Multiple --crate-type=X (--crate-type=staticlib --crate-type=staticlib) leads to a warning and then to assertion

[azat]

Repro

$ cargo --version
cargo 1.87.0-nightly (ab1463d63 2025-03-08)
$ rustc --version
rustc 1.87.0-nightly (cbfdf0b01 2025-03-13)

$ cargo new my_staticlib --lib

$ cargo rustc --lib --crate-type=staticlib --crate-type=staticlib
warning: output filename collision.
The lib target `my_staticlib` in package `my_staticlib v0.1.0 (/tmp/rust-test/my_staticlib)` has the same output filename as the lib target `my_staticlib` in package `my_staticlib v0.1.0 (/tmp/rust-test/my_staticlib)`.
Colliding filename is: /tmp/rust-test/my_staticlib/target/debug/deps/libmy_staticlib-6e3dfca3ee62c788.a
The targets should have unique names.
Consider changing their names to be unique or compiling them separately.
This may become a hard error in the future; see <https://github.com/rust-lang/cargo/issues/6313>.
warning: output filename collision.
The lib target `my_staticlib` in package `my_staticlib v0.1.0 (/tmp/rust-test/my_staticlib)` has the same output filename as the lib target `my_staticlib` in package `my_staticlib v0.1.0 (/tmp/rust-test/my_staticlib)`.
Colliding filename is: /tmp/rust-test/my_staticlib/target/debug/libmy_staticlib.a
The targets should have unique names.
Consider changing their names to be unique or compiling them separately.
This may become a hard error in the future; see <https://github.com/rust-lang/cargo/issues/6313>.
   Compiling my_staticlib v0.1.0 (/tmp/rust-test/my_staticlib)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.06s

$ cargo rustc --lib --crate-type=staticlib --crate-type=staticlib
warning: output filename collision.
The lib target `my_staticlib` in package `my_staticlib v0.1.0 (/tmp/rust-test/my_staticlib)` has the same output filename as the lib target `my_staticlib` in package `my_staticlib v0.1.0 (/tmp/rust-test/my_staticlib)`.
Colliding filename is: /tmp/rust-test/my_staticlib/target/debug/deps/libmy_staticlib-6e3dfca3ee62c788.a
The targets should have unique names.
Consider changing their names to be unique or compiling them separately.
This may become a hard error in the future; see <https://github.com/rust-lang/cargo/issues/6313>.
warning: output filename collision.
The lib target `my_staticlib` in package `my_staticlib v0.1.0 (/tmp/rust-test/my_staticlib)` has the same output filename as the lib target `my_staticlib` in package `my_staticlib v0.1.0 (/tmp/rust-test/my_staticlib)`.
Colliding filename is: /tmp/rust-test/my_staticlib/target/debug/libmy_staticlib.a
The targets should have unique names.
Consider changing their names to be unique or compiling them separately.
This may become a hard error in the future; see <https://github.com/rust-lang/cargo/issues/6313>.

thread 'main' panicked at src/tools/cargo/src/cargo/core/compiler/fingerprint/mod.rs:1180:13:
assertion failed: mtimes.insert(output.clone(), mtime).is_none()
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

So first it prints warning, second time - crash with assertion

Maybe duplicated --crate-type should be ignored? Thoughts?

[weihanglo]

Thank you for the issue report! Yeah, this could be deduplicated. The code lives here:

cargo/src/bin/cargo/commands/rustc.rs

Lines 95 to 102 in 611b7c4

	let crate_types = args
	.get_many::<String>(CRATE_TYPE_ARG_NAME)
	.into_iter()
	.flatten()
	.flat_map(|s| s.split(','))
	.filter(|s| !s.is_empty())
	.map(String::from)
	.collect::<Vec<String>>();