fix anonymous struct member initialization

[kroening]

The C front-end needs to ignore the unnamed bit-field during struct
initialization; issue #3709.

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[tautschnig]

This causes Struct_Padding1 to fail, which contains an anonymous struct as part of the test. Should this test here be restricted to bitfields?

[kroening]

fixed -- it should be restricted to scalars.

[tautschnig]

unions should be exempt as well:

#include <assert.h>

struct S
{
  int i;
  union
  {
    int a;
    int b;
  };
  int j;
} s = { 1, { 2 }, 3 };

int main()
{
  assert(s.i == 1);
  assert(s.a == 2);
  assert(s.b == 2);
  assert(s.j == 3);
  return 0;
}

(and it may be worth adding such a test)

[kroening]

done

[allredj]

🚫
This PR failed Diffblue compatibility checks (cbmc commit: 4338b33).
Build URL: https://travis-ci.com/diffblue/test-gen/builds/96610343
Status will be re-evaluated on next push.
Please contact @peterschrammel, @thk123, or @allredj for support.

Common spurious failures:

• the cbmc commit has disappeared in the mean time (e.g. in a force-push)
• the author is not in the list of contributors (e.g. first-time contributors).

The incompatibility may have been introduced by an earlier PR. In that case merging this
PR should be avoided unless it fixes the current incompatibility.

[allredj]

✔️
Passed Diffblue compatibility checks (cbmc commit: 4548fc1).
Build URL: https://travis-ci.com/diffblue/test-gen/builds/96632876