Auto merge of #12921 - epage:plugins, r=weihanglo

tests: Remove plugin tests

Compiler plugins were removed in rust-lang/rust#116412, so we don't need these tests.

As for the `plugin` field on build-targets, it appears to be [stable-but-deprecated](https://doc.rust-lang.org/cargo/reference/cargo-targets.html#the-plugin-field), so I left it alone

tests/testsuite/cross_compile.rs

@@ -411,92 +411,6 @@ fn linker() {
  .run();
 }
 
-#[cargo_test(nightly, reason = "plugins are unstable")]
-fn plugin_with_extra_dylib_dep() {
- if cross_compile::disabled() {
- return;
- }
-
- let foo = project()
- .file(
- "Cargo.toml",
- r#"
- [package]
- name = "foo"
- version = "0.0.1"
- authors = []
-
- [dependencies.bar]
- path = "../bar"
- "#,
- )
- .file(
- "src/main.rs",
- r#"
- #![feature(plugin)]
- #![plugin(bar)]
-
- fn main() {}
- "#,
- )
- .build();
- let _bar = project()
- .at("bar")
- .file(
- "Cargo.toml",
- r#"
- [package]
- name = "bar"
- version = "0.0.1"
- authors = []
-
- [lib]
- name = "bar"
- plugin = true
-
- [dependencies.baz]
- path = "../baz"
- "#,
- )
- .file(
- "src/lib.rs",
- r#"
- #![feature(rustc_private)]
-
- extern crate baz;
- extern crate rustc_driver;
-
- use rustc_driver::plugin::Registry;
-
- #[no_mangle]
- pub fn __rustc_plugin_registrar(reg: &mut Registry) {
- println!("{}", baz::baz());
- }
- "#,
- )
- .build();
- let _baz = project()
- .at("baz")
- .file(
- "Cargo.toml",
- r#"
- [package]
- name = "baz"
- version = "0.0.1"
- authors = []
-
- [lib]
- name = "baz"
- crate_type = ["dylib"]
- "#,
- )
- .file("src/lib.rs", "pub fn baz() -> i32 { 1 }")
- .build();
-
- let target = cross_compile::alternate();
- foo.cargo("build --target").arg(&target).run();
-}
-
 #[cargo_test]
 fn cross_tests() {
  if !cross_compile::can_run_on_host() {

tests/testsuite/main.rs

@@ -132,7 +132,6 @@ mod patch;
 mod path;
 mod paths;
 mod pkgid;
-mod plugins;
 mod proc_macro;
 mod profile_config;
 mod profile_custom;