From eb5525e282b0a7d2dc9eaaefe7a4b918040485be Mon Sep 17 00:00:00 2001
From: jzmaddock <john@johnmaddock.co.uk>
Date: Sun, 5 Feb 2023 12:01:41 +0000
Subject: [PATCH] Fix potentially uninitialized storage when parsing octal
 strings. Fixes https://github.com/boostorg/multiprecision/issues/526

---
 include/boost/multiprecision/cpp_int.hpp |  3 +++
 test/Jamfile.v2                          |  1 +
 test/git_issue_526.cpp                   | 18 ++++++++++++++++++
 3 files changed, 22 insertions(+)
 create mode 100644 test/git_issue_526.cpp

diff --git a/include/boost/multiprecision/cpp_int.hpp b/include/boost/multiprecision/cpp_int.hpp
index c10d327e..f0dad5a1 100644
--- a/include/boost/multiprecision/cpp_int.hpp
+++ b/include/boost/multiprecision/cpp_int.hpp
@@ -1854,7 +1854,10 @@ public:
                      {
                         // If this is the most-significant-limb, we may need to allocate an extra one for the overflow:
                         if (limb + 1 == newsize)
+                        {
                            result.resize(static_cast<unsigned>(newsize + 1), static_cast<unsigned>(newsize + 1));
+                           result.limbs()[limb + 1] = 0;
+                        }
                         if (result.size() > limb + 1)
                         {
                            result.limbs()[limb + 1] |= val;
diff --git a/test/Jamfile.v2 b/test/Jamfile.v2
index 3fea2298..87556009 100644
--- a/test/Jamfile.v2
+++ b/test/Jamfile.v2
@@ -1220,6 +1220,7 @@ test-suite misc :
       [ run git_issue_313.cpp ]
       [ run git_issue_488.cpp ]
       [ run git_issue_506.cpp ]
+      [ run git_issue_526.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_526.cpp b/test/git_issue_526.cpp
new file mode 100644
index 00000000..05d6a1df
--- /dev/null
+++ b/test/git_issue_526.cpp
@@ -0,0 +1,18 @@
+///////////////////////////////////////////////////////////////////////////////
+//  Copyright 2023 John Maddock. 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)
+
+#include <iostream>
+#include <boost/multiprecision/cpp_int.hpp>
+#include "test.hpp"
+
+int main()
+{
+   using namespace boost::multiprecision;
+   const std::string v("00000000000000000000000052222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222");
+   cpp_int           V(v);
+   std::string       r = V.str(0, std::ios_base::oct | std::ios_base::showbase);
+   BOOST_CHECK_EQUAL(r, v.substr(23));
+   return 0;
+}