From b30cfbb5dd7bf0a03730a5e25d35b4fd61add6e7 Mon Sep 17 00:00:00 2001
From: Matt Borland <matt@mattborland.com>
Date: Sat, 28 May 2022 08:53:35 -0700
Subject: [PATCH] Fix for issue #464

---
 .../boost/multiprecision/cpp_dec_float.hpp    | 22 +++++++++++--
 test/Jamfile.v2                               |  1 +
 test/git_issue_464.cpp                        | 31 +++++++++++++++++++
 3 files changed, 52 insertions(+), 2 deletions(-)
 create mode 100644 test/git_issue_464.cpp

diff --git a/include/boost/multiprecision/cpp_dec_float.hpp b/include/boost/multiprecision/cpp_dec_float.hpp
index bed38d5cf..074073827 100644
--- a/boost/multiprecision/cpp_dec_float.hpp
+++ b/boost/multiprecision/cpp_dec_float.hpp
@@ -26,6 +26,8 @@
 #include <string>
 #include <limits>
 #include <stdexcept>
+#include <sstream>
+#include <locale>
 #include <boost/multiprecision/detail/standalone_config.hpp>
 #include <boost/multiprecision/number.hpp>
 #include <boost/multiprecision/detail/fpclassify.hpp>
@@ -1603,7 +1605,15 @@ double cpp_dec_float<Digits10, ExponentType, Allocator>::extract_double() const
                      : -std::numeric_limits<double>::infinity());
    }
 
-   return std::strtod(str(std::numeric_limits<double>::digits10 + (2 + 1), std::ios_base::scientific).c_str(), nullptr);
+   std::stringstream ss;
+   ss.imbue(std::locale::classic());
+
+   ss << str(std::numeric_limits<double>::digits10 + (2 + 1), std::ios_base::scientific);
+
+   double d;
+   ss >> d;
+
+   return d;
 }
 
 template <unsigned Digits10, class ExponentType, class Allocator>
@@ -1642,7 +1652,15 @@ long double cpp_dec_float<Digits10, ExponentType, Allocator>::extract_long_doubl
                      : -std::numeric_limits<long double>::infinity());
    }
 
-   return std::strtold(str(std::numeric_limits<long double>::digits10 + (2 + 1), std::ios_base::scientific).c_str(), nullptr);
+   std::stringstream ss;
+   ss.imbue(std::locale::classic());
+
+   ss << str(std::numeric_limits<long double>::digits10 + (2 + 1), std::ios_base::scientific);
+
+   long double ld;
+   ss >> ld;
+
+   return ld;
 }
 
 template <unsigned Digits10, class ExponentType, class Allocator>
diff --git a/test/Jamfile.v2 b/test/Jamfile.v2
index 4ad012273..f5d88edf2 100644
--- a/libs/multiprecision/test/Jamfile.v2
+++ b/libs/multiprecision/test/Jamfile.v2
@@ -1176,6 +1176,7 @@ test-suite misc :
       [ run git_issue_426.cpp : : : [ check-target-builds ../config//has_mpfr : <source>gmp <source>mpfr <define>TEST_MPFR ] [ check-target-builds ../config//has_float128 : <source>quadmath <define>TEST_FLOAT128 ] ]
       [ run git_issue_277.cpp ]
       [ run git_issue_313.cpp ]
+      [ run git_issue_464.cpp ]
       [ compile git_issue_98.cpp : 
          [ check-target-builds ../config//has_float128 : <define>TEST_FLOAT128 <source>quadmath : ]
          [ check-target-builds ../config//has_gmp : <define>TEST_GMP <source>gmp : ]
diff --git a/test/git_issue_464.cpp b/test/git_issue_464.cpp
new file mode 100644
index 000000000..dc9d0054a
--- /dev/null
+++ b/libs/multiprecision/test/git_issue_464.cpp
@@ -0,0 +1,31 @@
+///////////////////////////////////////////////////////////////////////////////
+//  Copyright 2022 Matt Borland. Distributed under the Boost
+//  Software License, Version 1.0. (See accompanying file
+//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+//  See: https://github.com/boostorg/multiprecision/issues/464
+
+#include <boost/multiprecision/cpp_dec_float.hpp>
+#include <locale>
+#include "test.hpp"
+
+template <typename T>
+void test()
+{
+    auto a = boost::multiprecision::cpp_dec_float_50 {12345};
+
+    auto d1 = a.convert_to<T>();
+
+    std::locale::global(std::locale("de_DE"));
+    auto d2 = a.convert_to<T>();
+
+    BOOST_CHECK_EQUAL(d1, d2);
+}
+
+int main(void)
+{
+    test<double>();
+    test<long double>();
+
+    return boost::report_errors();
+}