rust: C/C++ targets collect all rlib dependencies of a staticlib as linker flags

[sdroege]

Project in question: https://github.com/HLTAS/hltas/tree/meson

When building this project with latest meson (plus #11719), the following commands are executed

[1/13] ccache c++ -Icpp/libhltas_cpp.a.p -Icpp -I../cpp -fdiagnostics-color=always -D_FILE_OFFSET_BITS=64 -Wall -Winvalid-pch -std=c++14 -O0 -g -fPIC -MD -MQ cpp/libhltas_cpp.a.p/src_hltas.cpp.o -MF cpp/libhltas_cpp.a.p/src_hltas.cpp.o.d -o cpp/libhltas_cpp.a.p/src_hltas.cpp.o -c ../cpp/src/hltas.cpp
[2/13] rm -f cpp/libhltas_cpp.a && gcc-ar csrDT cpp/libhltas_cpp.a cpp/libhltas_cpp.a.p/src_hltas.cpp.o
[3/13] ccache c++ -Icpp/hltas-cpp-tests.p -Icpp -I../cpp -I../cpp/src -I../cpp/catch2 -fdiagnostics-color=always -D_FILE_OFFSET_BITS=64 -Wall -Winvalid-pch -std=c++14 -O0 -g -MD -MQ cpp/hltas-cpp-tests.p/src_tests.cpp.o -MF cpp/hltas-cpp-tests.p/src_tests.cpp.o.d -o cpp/hltas-cpp-tests.p/src_tests.cpp.o -c ../cpp/src/tests.cpp
[4/13] rustc -C linker=cc --color=always -C debug-assertions=yes --crate-type rlib --edition=2018 -g -C relocation-model=pic --crate-name cfg_if --emit dep-info=subprojects/cfg-if-1.0.0/cfg_if.d --emit link -o subprojects/cfg-if-1.0.0/libcfg_if.rlib ../subprojects/cfg-if-1.0.0/src/lib.rs
[5/13] rustc -C linker=cc --color=always -C debug-assertions=yes --crate-type rlib --edition=2018 -g -C relocation-model=pic --crate-name minimal_lexical --emit dep-info=subprojects/minimal-lexical-0.2.1/minimal_lexical.d --emit link --cfg 'feature="default"' --cfg 'feature="std"' -o subprojects/minimal-lexical-0.2.1/libminimal_lexical.rlib ../subprojects/minimal-lexical-0.2.1/src/lib.rs
[6/13] rustc -C linker=cc --color=always -C debug-assertions=yes --crate-type rlib --edition=2018 -g -C relocation-model=pic --crate-name cookie_factory --emit dep-info=subprojects/cookie-factory-0.3.2/cookie_factory.d --emit link --cfg 'feature="default"' --cfg 'feature="std"' -o subprojects/cookie-factory-0.3.2/libcookie_factory.rlib ../subprojects/cookie-factory-0.3.2/src/lib.rs
[7/13] rustc -C linker=cc --color=always -C debug-assertions=yes --crate-type rlib --edition=2018 -g -C relocation-model=pic --crate-name memchr --emit dep-info=subprojects/memchr-2.5.0/memchr.d --emit link --cfg 'feature="default"' --cfg 'feature="std"' --cfg memchr_runtime_simd --cfg memchr_runtime_sse2 --cfg memchr_runtime_sse42 --cfg memchr_runtime_avx -o subprojects/memchr-2.5.0/libmemchr.rlib ../subprojects/memchr-2.5.0/src/lib.rs
[8/13] rustc -C linker=cc --color=always -C debug-assertions=yes --crate-type rlib --edition=2018 -g -C relocation-model=pic --crate-name nom --emit dep-info=subprojects/nom-7.1.3/nom.d --emit link --cfg 'feature="default"' --cfg 'feature="std"' --cfg 'feature="alloc"' -o subprojects/nom-7.1.3/libnom.rlib --extern memchr=subprojects/memchr-2.5.0/libmemchr.rlib --extern minimal_lexical=subprojects/minimal-lexical-0.2.1/libminimal_lexical.rlib -L subprojects/memchr-2.5.0 -L subprojects/minimal-lexical-0.2.1 ../subprojects/nom-7.1.3/src/lib.rs
