Auto merge of #86492 - hyd-dev:no-mangle-method, r=petrochenkov

Associated functions that contain extern indicator or have `#[rustc_std_internal_symbol]` are reachable

Previously these fails to link with ``undefined reference to `foo'``:

<details>
<summary>Example 1</summary>

```rs
struct AssocFn;

impl AssocFn {
    #[no_mangle]
    fn foo() {}
}

fn main() {
    extern "Rust" {
        fn foo();
    }
    unsafe { foo() }
}
```
([Playground](https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=f1244afcdd26e2a28445f6e82ca46b50))
</details>

<details>
<summary>Example 2</summary>

```rs
#![crate_name = "lib"]
#![crate_type = "lib"]

struct AssocFn;

impl AssocFn {
    #[no_mangle]
    fn foo() {}
}
```
```rs
extern crate lib;

fn main() {
    extern "Rust" {
        fn foo();
    }
    unsafe { foo() }
}
```
</details>

But I believe they should link successfully, because this works:
<details>

```rs
#[no_mangle]
fn foo() {}

fn main() {
    extern "Rust" {
        fn foo();
    }
    unsafe { foo() }
}
```
([Playground](https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=789b3f283ee6126f53939429103ed98d))
</details>

This PR fixes the problem, by adding associated functions that have "custom linkage" to `reachable_set`, just like normal functions.

I haven't tested whether #76211 and [Miri](https://github.com/rust-lang/miri/issues/1837) are fixed by this PR yet, but I'm submitting this anyway since this fixes the examples above.

I added a `run-pass` test that combines my two examples above, but I'm not sure if that's the right way to test this. Maybe I should add / modify an existing codegen test (`src/test/codegen/export-no-mangle.rs`?) instead?

src/test/ui/auxiliary/no-mangle-associated-fn.rs

@@ -0,0 +1,21 @@
+#![crate_type = "lib"]
+
+struct Bar;
+
+impl Bar {
+    #[no_mangle]
+    fn bar() -> u8 {
+        2
+    }
+}
+
+trait Foo {
+    fn baz() -> u8;
+}
+
+impl Foo for Bar {
+    #[no_mangle]
+    fn baz() -> u8 {
+        3
+    }
+}

src/test/ui/feature-gates/issue-43106-gating-of-builtin-attrs-error.rs

@@ -1,5 +1,5 @@
 //~ NOTE: not an `extern crate` item
-//~^ NOTE: not a function or static
+//~^ NOTE: not a free function, impl method or static
 //~^^ NOTE: not a function or closure
 // This is testing whether various builtin attributes signals an
 // error or warning when put in "weird" places.
@@ -25,7 +25,7 @@
 #![no_link]
 //~^ ERROR: attribute should be applied to an `extern crate` item
 #![export_name = "2200"]
-//~^ ERROR: attribute should be applied to a function or static
+//~^ ERROR: attribute should be applied to a free function, impl method or static
 #![inline]
 //~^ ERROR: attribute should be applied to function or closure
 #[inline]
@@ -83,27 +83,37 @@ mod no_link {
 }
 
 #[export_name = "2200"]
-//~^ ERROR attribute should be applied to a function or static
+//~^ ERROR attribute should be applied to a free function, impl method or static
 mod export_name {
-    //~^ NOTE not a function or static
+    //~^ NOTE not a free function, impl method or static
 
     mod inner { #![export_name="2200"] }
-    //~^ ERROR attribute should be applied to a function or static
-    //~| NOTE not a function or static
+    //~^ ERROR attribute should be applied to a free function, impl method or static
+    //~| NOTE not a free function, impl method or static
 
     #[export_name = "2200"] fn f() { }
 
     #[export_name = "2200"] struct S;
-    //~^ ERROR attribute should be applied to a function or static
-    //~| NOTE not a function or static
+    //~^ ERROR attribute should be applied to a free function, impl method or static
+    //~| NOTE not a free function, impl method or static
 
     #[export_name = "2200"] type T = S;
-    //~^ ERROR attribute should be applied to a function or static
-    //~| NOTE not a function or static
+    //~^ ERROR attribute should be applied to a free function, impl method or static
+    //~| NOTE not a free function, impl method or static
 
