third_party/libcxxabi: Add test suite (#1076)

Added the `libcxxabi` test suite as found in LLVM 17.0.6.

Some tests that do not apply to the current configuration of
comsopolitan are not added. These include:
- `backtrace_test`, `forced_unwind*`: Use unwind function unsupported in
SjLj mode.
- `noexception*`: Designed to test `libcxxabi` in no exceptions mode.

Some tests are added but not enabled due to bugs specific to GCC or
cosmopolitan. These are clearly indicated in the `BUILD.mk` file.

third_party/libcxxabi/test/catch_class_04.pass.cc

@@ -0,0 +1,221 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+/*
+    This test checks that adjustedPtr is correct as there exist offsets in this
+    object for the various subobjects, all of which have a unique id_ to
+    check against.  It also checks that virtual bases work properly
+*/
+
+// UNSUPPORTED: no-exceptions
+
+// Compilers emit warnings about exceptions of type 'Child' being caught by
+// an earlier handler of type 'Base'. Congrats, you've just diagnosed the
+// behavior under test.
+// ADDITIONAL_COMPILE_FLAGS: -Wno-exceptions
+
+#include "third_party/libcxx/exception"
+#include "libc/isystem/stdlib.h"
+#include "libc/isystem/assert.h"
+
+struct B
+{
+    static int count;
+    int id_;
+    explicit B(int id) : id_(id) {count++;}
+    B(const B& a) : id_(a.id_) {count++;}
+    ~B() {count--;}
+};
+
+int B::count = 0;
+
+struct C1
+    : virtual B
+{
+    static int count;
+    int id_;
+    explicit C1(int id) : B(id-2), id_(id) {count++;}
+    C1(const C1& a) : B(a.id_-2), id_(a.id_) {count++;}
+    ~C1() {count--;}
+};
+
+int C1::count = 0;
+
+struct C2
+    : virtual private B
+{
+    static int count;
+    int id_;
+    explicit C2(int id) : B(id-2), id_(id) {count++;}
+    C2(const C2& a) : B(a.id_-2), id_(a.id_) {count++;}
+    ~C2() {count--;}
+};
+
+int C2::count = 0;
+
+struct A
+    : C1, C2
+{
+    static int count;
+    int id_;
+    explicit A(int id) : B(id+3), C1(id-1), C2(id-2), id_(id) {count++;}
+    A(const A& a) :  B(a.id_+3), C1(a.id_-1), C2(a.id_-2), id_(a.id_) {count++;}
+    ~A() {count--;}
+};
+
+int A::count = 0;
+
+void f1()
+{
+    assert(A::count == 0);
+    assert(C1::count == 0);
+    assert(C2::count == 0);
+    assert(B::count == 0);
+    A a(5);
+    assert(A::count == 1);
+    assert(C1::count == 1);
+    assert(C2::count == 1);
+    assert(B::count == 1);
+
+    assert(a.id_ == 5);
+    assert(static_cast<C1&>(a).id_ == 4);
+    assert(static_cast<C2&>(a).id_ == 3);
+    assert(static_cast<B&>(a).id_ == 8);
+    throw a;
+    assert(false);
+}
+
+void f2()
+{
+    try
+    {
+        assert(A::count == 0);
+        assert(C1::count == 0);
+        assert(C2::count == 0);
+        assert(B::count == 0);
+        f1();
+        assert(false);
+    }
+    catch (const A& a)  // can catch A
+    {
+        assert(a.id_ == 5);
+        assert(static_cast<const C1&>(a).id_ == 4);
+        assert(static_cast<const C2&>(a).id_ == 3);
+        assert(static_cast<const B&>(a).id_ == 8);
+        throw;
+    }
+    catch (const C1&)
+    {
+        assert(false);
+    }
+    catch (const C2&)
+    {
+        assert(false);
+    }
+    catch (const B&)
+    {
+        assert(false);
+    }
+}
+
+void f3()
+{
+    try
+    {
+        assert(A::count == 0);
+        assert(C1::count == 0);
+        assert(C2::count == 0);
+        assert(B::count == 0);
+        f2();
+        assert(false);
+    }
+    catch (const B& a)  // can catch B
+    {
+        assert(static_cast<const B&>(a).id_ == 8);
+        throw;
+    }
+    catch (const C1& c1)
+    {
+        assert(false);
+    }
+    catch (const C2&)
+    {
+        assert(false);
+    }
+}
+
+void f4()
+{
+    try
+    {
+        assert(A::count == 0);
+        assert(C1::count == 0);
+        assert(C2::count == 0);
+        assert(B::count == 0);
+        f3();
+        assert(false);
+    }
+    catch (const C2& c2)  // can catch C2
+    {
+        assert(c2.id_ == 3);
+        throw;
+    }
+    catch (const B& a)  // can not catch B (ambiguous base)
+    {
+        assert(false);
+    }
+    catch (const C1&)
+    {
+        assert(false);
+    }
+}
+
+void f5()
+{
+    try
+    {
+        assert(A::count == 0);
+        assert(C1::count == 0);
+        assert(C2::count == 0);
+        assert(B::count == 0);
+        f4();
+        assert(false);
+    }
+    catch (const C1& c1)  // can catch C1
+    {
+        assert(c1.id_ == 4);
+        assert(static_cast<const B&>(c1).id_ == 8);
+        throw;
+    }
+    catch (const B& a)
+    {
+        assert(false);
+    }
+    catch (const C2&)
+    {
+        assert(false);
+    }
+}
+
+int main(int, char**)
+{
+    try
+    {
+        f5();
+        assert(false);
+    }
+    catch (...)
+    {
+    }
+    assert(A::count == 0);
+    assert(C1::count == 0);
+    assert(C2::count == 0);
+    assert(B::count == 0);
+
+    return 0;
+}