[package] boost/*: ios variant misses two define exports

[qwertzui11]

Package and Environment Details (include every applicable attribute)

• Package Name/Version: boost/1.74.0
• Operating System+version: iOS
• Compiler+version: clang 12
• Conan version: conan 1.31.0
• Python version: Python 3.8.5

Conan profiles

build.profile

[settings]
os=Macos
os_build=Macos
arch=x86_64
arch_build=x86_64
compiler=apple-clang
compiler.version=12.0
compiler.libcxx=libc++
build_type=Release
[options]
[build_requires]
[env]

host.profile (ios Simulator)

[settings]
os=iOS
os.version=12.0
arch=x86_64
compiler=apple-clang
compiler.version=12.0
compiler.libcxx=libc++
build_type=Debug
[options]
[build_requires]
[env]

Steps to reproduce

I'm cross compiling boost from MacOS to iOS Simulator (x86_64). Which works quite well. Awesome job!
However when consuming the library weird runtime crashes occur due to invalid memory access.
Two days of debugging and address sanitizer showed that the consuming product has two defines missing. -DBOOST_SP_USE_PTHREADS and -DBOOST_AC_USE_PTHREADS.

conan-center-index/recipes/boost/all/conanfile.py

Lines 764 to 767 in d956a46

	if self.settings.os == "iOS":
	if self.options.multithreading:
	cxx_flags.append("-DBOOST_AC_USE_PTHREADS")
	cxx_flags.append("-DBOOST_SP_USE_PTHREADS")

May I suggest that you add the flags -DBOOST_SP_USE_PTHREADS and -DBOOST_AC_USE_PTHREADS to the package_info method?

conan-center-index/recipes/boost/all/conanfile.py

Line 1014 in d956a46

def package_info(self):

Thanks for your time!

[madebr]

When googling for ios BOOST_AC_USE_PTHREADS BOOST_SP_USE_PTHREADS,
I indeed get results with problems.

Reading https://www.boost.org/doc/libs/1_74_0/libs/smart_ptr/doc/html/smart_ptr.html#shared_ptr_thread_safety,
it looks like the lock-free platform-specific implementation does not work on iOS.

Could you please report this at https://github.com/boostorg/smart_ptr/issues and/or https://github.com/boostorg/atomic/issues?
(Please put in the report with what arguments b2 is run and what compile options are passed when compiling your binaries)

[qwertzui11]

conan does everything right and boost too... the issue seems to be the projects USING the compiled ios boost version. because smart_ptr is header-only the USING projects must declare BOOST_AC_USE_PTHREADS and BOOST_SP_USE_PTHREADS too.

so in my opinion package_info should declare something like this:

def package_info(self):
  if self.settings.os == "iOS":
    self.cpp_info.components["no idea"].defines = ["BOOST_AC_USE_PTHREADS", "BOOST_SP_USE_PTHREADS"]

[madebr]

Sounds good,
I will add

def package_info(self):
--- a/recipes/boost/all/conanfile.py
+++ b/recipes/boost/all/conanfile.py
@@ -1245,3 +1245,10 @@
                         self.cpp_info.components["_libboost"].cxxflags.append("-pthread")
                         self.cpp_info.components["_libboost"].sharedlinkflags.extend(["-pthread","--shared-memory"])
                         self.cpp_info.components["_libboost"].exelinkflags.extend(["-pthread","--shared-memory"])
+            elif self.settings.os == "iOS":
+                if self.options.multithreading:
+                    # https://github.com/conan-io/conan-center-index/issues/3867
+                    # runtime crashes occur when using the default platform-specific reference counter/atomic
+                    self.cpp_info.components["headers"].extend(["BOOST_AC_USE_PTHREADS", "BOOST_SP_USE_PTHREADS"])
+                else:
+                    self.cpp_info.components["headers"].extend(["BOOST_AC_DISABLE_THREADS", "BOOST_SP_DISABLE_THREADS"])

to the pr at #3872

[madebr]

Do you happen to know whether watchOS and tvOS suffer from the same problem?

[qwertzui11]

Do you happen to know whether watchOS and tvOS suffer from the same problem?

No, no idea. And don't have the hardware. I can test the simulators if would like so? However, I'm quite sure, all iOS devices are affected.

[madebr]

Thanks, but only if it does not require much time.

I'm still thinking it would be interesting to open an issue at the boostorg repo(s).
It's always interesting to let them know that the default smartptr/atomic backend causes problems on iOS.
It's hard to believe that this problem appears now.

[SSE4]

I think it more or less going from https://stackoverflow.com/questions/14692802/boost-threads-in-ios-thread-info-object-is-being-destructed-before-the-thread

[madebr]

I'm just saying that the upstream project needs to be made aware of the problem.
They know their code the best.