     #[export_name = "2200"] impl S { }
-    //~^ ERROR attribute should be applied to a function or static
-    //~| NOTE not a function or static
+    //~^ ERROR attribute should be applied to a free function, impl method or static
+    //~| NOTE not a free function, impl method or static
+
+    trait Tr {
+        #[export_name = "2200"] fn foo();
+        //~^ ERROR attribute should be applied to a free function, impl method or static
+        //~| NOTE not a free function, impl method or static
+
+        #[export_name = "2200"] fn bar() {}
+        //~^ ERROR attribute should be applied to a free function, impl method or static
+        //~| NOTE not a free function, impl method or static
+    }
 }
 
 #[start]

src/test/ui/feature-gates/issue-43106-gating-of-builtin-attrs-error.stderr

@@ -17,31 +17,31 @@ LL |     #[inline = "2100"] fn f() { }
    = note: for more information, see issue #57571 <https://github.com/rust-lang/rust/issues/57571>
 
 error: `start` attribute can only be used on functions
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:109:1
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:119:1
    |
 LL | #[start]
    | ^^^^^^^^
 
 error: `start` attribute can only be used on functions
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:112:17
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:122:17
    |
 LL |     mod inner { #![start] }
    |                 ^^^^^^^^^
 
 error: `start` attribute can only be used on functions
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:117:5
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:127:5
    |
 LL |     #[start] struct S;
    |     ^^^^^^^^
 
 error: `start` attribute can only be used on functions
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:120:5
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:130:5
    |
 LL |     #[start] type T = S;
    |     ^^^^^^^^
 
 error: `start` attribute can only be used on functions
-  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:123:5
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:133:5
    |
 LL |     #[start] impl S { }
    |     ^^^^^^^^
@@ -76,7 +76,7 @@ LL | |
 LL | | }
    | |_- not an `extern crate` item
 
-error: attribute should be applied to a function or static
+error: attribute should be applied to a free function, impl method or static
   --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:85:1
    |
 LL |   #[export_name = "2200"]
@@ -87,9 +87,9 @@ LL | |
 LL | |
 LL | |     mod inner { #![export_name="2200"] }
 ...  |
-LL | |
+LL | |     }
 LL | | }
-   | |_- not a function or static
+   | |_- not a free function, impl method or static
 
 error: attribute should be applied to an `extern crate` item
   --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:25:1
@@ -97,7 +97,7 @@ error: attribute should be applied to an `extern crate` item
 LL | #![no_link]
    | ^^^^^^^^^^^
 
-error: attribute should be applied to a function or static
+error: attribute should be applied to a free function, impl method or static
   --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:27:1
    |
 LL | #![export_name = "2200"]
@@ -199,31 +199,43 @@ error: attribute should be applied to an `extern crate` item
 LL |     #[no_link] impl S { }
    |     ^^^^^^^^^^ ---------- not an `extern crate` item
 
-error: attribute should be applied to a function or static
+error: attribute should be applied to a free function, impl method or static
   --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:90:17
    |
 LL |     mod inner { #![export_name="2200"] }
-   |     ------------^^^^^^^^^^^^^^^^^^^^^^-- not a function or static
+   |     ------------^^^^^^^^^^^^^^^^^^^^^^-- not a free function, impl method or static
 
-error: attribute should be applied to a function or static
+error: attribute should be applied to a free function, impl method or static
   --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:96:5
    |
 LL |     #[export_name = "2200"] struct S;
-   |     ^^^^^^^^^^^^^^^^^^^^^^^ --------- not a function or static
+   |     ^^^^^^^^^^^^^^^^^^^^^^^ --------- not a free function, impl method or static
 
-error: attribute should be applied to a function or static
+error: attribute should be applied to a free function, impl method or static
   --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:100:5
    |
 LL |     #[export_name = "2200"] type T = S;
-   |     ^^^^^^^^^^^^^^^^^^^^^^^ ----------- not a function or static
+   |     ^^^^^^^^^^^^^^^^^^^^^^^ ----------- not a free function, impl method or static
 
-error: attribute should be applied to a function or static
+error: attribute should be applied to a free function, impl method or static
   --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:104:5
    |
 LL |     #[export_name = "2200"] impl S { }
-   |     ^^^^^^^^^^^^^^^^^^^^^^^ ---------- not a function or static
+   |     ^^^^^^^^^^^^^^^^^^^^^^^ ---------- not a free function, impl method or static
 
-error: aborting due to 32 previous errors
+error: attribute should be applied to a free function, impl method or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:109:9
+   |
+LL |         #[export_name = "2200"] fn foo();
+   |         ^^^^^^^^^^^^^^^^^^^^^^^ --------- not a free function, impl method or static
+
+error: attribute should be applied to a free function, impl method or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:113:9
+   |
+LL |         #[export_name = "2200"] fn bar() {}
+   |         ^^^^^^^^^^^^^^^^^^^^^^^ ----------- not a free function, impl method or static
+
+error: aborting due to 34 previous errors
 
