Bug 2415 – DMD allows void foo(int i, ); function definition

void foo(int i, ) //< note the comma { } void main() { foo(1); } compiles and runs.

I'm not sure but I think this might be intended in any place that accepts a comma separated list to make it easier to maintain long multi-line lists. For example, copy/pasting a bunch of entries from the start/middle of a list to the end and you don't have to worry about adding a comma after the former last element or removing the comma from the new last element. That's been my assumption, as I've actually found it useful for just that reason.

enum declaration has the same feature.

But not array literals. I wish they also had this feature. It is useful for compile time generated code.

From the newsgroup (Don): > > > I'm not sure but I think this might be intended in any place that accepts a > > comma separated list to make it easier to maintain long multi-line lists. For > > example, copy/pasting a bunch of entries from the start/middle of a list to the > > end and you don't have to worry about adding a comma after the former last > > element or removing the comma from the new last element. That's been my > > assumption, as I've actually found it useful for just that reason. > > Is it documented anywhere? For enums, and array and struct initializations: yes. For parameter and argument lists: not according to the grammars, however the inconsistency makes me wonder if (and hope) the "not allowed" ones were oversights. The following appear to be the same in both D1 docs and D2 docs: http://www.digitalmars.com/d/1.0/enum.html EnumMembers: EnumMember EnumMember , EnumMember , EnumMembers http://www.digitalmars.com/d/1.0/declaration.html ArrayMemberInitializations: ArrayMemberInitialization ArrayMemberInitialization , ArrayMemberInitialization , ArrayMemberInitializations StructMemberInitializers: StructMemberInitializer StructMemberInitializer , StructMemberInitializer , StructMemberInitializers ParameterList: Parameter Parameter , ParameterList Parameter ... ... DeclaratorIdentifierList: DeclaratorIdentifier DeclaratorIdentifier , DeclaratorIdentifierList http://www.digitalmars.com/d/1.0/template.html TemplateParameterList TemplateParameter TemplateParameter , TemplateParameterList TemplateArgumentList: TemplateArgument TemplateArgument , TemplateArgumentList http://www.digitalmars.com/d/1.0/expression.html NewExpression: NewArguments Type [ AssignExpression ] NewArguments Type ( ArgumentList ) NewArguments Type NewArguments ClassArguments BaseClasslistopt { DeclDefs } NewArguments: new ( ArgumentList ) new ( ) new ClassArguments: class ( ArgumentList ) class ( ) class ArrayLiteral: [ ArgumentList ] IndexExpression: PostfixExpression [ ArgumentList ] PostfixExpression: PrimaryExpression PostfixExpression . Identifier PostfixExpression . NewExpression PostfixExpression ++ PostfixExpression -- PostfixExpression ( ) PostfixExpression ( ArgumentList ) IndexExpression SliceExpression ArgumentList: AssignExpression AssignExpression , ArgumentList

This is the feature, not a bug.