Date: Sun, 12 Feb 2023 15:09:24 -0800 From: Mark Millard <marklmi@yahoo.com> To: David Chisnall <theraven@FreeBSD.org> Cc: FreeBSD Hackers <freebsd-hackers@freebsd.org>, shawn.webb@hardenedbsd.org, Dimitry Andric <dim@FreeBSD.org> Subject: Re: CFT: snmalloc as libc malloc (the source_location issue) Message-ID: <DA5C06D1-4649-40D2-858E-B96AE2A80B94@yahoo.com> In-Reply-To: <F363CC44-831B-41E8-BB82-564144C48AA4@FreeBSD.org> References: <22F8AD1A-C1F9-48FA-BCED-E165E2DA5260@yahoo.com> <1982263E-57E0-4709-AAB3-DBB4F75C7546@yahoo.com> <96652C51-EAB7-46C7-9039-557A5DCDAB75@yahoo.com> <F363CC44-831B-41E8-BB82-564144C48AA4@FreeBSD.org>
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[Previously noted in another exchange, I note the snmalloc source issue in reply to this message as well, to hopefully avoid confusions when someone reads this particular exchange.] On Feb 11, 2023, at 09:13, David Chisnall <theraven@FreeBSD.org> wrote: > On 10 Feb 2023, at 21:34, Mark Millard <marklmi@yahoo.com> wrote: >>=20 >> # find / -name source_location -print | more >> = /usr/obj/DESTDIRs/main-amd64-chroot/usr/local/lib/gcc12/include/c++/experi= mental/source_location >> = /usr/obj/DESTDIRs/main-amd64-chroot/usr/local/lib/gcc12/include/c++/source= _location >> /usr/local/lib/gcc12/include/c++/experimental/source_location >> /usr/local/lib/gcc12/include/c++/source_location >>=20 >> So, none for FreeBSD and its llvm15. >>=20 >> This makes sense, https://libcxx.llvm.org/Status/Cxx20.html shows: >>=20 >> P1208R6 LWG Adopt source_location for C++20 Cologne Complete 16.0 >>=20 >> So, likely FreeBSD will not have this until it progresses to >> LLVM16 . It just changed to LLVM15 in main [so: FreeBSD 14]. >=20 > The include of source_location is guarded under an #if __has_include, I do not see such when I look at: = https://github.com/microsoft/snmalloc/blob/main/src/snmalloc/ds_core/defin= es.h What I see is version checking that is based on llvm15 and above having source_location : #if (defined(__GNUC__) && !defined(__clang__) && __GNUC__ >=3D 11) || \ (defined(__clang__) && __clang_major__ >=3D 15) # include <source_location> . . . __clang_major__ >=3D 16 would be appropriate, based on: https://libcxx.llvm.org/Status/Cxx20.html Other tests, less dependent on version checking, might work instead. > it should be used only if it exists. If it doesn=E2=80=99t, there=E2=80= =99s a stub implementation. If you have GCC includes in your include = path, is it possible that it=E2=80=99s finding a source_location that is = then guarded behind a check for a compiler builtin that clang doesn=E2=80=99= t have? =3D=3D=3D Mark Millard marklmi at yahoo.com
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