[dmd-internals] Testcase that checks whether variable is allocated on stack programmatically

[Iain Buclaw]

There's a rather sour test in the testsuite (runnable/test42.d : test7290)
that looks at the address of the object, and infers locality based on the
value of the address.

This is very problematic and doesn't actually reliably test the feature, as
it makes big assumptions about the behaviour of what the compiler does.
Such as:

a) No functions are inlined.
b) There isn't any optimisations in place that omit the frame pointer from
the function.
c) The compiler pushes the objects on the stack in a deterministic order
when building under optimisations.

There needs to be a better defined test for this as the current one is
extremely implementation specific and fragile.

Only thought that immediately comes to mind other than pulling the test out
of the testsuite is to overload _d_allocmemory to ensure that it is never
called.


eg:

void* _d_allocmemory (size_t sz)
{
  assert(false);
}

void test7290()
{
  int add = 2;
  scope sdg = (int a) => a + add;  // OK, is a stack allocation.
  auto hdg = (int a) => a + add;  // Fails as _d_allocmemory is called to
initialise closure.
}


Though this would break test54 in that same file (would need to move it
out).

Thoughts?


Regards
-- 
Iain Buclaw

*(p < e ? p++ : p) = (c & 0x0f) + '0';
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