2.95.2 Internal compiler error on alpha (testcase included)

[J.H.M. Dassen (Ray)]

[This problem was reported via the Debian Bugtracking System
( http://bugs.debian.org ); please Cc: 55291@bugs.debian.org on on-topic
replies]

The following code triggers an internal compiler error with gcc 2.95.2 on
Alpha systems:

/*
$ gcc -v -c -O
Reading specs from /usr/lib/gcc-lib/alpha-linux/2.95.2/specs
gcc version 2.95.2 20000313 (Debian GNU/Linux)

Produces internal compiler error in find_basic_blocks_1', at flow.c:732.

The program evokes undefined behaviour by jumping over a nontrivial destructor,
so there is no need for the compiler to actually produce working code.  Ideally
one would like to see a warning message instead.

The word "must" in the following code refers to things that are necessary in
order to reproduce the problem.
*/

int foo(); // (some operation that won't be optimized away)

struct MyString
{
  MyString(int) {} // constructor must have at least one argument
  ~MyString() { foo(); } // destructor must be inline and nontrivial
};

void trigger()
{
  while (1) // must be a real loop--`if' or `while (false)' doesn't fail
  {
    MyString text(0); // create object with nontrivial destructor

    // conditionally skip past text.~MyString(): UNDEFINED BEHAVIOUR
    if (foo()) goto finish;

    foo(); // perform conditional operation, creating 2 realistic exit paths
  }

finish:
  {} // (not relevant)
} // (internal compiler error)
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