https://bugs.llvm.org/show_bug.cgi?id=18538

The assertion in the following program should never fail because
variables with automatic storage duration in a function should be
created for each recursive invocation, and such distinct objects'
address should not compare equal.

  #include <assert.h>
  #include <stdio.h>
  int f(const int* p)
  {
    const int c[] = {12345,56789};
    assert(p != c);
    if (p == 0) { return f(c); }
    puts("Done.");
    return 0;
  }
  int main()
  {
    f(0);
  }

Clang 3.3 seems violating the rule and causes an assertion failure.
http://melpon.org/wandbox/permlink/tYmnEVjMNP33nYHr
> prog.exe: prog.c:6: int f(const int *): Assertion `p != c' failed.


I'm referring WG14 N1570.
http://www.open-std.org/jtc1/sc22/wg14/www/standards.html

From 6.2.4 p6:
> For such an object that does not have a variable length array type, its
> lifetime extends from entry into the block with which it is associated
> until execution of that block ends in any way. (Entering an enclosed
> block or calling a function suspends, but does not end, execution of the
> current block.) If the block is entered recursively, a new instance of
> the object is created each time.


6.5.9 p6
> Two pointers compare equal if and only if both are null pointers, both
> are pointers to the same object ...


If the variable is not an array, there seems no problem.
http://melpon.org/wandbox/permlink/uYeR8GbRvuQN3CMC


-fmerge-all-constants being enabled required the kernel to implement a workaround: https://lkml.org/lkml/2018/3/20/872

Not highest priority since the workaround is in place, but it should be fixed eventually, changing the default seems trivial.