 Some errors have detailed explanations: E0518, E0658.
 For more information about an error, try `rustc --explain E0518`.

src/test/ui/feature-gates/issue-43106-gating-of-builtin-attrs.rs

@@ -295,31 +295,43 @@ mod automatically_derived {
 }
 
 #[no_mangle]
-//~^ WARN attribute should be applied to a function or static [unused_attributes]
+//~^ WARN attribute should be applied to a free function, impl method or static [unused_attributes]
 //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
 mod no_mangle {
-    //~^ NOTE not a function or static
+    //~^ NOTE not a free function, impl method or static
     mod inner { #![no_mangle] }
-    //~^ WARN attribute should be applied to a function or static [unused_attributes]
+    //~^ WARN attribute should be applied to a free function, impl method or static [unused_attributes]
     //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-    //~| NOTE not a function or static
+    //~| NOTE not a free function, impl method or static
 
     #[no_mangle] fn f() { }
 
     #[no_mangle] struct S;
-    //~^ WARN attribute should be applied to a function or static [unused_attributes]
+    //~^ WARN attribute should be applied to a free function, impl method or static [unused_attributes]
     //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-    //~| NOTE not a function or static
+    //~| NOTE not a free function, impl method or static
 
     #[no_mangle] type T = S;
-    //~^ WARN attribute should be applied to a function or static [unused_attributes]
+    //~^ WARN attribute should be applied to a free function, impl method or static [unused_attributes]
     //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-    //~| NOTE not a function or static
+    //~| NOTE not a free function, impl method or static
 
     #[no_mangle] impl S { }
-    //~^ WARN attribute should be applied to a function or static [unused_attributes]
+    //~^ WARN attribute should be applied to a free function, impl method or static [unused_attributes]
     //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-    //~| NOTE not a function or static
+    //~| NOTE not a free function, impl method or static
+
+    trait Tr {
+        #[no_mangle] fn foo();
+        //~^ WARN attribute should be applied to a free function, impl method or static [unused_attributes]
+        //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+        //~| NOTE not a free function, impl method or static
+
+        #[no_mangle] fn bar() {}
+        //~^ WARN attribute should be applied to a free function, impl method or static [unused_attributes]
+        //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+        //~| NOTE not a free function, impl method or static
+    }
 }
 
 #[should_panic]

src/test/ui/generics/generic-no-mangle.fixed

@@ -14,4 +14,146 @@ pub fn baz(x: &i32) -> &i32 { x }
 #[no_mangle]
 pub fn qux<'a>(x: &'a i32) -> &i32 { x }
 
