Auto merge of #59590 - Centril:rollup, r=Centril

Rollup of 7 pull requests

Successful merges:

 - #58805 (Lint for redundant imports)
 - #59506 (Use platform dependent mcount function)
 - #59519 (rustc_target: factor out common fields of non-Single Variants.)
 - #59580 (Allow closure to unsafe fn coercion)
 - #59581 (Stabilize refcell_replace_swap feature)
 - #59583 (match match match match match)
 - #59587 (Remove #[doc(hidden)] from Error::type_id)

Failed merges:

r? @ghost

18 files changed, 127 insertions, 20 deletions

diff --git a/src/test/codegen/instrument-mcount.rs b/src/test/codegen/instrument-mcount.rs
new file mode 100644
index 00000000000..c72d09f7a03
--- /dev/null
+++ b/src/test/codegen/instrument-mcount.rs
@@ -0,0 +1,7 @@
+// ignore-tidy-linelength
+// compile-flags: -Z instrument-mcount
+
+#![crate_type = "lib"]
+
+// CHECK: attributes #{{.*}} "instrument-function-entry-inlined"="{{.*}}mcount{{.*}}" "no-frame-pointer-elim"="true"
+pub fn foo() {}
diff --git a/src/test/compile-fail/coerce-unsafe-closure-to-unsafe-fn-ptr.rs b/src/test/compile-fail/coerce-unsafe-closure-to-unsafe-fn-ptr.rs
new file mode 100644
index 00000000000..36777693fab
--- /dev/null
+++ b/src/test/compile-fail/coerce-unsafe-closure-to-unsafe-fn-ptr.rs
@@ -0,0 +1,5 @@
+fn main() {
+    let _: unsafe fn() = || { ::std::pin::Pin::new_unchecked(&0_u8); };
+    //~^ ERROR E0133
+    let _: unsafe fn() = || unsafe { ::std::pin::Pin::new_unchecked(&0_u8); }; // OK
+}
diff --git a/src/test/run-pass/binding/match-arm-statics.rs b/src/test/run-pass/binding/match-arm-statics.rs
index 359c3921158..5f7e357eeb2 100644
--- a/src/test/run-pass/binding/match-arm-statics.rs
+++ b/src/test/run-pass/binding/match-arm-statics.rs
@@ -45,8 +45,6 @@ pub mod glfw {
 }
 
 fn issue_6533() {
-    use glfw;
-
     fn action_to_str(state: glfw::InputState) -> &'static str {
         use glfw::{RELEASE, PRESS, REPEAT};
         match state {
diff --git a/src/test/run-pass/ifmt.rs b/src/test/run-pass/ifmt.rs
index 56222fa46f7..8c17b01e2bd 100644
--- a/src/test/run-pass/ifmt.rs
+++ b/src/test/run-pass/ifmt.rs
@@ -238,7 +238,6 @@ pub fn main() {
 // Basic test to make sure that we can invoke the `write!` macro with an
 // fmt::Write instance.
 fn test_write() {
-    use std::fmt::Write;
     let mut buf = String::new();
     write!(&mut buf, "{}", 3);
     {
@@ -267,7 +266,6 @@ fn test_print() {
 // Just make sure that the macros are defined, there's not really a lot that we
 // can do with them just yet (to test the output)
 fn test_format_args() {
-    use std::fmt::Write;
     let mut buf = String::new();
     {
         let w = &mut buf;
diff --git a/src/test/run-pass/invalid_const_promotion.rs b/src/test/run-pass/invalid_const_promotion.rs
index 1524373895d..2775aac0156 100644
--- a/src/test/run-pass/invalid_const_promotion.rs
+++ b/src/test/run-pass/invalid_const_promotion.rs
@@ -25,7 +25,6 @@ fn foo() {
 #[cfg(unix)]
 fn check_status(status: std::process::ExitStatus)
 {
-    use libc;
     use std::os::unix::process::ExitStatusExt;
 
