[committed] libstdc++: Do not use std::vector::reference default ctor [PR115098]

[Jonathan Wakely]

This default constructor was made private by r15-3124-gb25b101bc38000 so
the pretty printer tests need a fix to stop using it. There's no
conforming way to get a default-constructed 'reference' now, e.g. trying
to access an element of a default-constructed std::vector<bool> will
trigger an assertion. Remove the tests, but leave a comment in the
printer code about handling it.

libstdc++-v3/ChangeLog:

        PR libstdc++/115098
        * python/libstdcxx/v6/printers.py (StdBitReferencePrinter): Add
        comment.
        * testsuite/libstdc++-prettyprinters/simple.cc: Do not default
        construct std::vector<bool>::reference.
        * testsuite/libstdc++-prettyprinters/simple11.cc: Likewise.
---
 libstdc++-v3/python/libstdcxx/v6/printers.py                | 3 +++
 libstdc++-v3/testsuite/libstdc++-prettyprinters/simple.cc   | 3 ---
 libstdc++-v3/testsuite/libstdc++-prettyprinters/simple11.cc | 3 ---
 3 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/libstdc++-v3/python/libstdcxx/v6/printers.py 
b/libstdc++-v3/python/libstdcxx/v6/printers.py
index a6c2ed4599f..92104937862 100644
--- a/libstdc++-v3/python/libstdcxx/v6/printers.py
+++ b/libstdc++-v3/python/libstdcxx/v6/printers.py
@@ -613,6 +613,9 @@ class StdBitReferencePrinter(printer_base):
 
     def to_string(self):
         if not self._val['_M_p']:
+            # PR libstdc++/115098 removed the reference default constructor
+            # that this case relates to. New code should never need this,
+            # but we still handle it for compatibility with old binaries.
             return 'invalid std::vector<bool>::reference'
         return bool(self._val['_M_p'].dereference() & (self._val['_M_mask']))
 
diff --git a/libstdc++-v3/testsuite/libstdc++-prettyprinters/simple.cc 
b/libstdc++-v3/testsuite/libstdc++-prettyprinters/simple.cc
index 7bdc6548f72..c6d18d3fe03 100644
--- a/libstdc++-v3/testsuite/libstdc++-prettyprinters/simple.cc
+++ b/libstdc++-v3/testsuite/libstdc++-prettyprinters/simple.cc
@@ -153,9 +153,6 @@ main()
   std::vector<bool>::reference br5 = *vbIt5;
 // { dg-final { note-test br5 {true} } }
 
- std::vector<bool>::reference br0;
-// { dg-final { note-test br0 {invalid std::vector<bool>::reference} } }
-
   __gnu_cxx::slist<int> sll;
   sll.push_front(23);
   sll.push_front(47);
diff --git a/libstdc++-v3/testsuite/libstdc++-prettyprinters/simple11.cc 
b/libstdc++-v3/testsuite/libstdc++-prettyprinters/simple11.cc
index 3658e3ef4eb..7fd0c4d76b2 100644
--- a/libstdc++-v3/testsuite/libstdc++-prettyprinters/simple11.cc
+++ b/libstdc++-v3/testsuite/libstdc++-prettyprinters/simple11.cc
@@ -146,9 +146,6 @@ main()
   std::vector<bool>::reference br5 = *vbIt5;
 // { dg-final { note-test br5 {true} } }
 
- std::vector<bool>::reference br0;
-// { dg-final { note-test br0 {invalid std::vector<bool>::reference} } }
-
   __gnu_cxx::slist<int> sll;
   sll.push_front(23);
   sll.push_front(47);
-- 
2.46.0