+pub struct Foo;
+
+impl Foo {
+    
+    pub fn foo<T>() {} //~ ERROR functions generic over types or consts must be mangled
+
+    
+    pub extern "C" fn bar<T>() {} //~ ERROR functions generic over types or consts must be mangled
+
+    #[no_mangle]
+    pub fn baz(x: &i32) -> &i32 { x }
+
+    #[no_mangle]
+    pub fn qux<'a>(x: &'a i32) -> &i32 { x }
+}
+
+trait Trait1 {
+    fn foo<T>();
+    extern "C" fn bar<T>();
+    fn baz(x: &i32) -> &i32;
+    fn qux<'a>(x: &'a i32) -> &i32;
+}
+
+impl Trait1 for Foo {
+    
+    fn foo<T>() {} //~ ERROR functions generic over types or consts must be mangled
+
+    
+    extern "C" fn bar<T>() {} //~ ERROR functions generic over types or consts must be mangled
+
+    #[no_mangle]
+    fn baz(x: &i32) -> &i32 { x }
+
+    #[no_mangle]
+    fn qux<'a>(x: &'a i32) -> &i32 { x }
+}
+
+trait Trait2<T> {
+    fn foo();
+    fn foo2<U>();
+    extern "C" fn bar();
+    fn baz(x: &i32) -> &i32;
+    fn qux<'a>(x: &'a i32) -> &i32;
+}
+
+impl<T> Trait2<T> for Foo {
+    
+    fn foo() {} //~ ERROR functions generic over types or consts must be mangled
+
+    
+    fn foo2<U>() {} //~ ERROR functions generic over types or consts must be mangled
+
+    
+    extern "C" fn bar() {} //~ ERROR functions generic over types or consts must be mangled
+
+    
+    fn baz(x: &i32) -> &i32 { x } //~ ERROR functions generic over types or consts must be mangled
+
+    
+    fn qux<'a>(x: &'a i32) -> &i32 { x } //~ ERROR functions generic over types or consts must be mangled
+}
+
+pub struct Bar<T>(T);
+
+impl<T> Bar<T> {
+    
+    pub fn foo() {} //~ ERROR functions generic over types or consts must be mangled
+
+    
+    pub extern "C" fn bar() {} //~ ERROR functions generic over types or consts must be mangled
+
+    
+    pub fn baz<U>() {} //~ ERROR functions generic over types or consts must be mangled
+}
+
+impl Bar<i32> {
+    #[no_mangle]
+    pub fn qux() {}
+}
+
+trait Trait3 {
+    fn foo();
+    extern "C" fn bar();
+    fn baz<U>();
+}
+
+impl<T> Trait3 for Bar<T> {
+    
+    fn foo() {} //~ ERROR functions generic over types or consts must be mangled
+
+    
+    extern "C" fn bar() {} //~ ERROR functions generic over types or consts must be mangled
+
+    
+    fn baz<U>() {} //~ ERROR functions generic over types or consts must be mangled
+}
+
+pub struct Baz<'a>(&'a i32);
+
+impl<'a> Baz<'a> {
+    #[no_mangle]
+    pub fn foo() {}
+
+    #[no_mangle]
+    pub fn bar<'b>(x: &'b i32) -> &i32 { x }
+}
+
+trait Trait4 {
+    fn foo();
+    fn bar<'a>(x: &'a i32) -> &i32;
+}
+
+impl Trait4 for Bar<i32> {
+    #[no_mangle]
+    fn foo() {}
+
+    #[no_mangle]
+    fn bar<'b>(x: &'b i32) -> &i32 { x }
+}
+
+impl<'a> Trait4 for Baz<'a> {
+    #[no_mangle]
+    fn foo() {}
+
+    #[no_mangle]
+    fn bar<'b>(x: &'b i32) -> &i32 { x }
+}
+
+trait Trait5<T> {
+    fn foo();
+}
+
+impl Trait5<i32> for Foo {
+    #[no_mangle]
+    fn foo() {}
+}
+
+impl Trait5<i32> for Bar<i32> {
+    #[no_mangle]
+    fn foo() {}
+}
+
 fn main() {}

src/test/ui/generics/generic-no-mangle.rs

@@ -14,4 +14,146 @@ pub fn baz(x: &i32) -> &i32 { x }
 #[no_mangle]
 pub fn qux<'a>(x: &'a i32) -> &i32 { x }
 
