Re: [PATCH] perf build: Fix broken feature check for clang due to C++ standard and changed library packaging

[Ian Rogers]

On Wed, Jul 12, 2023 at 8:02 PM Ian Rogers <irogers@xxxxxxxxxx> wrote:
>
> On Wed, Jul 12, 2023 at 1:35 AM Thomas Richter <tmricht@xxxxxxxxxxxxx> wrote:
> >
> > Perf build auto-detects features and packages already installed
> > for its build. This is done in directory tools/build/feature. This
> > directory contains small sample programs. When they successfully
> > compile the necessary prereqs in form of libraries and header
> > files are present.
> >
> > Such a check is also done for clang. And this check fails.
> >
> > Fix this and update to the latest C++ standard and use the
> > new library provided by clang (which contains new packaging)
> > see this link for reference:
> >  https://fedoraproject.org/wiki/Changes/Stop-Shipping-Individual-Component-Libraries-In-clang-lib-Package
> >
> > Output before:
> >  # rm -f ./test-clang.bin; make test-clang.bin; ./test-clang.bin; \
> >         ll test-clang.make.output
> >  g++  -MD -Wall -Werror -o test-clang.bin test-clang.cpp \
> >                 > test-clang.make.output 2>&1 -std=gnu++14 \
> >         -I/usr/include          \
> >         -L/usr/lib64            \
> >         -Wl,--start-group -lclangBasic -lclangDriver    \
> >           -lclangFrontend -lclangEdit -lclangLex        \
> >           -lclangAST -Wl,--end-group                    \
> >         -lLLVM-16       \
> >                         \
> >         > test-clang.make.output 2>&1
> >  make: *** [Makefile:356: test-clang.bin] Error 1
> >  -bash: ./test-clang.bin: No such file or directory
> >  -rw-r--r--. 1 root root 252041 Jul 12 09:56 test-clang.make.output
> >  #
> >
> > File test-clang.make.output contains many lines of unreferenced
> > symbols.
> >
> > Output after:
> >  # rm -f ./test-clang.bin; make test-clang.bin; ./test-clang.bin; \
> >         cat test-clang.make.output
> >  g++  -MD -Wall -Werror -o test-clang.bin test-clang.cpp \
> >          > test-clang.make.output 2>&1 -std=gnu++17     \
> >         -I/usr/include          \
> >         -L/usr/lib64            \
> >         -Wl,--start-group -lclang-cpp -Wl,--end-group   \
> >         -lLLVM-16       \
> >                         \
> >         > test-clang.make.output 2>&1
> >  #
> >
> > Signed-off-by: Thomas Richter <tmricht@xxxxxxxxxxxxx>
>
> Tested-by: Ian Rogers <irogers@xxxxxxxxxx>

Ah, presumably obsolete to:
https://lore.kernel.org/linux-perf-users/20230712083037.4081444-1-tmricht@xxxxxxxxxxxxx/

Thanks,
Ian



> Thanks!
> Ian
>
> > ---
> >  tools/build/feature/Makefile | 6 ++----
> >  1 file changed, 2 insertions(+), 4 deletions(-)
> >
> > diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
> > index f8db69654791..0b4a6e43c5cc 100644
> > --- a/tools/build/feature/Makefile
> > +++ b/tools/build/feature/Makefile
> > @@ -353,12 +353,10 @@ $(OUTPUT)test-llvm-version.bin:
> >                 > $(@:.bin=.make.output) 2>&1
> >
> >  $(OUTPUT)test-clang.bin:
> > -       $(BUILDXX) -std=gnu++14                                 \
> > +       $(BUILDXX) -std=gnu++17                                 \
> >                 -I$(shell $(LLVM_CONFIG) --includedir)          \
> >                 -L$(shell $(LLVM_CONFIG) --libdir)              \
> > -               -Wl,--start-group -lclangBasic -lclangDriver    \
> > -                 -lclangFrontend -lclangEdit -lclangLex        \
> > -                 -lclangAST -Wl,--end-group                    \
> > +               -Wl,--start-group -lclang-cpp -Wl,--end-group   \
> >                 $(shell $(LLVM_CONFIG) --libs Core option)      \
> >                 $(shell $(LLVM_CONFIG) --system-libs)           \
> >                 > $(@:.bin=.make.output) 2>&1
> > --
> > 2.41.0
> >