[9/13] rustc -C linker=cc --color=always -C debug-assertions=yes --crate-type rlib --edition=2021 -g -C relocation-model=pic --crate-name hltas --emit dep-info=hltas.d --emit link -o libhltas.rlib --extern nom=subprojects/nom-7.1.3/libnom.rlib --extern cookie_factory=subprojects/cookie-factory-0.3.2/libcookie_factory.rlib -L subprojects/nom-7.1.3 -L subprojects/minimal-lexical-0.2.1 -L subprojects/memchr-2.5.0 -L subprojects/cookie-factory-0.3.2 ../src/lib.rs
[10/13] rustc -C linker=cc --color=always -C debug-assertions=yes --crate-type staticlib --edition=2021 -g -C relocation-model=pic --crate-name hltas_cpp_bridge --emit dep-info=hltas-cpp-bridge/hltas_cpp_bridge.d --emit link -o hltas-cpp-bridge/libhltas_cpp_bridge.a --extern hltas=libhltas.rlib --extern nom=subprojects/nom-7.1.3/libnom.rlib --extern cfg_if=subprojects/cfg-if-1.0.0/libcfg_if.rlib -L . -L subprojects/cookie-factory-0.3.2 -L subprojects/nom-7.1.3 -L subprojects/minimal-lexical-0.2.1 -L subprojects/memchr-2.5.0 -L subprojects/cfg-if-1.0.0 ../hltas-cpp-bridge/src/lib.rs
[11/13] rustc -C linker=cc --color=always -C debug-assertions=yes --crate-type bin --edition=2021 -g --crate-name hltas_tests --emit dep-info=hltas-tests.d --emit link --test -o hltas-tests --extern nom=subprojects/nom-7.1.3/libnom.rlib --extern cookie_factory=subprojects/cookie-factory-0.3.2/libcookie_factory.rlib -L subprojects/nom-7.1.3 -L subprojects/minimal-lexical-0.2.1 -L subprojects/memchr-2.5.0 -L subprojects/cookie-factory-0.3.2 ../src/lib.rs
[12/13] rustc -C linker=cc --color=always -C debug-assertions=yes --crate-type bin --edition=2021 -g --crate-name hltas_cpp_bridge_tests --emit dep-info=hltas-cpp-bridge/hltas-cpp-bridge-tests.d --emit link --test -o hltas-cpp-bridge/hltas-cpp-bridge-tests --extern hltas=libhltas.rlib --extern nom=subprojects/nom-7.1.3/libnom.rlib --extern cfg_if=subprojects/cfg-if-1.0.0/libcfg_if.rlib -L . -L subprojects/cookie-factory-0.3.2 -L subprojects/nom-7.1.3 -L subprojects/minimal-lexical-0.2.1 -L subprojects/memchr-2.5.0 -L subprojects/cfg-if-1.0.0 ../hltas-cpp-bridge/src/lib.rs
[13/13] c++  -o cpp/hltas-cpp-tests cpp/hltas-cpp-tests.p/src_tests.cpp.o -Wl,--as-needed -Wl,--no-undefined -Wl,--start-group cpp/libhltas_cpp.a hltas-cpp-bridge/libhltas_cpp_bridge.a -Wl,--end-group libhltas.rlib subprojects/nom-7.1.3/libnom.rlib subprojects/memchr-2.5.0/libmemchr.rlib subprojects/minimal-lexical-0.2.1/libminimal_lexical.rlib subprojects/cookie-factory-0.3.2/libcookie_factory.rlib subprojects/cfg-if-1.0.0/libcfg_if.rlib

Step 10 is building a staticlib, step 13 is then linking this into a C++ executable. All rlibs of step 10 (recursively) are added here.

meson should probably treat staticlib rlib dependencies as if they were link_whole instead of link_with.

CC @nirbheek @dcbaker @YaLTeR

[sdroege]

Note that this does not happen if the staticlib in step 10 is changed to a cdylib.

[sdroege]

See #11723 for a try.