Issue 6934

It seems transversal() can't run at compile-time:
import std.range: transversal;
int foo() {
 auto M = [[1,2], [3,4]];
 foreach (x; transversal(M, 0)) {}
 return 0;
}
enum _ = foo();
void main() {}
DMD 2.057head gives:
...\dmd2\src\phobos\std\array.d(328): Error: Cannot determine length of Transversal([[1,2],[3,4]],0u)._input at compile time
...\dmd2\src\phobos\std\range.d(4648): called from here: popFront(this._input)
test.d(4): called from here: __r1.popFront()
test.d(7): called from here: foo()

Reduced test case:
------
struct Struct6934 {
 int[] x = [1,2];
}
void bar6934(ref int[] p) {
 p = p[1..$];
}
int bug6934() {
 Struct6934 q;
 bar6934(q.x);
 return 1;
}
static assert(bug6934());

In fact passing arrays by reference is broken in non-trivial cases.
Changing the test case to include an index or slice assignment reveals wrong-code problems:
void bar6934(ref int[] p) {
 p[0] = 12;
 assert(p[0] == 12); // fails!!!
 p[0..1] = 17;
 assert(p[0] == 17); // fails!!! 
 p = p[1..$];
}
This applies to any complicated passing of an array by ref (any dotvar or index expression, or combination thereof).
It applies to array index assignment, and slice assignment.

https://github.com/D-Programming-Language/dmd/commit/746d98fb0daacbd6a9efab1da6aacd2d7b55b39f
https://github.com/D-Programming-Language/dmd/commit/0051ed8ea86472083ed205a4857399d1f8defd71 

*** Issue 7109 has been marked as a duplicate of this issue. ***