[gcc r16-114] libstdc++: Add std::deque<>::shrink_to_fit test

[Francois Dumont]

https://gcc.gnu.org/g:2fb6ddd45872f04306375572c281ec65ee59c761

commit r16-114-g2fb6ddd45872f04306375572c281ec65ee59c761
Author: François Dumont <frs.dumont@gmail.com>
Date:   Thu Apr 10 20:58:11 2025 +0200

    libstdc++: Add std::deque<>::shrink_to_fit test
    
    The existing test is currently testing std::vector. Adapt it for std::deque.
    
    libstdc++-v3/ChangeLog:
    
            * testsuite/util/replacement_memory_operators.h: Adapt for -fno-exceptions
            context.
            * testsuite/23_containers/deque/capacity/shrink_to_fit.cc: Adapt test
            to check std::deque shrink_to_fit method.
    
    Reviewed-by: Jonathan Wakely <jwakely@redhat.com>
    Reviewed-by: Tomasz Kaminski <tkaminsk@redhat.com>

Diff:
---
 .../23_containers/deque/capacity/shrink_to_fit.cc  | 38 ++++++++++++++++++----
 .../testsuite/util/replacement_memory_operators.h  |  8 +++++
 2 files changed, 40 insertions(+), 6 deletions(-)

diff --git a/libstdc++-v3/testsuite/23_containers/deque/capacity/shrink_to_fit.cc b/libstdc++-v3/testsuite/23_containers/deque/capacity/shrink_to_fit.cc
index 7cb67079214f..4dbf405d57b8 100644
--- a/libstdc++-v3/testsuite/23_containers/deque/capacity/shrink_to_fit.cc
+++ b/libstdc++-v3/testsuite/23_containers/deque/capacity/shrink_to_fit.cc
@@ -1,4 +1,6 @@
 // { dg-do run { target c++11 } }
+// { dg-require-effective-target std_allocator_new }
+// { dg-xfail-run-if "AIX operator new" { powerpc-ibm-aix* } }
 
 // 2010-01-08  Paolo Carlini  <paolo.carlini@oracle.com>
 
@@ -19,18 +21,42 @@
 // with this library; see the file COPYING3.  If not see
 // <http://www.gnu.org/licenses/>.
 
-#include <vector>
+#include <deque>
 #include <testsuite_hooks.h>
+#include <replacement_memory_operators.h>
 
 // libstdc++/42573
 void test01()
 {
-  std::vector<int> d(100);
-  d.push_back(1);
-  d.push_back(1);
-  // VERIFY( d.size() < d.capacity() );
+  using namespace std;
+  __gnu_test::counter::reset();
+
+  const size_t buf_size = _GLIBCXX_STD_C::__deque_buf_size(sizeof(size_t));
+  deque<size_t> d;
+  for (size_t i = 0; i != buf_size; ++i)
+    d.push_back(i);
+
+  // No shrink if 1st buffer is full, create some front capacity.
+  d.pop_front();
+
+  // 1 node array allocation + 2 node allocation = 3.
+  VERIFY( __gnu_test::counter::count() == 3 );
+  VERIFY( __gnu_test::counter::get()._M_increments == 3 );
+
   d.shrink_to_fit();
-  // VERIFY( d.size() == d.capacity() );
+
+  // No reallocation if no exception support, shrink_to_fit is then a
+  // no-op.
+#if __cpp_exceptions
+  // 1 node array allocation + 1 node allocation = 2.
+  const int expected_count = 2;
+  const int expected_increments = 2;
+#else
+  const int expected_count = 3;
+  const int expected_increments = 0;
+#endif
+  VERIFY( __gnu_test::counter::count() == expected_count );
+  VERIFY( __gnu_test::counter::get()._M_increments == 3 + expected_increments );
 }
 
 int main()
diff --git a/libstdc++-v3/testsuite/util/replacement_memory_operators.h b/libstdc++-v3/testsuite/util/replacement_memory_operators.h
index 2516cd24ae1e..69afa77754d5 100644
--- a/libstdc++-v3/testsuite/util/replacement_memory_operators.h
+++ b/libstdc++-v3/testsuite/util/replacement_memory_operators.h
@@ -36,8 +36,12 @@ namespace __gnu_test
 
     ~counter() THROW (counter_error)
     {
+#if __cpp_exceptions
       if (_M_throw && _M_count != 0)
 	throw counter_error();
+#else
+      VERIFY( !_M_throw || _M_count == 0 );
+#endif
     }
 
     static void
@@ -133,8 +137,12 @@ void* operator new(std::size_t size) THROW(std::bad_alloc)
 {
   std::printf("operator new is called \n");
   void* p = std::malloc(size);
+#if __cpp_exceptions
   if (!p)
     throw std::bad_alloc();
+#else
+  VERIFY( p );
+#endif
   __gnu_test::counter::increment();
   return p;
 }