1.0: Remove all instances of `link(name = ...)`

[tgross35]

Currently, libc expects std to provide all link directives necessary. If the std feature is disabled, instead libc emits link attributes:

libc/src/unix/mod.rs

Lines 439 to 624 in f24764d

	// FIXME(1.0): We want to remove these directives and instead expect that no-std users add their
	// own link configuration when required, rather than unconditionally linking everything that may
	// possibly be needed.
	cfg_if! {
	if #[cfg(any(
	target_os = "l4re",
	target_os = "espidf",
	target_os = "nuttx"
	))] {
	// required libraries are linked externally for these platforms:
	// * L4Re
	// * ESP-IDF
	// * NuttX
	} else if #[cfg(feature = "std")] {
	// cargo build, don't pull in anything extra as the std dep
	// already pulls in all libs.
	} else if #[cfg(all(
	any(
	all(
	target_os = "linux",
	any(target_env = "gnu", target_env = "uclibc")
	),
	target_os = "cygwin"
	),
	feature = "rustc-dep-of-std"
	))] {
	#[link(
	name = "util",
	kind = "static",
	modifiers = "-bundle",
	cfg(target_feature = "crt-static")
	)]
	#[link(
	name = "rt",
	kind = "static",
	modifiers = "-bundle",
	cfg(target_feature = "crt-static")
	)]
	#[link(
	name = "pthread",
	kind = "static",
	modifiers = "-bundle",
	cfg(target_feature = "crt-static")
	)]
	#[link(
	name = "m",
	kind = "static",
	modifiers = "-bundle",
	cfg(target_feature = "crt-static")
	)]
	#[link(
	name = "dl",
	kind = "static",
	modifiers = "-bundle",
	cfg(target_feature = "crt-static")
	)]
	#[link(
	name = "c",
	kind = "static",
	modifiers = "-bundle",
	cfg(target_feature = "crt-static")
	)]
	#[link(
	name = "gcc_eh",
	kind = "static",
	modifiers = "-bundle",
	cfg(target_feature = "crt-static")
	)]
	#[link(
	name = "gcc",
	kind = "static",
	modifiers = "-bundle",
	cfg(target_feature = "crt-static")
	)]
	#[link(
	name = "c",
	kind = "static",
	modifiers = "-bundle",
	cfg(target_feature = "crt-static")
	)]
	#[link(name = "util", cfg(not(target_feature = "crt-static")))]
	#[link(name = "rt", cfg(not(target_feature = "crt-static")))]
	#[link(name = "pthread", cfg(not(target_feature = "crt-static")))]
	#[link(name = "m", cfg(not(target_feature = "crt-static")))]
	#[link(name = "dl", cfg(not(target_feature = "crt-static")))]
	#[link(name = "c", cfg(not(target_feature = "crt-static")))]
	extern "C" {}
	} else if #[cfg(libc_pauthtest)] {
	#[link(name = "c")]
	#[link(name = "m")]
	#[link(name = "rt")]
	#[link(name = "pthread")]
	#[link(name = "dl")]
	extern "C" {}
	} else if #[cfg(any(
	all(target_env = "musl", not(libc_pauthtest)),
	target_env = "ohos"
	))] {
	#[cfg_attr(
	feature = "rustc-dep-of-std",
	link(
	name = "c",
	kind = "static",
	modifiers = "-bundle",
	cfg(target_feature = "crt-static")
	)
	)]
	#[cfg_attr(
	feature = "rustc-dep-of-std",
	link(name = "c", cfg(not(target_feature = "crt-static")))
	)]
	extern "C" {}
	} else if #[cfg(target_os = "emscripten")] {
	// Don't pass -lc to Emscripten, it breaks. See:
	// https://github.com/emscripten-core/emscripten/issues/22758
	} else if #[cfg(all(target_os = "android", feature = "rustc-dep-of-std"))] {
	#[link(
	name = "c",
	kind = "static",
	modifiers = "-bundle",
	cfg(target_feature = "crt-static")
	)]
	#[link(
	name = "m",
	kind = "static",
	modifiers = "-bundle",
	cfg(target_feature = "crt-static")
	)]
	#[link(name = "m", cfg(not(target_feature = "crt-static")))]
	#[link(name = "c", cfg(not(target_feature = "crt-static")))]
	extern "C" {}
	} else if #[cfg(any(
	target_os = "macos",
	target_os = "ios",
	target_os = "tvos",
	target_os = "watchos",
	target_os = "visionos",
	target_os = "android",
	target_os = "openbsd",
	target_os = "nto",
	target_os = "qnx",
	))] {
	#[link(name = "c")]
	#[link(name = "m")]
	extern "C" {}
	} else if #[cfg(target_os = "haiku")] {
	#[link(name = "root")]
	#[link(name = "network")]
	extern "C" {}
	} else if #[cfg(target_env = "newlib")] {
	#[link(name = "c")]
	#[link(name = "m")]
	extern "C" {}
	} else if #[cfg(target_env = "illumos")] {
	#[link(name = "c")]
	#[link(name = "m")]
	extern "C" {}
	} else if #[cfg(target_os = "redox")] {
	#[cfg_attr(
	feature = "rustc-dep-of-std",
	link(
	name = "c",
	kind = "static",
	modifiers = "-bundle",
	cfg(target_feature = "crt-static")
	)
	)]
	#[cfg_attr(
	feature = "rustc-dep-of-std",
	link(name = "c", cfg(not(target_feature = "crt-static")))
	)]
	extern "C" {}
	} else if #[cfg(target_os = "aix")] {
	#[link(name = "c")]
	#[link(name = "m")]
	#[link(name = "bsd")]
	#[link(name = "pthread")]
	extern "C" {}
	} else {
	#[link(name = "c")]
	#[link(name = "m")]
	#[link(name = "rt")]
	#[link(name = "pthread")]
	extern "C" {}
	}
	}

We discussed at rustweek 2025 that we should remove this and expect users to add their own link attributes when building in no-std environments. This way you can still use the bindings even if some of the libraries aren't available.