null) {
 		base ("resize", new VoidType (), source_reference);
 		external = true;
 		set_attribute_double ("CCode", "instance_pos", 0.1);
diff --git a/vala/valaarraytype.vala b/vala/valaarraytype.vala
index 9a8a039c9..c1ddb8829 100644
--- a/vala/valaarraytype.vala
+++ b/vala/valaarraytype.vala
@@ -83,7 +83,7 @@ public class Vala.ArrayType : ReferenceType {
 	private ArrayMoveMethod move_method;
 	private ArrayCopyMethod copy_method;
 
-	public ArrayType (DataType element_type, int rank, SourceReference? source_reference) {
+	public ArrayType (DataType element_type, int rank, SourceReference? source_reference = null) {
 		base (null);
 		this.element_type = element_type;
 		this.rank = rank;
diff --git a/vala/valablock.vala b/vala/valablock.vala
index a702ea011..5ae943c32 100644
--- a/vala/valablock.vala
+++ b/vala/valablock.vala
@@ -43,7 +43,7 @@ public class Vala.Block : Symbol, Statement {
 	 *
 	 * @param source_reference  reference to source code
 	 */
-	public Block (SourceReference? source_reference) {
+	public Block (SourceReference? source_reference = null) {
 		base (null, source_reference);
 	}
 
diff --git a/vala/valabreakstatement.vala b/vala/valabreakstatement.vala
index e8f2dd8bf..d1c0a10c6 100644
--- a/vala/valabreakstatement.vala
+++ b/vala/valabreakstatement.vala
@@ -32,7 +32,7 @@ public class Vala.BreakStatement : CodeNode, Statement {
 	 * @param source reference to source code
 	 * @return       newly created break statement
 	 */
-	public BreakStatement (SourceReference? source) {
+	public BreakStatement (SourceReference? source = null) {
 		source_reference = source;
 	}
 
diff --git a/vala/valacastexpression.vala b/vala/valacastexpression.vala
index f86aad157..d938b5391 100644
--- a/vala/valacastexpression.vala
+++ b/vala/valacastexpression.vala
@@ -67,7 +67,7 @@ public class Vala.CastExpression : Expression {
 	 * @param type_reference  target type
 	 * @return                newly created cast expression
 	 */
-	public CastExpression (Expression inner, DataType type_reference, SourceReference source_reference) {
+	public CastExpression (Expression inner, DataType type_reference, SourceReference? source_reference = null) {
 		this.type_reference = type_reference;
 		this.source_reference = source_reference;
 		this.is_silent_cast = false;
@@ -75,7 +75,7 @@ public class Vala.CastExpression : Expression {
 		this.inner = inner;
 	}
 
-	public CastExpression.silent (Expression inner, DataType type_reference, SourceReference source_reference) {
+	public CastExpression.silent (Expression inner, DataType type_reference, SourceReference? source_reference = null) {
 		this.type_reference = type_reference;
 		this.source_reference = source_reference;
 		this.is_silent_cast = true;
@@ -83,7 +83,7 @@ public class Vala.CastExpression : Expression {
 		this.inner = inner;
 	}
 
-	public CastExpression.non_null (Expression inner, SourceReference source_reference) {
+	public CastExpression.non_null (Expression inner, SourceReference? source_reference = null) {
 		this.inner = inner;
 		this.is_non_null_cast = true;
 		this.source_reference = source_reference;
diff --git a/vala/valaconditionalexpression.vala b/vala/valaconditionalexpression.vala
index db9342c4e..1bc100081 100644
--- a/vala/valaconditionalexpression.vala
+++ b/vala/valaconditionalexpression.vala
@@ -77,7 +77,7 @@ public class Vala.ConditionalExpression : Expression {
 	 * @param false_expr expression to be evaluated if condition is false
 	 * @return           newly created conditional expression
 	 */
-	public ConditionalExpression (Expression cond, Expression true_expr, Expression false_expr, SourceReference source) {
+	public ConditionalExpression (Expression cond, Expression true_expr, Expression false_expr, SourceReference? source = null) {
 		condition = cond;
 		true_expression = true_expr;
 		false_expression = false_expr;
diff --git a/vala/valaconstant.vala b/vala/valaconstant.vala
index ba0c5660c..871cff62e 100644
--- a/vala/valaconstant.vala
+++ b/vala/valaconstant.vala
@@ -63,7 +63,7 @@ public class Vala.Constant : Symbol {
 	 * @param source_reference reference to source code
 	 * @return                 newly created constant
 	 */
-	public Constant (string name, DataType? type_reference, Expression? value, SourceReference? source_reference, Comment? comment = null) {
+	public Constant (string name, DataType? type_reference, Expression? value, SourceReference? source_reference = null, Comment? comment = null) {
 		base (name, source_reference, comment);
 		if (type_reference != null) {
 			this.type_reference = type_reference;
diff --git a/vala/valaconstructor.vala b/vala/valaconstructor.vala
index a867f3a39..733a1566d 100644
--- a/vala/valaconstructor.vala
+++ b/vala/valaconstructor.vala
@@ -46,7 +46,7 @@ public class Vala.Constructor : Subroutine {
 	 * @param source reference to source code
 	 * @return       newly created constructor
 	 */
-	public Constructor (SourceReference? source) {
+	public Constructor (SourceReference? source = null) {
 		base (null, source);
 	}
 
