GoToDefinition on var in var pattern doesn't navigate to type

[jcouv]

It is possible to use GoToDefinition on var in local declarations, out variables and deconstructions.
But it doesn't work on a var pattern:

string M() { }

void M2()
{
  if (M() is var$$ x && x.Length > 0) // GoToDefinition on `var` should go to definition of `string` type
  {
  }
}

Looking at compiler test SwitchExpression_10, I think that GetDeclaredSymbol and GetTypeInfo work on var patterns, so I suspect this is an IDE problem.

[Youssef1313]

One difference to note is that var in patterns is parsed as VarKeyword. While in local declarations it's parsed as IdentifierToken.

[Youssef1313]

I'm not able to debug currently.

But I see the following method is used by SymbolFinder:

roslyn/src/Workspaces/SharedUtilitiesAndExtensions/Compiler/CSharp/Services/SyntaxFacts/CSharpSyntaxFacts.cs

Lines 513 to 534 in 1209b91

	public bool IsBindableToken(SyntaxToken token)
	{
	if (this.IsWord(token) || this.IsLiteral(token) || this.IsOperator(token))
	{
	switch ((SyntaxKind)token.RawKind)
	{
	case SyntaxKind.DelegateKeyword:
	case SyntaxKind.VoidKeyword:
	return false;
	}
	return true;
	}
	// In the order by clause a comma might be bound to ThenBy or ThenByDescending
	if (token.Kind() == SyntaxKind.CommaToken && token.Parent.IsKind(SyntaxKind.OrderByClause))
	{
	return true;
	}
	return false;
	}

I suspect that it returns true for var when it's IdentifierToken, but not when it's VarKeyword. (I was incorrect)

[Youssef1313]

@jcouv I opened #51620 in an attempt to fix this.