Date: Sun, 24 Jan 2016 17:43:40 -0800 From: Mark Millard <markmi@dsl-only.net> To: Dimitry Andric <dim@FreeBSD.org> Cc: FreeBSD Toolchain <freebsd-toolchain@freebsd.org>, FreeBSD PowerPC ML <freebsd-ppc@freebsd.org> Subject: Re: powerpc64-gcc unable to compile clang 3.8.0 from clang380-import -r294609 via buildworld [correction] Message-ID: <D926875C-9308-45BC-B97E-7C335AB05D16@dsl-only.net> In-Reply-To: <7B4DCD0C-8EE5-4A58-9A11-40C2C4570733@dsl-only.net> References: <67523280-9F20-4638-BF24-1BFAE8583805@dsl-only.net> <5B511209-F26D-4788-B80B-E0328963C263@FreeBSD.org> <582B67B0-25F4-40BE-A92F-D4818DCB9F97@dsl-only.net> <EE2741F6-406D-4D93-8DF6-91B788F99182@dsl-only.net> <6BA37DD4-3F58-438B-B1E0-7312389B576D@dsl-only.net> <693CD1BD-6F32-47A5-B399-701219F5A6DA@FreeBSD.org> <7B4DCD0C-8EE5-4A58-9A11-40C2C4570733@dsl-only.net>
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Looks like I screwed up by thinking that one of my tests had neither of _LIBCPP_HAS_NO_TRAILING_RETURN nor _LIBCPP_HAS_NO_RVALUE_REFERENCES defined when in fact _LIBCPP_HAS_NO_TRAILING_RETURN was still defined (making _LIBCPP_HAS_NO_RVALUE_REFERENCES irrelevant). Other forms of checking if __GXX_EXPERIMENTAL_CXX0X__ is defined or not when -std=c++11 is used have all shown that it is defined for the g++ vintages in question. (SOME_GCC_CMD -std=c++11 -dM -E - < /dev/null can not be used: an actual source code file name is required on the command line to get an actual C++ compile even when -std=c++11 is specified. The - < /dev/null use reverts to a C compile with a message about doing so.) So I'm running a buildworld to cross-check but I now expect that you [Dimitry] are correct that my > -#ifndef __GXX_EXPERIMENTAL_CXX0X__ > +#if !defined(__GXX_EXPERIMENTAL_CXX0X__) && __cplusplus < 201103L was not and is not needed. === Mark Millard markmi at dsl-only.net On 2016-Jan-24, at 12:39 PM, Mark Millard <markmi@dsl-only.net> wrote: On 2016-Jan-24, at 9:20 AM, Dimitry Andric <dim at FreeBSD.org> wrote: > > On 24 Jan 2016, at 12:20, Mark Millard <markmi at dsl-only.net> wrote: >> >> My current trial powerpc64-gcc based buildworld is well past where it stopped before (in a clang 3.8.0 part of the build). What I changed in libc++ was just a little of __config: > > It appears upstream has done approximately the same thing here: > http://llvm.org/viewvc/llvm-project?view=revision&revision=255585 > > >> # svnlite diff /usr/src/contrib/libc++/include/__config >> Index: /usr/src/contrib/libc++/include/__config >> =================================================================== >> --- /usr/src/contrib/libc++/include/__config (revision 294609) >> +++ /usr/src/contrib/libc++/include/__config (working copy) >> @@ -432,13 +432,15 @@ >> // No version of GCC supports relaxed constexpr rules >> #define _LIBCPP_HAS_NO_CXX14_CONSTEXPR >> // GCC 5 will support variable templates >> +#if !defined(__cpp_variable_templates) || __cpp_variable_templates < 201304L >> #define _LIBCPP_HAS_NO_VARIABLE_TEMPLATES >> +#endif >> >> #define _NOEXCEPT throw() >> #define _NOEXCEPT_(x) >> #define _NOEXCEPT_OR_FALSE(x) false >> >> -#ifndef __GXX_EXPERIMENTAL_CXX0X__ >> +#if !defined(__GXX_EXPERIMENTAL_CXX0X__) && __cplusplus < 201103L > > Except for this change. Why was this needed? -r255585 (and later) upstream still has (quoted extractions from file showing more context): > #elif defined(__GNUC__) . . . > #define _NOEXCEPT throw() > #define _NOEXCEPT_(x) > #define _NOEXCEPT_OR_FALSE(x) false > > #ifndef __GXX_EXPERIMENTAL_CXX0X__ > > #define _LIBCPP_HAS_NO_ADVANCED_SFINAE > #define _LIBCPP_HAS_NO_DECLTYPE > #define _LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS > #define _LIBCPP_HAS_NO_DELETED_FUNCTIONS > #define _LIBCPP_HAS_NO_NULLPTR > #define _LIBCPP_HAS_NO_STATIC_ASSERT > #define _LIBCPP_HAS_NO_UNICODE_CHARS > #define _LIBCPP_HAS_NO_VARIADICS > #define _LIBCPP_HAS_NO_RVALUE_REFERENCES > #define _LIBCPP_HAS_NO_ALWAYS_INLINE_VARIADICS > #define _LIBCPP_HAS_NO_STRONG_ENUMS > > #else // __GXX_EXPERIMENTAL_CXX0X__ . . . In modern times for -std=c++11 this turns off the 11 or so features by defining the 11 or so macros. This is because -std=c++11 in powerpc64-gcc is no longer classfied as experimental (experimental before 5.1, not 5.1 and later if I what I read is correct). Those disabled things are no longer experimental and __GXX_EXPERIMENTAL_CXX0X__ no longer determines their status in sufficiently modern g++'s. And it appears that clang/llvm is gradually doing things that add more dependence on having enabled c++11 features, such as now getting the error that I originally showed. Without such a __config change powerpc64-gcc will not compile the 3.8.0 source: I tried before changing it. (_LIBCPP_HAS_NO_TRAILING_RETURN also needs to not be defined to avoid the specific error that I showed. It is not just _LIBCPP_HAS_NO_RVALUE_REFERENCES that matters.) I picked the __cplusplus version check based on using boost's long-established version check (1.57.0-1.60.0 of boost) but using 201103L makes sense from the language definition point of view as well. The specific error that I originally showed traced back to std::begin(. . .) and std::end(. . .) getting old definitions because of the conditional logic in <iterator> that was engaged by 2 of the mistaken disables overall (more quoted extractions, this time from <iterator>): . . . > #if !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES) && !defined(_LIBCPP_HAS_NO_TRAILING_RETURN) . . . Modern std::begin and std::end definitions (and more) . . . > #else // !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES) && !defined(_LIBCPP_HAS_NO_TRAILING_RETURN) . . . Old std::begin and std::end definitions . . . > #endif // !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES) && !defined(_LIBCPP_HAS_NO_TRAILING_RETURN) . . . Other notes: It looks like -r255585 upstream also added to the logic for _LIBCPP_HAS_NO_CONSTEXPR and has: > // constexpr was added to GCC in 4.6. > #if _GNUC_VER < 406 > #define _LIBCPP_HAS_NO_CONSTEXPR > // Can only use constexpr in c++11 mode. > #elif !defined(__GXX_EXPERIMENTAL_CXX0X__) && __cplusplus < 201103L > #define _LIBCPP_HAS_NO_CONSTEXPR > #endif that I did not that way. There are also versions: -r257707 2016-Jan-13 -r257629 2016-Jan-13 (marked as "Update version to 3.9") -r257422 2016-Jan-11 -r257368 2016-Jan-11 -r256652 2015-Dec-30 -r256325 2015-Dec-23 -r255868 2015-Dec-15 -r255683 2015-Dec-15 -r255585 2015-Dec-14 (the one that you identified) But I did not try to pick a point from this history of changes at all and so may have missed other things that would be appropriate beyond the issue that I was trying to address. I may well be the only one that cares if powerpc64-gcc (or analogous ???-gcc's) can buildworld for clang380-import before it is merged into 11.0-CURRENT. Since I've been able to rebuild (non-LIB32) I'm not stuck if you leave things as they are for now. If __config is not changed now, I'll try to be a cross check on remembering the issue later so that 11.0-CURRENT can continue to build (non-LIB32) with powerpc64-gcc. (I do not have any hardware context for other ???-gcc xtoolchain use but all should track powerpc64-gcc on the issue as far as I know.) === Mark Millard markmi at dsl-only.nethelp
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