Fix UB in emplace functions

.drone.star

@@ -45,6 +45,10 @@ def main(ctx):
             },
         ],
         extras=[
+            { 'match': {'compiler': 'gcc =latest', 'os': 'linux'},
+              'name': 'GCC static linking',
+              'environment': {'B2_LINK': 'static'},
+            },
             { 'match': {'compiler': 'gcc =8', 'os': 'linux'},
               'name': 'GCC 8 CMake superproject',
               'type': 'cmake-superproject',
@@ -114,6 +118,9 @@ def main(ctx):
             { 'match': {'compiler': 'clang =latest', 'os': 'linux'},
               'special': 'valgrind',
             },
+            { 'match': {'compiler': 'gcc =latest', 'os': 'linux'},
+              'special': 'valgrind',
+            },
         ],
     ) + [
         linux_cxx("docs", "g++", buildtype="docs", buildscript="drone", image="cppalliance/boost_superproject_build:24.04-v3", environment={'COMMENT': 'docs'}, globalenv=globalenv),
@@ -383,24 +390,24 @@ def apply_special(job, special):
 
     elif special == 'valgrind':
         job['name'] = 'Valgrind ' + job['name']
-        job['type'] = 'valgrind'
         set_or_append(
             job['environment'], 'B2_TESTFLAGS', 'testing.launcher=valgrind',
         )
         job['environment']['VALGRIND_OPTS'] = '--error-exitcode=1'
+        job.setdefault('packages', []).append('valgrind')
 
         if job['compiler'] == 'clang' and job['os'] == 'linux':
-            job.setdefault('packages', []).append('libc6-dbg')
+            job['packages'].append('libc6-dbg')
 
     if special in ('asan', 'tsan', 'ubsan'):
         job['environment']['B2_' + special.upper()] = '1'
+        job['environment']['B2_VARIANT'] = 'debug'
 
         if job['compiler'] == 'clang' and job['os'] == 'linux':
             job.setdefault('packages', []).append(
                 'libclang-rt-%s-dev' % job['version']
             )
     if special in ('asan', 'tsan', 'ubsan', 'valgrind'):
-        job['environment']['B2_VARIANT'] = 'debug'
         job['environment']['COMMENT'] = special
         set_or_append(
             job['environment'], 'B2_DEFINES', 'BOOST_NO_STRESS_TEST=1',

.drone/drone.sh

@@ -137,17 +137,6 @@ echo '==================================> SCRIPT'
 cd $BOOST_ROOT/libs/$SELF
 ci/travis/codecov.sh
 
-elif [ "$DRONE_JOB_BUILDTYPE" == "valgrind" ]; then
-
-echo '==================================> INSTALL'
-
-common_install
-
-echo '==================================> SCRIPT'
-
-cd $BOOST_ROOT/libs/$SELF
-ci/travis/valgrind.sh
-
 elif [ "$DRONE_JOB_BUILDTYPE" == "coverity" ]; then
 
 echo '==================================> INSTALL'

include/boost/json/impl/value.ipp

@@ -637,21 +637,24 @@ string&
 value::
 emplace_string() noexcept
 {
-    return *::new(&str_) string(destroy());
+    storage_ptr sp = destroy();
+    return *::new(&str_) string(sp);
 }
 
 array&
 value::
 emplace_array() noexcept
 {
-    return *::new(&arr_) array(destroy());
+    storage_ptr sp = destroy();
+    return *::new(&arr_) array(sp);
 }
 
 object&
 value::
 emplace_object() noexcept
 {
-    return *::new(&obj_) object(destroy());
+    storage_ptr sp = destroy();
+    return *::new(&obj_) object(sp);
 }
 
 void

test/CMakeLists.txt

@@ -23,6 +23,7 @@ endif()
 file(GLOB_RECURSE BOOST_JSON_TESTS_FILES CONFIGURE_DEPENDS Jamfile *.cpp *.hpp)
 list(FILTER BOOST_JSON_TESTS_FILES EXCLUDE REGEX cmake_install_test/.*$)
 list(FILTER BOOST_JSON_TESTS_FILES EXCLUDE REGEX cmake-subdir/.*$)
+list(FILTER BOOST_JSON_TESTS_FILES EXCLUDE REGEX header_only\.cpp$)
 list(FILTER BOOST_JSON_TESTS_FILES EXCLUDE REGEX intrusive_macros\.cpp$)
 list(FILTER BOOST_JSON_TESTS_FILES EXCLUDE REGEX limits\.cpp$)
 list(FILTER BOOST_JSON_TESTS_FILES EXCLUDE REGEX no_exceptions\.cpp$)
@@ -54,6 +55,12 @@ target_compile_definitions(boost_json-limits PRIVATE
 add_test(NAME boost_json-limits COMMAND boost_json-limits)
 add_dependencies(tests boost_json-limits)
 
+add_executable(boost_json-header_only ${EXCLUDE_TESTS_FROM_ALL} header_only.cpp Jamfile)
+boost_json_setup_properties(boost_json-header_only)
+
+add_test(NAME boost_json-header_only COMMAND boost_json-header_only)
+add_dependencies(tests boost_json-header_only)
+
 add_executable(boost_json-no_exceptions ${EXCLUDE_TESTS_FROM_ALL} no_exceptions.cpp main.cpp ../src/src.cpp Jamfile)
 boost_json_setup_properties(boost_json-no_exceptions)
 

test/Jamfile

@@ -87,6 +87,12 @@ run limits.cpp main.cpp /boost/json//json_sources
       <define>BOOST_JSON_STACK_BUFFER_SIZE=256
     ;
 
+run header_only.cpp
+    : requirements
+      <include>../include
+      <dependency>/boost/json//boost_json
+    ;
+
 run no_exceptions.cpp main.cpp /boost/json//json_sources
     : requirements
       <exception-handling>off
@@ -103,5 +109,5 @@ boost-pretty-printers.test-gdb-printers gdb-printers
     ;
 explicit gdb-printers ;
 
-alias common : $(SOURCES:B) limits no_exceptions intrusive_macros ;
+alias common : $(SOURCES:B) limits header_only no_exceptions intrusive_macros ;
 alias heavy : $(HEAVY_SOURCES:B) ;

test/header_only.cpp

@@ -0,0 +1,32 @@
+#include <boost/json/src.hpp>
+
+void
+with_array()
+{
+    boost::json::value jv;
+    jv.emplace_array();
+}
+
+void
+with_object()
+{
+    boost::json::value jv;
+    jv.emplace_object();
+}
+
+void
+with_string()
+{
+    boost::json::value jv;
+    jv.emplace_string();
+}
+
+int main(int, char **)
+{
+    // it's important these are separate functions, otherwise the warnings this
+    // file is supposed to produce do not manifest
+    with_array();
+    with_object();
+    with_string();
+    return 0;
+}