[Bug ld/26668] New: incremental linking of LTO and non-LTO objects always warns

[goswin-v-b at web dot de]

https://sourceware.org/bugzilla/show_bug.cgi?id=26668

            Bug ID: 26668
           Summary: incremental linking of LTO and non-LTO objects always
                    warns
           Product: binutils
           Version: 2.35
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: ld
          Assignee: unassigned at sourceware dot org
          Reporter: goswin-v-b at web dot de
  Target Milestone: ---

I'm building a temporary library out of LTO and non-LTO object files like this:

    x86_64-elf-ld -plugin
/home/mrvn/cross/libexec/gcc/x86_64-elf/10.2.0/liblto_plugin.so
-plugin-opt=/home/mrvn/cross/libexec/gcc/x86_64-elf/10.2.0/lto-wrapper
-plugin-opt=-fresolution=kernel/_tmp-y.o.res -T kernel/ldscript  -i -o
kernel/_tmp-y.o --start-group _empty.c.o kernel/main.cc.lto --end-group

and the linker warns:

    x86_64-elf-ld: warning: incremental linking of LTO and non-LTO objects;
using -flinker-output=nolto-rel which will bypass whole program optimization

My understanding is that the linker will then optimize all the LTO objects
given and produce a non-LTO object file, which is what I want. The library
should be optimized internally but should not later optimize with other LTO
code outside the library.

My problem now is that the warning can not be avoided. I can't tell the linker
that nolto-rel is what I want because adding -flinker-output=nolto-rel results
in:

    x86_64-elf-ld: -f may not be used without -shared

and adding -shared results in:

    x86_64-elf-ld: -r and -shared may not be used together

Please add a way to specify that nolto-res is the desired behavior.

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