struct initialization and assignment by field name

[Bobby Bingham]

I'm just starting out with D, and am wondering about some differences 
with C regarding struct literals. In C99, I can do this:

struct MyStruct {
    int  number;
    char letter;
};

int main() {
    static struct MyStruct foo = { .number = 42, .letter = 'a' };
    struct MyStruct bar = { .number = 42, .letter = 'a' };
    bar = (struct MyStruct) { .number = 42, .letter = 'a' };
    return 0;
}

That is, I can initialize static and non-static struct variables by 
specifying the fields as key-value pairs.  I can also assign a struct 
literal to an already-declared struct variable in the same way.

If we try this in D:

struct MyStruct {
    int  number;
    char letter;
}

int main() {
    static MyStruct foo = { number:42, letter:'a' }; // works
    MyStruct bar = { number:42, letter:'a' };        // works despite [1]
    bar = { number:42, letter:'a' };                 // fails to compile
    return 0;
}

That is, I can do something similar for static struct initializers in D, 
and non-static struct initializers despite this being documented as not 
allowed.

It appears that this form of struct literal really can only be used in 
initializers -- the assignment to a previously declared varaible fails to 
compile.

I'm hoping somebody can shed some light on the rationale for only 
supporting this form of struct literal in initializers. And also why it's 
documented to only work for static initializers -- is this an error in 
the documentation, or is the compiler allowing things it shouldn't?

Thanks,
Bobby

1. http://dlang.org/struct.html
   "The sta­tic ini­tial­izer syn­tax can also be used to ini­tial­ize non-
    static vari­ables, pro­vided that the mem­ber names are not given."