Date: Wed, 13 Sep 2023 17:37:21 +0200 From: Jan Beich <jbeich@FreeBSD.org> To: Emmanuel Vadot <manu@bidouilliste.com> Cc: Gleb Popov <arrowd@freebsd.org>, "Tobias C. Berner" <tcberner@freebsd.org>, ports-committers@freebsd.org, dev-commits-ports-all@freebsd.org, dev-commits-ports-main@freebsd.org Subject: Re: git: 4df0e66a3662 - main - llvm.mk: add export/noexport to handle CC/CXX/CPP exports Message-ID: <r0n2-2ifi-wny@FreeBSD.org> In-Reply-To: <msxq-5dgh-wny@FreeBSD.org> (Jan Beich's message of "Wed, 13 Sep 2023 16:56:30 %2B0200") References: <202309130518.38D5INm2018105@gitrepo.freebsd.org> <CALH631mauenLxm13nmEo9SCyqGMu2yRJ9C-gjjJ9yS4Wg0L33g@mail.gmail.com> <20230913102352.b641f29cd7cb76f2937d1a61@bidouilliste.com> <zg1q-fhbp-wny@FreeBSD.org> <msxq-5dgh-wny@FreeBSD.org>
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Jan Beich <jbeich@FreeBSD.org> writes: > Jan Beich <jbeich@FreeBSD.org> writes: > >> Emmanuel Vadot <manu@bidouilliste.com> writes: >> >>> On Wed, 13 Sep 2023 08:55:48 +0300 >>> Gleb Popov <arrowd@freebsd.org> wrote: >>> >>>> On Wed, Sep 13, 2023 at 8:20?AM Tobias C. Berner <tcberner@freebsd.org> wrote: >>>> > >>>> > + USES=llvm.mk now supports 'export' (default) and 'noexport' arguments. >>>> > + When export is set, CC, CXX and CPP will be set to the path corresponding >>>> > + to the chosen llvm-version. >>>> >>>> The choice for the default seems strange to me. Now every port that >>>> has USES=llvm will be switching to building with a non-base compiler. >>>> Is this really a sensible default? >>> >>> Isn't that what you want when you add USES=llvm ? >> >> Changing CC is USES=compiler job. Contributors starting using USES=llvm >> for changing Clang version because USES=compiler is poorly maintained. >> >> I predominantly add USES=llvm to satisfy libLLVM (mesa-devel, rpcs3) or >> libclang (USES=cargo + CARGO_CRATES=bindgen). In a few cases when I need >> newer Clang (for C++20 std:ranges, C++23) I also need newer libc++ but >> devel/llvm* maintainer refuses to provide libc++ (bug 260139). >> >> Forcing CC/CXX/CPP without testing all consumers has a chance of >> introducing regressions. For example, when using LTO it's important to >> make sure CMake doesn't pick up /usr/bin/llvm-ar or /usr/bin/llvm-ranlib >> because those may not support LLVM bitcode used by devel/llvm*. >> >> https://cgit.freebsd.org/ports/commit/?id=5e71e4d45129 >> https://cgit.freebsd.org/ports/commit/?id=2ce01a07d7c9 >> >> While the affected ports had LTO enabled by default there's also >> WITH_LTO knob handled by /usr/ports/Mk/Features/lto.mk. > > D37747 had TEST PLAN with "Actually test", SUMMARY with "Heavily WIP", > said :lib wasn't affected and limited port Clang to older base Clang. > The mini exp-run by a reviewer was limited to "the specific ports of interest" > thus didn't cover all consumers (let alone all ports). For example, > I've discovered this broke one of my ports: > > https://cgit.freebsd.org/ports/commit/?id=391f28644973 and https://cgit.freebsd.org/ports/commit/?id=07fe3d738b39 > The commit message is no better: didn't mention the new default is "export". > For example, FreeBSD >= 14.0 now uses port Clang 15 instead of base Clang 16. > This may degrade optimization slightly, assuming Clang improves each version. WITH_CCACHE_BUILD is also pessimized. Besides different Clang version, different Clang binary name (bin/clang15 vs. llvm15/bin/clang) there's also relative (using ccache via symlink in PATH) vs. absolute path.
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