Boost has its own implementation of a spinlock and atomic counters inside its shared_ptr implementation, which is used by (at least) the signals2 implementation. By default, it prefers its own implementations over C++11 atomics.
Add two macro definitions to make it choose the std::atomics based implementations instead.
These macros are supported since Boost 1.56, and the behaviour is default since Boost 1.63.
235 | @@ -236,7 +236,7 @@ if test "x$CXXFLAGS_overridden" = "xno"; then 236 | AX_CHECK_COMPILE_FLAG([-Wunused-local-typedef],[CXXFLAGS="$CXXFLAGS -Wno-unused-local-typedef"],,[[$CXXFLAG_WERROR]]) 237 | AX_CHECK_COMPILE_FLAG([-Wdeprecated-register],[CXXFLAGS="$CXXFLAGS -Wno-deprecated-register"],,[[$CXXFLAG_WERROR]]) 238 | fi 239 | -CPPFLAGS="$CPPFLAGS -DHAVE_BUILD_INFO -D__STDC_FORMAT_MACROS" 240 | +CPPFLAGS="$CPPFLAGS -DHAVE_BUILD_INFO -D__STDC_FORMAT_MACROS -DBOOST_SP_USE_STD_ATOMIC -DBOOST_\A\C_USE_STD_ATOMIC"
-DBOOST_\A\C_USE_STD_ATOMIC that looks strange
Very much so, but I don't know how else to prevent autoconf from interpreting it as a macro.
I think wrapping the whole line in [ ] might shut it up?
I had tried that already:
CPPFLAGS=["$CPPFLAGS -DHAVE_BUILD_INFO -D__STDC_FORMAT_MACROS -DBOOST_SP_USE_STD_ATOMIC -DBOOST_AC_USE_STD_ATOMIC"]
does not work.
The error is:
configure.ac:239: error: possibly undefined macro: DBOOST_AC_USE_STD_ATOMIC
If this token and others are legitimate, please use m4_pattern_allow.
See the Autoconf documentation.
autoreconf: /usr/bin/autoconf failed with exit status: 1
Ok, the recommended m4_pattern_allow hack works. Seems reasonable, there's no way that will ever become a macro.
Also, please stick this in BOOST_CPPFLAGS (after the AX_BOOST_* checks) rather than in the global one:
m4_pattern_allow(DBOOST_AC_USE_STD_ATOMIC) dnl otherwise it's treated like a macro
BOOST_CPPFLAGS="-DBOOST_SP_USE_STD_ATOMIC -DBOOST_AC_USE_STD_ATOMIC $BOOST_CPPFLAGS"
Concept ACK, I think using the same atomics everywhere (those of the compiler) is a good thing.
Apparently Boost will use std::atomic by default since 1.63 (verified by looking at the code, nothing in release notes).
Concept ACK. Are you sure these are the only two necessary?
I grepped the source code for other BOOST_*_USE things, but nothing seems relevant.
Thanks. utACK 394ccf76adb016b48908cd9a0fa08a1663a7ddba
I cloned the boost smart_ptr repo and verified that these are the only defines needed, and that there are no uses of them in any cpp files (duh, it's a header-only lib).
utACK