     assert!(status.signal() == Some(libc::SIGILL)
diff --git a/src/test/run-pass/issues/issue-38556.rs b/src/test/run-pass/issues/issue-38556.rs
index 0cc247f5b9c..63fd9db08ff 100644
--- a/src/test/run-pass/issues/issue-38556.rs
+++ b/src/test/run-pass/issues/issue-38556.rs
@@ -9,6 +9,5 @@ macro_rules! reexport {
 reexport!();
 
 fn main() {
-    use Bar;
     fn f(_: Bar) {}
 }
diff --git a/src/test/run-pass/issues/issue-39367.rs b/src/test/run-pass/issues/issue-39367.rs
index bd92224bce1..484cd782a09 100644
--- a/src/test/run-pass/issues/issue-39367.rs
+++ b/src/test/run-pass/issues/issue-39367.rs
@@ -15,7 +15,6 @@ fn arena() -> &'static ArenaSet<Vec<u8>> {
         fn require_sync<T: Sync>(_: &T) { }
         unsafe fn __stability() -> &'static ArenaSet<Vec<u8>> {
             use std::mem::transmute;
-            use std::boxed::Box;
             static mut DATA: *const ArenaSet<Vec<u8>> = 0 as *const ArenaSet<Vec<u8>>;
 
             static mut ONCE: Once = ONCE_INIT;
diff --git a/src/test/run-pass/out-of-stack.rs b/src/test/run-pass/out-of-stack.rs
index 72d6d680622..9f868d6e5c3 100644
--- a/src/test/run-pass/out-of-stack.rs
+++ b/src/test/run-pass/out-of-stack.rs
@@ -36,7 +36,6 @@ fn loud_recurse() {
 #[cfg(unix)]
 fn check_status(status: std::process::ExitStatus)
 {
-    use libc;
     use std::os::unix::process::ExitStatusExt;
 
     assert!(!status.success());
diff --git a/src/test/run-pass/rfcs/rfc-2126-extern-absolute-paths/basic.rs b/src/test/run-pass/rfcs/rfc-2126-extern-absolute-paths/basic.rs
index 15449a6b83e..566b3581046 100644
--- a/src/test/run-pass/rfcs/rfc-2126-extern-absolute-paths/basic.rs
+++ b/src/test/run-pass/rfcs/rfc-2126-extern-absolute-paths/basic.rs
@@ -4,6 +4,8 @@
 // compile-flags:--extern xcrate
 // edition:2018
 
+#![allow(unused_imports)]
+
 use xcrate::Z;
 
 fn f() {
diff --git a/src/test/run-pass/traits/traits-multidispatch-infer-convert-target.rs b/src/test/run-pass/traits/traits-multidispatch-infer-convert-target.rs
index ca47d9736f6..626e1ae71bc 100644
--- a/src/test/run-pass/traits/traits-multidispatch-infer-convert-target.rs
+++ b/src/test/run-pass/traits/traits-multidispatch-infer-convert-target.rs
@@ -28,7 +28,6 @@ where T : Convert<U>
 }
 
 fn main() {
-    use std::default::Default;
     // T = i16, U = u32
     test(22_i16, Default::default(),  2, 4);
 
diff --git a/src/test/run-pass/typeck-closure-to-unsafe-fn-ptr.rs b/src/test/run-pass/typeck-closure-to-unsafe-fn-ptr.rs
new file mode 100644
index 00000000000..fe15b912d60
--- /dev/null
+++ b/src/test/run-pass/typeck-closure-to-unsafe-fn-ptr.rs
@@ -0,0 +1,7 @@
+unsafe fn call_unsafe(func: unsafe fn() -> ()) -> () {
+    func()
+}
+
+pub fn main() {
+    unsafe { call_unsafe(|| {}); }
+}
diff --git a/src/test/run-pass/weird-exprs.rs b/src/test/run-pass/weird-exprs.rs
index 7ce7e29e872..ae4de92ff74 100644
--- a/src/test/run-pass/weird-exprs.rs
+++ b/src/test/run-pass/weird-exprs.rs
@@ -127,6 +127,21 @@ fn punch_card() -> impl std::fmt::Debug {
     ..=.. ..=..    .. ..=..=..    ..=..=.. ..    .. ..=.. ..
 }
 
