Confused by struct constructors

[Simen kjaeraas]

In attempting to create a function to initialize any array of structs in a  
simple manner, I created this code:

void fillArr( uint n, T, U... )( ref T[] arr, U args ) {
   arr[0] = T( U[0..n] );
   static if ( U.length > n ) {
     fillArr!( n )( arr[ 1..$ ], args[ n..$ ] );
   }
}

T[] initArray( T, uint n = U.length, U... )( U args ) if ( n > 0 ) {
   static if (
//      ( __traits( compiles, T( args[ 0..n ] ) ) ) && // Same as below.  
Added for completeness.
       ( is( typeof( T( args[ 0..n ] ) ) ) ) &&  // If we can instantiate a  
struct with this
       ( U.length % n == 0 )                     // and it matches the  
number of arguments,
       ) {
     T[] result = new T[ U.length / n ];         // Create an array
     fillArr!( n )( result, args );              // and fill it.
     return result;
   } else {
     return initArray!( T, n-1, U )( args );     // Didn't work. Try  
another parameter count.
   }
}

However, upon testing it with this code:

struct S {
   int n;
   string s;
}
auto s = initArray!( S )( 1, "a", 2, "b", 3, "c" );

I get this error:

foo.d(34): Error: cannot implicitly convert expression ((int _param_1,  
string _param_2)) of type (int _param_1, string _param_2) to int


The problem is apparently on this line:
   arr[0] = T( U[0..n] );
Though I am confuzzled as to why it does not work ( it works in initArray,  
line 2 ). Any ideas?

-- 
Simen