diff --git a/vala/valacontinuestatement.vala b/vala/valacontinuestatement.vala
index dc9c93950..f10b058d5 100644
--- a/vala/valacontinuestatement.vala
+++ b/vala/valacontinuestatement.vala
@@ -32,7 +32,7 @@ public class Vala.ContinueStatement : CodeNode, Statement {
 	 * @param source reference to source code
 	 * @return       newly created continue statement
 	 */
-	public ContinueStatement (SourceReference source) {
+	public ContinueStatement (SourceReference? source = null) {
 		source_reference = source;
 	}
 
diff --git a/vala/valadeclarationstatement.vala b/vala/valadeclarationstatement.vala
index ebc2e3624..30732b4a6 100644
--- a/vala/valadeclarationstatement.vala
+++ b/vala/valadeclarationstatement.vala
@@ -49,7 +49,7 @@ public class Vala.DeclarationStatement : CodeNode, Statement {
 	 * @param source_reference  reference to source code
 	 * @return                  newly created declaration statement
 	 */
-	public DeclarationStatement (Symbol declaration, SourceReference? source_reference) {
+	public DeclarationStatement (Symbol declaration, SourceReference? source_reference = null) {
 		this.declaration = declaration;
 		this.source_reference = source_reference;
 	}
diff --git a/vala/valadelegatedestroyfield.vala b/vala/valadelegatedestroyfield.vala
index e175b172a..3f2613cee 100644
--- a/vala/valadelegatedestroyfield.vala
+++ b/vala/valadelegatedestroyfield.vala
@@ -29,7 +29,7 @@ public class Vala.DelegateDestroyField : Field {
 	 *
 	 * @return newly created field
 	 */
-	public DelegateDestroyField (SourceReference source_reference) {
+	public DelegateDestroyField (SourceReference? source_reference = null) {
 		base ("destroy", CodeContext.get ().analyzer.delegate_target_destroy_type, null, source_reference);
 		external = true;
 	}
diff --git a/vala/valadelegatetargetfield.vala b/vala/valadelegatetargetfield.vala
index 6f3782782..06bbd6c39 100644
--- a/vala/valadelegatetargetfield.vala
+++ b/vala/valadelegatetargetfield.vala
@@ -29,7 +29,7 @@ public class Vala.DelegateTargetField : Field {
 	 *
 	 * @return newly created field
 	 */
-	public DelegateTargetField (SourceReference source_reference) {
+	public DelegateTargetField (SourceReference? source_reference = null) {
 		base ("target", new PointerType (new VoidType ()), null, source_reference);
 		external = true;
 	}
diff --git a/vala/valaelementaccess.vala b/vala/valaelementaccess.vala
index 3e8d111ad..45b02ecdb 100644
--- a/vala/valaelementaccess.vala
+++ b/vala/valaelementaccess.vala
@@ -59,7 +59,7 @@ public class Vala.ElementAccess : Expression {
 		return indices;
 	}
 
-	public ElementAccess (Expression container, SourceReference source_reference) {
+	public ElementAccess (Expression container, SourceReference? source_reference = null) {
 		this.source_reference = source_reference;
 		this.container = container;
 	}
diff --git a/vala/valaemptystatement.vala b/vala/valaemptystatement.vala
index 259574ac4..bcd136f74 100644
--- a/vala/valaemptystatement.vala
+++ b/vala/valaemptystatement.vala
@@ -32,7 +32,7 @@ public class Vala.EmptyStatement : CodeNode, Statement {
 	 * @param source reference to source code
 	 * @return       newly created empty statement
 	 */
-	public EmptyStatement (SourceReference source) {
+	public EmptyStatement (SourceReference? source = null) {
 		source_reference = source;
 	}
 
