<random>: Fixes subtract_with_carry_engine io

stl/inc/random

@@ -12,7 +12,7 @@
 #include <algorithm>
 #include <cmath>
 #include <cstdint>
-#include <iosfwd>
+#include <ios>
 #include <vector>
 #include <xbit_ops.h>
 #include <xstring>
@@ -674,6 +674,12 @@ public:
         return _Ostr;
     }
 
+    template <class _Elem, class _Traits>
+    basic_ostream<_Elem, _Traits>& _Write_full(basic_ostream<_Elem, _Traits>& _Ostr) const { // write state to _Ostr
+        _Swc_Traits::_Write_full(_Ostr, *this, _Carry);
+        return _Ostr;
+    }
+
 protected:
     template <class _Gen>
     void _Seed(_Gen& _Gx, bool _Readcy, true_type) { // reset sequence from numeric value
@@ -816,14 +822,24 @@ struct _Swc_traits { // traits for subtract_with_carry generator
         int _Kx = _Get_wc();
 
         for (size_t _Ix = 0; _Ix < _Nw; ++_Ix) {
-            for (int _Jx = 1; _Jx <= _Kx; ++_Jx) { // unpack into _Kx words
-                unsigned int _Word = static_cast<unsigned int>(_Buf._At(_Ix) >> ((_Kx - _Jx) * 32));
+            for (int _Jx = 0; _Jx < _Kx; ++_Jx) { // unpack into _Kx words
+                const unsigned int _Word = static_cast<unsigned int>(_Buf._At(_Ix) >> (_Jx * 32));
                 _Ostr << _Word << ' ';
             }
         }
 
         _Ostr << _Cy;
     }
+
+    template <class _Elem, class _Traits>
+    static void _Write_full(
+        basic_ostream<_Elem, _Traits>& _Ostr, const _Circ_buf<_Ty, _Nw>& _Buf, _Cy_t _Cy) { // write state to _Ostr
+        for (size_t _Ix = 0; _Ix < _Nw; ++_Ix) {
+            _Ostr << _Buf._At(_Ix) << ' ';
+        }
+
+        _Ostr << _Cy;
+    }
 };
 
 template <class _Ty, _Ty _Mx, size_t _Sx, size_t _Rx>
@@ -908,6 +924,44 @@ public:
     _NODISCARD static constexpr _Ty(max)() {
         return _Mx - 1;
     }
+
+    template <class _Elem, class _Traits>
+    friend basic_ostream<_Elem, _Traits>& operator<<(
+        basic_ostream<_Elem, _Traits>& _Ostr, const subtract_with_carry_engine& _Eng) {
+        const auto _Save_flags = _Ostr.flags(ios_base::dec | ios_base::left);
+        const auto _Save_fill  = _Ostr.fill(' ');
+        _Eng._Write_full(_Ostr);
+        _Ostr.flags(_Save_flags);
+        _Ostr.fill(_Save_fill);
+        return _Ostr;
+    }
+
+    template <class _Elem, class _Traits>
+    friend basic_istream<_Elem, _Traits>& operator>>(
+        basic_istream<_Elem, _Traits>& _Istr, subtract_with_carry_engine& _Eng) {
+        constexpr auto _Nx = long_lag;
+        result_type _Buffer[_Nx];
+        typename _Mybase::_Traits::_Cy_t _Carry_buf;
+        const auto _Save_flags = _Istr.flags(ios_base::dec | ios_base::skipws);
+        for (size_t _Ix = 0; _Ix < _Nx; ++_Ix) {
+            _Istr >> _Buffer[_Ix];
+        }
+
+        _Istr >> _Carry_buf;
+        if (_Istr) {
+            for (size_t _Ix = 0; _Ix < _Nx; ++_Ix) {
+                _Eng._Ax[_Ix] = _Buffer[_Ix];
+            }
+
+            _Eng._Carry = _Carry_buf;
+            _Eng._Idx   = _Nx;
+        } else {
+            _Istr.setstate(ios_base::failbit);
+        }
+
+        _Istr.flags(_Save_flags);
+        return _Istr;
+    }
 };
 
 #if _HAS_TR1_NAMESPACE

tests/libcxx/expected_results.txt

@@ -779,19 +779,6 @@ std/input.output/iostream.format/ext.manip/get_money.pass.cpp FAIL
 std/input.output/iostream.format/ext.manip/put_money.pass.cpp FAIL
 std/input.output/iostreams.base/ios/basic.ios.members/copyfmt.pass.cpp FAIL
 
