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96 lines
4.0 KiB
C++
96 lines
4.0 KiB
C++
/* -*- indent-tabs-mode: nil; tab-width: 4; -*- */
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#ifndef GREENLET_COMPILER_COMPAT_HPP
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#define GREENLET_COMPILER_COMPAT_HPP
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/**
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* Definitions to aid with compatibility with different compilers.
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*
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* .. caution:: Use extreme care with noexcept.
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* Some compilers and runtimes, specifically gcc/libgcc/libstdc++ on
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* Linux, implement stack unwinding by throwing an uncatchable
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* exception, one that specifically does not appear to be an active
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* exception to the rest of the runtime. If this happens while we're in a noexcept function,
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* we have violated our dynamic exception contract, and so the runtime
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* will call std::terminate(), which kills the process with the
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* unhelpful message "terminate called without an active exception".
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*
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* This has happened in this scenario: A background thread is running
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* a greenlet that has made a native call and released the GIL.
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* Meanwhile, the main thread finishes and starts shutting down the
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* interpreter. When the background thread is scheduled again and
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* attempts to obtain the GIL, it notices that the interpreter is
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* exiting and calls ``pthread_exit()``. This in turn starts to unwind
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* the stack by throwing that exception. But we had the ``PyCall``
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* functions annotated as noexcept, so the runtime terminated us.
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*
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* #2 0x00007fab26fec2b7 in std::terminate() () from /lib/x86_64-linux-gnu/libstdc++.so.6
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* #3 0x00007fab26febb3c in __gxx_personality_v0 () from /lib/x86_64-linux-gnu/libstdc++.so.6
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* #4 0x00007fab26f34de6 in ?? () from /lib/x86_64-linux-gnu/libgcc_s.so.1
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* #6 0x00007fab276a34c6 in __GI___pthread_unwind at ./nptl/unwind.c:130
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* #7 0x00007fab2769bd3a in __do_cancel () at ../sysdeps/nptl/pthreadP.h:280
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* #8 __GI___pthread_exit (value=value@entry=0x0) at ./nptl/pthread_exit.c:36
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* #9 0x000000000052e567 in PyThread_exit_thread () at ../Python/thread_pthread.h:370
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* #10 0x00000000004d60b5 in take_gil at ../Python/ceval_gil.h:224
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* #11 0x00000000004d65f9 in PyEval_RestoreThread at ../Python/ceval.c:467
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* #12 0x000000000060cce3 in setipaddr at ../Modules/socketmodule.c:1203
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* #13 0x00000000006101cd in socket_gethostbyname
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*/
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#include <cstdint>
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# if defined(__clang__)
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# define G_FP_TMPL_STATIC static
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# else
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// GCC has no problem allowing static function pointers, but emits
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// tons of warnings about "whose type uses the anonymous namespace [-Wsubobject-linkage]"
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# define G_FP_TMPL_STATIC
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# endif
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# define G_NO_COPIES_OF_CLS(Cls) private: \
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Cls(const Cls& other) = delete; \
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Cls& operator=(const Cls& other) = delete
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# define G_NO_ASSIGNMENT_OF_CLS(Cls) private: \
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Cls& operator=(const Cls& other) = delete
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# define G_NO_COPY_CONSTRUCTOR_OF_CLS(Cls) private: \
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Cls(const Cls& other) = delete;
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// CAUTION: MSVC is stupidly picky:
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//
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// "The compiler ignores, without warning, any __declspec keywords
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// placed after * or & and in front of the variable identifier in a
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// declaration."
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// (https://docs.microsoft.com/en-us/cpp/cpp/declspec?view=msvc-160)
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//
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// So pointer return types must be handled differently (because of the
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// trailing *), or you get inscrutable compiler warnings like "error
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// C2059: syntax error: ''"
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//
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// In C++ 11, there is a standard syntax for attributes, and
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// GCC defines an attribute to use with this: [[gnu:noinline]].
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// In the future, this is expected to become standard.
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#if defined(__GNUC__) || defined(__clang__)
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/* We used to check for GCC 4+ or 3.4+, but those compilers are
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laughably out of date. Just assume they support it. */
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# define GREENLET_NOINLINE(name) __attribute__((noinline)) name
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# define GREENLET_NOINLINE_P(rtype, name) rtype __attribute__((noinline)) name
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# define UNUSED(x) UNUSED_ ## x __attribute__((__unused__))
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#elif defined(_MSC_VER)
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/* We used to check for && (_MSC_VER >= 1300) but that's also out of date. */
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# define GREENLET_NOINLINE(name) __declspec(noinline) name
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# define GREENLET_NOINLINE_P(rtype, name) __declspec(noinline) rtype name
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# define UNUSED(x) UNUSED_ ## x
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#endif
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#if defined(_MSC_VER)
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# define G_NOEXCEPT_WIN32 noexcept
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#else
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# define G_NOEXCEPT_WIN32
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#endif
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#endif
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