Why can't gsl_vector_alloc be called before main starts?

Question

From the 21st century C book:

Static variables, even those inside of a function, are initialized when the program starts, before main, so you can’t initialize them with a nonconstant value.
//this fails: can't call gsl_vector_alloc() before main() starts
static gsl_vector *scratch = gsl_vector_alloc(20);

Because it yields a nonconstant value. What else ? – Quentin Oct 17 '14 at 21:05 — Quentin, Oct 17 '14 at 21:05

score 1 · Accepted Answer · answered Oct 17 '14 at 21:09

What you quoted from the book is the answer, i.e. because it wouldn't be compliant to the C standard.

All the expressions in an initializer for an object that has static storage 
duration shall be constant expressions or string literals.

Although I believe something like this is possible in C++ under certain conditions.

Why can't gsl_vector_alloc be called before main starts?

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