-# Not yet analyzed, likely STL bugs. Assertion failed: os.str() == a
-std/numerics/rand/rand.adapt/rand.adapt.disc/ctor_result_type.pass.cpp FAIL
-std/numerics/rand/rand.adapt/rand.adapt.disc/ctor_sseq.pass.cpp FAIL
-std/numerics/rand/rand.adapt/rand.adapt.ibits/ctor_result_type.pass.cpp FAIL
-std/numerics/rand/rand.adapt/rand.adapt.ibits/ctor_sseq.pass.cpp FAIL
-std/numerics/rand/rand.eng/rand.eng.sub/ctor_result_type.pass.cpp FAIL
-std/numerics/rand/rand.eng/rand.eng.sub/ctor_sseq.pass.cpp FAIL
-
-# Not yet analyzed, likely STL bugs. Assertion failed: e1 == e2
-std/numerics/rand/rand.adapt/rand.adapt.disc/io.pass.cpp FAIL
-std/numerics/rand/rand.adapt/rand.adapt.ibits/io.pass.cpp FAIL
-std/numerics/rand/rand.eng/rand.eng.sub/io.pass.cpp FAIL
-
 # Likely STL bug: Looks like we shouldn't be using assignment.
 std/thread/futures/futures.promise/set_rvalue.pass.cpp FAIL
 

tests/libcxx/skipped_tests.txt

@@ -779,19 +779,6 @@ input.output\iostream.format\ext.manip\get_money.pass.cpp
 input.output\iostream.format\ext.manip\put_money.pass.cpp
 input.output\iostreams.base\ios\basic.ios.members\copyfmt.pass.cpp
 
-# Not yet analyzed, likely STL bugs. Assertion failed: os.str() == a
-numerics\rand\rand.adapt\rand.adapt.disc\ctor_result_type.pass.cpp
-numerics\rand\rand.adapt\rand.adapt.disc\ctor_sseq.pass.cpp
-numerics\rand\rand.adapt\rand.adapt.ibits\ctor_result_type.pass.cpp
-numerics\rand\rand.adapt\rand.adapt.ibits\ctor_sseq.pass.cpp
-numerics\rand\rand.eng\rand.eng.sub\ctor_result_type.pass.cpp
-numerics\rand\rand.eng\rand.eng.sub\ctor_sseq.pass.cpp
-
-# Not yet analyzed, likely STL bugs. Assertion failed: e1 == e2
-numerics\rand\rand.adapt\rand.adapt.disc\io.pass.cpp
-numerics\rand\rand.adapt\rand.adapt.ibits\io.pass.cpp
-numerics\rand\rand.eng\rand.eng.sub\io.pass.cpp
-
 # Likely STL bug: Looks like we shouldn't be using assignment.
 thread\futures\futures.promise\set_rvalue.pass.cpp
 

tests/std/test.lst

@@ -161,6 +161,7 @@ tests\GH_000431_equal_memcmp_is_safe
 tests\GH_000431_iter_copy_move_cat
 tests\GH_000431_lex_compare_family
 tests\GH_000431_lex_compare_memcmp_classify
+tests\GH_000442_random_subtract_with_carry_engine_io
 tests\GH_000457_system_error_message
 tests\GH_000545_include_compare
 tests\GH_000625_vector_bool_optimization

tests/std/tests/GH_000442_random_subtract_with_carry_engine_io/env.lst

@@ -0,0 +1,4 @@
+# Copyright (c) Microsoft Corporation.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+RUNALL_INCLUDE ..\usual_matrix.lst

tests/std/tests/GH_000442_random_subtract_with_carry_engine_io/test.cpp

@@ -0,0 +1,80 @@
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#include <cassert>
+#include <cstddef>
+#include <ios>
+#include <random>
+#include <sstream>
+#include <string>
+using namespace std;
+
+void check_state(const string& state_str) {
+    // Check word-by-word in case of whitespace differences.
+    static constexpr const char* state_ref[] = {
+        "10880375256626",
+        "126660097854724",
+        "33643165434010",
+        "78293780235492",
+        "179418984296008",
+        "96783156950859",
+        "238199764491708",
+        "34339434557790",
+        "155299155394531",
+        "29014415493780",
+        "209265474179052",
+        "263777435457028",
+        "0",
+    };
+    constexpr auto state_size = size(state_ref);
+    stringstream sstr(state_str);
+
+    size_t idx = 0;
+    string word;
+    while (sstr && idx < state_size) {
+        sstr >> word;
+        assert(word == state_ref[idx]);
+        ++idx;
+    }
+
+    assert(sstr.rdstate() == ios_base::eofbit);
+    assert(idx == state_size);
+}
+
+void check(stringstream& sstr) {
+    // N4892 [tab:rand.req.eng]: "Postconditions: The os.fmtflags and fill character are unchanged."
+    // and "Postconditions: The is.fmtflags are unchanged."
+    const auto old_flags = sstr.flags();
+    const auto old_fill  = sstr.fill();
+    ranlux48_base eng1;
+    ranlux48_base eng2;
+    sstr << eng1;
+    check_state(sstr.str());
+    sstr >> eng2;
+    assert(eng1 == eng2);
+    assert(sstr.flags() == old_flags);
+    assert(sstr.fill() == old_fill);
+}
+
+int main() {
+    {
+        stringstream sstr;
+        sstr << hex;
+        check(sstr);
+    }
+
+    {
+        stringstream sstr;
+        sstr.unsetf(ios_base::skipws);
+        check(sstr);
+    }
+
+    {
+        stringstream sstr;
+        sstr.fill('.');
+        sstr.width(40);
+        check(sstr);
+    }
+
+    return 0;
+}