nl_tokens: Check each type parameter and check that list has no duplicate type parameter declarations
pl_tokens: function checkTypeParameters ( typeParameterDeclarations ) { if ( typeParameterDeclarations ) { for ( var i = 0 , n = typeParameterDeclarations . length ; i < n ; i ++ ) { var node = typeParameterDeclarations [ i ] ; checkTypeParameter ( node ) ; if ( produceDiagnostics ) { for ( var j = 0 ; j < i ; j ++ ) { if ( typeParameterDeclarations [ j ] . symbol === node . symbol ) { error ( node . name , ts . Diagnostics . Duplicate_identifier_0 , ts . declarationNameToString ( <mask> . name ) ) ; } } } } } }