diff --git a/vala/valaforeachstatement.vala b/vala/valaforeachstatement.vala
index 383814085..2c74773e8 100644
--- a/vala/valaforeachstatement.vala
+++ b/vala/valaforeachstatement.vala
@@ -103,7 +103,7 @@ public class Vala.ForeachStatement : Block {
 	 * @param source_reference  reference to source code
 	 * @return                  newly created foreach statement
 	 */
-	public ForeachStatement (DataType? type_reference, string variable_name, Expression collection, Block body, SourceReference source_reference) {
+	public ForeachStatement (DataType? type_reference, string variable_name, Expression collection, Block body, SourceReference? source_reference = null) {
 		base (source_reference);
 		this.variable_name = variable_name;
 		this.collection = collection;
diff --git a/vala/valagenericdestroyfield.vala b/vala/valagenericdestroyfield.vala
index 6627bcca2..a4dfd3f8d 100644
--- a/vala/valagenericdestroyfield.vala
+++ b/vala/valagenericdestroyfield.vala
@@ -29,7 +29,7 @@ public class Vala.GenericDestroyField : Field {
 	 *
 	 * @return newly created field
 	 */
-	public GenericDestroyField (SourceReference source_reference) {
+	public GenericDestroyField (SourceReference? source_reference = null) {
 		base ("destroy", CodeContext.get ().analyzer.delegate_target_destroy_type, null, source_reference);
 		external = true;
 	}
diff --git a/vala/valagenericdupfield.vala b/vala/valagenericdupfield.vala
index 12ab9ecea..97e816c0d 100644
--- a/vala/valagenericdupfield.vala
+++ b/vala/valagenericdupfield.vala
@@ -29,7 +29,7 @@ public class Vala.GenericDupField : Field {
 	 *
 	 * @return newly created field
 	 */
-	public GenericDupField (SourceReference source_reference) {
+	public GenericDupField (SourceReference? source_reference = null) {
 		base ("dup", CodeContext.get ().analyzer.generics_dup_func_type, null, source_reference);
 		external = true;
 	}
diff --git a/vala/valaifstatement.vala b/vala/valaifstatement.vala
index e6f602de1..bed1dfe9a 100644
--- a/vala/valaifstatement.vala
+++ b/vala/valaifstatement.vala
@@ -74,7 +74,7 @@ public class Vala.IfStatement : CodeNode, Statement {
 	 * @param false_stmt statement to be evaluated if condition is false
 	 * @return           newly created if statement
 	 */
-	public IfStatement (Expression cond, Block true_stmt, Block? false_stmt, SourceReference? source) {
+	public IfStatement (Expression cond, Block true_stmt, Block? false_stmt, SourceReference? source = null) {
 		condition = cond;
 		true_statement = true_stmt;
 		false_statement = false_stmt;
diff --git a/vala/valainitializerlist.vala b/vala/valainitializerlist.vala
index ac81cb07d..5451739ef 100644
--- a/vala/valainitializerlist.vala
+++ b/vala/valainitializerlist.vala
@@ -62,7 +62,7 @@ public class Vala.InitializerList : Expression {
 	 * @param source_reference reference to source code
 	 * @return                 newly created initializer list
 	 */
-	public InitializerList (SourceReference source_reference) {
+	public InitializerList (SourceReference? source_reference = null) {
 		this.source_reference = source_reference;
 	}
 
