Re: [PING] [PATCH] libstdc++: Pretty printers for std::_Bit_reference, std::_Bit_iterator and std::_Bit_const_iterator

[Jonathan Wakely <jwakely@redhat.com>]

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On 27/11/20 16:33 +0000, Jonathan Wakely wrote:
>On 25/11/20 15:05 +0100, Michael Weghorn via Libstdc++ wrote:
>>I'd like to ping for this patch:
>>https://gcc.gnu.org/pipermail/gcc-patches/2020-September/553870.html
>
>Thanks, I'll take another look next week.

I've applied the patch now, thanks.

I adjusted it slightly, to add a test for const_iterator to the C++98
test, simple.cc, consistent with the C++11 one, simple11.cc

Tested powerpc64le-linux, committed to trunk.

Thanks again for the patch, and your patience.


>>Michael
>>
>>On 11/10/2020 19.22, Michael Weghorn via Gcc-patches wrote:
>>>On 22/09/2020 12.04, Jonathan Wakely wrote:
>>>>On 14/09/20 16:49 +0200, Michael Weghorn via Libstdc++ wrote:
>>>>>Hi,
>>>>>
>>>>>the attached patch implements pretty printers relevant for iteration
>>>>>over std::vector<bool>, thus handling the TODO
>>>>>added in commit 36d0dada6773d7fd7c5ace64c90e723930a3b81e
>>>>>("Have std::vector printer's iterator return bool for vector<bool>",
>>>>>2019-06-19):
>>>>>
>>>>>   TODO add printer for vector<bool>'s _Bit_iterator and
>>>>>_Bit_const_iterator
>>>>>
>>>>>Tested on x86_64-pc-linux-gnu (Debian testing).
>>>>>
>>>>>I haven't filed any copyright assignment for GCC yet, but I'm happy to
>>>>>do so when pointed to the right place.
>>>>
>>>>Thanks for the patch! I'll send you the form to start the copyuright
>>>>assignment process.
>>>>
>>>>
>>>
>>>Thanks! The copyright assignment is done now. Is there anything else to
>>>do from my side at the moment?
>>>
>>

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commit 39836f8324d819459cb21198e95b993588c6a2b1
Author: Michael Weghorn <m.weghorn@posteo.de>
Date:   Tue Dec 1 21:19:20 2020

    libstdc++: Pretty printers for _Bit_reference and _Bit_iterator
    
    'std::_Bit_iterator' and 'std::_Bit_const_iterator' are the iterators
    used by 'std::vector<bool>'.
    'std::_Bit_reference' is e.g. used in range-based for loops over
    'std::vector<bool>'  like
    
        std::vector<bool> vb {true, false, false};
        for (auto b : vb) {
            // b is of type std::_Bit_reference here
            // ...
        }
    
    Like iterators of vectors for other types, the actual value is printed.
    
    libstdc++-v3/ChangeLog:
    
            * python/libstdcxx/v6/printers.py (StdBitIteratorPrinter)
            (StdBitReferencePrinter): Add pretty-printers for
            _Bit_reference, _Bit_iterator and _Bit_const_iterator.
            * testsuite/libstdc++-prettyprinters/simple.cc: Test
            std::_Bit_reference, std::_Bit_iterator and
            std::_Bit_const_iterator.
            * testsuite/libstdc++-prettyprinters/simple11.cc: Likewise.

diff --git a/libstdc++-v3/python/libstdcxx/v6/printers.py b/libstdc++-v3/python/libstdcxx/v6/printers.py
index c0f061f79c1..478e44eefdf 100644
--- a/libstdc++-v3/python/libstdcxx/v6/printers.py
+++ b/libstdc++-v3/python/libstdcxx/v6/printers.py
@@ -479,7 +479,27 @@ class StdVectorIteratorPrinter:
             return 'non-dereferenceable iterator for std::vector'
         return str(self.val['_M_current'].dereference())
 
-# TODO add printer for vector<bool>'s _Bit_iterator and _Bit_const_iterator
+class StdBitIteratorPrinter:
+    "Print std::vector<bool>'s _Bit_iterator and _Bit_const_iterator"
+
+    def __init__(self, typename, val):
+        self.val = val
+
+    def to_string(self):
+        if not self.val['_M_p']:
+            return 'non-dereferenceable iterator for std::vector<bool>'
+        return bool(self.val['_M_p'].dereference() & (1 << self.val['_M_offset']))
+
+class StdBitReferencePrinter:
+    "Print std::_Bit_reference"
+
+    def __init__(self, typename, val):
+        self.val = val
+
+    def to_string(self):
+        if not self.val['_M_p']:
+            return 'invalid std::_Bit_reference'
+        return bool(self.val['_M_p'].dereference() & (self.val['_M_mask']))
 