+fn r#match() {
+    let val = match match match match match () {
+        () => ()
+    } {
+        () => ()
+    } {
+        () => ()
+    } {
+        () => ()
+    } {
+        () => ()
+    };
+    assert_eq!(val, ());
+}
+
 pub fn main() {
     strange();
     funny();
@@ -142,4 +157,5 @@ pub fn main() {
     union();
     special_characters();
     punch_card();
+    r#match();
 }
diff --git a/src/test/ui/lint/lint-unused-imports.rs b/src/test/ui/lint/lint-unused-imports.rs
index 9c5b206203c..4754d888076 100644
--- a/src/test/ui/lint/lint-unused-imports.rs
+++ b/src/test/ui/lint/lint-unused-imports.rs
@@ -66,6 +66,7 @@ mod bar {
 
 fn g() {
     use self::g; //~ ERROR unused import: `self::g`
+    //~^ ERROR the item `g` is imported redundantly
     fn f() {
         self::g();
     }
@@ -75,6 +76,7 @@ fn g() {
 #[allow(unused_variables)]
 fn h() {
     use test2::foo; //~ ERROR unused import: `test2::foo`
+    //~^ ERROR the item `foo` is imported redundantly
     let foo = 0;
 }
 
diff --git a/src/test/ui/lint/lint-unused-imports.stderr b/src/test/ui/lint/lint-unused-imports.stderr
index f9a54f477f9..96d71a228a5 100644
--- a/src/test/ui/lint/lint-unused-imports.stderr
+++ b/src/test/ui/lint/lint-unused-imports.stderr
@@ -34,14 +34,36 @@ error: unused import: `foo::Square`
 LL |         use foo::Square;
    |             ^^^^^^^^^^^
 
+error: the item `g` is imported redundantly
+  --> $DIR/lint-unused-imports.rs:68:9
+   |
+LL | / fn g() {
+LL | |     use self::g;
+   | |         ^^^^^^^
+LL | |
+LL | |     fn f() {
+LL | |         self::g();
+LL | |     }
+LL | | }
+   | |_- the item `g` is already defined here
+
 error: unused import: `self::g`
   --> $DIR/lint-unused-imports.rs:68:9
    |
 LL |     use self::g;
    |         ^^^^^^^
 
+error: the item `foo` is imported redundantly
+  --> $DIR/lint-unused-imports.rs:78:9
+   |
+LL | use test2::{foo, bar};
+   |             --- the item `foo` is already imported here
+...
+LL |     use test2::foo;
+   |         ^^^^^^^^^^
+
 error: unused import: `test2::foo`
-  --> $DIR/lint-unused-imports.rs:77:9
+  --> $DIR/lint-unused-imports.rs:78:9
    |
 LL |     use test2::foo;
    |         ^^^^^^^^^^
@@ -52,5 +74,5 @@ error: unused import: `test::B2`
 LL | use test::B2;
    |     ^^^^^^^^
 
-error: aborting due to 8 previous errors
+error: aborting due to 10 previous errors
 