diff --git a/vala/valalambdaexpression.vala b/vala/valalambdaexpression.vala
index 9a6940f90..f48f73b9d 100644
--- a/vala/valalambdaexpression.vala
+++ b/vala/valalambdaexpression.vala
@@ -74,7 +74,7 @@ public class Vala.LambdaExpression : Expression {
 	 * @param source_reference reference to source code
 	 * @return                 newly created lambda expression
 	 */
-	public LambdaExpression (Expression expression_body, SourceReference source_reference) {
+	public LambdaExpression (Expression expression_body, SourceReference? source_reference = null) {
 		this.source_reference = source_reference;
 		this.expression_body = expression_body;
 	}
@@ -86,7 +86,7 @@ public class Vala.LambdaExpression : Expression {
 	 * @param source_reference reference to source code
 	 * @return                 newly created lambda expression
 	 */
-	public LambdaExpression.with_statement_body (Block statement_body, SourceReference source_reference) {
+	public LambdaExpression.with_statement_body (Block statement_body, SourceReference? source_reference = null) {
 		this.statement_body = statement_body;
 		this.source_reference = source_reference;
 	}
diff --git a/vala/valanulltype.vala b/vala/valanulltype.vala
index ddb8c72b8..c2accf907 100644
--- a/vala/valanulltype.vala
+++ b/vala/valanulltype.vala
@@ -26,7 +26,7 @@ using GLib;
  * The type of the null literal.
  */
 public class Vala.NullType : ReferenceType {
-	public NullType (SourceReference? source_reference) {
+	public NullType (SourceReference? source_reference = null) {
 		base (null);
 		this.nullable = true;
 		this.source_reference = source_reference;
diff --git a/vala/valapostfixexpression.vala b/vala/valapostfixexpression.vala
index 9e39773ba..e38de9bec 100644
--- a/vala/valapostfixexpression.vala
+++ b/vala/valapostfixexpression.vala
@@ -52,7 +52,7 @@ public class Vala.PostfixExpression : Expression {
 	 * @param source  reference to source code
 	 * @return newly  created postfix expression
 	 */
-	public PostfixExpression (Expression _inner, bool inc, SourceReference source) {
+	public PostfixExpression (Expression _inner, bool inc, SourceReference? source = null) {
 		inner = _inner;
 		increment = inc;
 		source_reference = source;
diff --git a/vala/valapropertyaccessor.vala b/vala/valapropertyaccessor.vala
index 6b24c2bbf..92f9a9315 100644
--- a/vala/valapropertyaccessor.vala
+++ b/vala/valapropertyaccessor.vala
@@ -88,7 +88,7 @@ public class Vala.PropertyAccessor : Subroutine {
 	 * @param source_reference   reference to source code
 	 * @return                   newly created property accessor
 	 */
-	public PropertyAccessor (bool readable, bool writable, bool construction, DataType? value_type, Block? body, SourceReference? source_reference, Comment? comment = null) {
+	public PropertyAccessor (bool readable, bool writable, bool construction, DataType? value_type, Block? body, SourceReference? source_reference = null, Comment? comment = null) {
 		base (null, source_reference, comment);
 		this.readable = readable;
 		this.writable = writable;
diff --git a/vala/valasemanticanalyzer.vala b/vala/valasemanticanalyzer.vala
index 8242efd35..fed1e86b0 100644
--- a/vala/valasemanticanalyzer.vala
+++ b/vala/valasemanticanalyzer.vala
@@ -701,7 +701,7 @@ public class Vala.SemanticAnalyzer : CodeVisitor {
 		return true;
 	}
 
-	public bool check_variadic_arguments (Iterator<Expression>? arg_it, int i, SourceReference source_reference) {
+	public bool check_variadic_arguments (Iterator<Expression>? arg_it, int i, SourceReference? source_reference = null) {
 		while (arg_it != null && arg_it.next ()) {
 			var arg = arg_it.get ();
 			if (arg.error) {
@@ -729,7 +729,7 @@ public class Vala.SemanticAnalyzer : CodeVisitor {
 		return true;
 	}
 
-	public bool check_print_format (string format, Iterator<Expression> arg_it, SourceReference source_reference) {
+	public bool check_print_format (string format, Iterator<Expression> arg_it, SourceReference? source_reference = null) {
 		bool unsupported_format = false;
 
 		weak string format_it = format;
diff --git a/vala/valasizeofexpression.vala b/vala/valasizeofexpression.vala
index 67d0b8226..1942b8eed 100644
--- a/vala/valasizeofexpression.vala
+++ b/vala/valasizeofexpression.vala
@@ -46,7 +46,7 @@ public class Vala.SizeofExpression : Expression {
 	 * @param source reference to source code
 	 * @return       newly created sizeof expression
 	 */
-	public SizeofExpression (DataType type, SourceReference source) {
+	public SizeofExpression (DataType type, SourceReference? source = null) {
 		type_reference = type;
 		source_reference = source;
 	}
diff --git a/vala/valastatementlist.vala b/vala/valastatementlist.vala
index f773a5ca7..b76b74cae 100644
--- a/vala/valastatementlist.vala
+++ b/vala/valastatementlist.vala
@@ -28,7 +28,7 @@ public class Vala.StatementList : CodeNode, Statement {
 		get { return list.size; }
 	}
 
