No check that we do not call an export function

[eponier]

If we try to call an export function, we do not get a clear message "cannot call an export function". Instead, we can get:

• an assertion false in regalloc.ml

export fn f(reg u64 arg) -> reg u64 {
  reg u64 res;
  res = arg;
  return res;
}

export fn main () -> reg u64 {
  reg u64 res x;
  x = 2;
  res = f (res);
  res += x;
  return res;
}

• the error linearisation: (one_varmap) nowhere to store the return address

export fn f(reg u64 arg) -> reg u64 {
  reg u64 res;
  res = arg;
  return res;
}

export fn main () -> reg u64 {
  reg u64 res;
  res = f (res);
  return res;
}

[vbgl]

Current version says:

typing error: call to export function needs to be inlined

Can this be closed?

[eponier]

Indeed, the error message is now clear.