diff --git a/src/test/ui/lint/use-redundant.rs b/src/test/ui/lint/use-redundant.rs
new file mode 100644
index 00000000000..328f8232baf
--- /dev/null
+++ b/src/test/ui/lint/use-redundant.rs
@@ -0,0 +1,27 @@
+// compile-pass
+#![warn(unused_imports)]
+
+use crate::foo::Bar; //~ WARNING first import
+
+mod foo {
+    pub type Bar = i32;
+}
+
+fn baz() -> Bar {
+    3
+}
+
+mod m1 { pub struct S {} }
+mod m2 { pub struct S {} }
+
+use m1::*;
+use m2::*;
+
+fn main() {
+    use crate::foo::Bar; //~ WARNING redundant import
+    let _a: Bar = 3;
+    baz();
+
+    use m1::S; //~ WARNING redundant import
+    let _s = S {};
+}
diff --git a/src/test/ui/lint/use-redundant.stderr b/src/test/ui/lint/use-redundant.stderr
new file mode 100644
index 00000000000..fbd9f81f18f
--- /dev/null
+++ b/src/test/ui/lint/use-redundant.stderr
@@ -0,0 +1,27 @@
+warning: unused import: `m1::*`
+  --> $DIR/use-redundant.rs:17:5
+   |
+LL | use m1::*;
+   |     ^^^^^
+   |
+note: lint level defined here
+  --> $DIR/use-redundant.rs:2:9
+   |
+LL | #![warn(unused_imports)]
+   |         ^^^^^^^^^^^^^^
+
+warning: unused import: `m2::*`
+  --> $DIR/use-redundant.rs:18:5
+   |
+LL | use m2::*;
+   |     ^^^^^
+
+warning: the item `Bar` is imported redundantly
+  --> $DIR/use-redundant.rs:21:9
+   |
+LL | use crate::foo::Bar;
+   |     --------------- the item `Bar` is already imported here
+...
+LL |     use crate::foo::Bar;
+   |         ^^^^^^^^^^^^^^^
+
diff --git a/src/test/ui/rust-2018/future-proofing-locals.rs b/src/test/ui/rust-2018/future-proofing-locals.rs
index 1e53c2d1dac..2c388cf3713 100644
--- a/src/test/ui/rust-2018/future-proofing-locals.rs
+++ b/src/test/ui/rust-2018/future-proofing-locals.rs
@@ -1,6 +1,7 @@
 // edition:2018
 
 #![allow(non_camel_case_types)]
+#![allow(unused_imports)]
 
 mod T {
     pub struct U;
diff --git a/src/test/ui/rust-2018/future-proofing-locals.stderr b/src/test/ui/rust-2018/future-proofing-locals.stderr
index 4d666d22afe..7021489a6dd 100644
--- a/src/test/ui/rust-2018/future-proofing-locals.stderr
+++ b/src/test/ui/rust-2018/future-proofing-locals.stderr
@@ -1,53 +1,53 @@
 error: imports cannot refer to type parameters
-  --> $DIR/future-proofing-locals.rs:13:9
+  --> $DIR/future-proofing-locals.rs:14:9
    |
 LL |     use T as _;
    |         ^
 
 error: imports cannot refer to type parameters
-  --> $DIR/future-proofing-locals.rs:14:9
+  --> $DIR/future-proofing-locals.rs:15:9
    |
 LL |     use T::U;
    |         ^
 
 error: imports cannot refer to type parameters
-  --> $DIR/future-proofing-locals.rs:15:9
+  --> $DIR/future-proofing-locals.rs:16:9
    |
 LL |     use T::*;
    |         ^
 
 error: imports cannot refer to type parameters
-  --> $DIR/future-proofing-locals.rs:19:9
+  --> $DIR/future-proofing-locals.rs:20:9
    |
 LL |     use T;
    |         ^
 
 error: imports cannot refer to local variables
-  --> $DIR/future-proofing-locals.rs:25:9
+  --> $DIR/future-proofing-locals.rs:26:9
    |
 LL |     use x as _;
    |         ^
 
 error: imports cannot refer to local variables
-  --> $DIR/future-proofing-locals.rs:31:9
+  --> $DIR/future-proofing-locals.rs:32:9
    |
 LL |     use x;
    |         ^
 
 error: imports cannot refer to local variables
-  --> $DIR/future-proofing-locals.rs:37:17
+  --> $DIR/future-proofing-locals.rs:38:17
    |
 LL |             use x;
    |                 ^
 
 error: imports cannot refer to type parameters
-  --> $DIR/future-proofing-locals.rs:45:10
+  --> $DIR/future-proofing-locals.rs:46:10
    |
 LL |     use {T as _, x};
    |          ^
 
 error: imports cannot refer to local variables
-  --> $DIR/future-proofing-locals.rs:45:18
+  --> $DIR/future-proofing-locals.rs:46:18
    |
 LL |     use {T as _, x};
    |                  ^