-	public StatementList (SourceReference source_reference) {
+	public StatementList (SourceReference? source_reference = null) {
 		this.source_reference = source_reference;
 	}
 
diff --git a/vala/valasubroutine.vala b/vala/valasubroutine.vala
index e9c05ac23..a736496b3 100644
--- a/vala/valasubroutine.vala
+++ b/vala/valasubroutine.vala
@@ -36,7 +36,7 @@ public abstract class Vala.Subroutine : Symbol {
 
 	public abstract bool has_result { get; }
 
-	protected Subroutine (string? name, SourceReference? source_reference, Comment? comment = null) {
+	protected Subroutine (string? name, SourceReference? source_reference = null, Comment? comment = null) {
 		base (name, source_reference, comment);
 	}
 
diff --git a/vala/valaswitchsection.vala b/vala/valaswitchsection.vala
index 075feaa38..af5be68dc 100644
--- a/vala/valaswitchsection.vala
+++ b/vala/valaswitchsection.vala
@@ -34,7 +34,7 @@ public class Vala.SwitchSection : Block {
 	 * @param source_reference reference to source code
 	 * @return                 newly created switch section
 	 */
-	public SwitchSection (SourceReference? source_reference) {
+	public SwitchSection (SourceReference? source_reference = null) {
 		base (source_reference);
 	}
 
diff --git a/vala/valaswitchstatement.vala b/vala/valaswitchstatement.vala
index 39c95d0f3..31ef82622 100644
--- a/vala/valaswitchstatement.vala
+++ b/vala/valaswitchstatement.vala
@@ -49,7 +49,7 @@ public class Vala.SwitchStatement : CodeNode, Statement {
 	 * @param source_reference reference to source code
 	 * @return                 newly created switch statement
 	 */
-	public SwitchStatement (Expression expression, SourceReference? source_reference) {
+	public SwitchStatement (Expression expression, SourceReference? source_reference = null) {
 		this.source_reference = source_reference;
 		this.expression = expression;
 	}
diff --git a/vala/valasymbol.vala b/vala/valasymbol.vala
index 770212d47..a55299b19 100644
--- a/vala/valasymbol.vala
+++ b/vala/valasymbol.vala
@@ -210,7 +210,7 @@ public abstract class Vala.Symbol : CodeNode {
 	private Scope _scope;
 	private bool? _external;
 
-	protected Symbol (string? name, SourceReference? source_reference, Comment? comment = null) {
+	protected Symbol (string? name, SourceReference? source_reference = null, Comment? comment = null) {
 		this.name = name;
 		this.source_reference = source_reference;
 		this.comment = comment;
diff --git a/vala/valatypecheck.vala b/vala/valatypecheck.vala
index b65b2ce27..abcfeb830 100644
--- a/vala/valatypecheck.vala
+++ b/vala/valatypecheck.vala
@@ -59,7 +59,7 @@ public class Vala.TypeCheck : Expression {
 	 * @param source reference to source code
 	 * @return       newly created type check expression
 	 */
-	public TypeCheck (Expression expr, DataType type, SourceReference source) {
+	public TypeCheck (Expression expr, DataType type, SourceReference? source = null) {
 		expression = expr;
 		type_reference = type;
 		source_reference = source;
diff --git a/vala/valatypeofexpression.vala b/vala/valatypeofexpression.vala
index b2b6c536b..2449b6086 100644
--- a/vala/valatypeofexpression.vala
+++ b/vala/valatypeofexpression.vala
@@ -46,7 +46,7 @@ public class Vala.TypeofExpression : Expression {
 	 * @param source reference to source code
 	 * @return       newly created typeof expression
 	 */
-	public TypeofExpression (DataType type, SourceReference source) {
+	public TypeofExpression (DataType type, SourceReference? source = null) {
 		type_reference = type;
 		source_reference = source;
 	}
diff --git a/vala/valatypeparameter.vala b/vala/valatypeparameter.vala
index de0023b0c..8da52fd67 100644
--- a/vala/valatypeparameter.vala
+++ b/vala/valatypeparameter.vala
@@ -33,7 +33,7 @@ public class Vala.TypeParameter : Symbol {
 	 * @param source_reference  reference to source code
 	 * @return                  newly created generic type parameter
 	 */
-	public TypeParameter (string name, SourceReference source_reference) {
+	public TypeParameter (string name, SourceReference? source_reference = null) {
 		base (name, source_reference);
 	}
 
diff --git a/vala/valaunaryexpression.vala b/vala/valaunaryexpression.vala
index 2a010b6b7..a97c0b204 100644
--- a/vala/valaunaryexpression.vala
+++ b/vala/valaunaryexpression.vala
@@ -55,7 +55,7 @@ public class Vala.UnaryExpression : Expression {
 	 * @param source reference to source code
 	 * @return       newly created binary expression
 	 */
-	public UnaryExpression (UnaryOperator op, Expression _inner, SourceReference source) {
+	public UnaryExpression (UnaryOperator op, Expression _inner, SourceReference? source = null) {
 		operator = op;
 		inner = _inner;
 		source_reference = source;