remove or change lib.plugin related test

Author: heisen-li

tests/testsuite/build_script.rs

@@ -2177,61 +2177,6 @@ fn shared_dep_with_a_build_script() {
     p.cargo("build -v").run();
 }
 
-#[cargo_test]
-fn transitive_dep_host() {
-    let p = project()
-        .file(
-            "Cargo.toml",
-            r#"
-                [package]
-                name = "foo"
-                version = "0.5.0"
-                edition = "2015"
-                authors = []
-                build = "build.rs"
-
-                [build-dependencies.b]
-                path = "b"
-            "#,
-        )
-        .file("src/lib.rs", "")
-        .file("build.rs", "fn main() {}")
-        .file(
-            "a/Cargo.toml",
-            r#"
-                [package]
-                name = "a"
-                version = "0.5.0"
-                edition = "2015"
-                authors = []
-                links = "foo"
-                build = "build.rs"
-            "#,
-        )
-        .file("a/build.rs", "fn main() {}")
-        .file("a/src/lib.rs", "")
-        .file(
-            "b/Cargo.toml",
-            r#"
-                [package]
-                name = "b"
-                version = "0.5.0"
-                edition = "2015"
-                authors = []
-
-                [lib]
-                name = "b"
-                plugin = true
-
-                [dependencies.a]
-                path = "../a"
-            "#,
-        )
-        .file("b/src/lib.rs", "")
-        .build();
-    p.cargo("build").run();
-}
-
 #[cargo_test]
 fn test_a_lib_with_a_build_command() {
     let p = project()

tests/testsuite/cross_compile.rs

@@ -883,47 +883,6 @@ fn build_script_only_host() {
     p.cargo("build -v --target").arg(&target).run();
 }
 
-#[cargo_test]
-fn plugin_build_script_right_arch() {
-    if cross_compile::disabled() {
-        return;
-    }
-    let p = project()
-        .file(
-            "Cargo.toml",
-            r#"
-                [package]
-                name = "foo"
-                version = "0.0.1"
-                edition = "2015"
-                authors = []
-                build = "build.rs"
-
-                [lib]
-                name = "foo"
-                plugin = true
-            "#,
-        )
-        .file("build.rs", "fn main() {}")
-        .file("src/lib.rs", "")
-        .build();
-
-    p.cargo("build -v --target")
-        .arg(cross_compile::alternate())
-        .with_stderr(
-            "\
-[WARNING] support for rustc plugins has been removed from rustc. library `foo` should not specify `plugin = true`
-[WARNING] support for `plugin = true` will be removed from cargo in the future
-[COMPILING] foo v0.0.1 ([..])
-[RUNNING] `rustc [..] build.rs [..]`
-[RUNNING] `[..]/build-script-build`
-[RUNNING] `rustc [..] src/lib.rs [..]`
-[FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [..]
-",
-        )
-        .run();
-}
-
 #[cargo_test]
 fn build_script_with_platform_specific_dependencies() {
     if cross_compile::disabled() {

tests/testsuite/proc_macro.rs

@@ -346,7 +346,7 @@ fn proc_macro_crate_type_warning() {
 }
 
 #[cargo_test]
-fn proc_macro_crate_type_warning_plugin() {
+fn lib_plugin_unused_key_warning() {
     let foo = project()
         .file(
             "Cargo.toml",
@@ -356,26 +356,40 @@ fn proc_macro_crate_type_warning_plugin() {
                 version = "0.1.0"
                 edition = "2015"
                 [lib]
-                crate-type = ["proc-macro"]
                 plugin = true
             "#,
         )
         .file("src/lib.rs", "")
         .build();
 
     foo.cargo("check")
-        .with_stderr_contains(
-            "[WARNING] support for rustc plugins has been removed from rustc. \
-            library `foo` should not specify `plugin = true`")
-        .with_stderr_contains(
-            "[WARNING] support for `plugin = true` will be removed from cargo in the future")
-        .with_stderr_contains(
-            "[WARNING] proc-macro library `foo` should not specify `plugin = true`")
-        .with_stderr_contains(
-            "[WARNING] library `foo` should only specify `proc-macro = true` instead of setting `crate-type`")
+        .with_stderr_contains("[WARNING] unused manifest key: lib.plugin")
         .run();
 }
 
+#[cargo_test]
+fn proc_macro_crate_type_warning_plugin() {
+    let foo = project()
+        .file(
+            "Cargo.toml",
+            r#"
+                [package]
+                name = "foo"
+                version = "0.1.0"
+                edition = "2015"
+                [lib]
+                crate-type = ["proc-macro"]
+            "#,
+        )
+        .file("src/lib.rs", "")
+        .build();
+
+    foo.cargo("check")
+    .with_stderr_contains(
+        "[WARNING] library `foo` should only specify `proc-macro = true` instead of setting `crate-type`")
+    .run();
+}
+
 #[cargo_test]
 fn proc_macro_crate_type_multiple() {
     let foo = project()