Description
Describe the bug
When linking in a Rust rlib/dylib dependency into some target, currently meson is adding an --extern commandline parameter to rustc too for all dependencies of the dependency. This is not necessary: it is only required when the target is directly using a crate.
More importantly, it is adding the transitive dependencies all to the global namespace.
To Reproduce
meson.build:
project('test-rs', 'rust',
version : '1.0.0',
meson_version : '>= 1.0.0',
default_options : ['buildtype=debugoptimized',
'rust_std=2021'
]
)
rustc = meson.get_compiler('rust')
a = static_library('a', 'a/lib.rs',
rust_crate_type : 'rlib',
)
a_dep = declare_dependency(link_with : a)
b = static_library('b', 'b/lib.rs',
rust_crate_type : 'rlib',
dependencies : [a_dep],
)
b_dep = declare_dependency(link_with : b,
dependencies : [a_dep],
)
c = executable('c', 'c/main.rs',
dependencies : [b_dep],
)a/lib.rs:
pub fn foo() -> i32 {
123
}b/lib.rs:
pub fn bar() -> i32 {
a::foo() * 2
}c/main.rs:
fn main() {
println!("{}", b::bar());
}This results in the following rustc invocations
[1/3] rustc -C linker=cc --color=always --crate-type rlib --edition=2021 -C opt-level=2 -g --crate-name a --emit dep-info=a.d --emit link -o liba.rlib ../a/lib.rs
[2/3] rustc -C linker=cc --color=always --crate-type rlib --edition=2021 -C opt-level=2 -g --crate-name b --emit dep-info=b.d --emit link -o libb.rlib --extern a=liba.rlib -L . ../b/lib.rs
[3/3] rustc -C linker=cc --color=always --crate-type bin --edition=2021 -C opt-level=2 -g --crate-name c --emit dep-info=c.d --emit link -o c --extern b=libb.rlib --extern a=liba.rlib -L . ../c/main.rs
Expected behavior
Only adding -L parameters as needed (i.e. not at all in this example because all build results are in the same directory).
[1/3] rustc -C linker=cc --color=always --crate-type rlib --edition=2021 -C opt-level=2 -g --crate-name a --emit dep-info=a.d --emit link -o liba.rlib ../a/lib.rs
[2/3] rustc -C linker=cc --color=always --crate-type rlib --edition=2021 -C opt-level=2 -g --crate-name b --emit dep-info=b.d --emit link -o libb.rlib --extern a=liba.rlib -L . ../b/lib.rs
[3/3] rustc -C linker=cc --color=always --crate-type bin --edition=2021 -C opt-level=2 -g --crate-name c --emit dep-info=c.d --emit link -o c --extern b=libb.rlib -L . ../c/main.rs
CC @dcbaker Am I missing anything here? Where would this best be fixed, I guess already when declaring the dependency?