Jonathan Wakely <jwak...@redhat.com> writes: > On Thu, 20 Oct 2022 at 16:53, Arsen Arsenović via Libstdc++ > <libstd...@gcc.gnu.org> wrote: >> >> This enables us to provide symbols for placeholders and numeric limits, > > > I'm not convinced this is worth doing. > > The placeholders and the numeric_limits members are all inline > variables for C++17 and later, and C++17 is the compiler's default > mode. The placeholders aren't even required to exist for freestanding > prior to C++23. For the numeric_limits definitions, I suppose it is a > problem that users can't take their address in freestanding today > unless they compile as C++17. > >> and allows users to mess about with linker flags less. > > i.e. they don't have to use -nostdlib and/or link with gcc -lsupc++, > but can just use g++? > > That seems more compelling than providing definitions of the > placeholders and limits members.
Indeed, with just a few more changes that I didn't get the chance to
polish up before S3 (setting the MATH_LIBRARY target macro to "" and
disabling linking crt0 when building --without-headers
--without-newlib), and the other patches I did submit, I could get a
freestanding test program building with just -nolibc:
i686-elf-g++ -ffreestanding -ggdb3 -O2 -fno-omit-frame-pointer \
-std=gnu++20 -T ../linkscript.ld -nolibc \
-Wl,-z,max-page-size=0x1000 -o frello frello-main.o frello-abort.o \
-frello-support.o frello-memory.o frello-logging.o frello-assert.o \
frello-entry.o
Most of these flags serve unrelated purposes, and the linker script is
the default one for this configuration, with some sections shifted
about.
Have a great evening!
--
Arsen Arsenović
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