allow forcing the static backtrace_state

References: #118

doc/stacktrace.qbk

@@ -289,7 +289,7 @@ In header only mode library could be tuned by macro. If one of the link macro fr
     [[['default for MSVC, Intel on Windows, MinGW-w64] / *BOOST_STACKTRACE_USE_WINDBG*] [*boost_stacktrace_windbg*] [ Uses `dbgeng.h` to show debug info. May require linking with *ole32* and *dbgeng*. ] [MSVC, MinGW-w64, Intel on Windows] [yes] [no]]
     [[['default for other platforms]] [*boost_stacktrace_basic*] [Uses compiler intrinsics to collect stacktrace and if possible `::dladdr` to show information about the symbol. Requires linking with *libdl* library on POSIX platforms.] [Any compiler on POSIX or MinGW] [no] [yes]]
     [[*BOOST_STACKTRACE_USE_WINDBG_CACHED*] [*boost_stacktrace_windbg_cached*] [ Uses `dbgeng.h` to show debug info and caches internals in TLS for better performance. Useful only for cases when traces are gathered very often. May require linking with *ole32* and *dbgeng*. ] [MSVC, Intel on Windows] [yes] [no]]
-    [[*BOOST_STACKTRACE_USE_BACKTRACE*] [*boost_stacktrace_backtrace*] [Requires linking with *libdl* on POSIX and *libbacktrace* libraries. *libbacktrace* is probably already installed in your system[footnote If you are using Clang with libstdc++ you could get into troubles of including `<backtrace.h>`, because on some platforms Clang does not search for headers in the GCC's include paths and any attempt to add GCC's include path leads to linker errors. To explicitly specify a path to the `<backtrace.h>` header you could define the *BOOST_STACKTRACE_BACKTRACE_INCLUDE_FILE* to a full path to the header. For example on Ubuntu Xenial use the command line option *-DBOOST_STACKTRACE_BACKTRACE_INCLUDE_FILE=</usr/lib/gcc/x86_64-linux-gnu/5/include/backtrace.h>* while building with Clang. ], or built into your compiler.
+    [[*BOOST_STACKTRACE_USE_BACKTRACE*] [*boost_stacktrace_backtrace*] [Requires linking with *libdl* on POSIX and *libbacktrace* libraries[footnote Some *libbacktrace* packages SEGFAULT if there's a concurrent work with the same `backtrace_state` instance. To avoid that issue the Boost.Stacktrace library uses `thread_local` states, unfortuantely this may consume a lot of memory if you often create and destroy execution threads in your application. Define *BOOST_STACKTRACE_BACKTRACE_FORCE_STATIC* to force single instance, but make sure that [@https://github.com/boostorg/stacktrace/blob/develop/test/thread_safety_checking.cpp thread_safety_checking.cpp] works well in your setup. ]. *libbacktrace* is probably already installed in your system[footnote If you are using Clang with libstdc++ you could get into troubles of including `<backtrace.h>`, because on some platforms Clang does not search for headers in the GCC's include paths and any attempt to add GCC's include path leads to linker errors. To explicitly specify a path to the `<backtrace.h>` header you could define the *BOOST_STACKTRACE_BACKTRACE_INCLUDE_FILE* to a full path to the header. For example on Ubuntu Xenial use the command line option *-DBOOST_STACKTRACE_BACKTRACE_INCLUDE_FILE=</usr/lib/gcc/x86_64-linux-gnu/5/include/backtrace.h>* while building with Clang. ], or built into your compiler.
 
      Otherwise (if you are a *MinGW*/*MinGW-w64* user for example) it can be downloaded [@https://github.com/ianlancetaylor/libbacktrace from here] or [@https://github.com/gcc-mirror/gcc/tree/master/libbacktrace from here]. ] [Any compiler on POSIX, or MinGW, or MinGW-w64] [yes] [yes]]
     [[*BOOST_STACKTRACE_USE_ADDR2LINE*] [*boost_stacktrace_addr2line*] [Use *addr2line* program to retrieve stacktrace. Requires linking with *libdl* library and `::fork` system call. Macro *BOOST_STACKTRACE_ADDR2LINE_LOCATION* must be defined to the absolute path to the addr2line executable if it is not located in /usr/bin/addr2line. ] [Any compiler on POSIX] [yes] [yes]]

include/boost/stacktrace/detail/libbacktrace_impls.hpp

@@ -82,10 +82,11 @@ BOOST_SYMBOL_VISIBLE inline ::backtrace_state* construct_state(const program_loc
     //
     //
     // Unfortunately, that solution segfaults when `construct_state()` function is in .so file
-    // and multiple threads concurrently work with state.
+    // and multiple threads concurrently work with state. I failed to localize the root cause:
+    // https://gcc.gnu.org/bugzilla//show_bug.cgi?id=87653
 
 
-#ifndef BOOST_HAS_THREADS
+#if !defined(BOOST_HAS_THREADS) || defined(BOOST_STACKTRACE_BACKTRACE_FORCE_STATIC)
     static
 #else
 

test/Jamfile.v2

@@ -81,6 +81,7 @@ test-suite stacktrace_tests
 
     # Header only tests with debug symbols
     [ run test.cpp test_impl.cpp        : : : <debug-symbols>on <define>BOOST_STACKTRACE_USE_BACKTRACE        $(BT_DEPS)    : backtrace_ho ]
+    [ run test.cpp test_impl.cpp        : : : <debug-symbols>on <define>BOOST_STACKTRACE_USE_BACKTRACE <define>BOOST_STACKTRACE_BACKTRACE_FORCE_STATIC $(BT_DEPS) : backtrace_ho_static ]
     [ run test.cpp test_impl.cpp        : : : <debug-symbols>on <define>BOOST_STACKTRACE_USE_ADDR2LINE        $(AD2L_DEPS)  : addr2line_ho ]
     [ run test_noop.cpp test_impl.cpp   : : : <debug-symbols>on <define>BOOST_STACKTRACE_USE_NOOP             $(NOOP_DEPS)  : noop_ho ]
     [ run test.cpp test_impl.cpp        : : : <debug-symbols>on                                               $(WIND_DEPS)  : windbg_ho ]
@@ -117,6 +118,10 @@ test-suite stacktrace_tests
     [ run thread_safety_checking.cpp
         : : : <debug-symbols>on <library>/boost/thread//boost_thread <library>/boost/timer//boost_timer <library>.//test_impl_lib_backtrace       $(LINKSHARED_BT)
         : backtrace_lib_threaded ]
+    [ run thread_safety_checking.cpp
+        : : : <debug-symbols>on <library>/boost/thread//boost_thread <library>/boost/timer//boost_timer <library>.//test_impl_lib_backtrace       $(LINKSHARED_BT)
+              <define>BOOST_STACKTRACE_BACKTRACE_FORCE_STATIC
+        : backtrace_lib_threaded_ststic ]
     [ run thread_safety_checking.cpp
         : : : <debug-symbols>on <library>/boost/thread//boost_thread <library>/boost/timer//boost_timer <library>.//test_impl_lib_windbg          $(LINKSHARED_WIND)
         : windbg_lib_threaded ]