 class StdTuplePrinter:
     "Print a std::tuple"
@@ -1965,6 +1985,12 @@ def build_libstdcxx_dictionary ():
                                         StdDequeIteratorPrinter)
         libstdcxx_printer.add_version('__gnu_cxx::', '__normal_iterator',
                                       StdVectorIteratorPrinter)
+        libstdcxx_printer.add_version('std::', '_Bit_iterator',
+                                      StdBitIteratorPrinter)
+        libstdcxx_printer.add_version('std::', '_Bit_const_iterator',
+                                      StdBitIteratorPrinter)
+        libstdcxx_printer.add_version('std::', '_Bit_reference',
+                                      StdBitReferencePrinter)
         libstdcxx_printer.add_version('__gnu_cxx::', '_Slist_iterator',
                                       StdSlistIteratorPrinter)
         libstdcxx_printer.add_container('std::', '_Fwd_list_iterator',
diff --git a/libstdc++-v3/testsuite/libstdc++-prettyprinters/simple.cc b/libstdc++-v3/testsuite/libstdc++-prettyprinters/simple.cc
index 4b44be594f5..9821d1805cf 100644
--- a/libstdc++-v3/testsuite/libstdc++-prettyprinters/simple.cc
+++ b/libstdc++-v3/testsuite/libstdc++-prettyprinters/simple.cc
@@ -127,6 +127,37 @@ main()
   vb.erase(vb.begin());
 // { dg-final { regexp-test vb {std::(__debug::)?vector<bool> of length 5, capacity 128 = \\{true, true, false, false, true\\}} } }
 
+  std::vector<bool>::iterator vbIt = vb.begin();
+// { dg-final { note-test vbIt {true} } }
+  std::vector<bool>::iterator vbIt2 = ++vbIt;
+// { dg-final { note-test vbIt2 {true} } }
+  std::vector<bool>::iterator vbIt3 = ++vbIt;
+// { dg-final { note-test vbIt3 {false} } }
+  std::vector<bool>::iterator vbIt4 = ++vbIt;
+// { dg-final { note-test vbIt4 {false} } }
+  std::vector<bool>::iterator vbIt5 = ++vbIt;
+// { dg-final { note-test vbIt5 {true} } }
+
+  std::vector<bool>::const_iterator vbcIt = vb.begin();
+// { dg-final { note-test vbcIt {true} } }
+
+  std::vector<bool>::iterator vbIt0;
+// { dg-final { note-test vbIt0 {non-dereferenceable iterator for std::vector<bool>} } }
+
+  std::_Bit_reference br = *vb.begin();
+// { dg-final { note-test br {true} } }
+  std::_Bit_reference br2 = *vbIt2;
+// { dg-final { note-test br2 {true} } }
+  std::_Bit_reference br3 = *vbIt3;
+// { dg-final { note-test br3 {false} } }
+  std::_Bit_reference br4 = *vbIt4;
+// { dg-final { note-test br4 {false} } }
+  std::_Bit_reference br5 = *vbIt5;
+// { dg-final { note-test br5 {true} } }
+
+ std::_Bit_reference br0;
+// { dg-final { note-test br0 {invalid std::_Bit_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 0ebd80a42e9..519565693b7 100644
--- a/libstdc++-v3/testsuite/libstdc++-prettyprinters/simple11.cc
+++ b/libstdc++-v3/testsuite/libstdc++-prettyprinters/simple11.cc
@@ -120,6 +120,37 @@ main()
   vb.erase(vb.begin());
 // { dg-final { regexp-test vb {std::(__debug::)?vector<bool> of length 5, capacity 128 = \\{true, true, false, false, true\\}} } }
 
+  std::vector<bool>::iterator vbIt = vb.begin();
+// { dg-final { note-test vbIt {true} } }
+  std::vector<bool>::iterator vbIt2 = ++vbIt;
+// { dg-final { note-test vbIt2 {true} } }
+  std::vector<bool>::iterator vbIt3 = ++vbIt;
+// { dg-final { note-test vbIt3 {false} } }
+  std::vector<bool>::iterator vbIt4 = ++vbIt;
+// { dg-final { note-test vbIt4 {false} } }
+  std::vector<bool>::iterator vbIt5 = ++vbIt;
+// { dg-final { note-test vbIt5 {true} } }
+
+  std::vector<bool>::const_iterator vbcIt = vb.cbegin();
+// { dg-final { note-test vbcIt {true} } }
+
+  std::vector<bool>::iterator vbIt0;
+// { dg-final { note-test vbIt0 {non-dereferenceable iterator for std::vector<bool>} } }
+
+  std::_Bit_reference br = *vb.begin();
+// { dg-final { note-test br {true} } }
+  std::_Bit_reference br2 = *vbIt2;
+// { dg-final { note-test br2 {true} } }
+  std::_Bit_reference br3 = *vbIt3;
+// { dg-final { note-test br3 {false} } }
+  std::_Bit_reference br4 = *vbIt4;
+// { dg-final { note-test br4 {false} } }
+  std::_Bit_reference br5 = *vbIt5;
+// { dg-final { note-test br5 {true} } }
+
+ std::_Bit_reference br0;
+// { dg-final { note-test br0 {invalid std::_Bit_reference} } }
+
   __gnu_cxx::slist<int> sll;
   sll.push_front(23);
   sll.push_front(47);