How do I declare a var variable with Roslyn?
I've got the following piece of code, but I can't find how to get the var TypeSyntax. Any ideas?
Syntax.LocalDeclarationStatement( declaration: Syntax.VariableDeclaration( type: Syntax.PredefinedType(Syntax.Token(SyntaxKind.VarKeyword)), variables: Syntax.SeparatedList( Syntax.VariableDeclarator( identifier: Syntax.Identifier(name))) ) ) );
this fails with an Argument exception that says: "keyword"
Syntax.LocalDeclarationStatement( declaration: Syntax.VariableDeclaration( type: Syntax.IdentifierName(Syntax.Token(SyntaxKind.VarKeyword)), variables: Syntax.SeparatedList( Syntax.VariableDeclarator( identifier: Syntax.Identifier(name)))));
Jb Evain's answer is correct; I just thought that I would add that the reason for the error is because "var" is not a predefined type. A predefined type is something like "int" or "string".
The syntactic analyzer does not know whether or not you have a class named "var" in scope; "var" is treated not as a predefined type, but rather as just another name for just another type. Only if we cannot find a type in scope named "var" does the semantic analyzer then decide, oh, this must be an implicitly typed local.
The reason for this is because "var" was added in C# 3, and there might be C# 1 or 2 programs that use "var" as the name of a type. We did not want to break those programs.
Not a precise answer to your question, but another (and simpler) way to achieve the same affect would be to use Syntax.ParseStatement:
Syntax.ParseStatement("var " + name);
To simplify answering questions like these, I've written a tool called Quoter that can generate syntax tree API calls for any given C# program: