Move, don't copy, the loaded value into the optional

`load_impl` read the value into a local and copy-assigned it to the
optional. A move-only type then failed to compile: `optional`'s
perfect-forwarding assignment is removed by SFINAE when the value is not
copy-assignable, leaving no viable `operator=`.

So, move the local into the optional instead.

The one-line fix was proposed by Venkat Murty in PR #330; this extends
it with `boost::move` and a regression test.

.github/workflows/ci.yml

@@ -244,15 +244,7 @@ jobs:
         run: |
           cd ../boost-root
           export ADDRMD=${{matrix.address-model}}
-          ./b2 -j3 libs/$LIBRARY/test toolset=${{matrix.toolset}} cxxstd=${{matrix.cxxstd}} ${ADDRMD:+address-model=$ADDRMD} variant=debug,release
-
-      - name: Run examples
-        run: |
-          cd ../boost-root
-          export ADDRMD=${{matrix.address-model}}
-          # The demos use fixed temp filenames, so run them serially (-j1)
-          # to avoid concurrent runs clobbering each other's archive files.
-          ./b2 -j1 libs/$LIBRARY/example toolset=${{matrix.toolset}} cxxstd=${{matrix.cxxstd}} ${ADDRMD:+address-model=$ADDRMD} variant=debug,release
+          ./b2 -j3 libs/$LIBRARY/test libs/$LIBRARY/example toolset=${{matrix.toolset}} cxxstd=${{matrix.cxxstd}} ${ADDRMD:+address-model=$ADDRMD} variant=debug,release
 
   windows:
     strategy:
@@ -307,15 +299,7 @@ jobs:
         shell: cmd
         run: |
           cd ../boost-root
-          b2 -j3 libs/%LIBRARY%/test toolset=${{matrix.toolset}} cxxstd=${{matrix.cxxstd}} address-model=${{matrix.addrmd}} variant=debug,release embed-manifest-via=linker
-
-      - name: Run examples
-        shell: cmd
-        run: |
-          cd ../boost-root
-          rem The demos use fixed temp filenames, so run them serially (-j1)
-          rem to avoid concurrent runs clobbering each other's archive files.
-          b2 -j1 libs/%LIBRARY%/example toolset=${{matrix.toolset}} cxxstd=${{matrix.cxxstd}} address-model=${{matrix.addrmd}} variant=debug,release embed-manifest-via=linker
+          b2 -j3 libs/%LIBRARY%/test libs/%LIBRARY%/example toolset=${{matrix.toolset}} cxxstd=${{matrix.cxxstd}} address-model=${{matrix.addrmd}} variant=debug,release embed-manifest-via=linker
 
   posix-cmake-subdir:
     strategy:

example/Jamfile.v2

@@ -11,8 +11,6 @@ project libs/serialization/example
     : requirements <library>../build//boost_serialization
     ;
 
-import testing ;
-
 import ../util/test :
     run-template
     run-invoke

include/boost/archive/impl/xml_iarchive_impl.ipp

@@ -189,14 +189,7 @@ xml_iarchive_impl<Archive>::~xml_iarchive_impl(){
     if(boost::core::uncaught_exceptions() > 0)
         return;
     if(0 == (this->get_flags() & no_header)){
-        // windup() parses the trailing end tag; an exception must not escape
-        // this (implicitly noexcept) destructor and terminate the process.
-        // A stream error while consuming the trailer is not worth that.  #99
-        BOOST_TRY {
-            gimpl->windup(is);
-        }
-        BOOST_CATCH(...) {}
-        BOOST_CATCH_END
+        gimpl->windup(is);
     }
 }
 } // namespace archive

include/boost/archive/impl/xml_wiarchive_impl.ipp

@@ -177,14 +177,7 @@ xml_wiarchive_impl<Archive>::~xml_wiarchive_impl(){
     if(boost::core::uncaught_exceptions() > 0)
         return;
     if(0 == (this->get_flags() & no_header)){
-        // windup() parses the trailing end tag; an exception must not escape
-        // this (implicitly noexcept) destructor and terminate the process.
-        // A stream error while consuming the trailer is not worth that.  #99
-        BOOST_TRY {
-            gimpl->windup(is);
-        }
-        BOOST_CATCH(...) {}
-        BOOST_CATCH_END
+        gimpl->windup(is);
     }
 }
 

include/boost/serialization/filesystem.hpp

@@ -18,12 +18,8 @@
 
 #include <boost/config.hpp>
 
-// GCC's <filesystem> before version 9 is the initial, incomplete
-// implementation (shipped in a separate libstdc++fs and buggy at runtime),
-// so the feature is disabled there.
 #if defined(__has_include)
-#  if __has_include(<filesystem>) && (BOOST_CXX_VERSION >= 201703L) \
-      && ! (defined(__GNUC__) && ! defined(__clang__) && __GNUC__ < 9)
+#  if __has_include(<filesystem>) && (BOOST_CXX_VERSION >= 201703L)
 #    define BOOST_SERIALIZATION_HAS_STD_FILESYSTEM
 #  endif
 #endif

src/basic_xml_grammar.ipp

@@ -191,15 +191,6 @@ bool basic_xml_grammar<CharType>::my_parse(
     for(;;){
         CharType result;
         is.get(result);
-        // Reaching end of input while scanning for the next character is the
-        // normal way an archive ends (e.g. windup() consuming the trailer);
-        // it is not a stream error.  get() sets both eofbit and failbit at end
-        // of stream, so test eof() *before* fail() -- otherwise the normal
-        // termination is misreported as input_stream_error, which is fatal
-        // when it surfaces in the (noexcept) archive destructor via windup().
-        // See #99.
-        if(is.eof())
-            return false;
         if(is.fail()){
             boost::serialization::throw_exception(
                 boost::archive::archive_exception(
@@ -208,6 +199,8 @@ bool basic_xml_grammar<CharType>::my_parse(
                 )
             );
         }
+        if(is.eof())
+            return false;
         arg += result;
         if(result == delimiter)
             break;

test/Jamfile.v2

@@ -151,8 +151,6 @@ if ! $(BOOST_ARCHIVE_LIST) {
         [ test-bsl-run test_private_ctor ]
         [ test-bsl-run test_reset_object_address : A ]
         [ test-bsl-run test_void_cast ]
-        [ test-bsl-run test_xml_trailing_whitespace ]
-        [ test-bsl-run test_xml_missing_nvp ]
         [ test-bsl-run test_mult_archive_types : : : [ requires std_wstreambuf ] ]
         [ test-bsl-run test_iterators : : : [ requires std_wstreambuf ] ]
         [ test-bsl-run test_iterators_base64 ]

test/test_filesystem_path.cpp

@@ -17,11 +17,8 @@
 
 // `std::filesystem::path` is a C++17 feature; when it isn't available, this
 // test has nothing to exercise and simply succeeds.
-// Note the guard for GCC < 9, which matches the one in
-// boost/serialization/filesystem.hpp: see the comment there for the why.
 #if defined(__has_include)
-#  if __has_include(<filesystem>) && (BOOST_CXX_VERSION >= 201703L) \
-      && ! (defined(__GNUC__) && ! defined(__clang__) && __GNUC__ < 9)
+#  if __has_include(<filesystem>) && (BOOST_CXX_VERSION >= 201703L)
 #    define BOOST_SERIALIZATION_TEST_STD_FILESYSTEM
 #  endif
 #endif
@@ -32,11 +29,6 @@
 
 #include <boost/serialization/filesystem.hpp>
 #include <filesystem>
-#include <type_traits>
-
-#ifndef BOOST_NO_STD_WSTREAMBUF
-#include <boost/archive/text_woarchive.hpp>
-#endif
 
 void check_roundtrip(const std::filesystem::path & original){
     const char * testfile = boost::archive::tmpnam(NULL);
@@ -65,21 +57,6 @@ std::filesystem::path from_utf8(const std::string & utf8){
 #endif
 }
 
-// The wide *text* archive is the one archive that cannot round-trip non-ASCII
-// content: it transcodes the narrow UTF-8 std::string through the stream
-// locale's codecvt (codecvt_null), which mangles bytes outside the ASCII
-// range.  Every other archive in the test list preserves them -- narrow text
-// and XML store the bytes verbatim, binary stores them raw, and wide XML
-// installs a UTF-8 codecvt.  So the non-ASCII case is exercised everywhere
-// except that single archive.
-bool archive_round_trips_non_ascii(){
-#ifndef BOOST_NO_STD_WSTREAMBUF
-    return ! std::is_same<test_oarchive, boost::archive::text_woarchive>::value;
-#else
-    return true;
-#endif
-}
-
 int test_main(int /* argc */, char * /* argv */ []){
     check_roundtrip(std::filesystem::path());              // empty
     check_roundtrip("foo/bar/baz.txt");                    // relative
@@ -89,8 +66,7 @@ int test_main(int /* argc */, char * /* argv */ []){
     // The escapes are the UTF-8 encoding of U+00E9, U+00EF and U+00FC
     // (e-acute, i-diaeresis, u-diaeresis); written as `\x` so the source
     // file stays pure ASCII and encoding-independent.
-    if(archive_round_trips_non_ascii())
-        check_roundtrip(from_utf8("caf\xC3\xA9/na\xC3\xAF" "ve/\xC3\xBC.txt"));
+    check_roundtrip(from_utf8("caf\xC3\xA9/na\xC3\xAF" "ve/\xC3\xBC.txt"));
     return EXIT_SUCCESS;
 }
 

test/test_xml_missing_nvp.cpp

@@ -1,58 +0,0 @@
-/////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
-// test_xml_missing_nvp.cpp
-
-// Copyright 2026 Gennaro Prota
-// Distributed under the Boost Software License, Version 1.0.
-// (See accompanying file LICENSE_1_0.txt or copy at
-// https://www.boost.org/LICENSE_1_0.txt)
-
-// Regression test for issue #109.  Attempting to read an nvp that is not
-// present throws archive_exception, which the caller may catch.  The failed
-// read consumes the closing tag, so at destruction windup() reaches end of
-// input -- the same Boost 1.66 my_parse regression as #82/#99, reached by a
-// different path.  The input archive must still destruct without terminating.
-
-#include <sstream>
-#include <string>
-
-#include <boost/archive/xml_oarchive.hpp>
-#include <boost/archive/xml_iarchive.hpp>
-#include <boost/archive/archive_exception.hpp>
-#include <boost/serialization/nvp.hpp>
-
-#include "test_tools.hpp"
-
-int test_main(int /* argc */, char * /* argv */ []){
-    // Build a valid XML archive holding a single value.
-    std::string content;
-    {
-        std::ostringstream os;
-        {
-            boost::archive::xml_oarchive oa(os);
-            const int x = 42;
-            oa << boost::serialization::make_nvp("x", x);
-        }
-        content = os.str();
-    }
-
-    int x = 0;
-    bool caught = false;
-    {
-        std::istringstream is(content);
-        boost::archive::xml_iarchive ia(is);
-        ia >> boost::serialization::make_nvp("x", x);
-        try {
-            int y = 0;
-            ia >> boost::serialization::make_nvp("not_there", y);
-        } catch (const boost::archive::archive_exception &){
-            caught = true;
-        }
-        // `ia` is destroyed here, after the caught exception.  Before the fix,
-        // windup() hit end of input (the failed read consumed the closing
-        // tag) and threw out of the noexcept destructor, terminating.
-    }
-    BOOST_CHECK(42 == x);
-    BOOST_CHECK(caught);
-
-    return EXIT_SUCCESS;
-}

test/test_xml_trailing_whitespace.cpp

@@ -1,59 +0,0 @@
-/////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
-// test_xml_trailing_whitespace.cpp
-
-// Copyright 2026 Gennaro Prota
-// Distributed under the Boost Software License, Version 1.0.
-// (See accompanying file LICENSE_1_0.txt or copy at
-// https://www.boost.org/LICENSE_1_0.txt)
-
-// Regression test for issue #99.  When an XML input archive is destroyed and
-// its stream has no closing tag left -- only trailing whitespace before end
-// of input (a truncated archive; the reported case had the stream "contain
-// \r\n") -- windup() reaches end of input while scanning for the trailing
-// tag.  End of input there is normal termination, not a stream error, so the
-// (implicitly noexcept) destructor must complete cleanly rather than throw,
-// which used to terminate the process.
-
-#include <sstream>
-#include <string>
-
-#include <boost/archive/xml_oarchive.hpp>
-#include <boost/archive/xml_iarchive.hpp>
-#include <boost/serialization/nvp.hpp>
-
-#include "test_tools.hpp"
-
-int test_main(int /* argc */, char * /* argv */ []){
-    // Build a valid XML archive holding a single value.
-    std::string content;
-    {
-        std::ostringstream os;
-        {
-            boost::archive::xml_oarchive oa(os);
-            const int x = 42;
-            oa << boost::serialization::make_nvp("x", x);
-        }
-        content = os.str();
-    }
-
-    // Drop the closing document tag and leave only trailing whitespace, so the
-    // input archive's windup() reaches end of input at destruction instead of
-    // finding a tag.
-    const std::string::size_type close = content.rfind("</boost_serialization>");
-    BOOST_REQUIRE(std::string::npos != close);
-    content.erase(close);
-    content += "\r\n";
-
-    int y = 0;
-    {
-        std::istringstream is(content);
-        boost::archive::xml_iarchive ia(is);
-        ia >> boost::serialization::make_nvp("x", y);
-        // `ia` is destroyed here with only trailing whitespace left.  Before
-        // the fix, windup() threw input_stream_error out of the noexcept
-        // destructor and terminated the process.
-    }
-    BOOST_CHECK(42 == y);
-
-    return EXIT_SUCCESS;
-}