+pub struct Foo;
+
+impl Foo {
+    #[no_mangle]
+    pub fn foo<T>() {} //~ ERROR functions generic over types or consts must be mangled
+
+    #[no_mangle]
+    pub extern "C" fn bar<T>() {} //~ ERROR functions generic over types or consts must be mangled
+
+    #[no_mangle]
+    pub fn baz(x: &i32) -> &i32 { x }
+
+    #[no_mangle]
+    pub fn qux<'a>(x: &'a i32) -> &i32 { x }
+}
+
+trait Trait1 {
+    fn foo<T>();
+    extern "C" fn bar<T>();
+    fn baz(x: &i32) -> &i32;
+    fn qux<'a>(x: &'a i32) -> &i32;
+}
+
+impl Trait1 for Foo {
+    #[no_mangle]
+    fn foo<T>() {} //~ ERROR functions generic over types or consts must be mangled
+
+    #[no_mangle]
+    extern "C" fn bar<T>() {} //~ ERROR functions generic over types or consts must be mangled
+
+    #[no_mangle]
+    fn baz(x: &i32) -> &i32 { x }
+
+    #[no_mangle]
+    fn qux<'a>(x: &'a i32) -> &i32 { x }
+}
+
+trait Trait2<T> {
+    fn foo();
+    fn foo2<U>();
+    extern "C" fn bar();
+    fn baz(x: &i32) -> &i32;
+    fn qux<'a>(x: &'a i32) -> &i32;
+}
+
+impl<T> Trait2<T> for Foo {
+    #[no_mangle]
+    fn foo() {} //~ ERROR functions generic over types or consts must be mangled
+
+    #[no_mangle]
+    fn foo2<U>() {} //~ ERROR functions generic over types or consts must be mangled
+
+    #[no_mangle]
+    extern "C" fn bar() {} //~ ERROR functions generic over types or consts must be mangled
+
+    #[no_mangle]
+    fn baz(x: &i32) -> &i32 { x } //~ ERROR functions generic over types or consts must be mangled
+
+    #[no_mangle]
+    fn qux<'a>(x: &'a i32) -> &i32 { x } //~ ERROR functions generic over types or consts must be mangled
+}
+
+pub struct Bar<T>(T);
+
+impl<T> Bar<T> {
+    #[no_mangle]
+    pub fn foo() {} //~ ERROR functions generic over types or consts must be mangled
+
+    #[no_mangle]
+    pub extern "C" fn bar() {} //~ ERROR functions generic over types or consts must be mangled
+
+    #[no_mangle]
+    pub fn baz<U>() {} //~ ERROR functions generic over types or consts must be mangled
+}
+
+impl Bar<i32> {
+    #[no_mangle]
+    pub fn qux() {}
+}
+
+trait Trait3 {
+    fn foo();
+    extern "C" fn bar();
+    fn baz<U>();
+}
+
+impl<T> Trait3 for Bar<T> {
+    #[no_mangle]
+    fn foo() {} //~ ERROR functions generic over types or consts must be mangled
+
+    #[no_mangle]
+    extern "C" fn bar() {} //~ ERROR functions generic over types or consts must be mangled
+
+    #[no_mangle]
+    fn baz<U>() {} //~ ERROR functions generic over types or consts must be mangled
+}
+
+pub struct Baz<'a>(&'a i32);
+
+impl<'a> Baz<'a> {
+    #[no_mangle]
+    pub fn foo() {}
+
+    #[no_mangle]
+    pub fn bar<'b>(x: &'b i32) -> &i32 { x }
+}
+
+trait Trait4 {
+    fn foo();
+    fn bar<'a>(x: &'a i32) -> &i32;
+}
+
+impl Trait4 for Bar<i32> {
+    #[no_mangle]
+    fn foo() {}
+
+    #[no_mangle]
+    fn bar<'b>(x: &'b i32) -> &i32 { x }
+}
+
+impl<'a> Trait4 for Baz<'a> {
+    #[no_mangle]
+    fn foo() {}
+
+    #[no_mangle]
+    fn bar<'b>(x: &'b i32) -> &i32 { x }
+}
+
+trait Trait5<T> {
+    fn foo();
+}
+
+impl Trait5<i32> for Foo {
+    #[no_mangle]
+    fn foo() {}
+}
+
+impl Trait5<i32> for Bar<i32> {
+    #[no_mangle]
+    fn foo() {}
+}
+
 fn main() {}

src/test/ui/generics/generic-no-mangle.stderr

@@ -20,5 +20,125 @@ LL | #[no_mangle]
 LL | pub extern "C" fn bar<T>() {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 2 previous errors
+error: functions generic over types or consts must be mangled
+  --> $DIR/generic-no-mangle.rs:21:5
+   |
+LL |     #[no_mangle]
+   |     ------------ help: remove this attribute
+LL |     pub fn foo<T>() {}
+   |     ^^^^^^^^^^^^^^^^^^
+
+error: functions generic over types or consts must be mangled
+  --> $DIR/generic-no-mangle.rs:24:5
+   |
+LL |     #[no_mangle]
+   |     ------------ help: remove this attribute
+LL |     pub extern "C" fn bar<T>() {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: functions generic over types or consts must be mangled
+  --> $DIR/generic-no-mangle.rs:42:5
+   |
+LL |     #[no_mangle]
+   |     ------------ help: remove this attribute
+LL |     fn foo<T>() {}
+   |     ^^^^^^^^^^^^^^
+
+error: functions generic over types or consts must be mangled
+  --> $DIR/generic-no-mangle.rs:45:5
+   |
+LL |     #[no_mangle]
+   |     ------------ help: remove this attribute
+LL |     extern "C" fn bar<T>() {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: functions generic over types or consts must be mangled
+  --> $DIR/generic-no-mangle.rs:64:5
+   |
+LL |     #[no_mangle]
+   |     ------------ help: remove this attribute
+LL |     fn foo() {}
+   |     ^^^^^^^^^^^
+
+error: functions generic over types or consts must be mangled
+  --> $DIR/generic-no-mangle.rs:67:5
+   |
+LL |     #[no_mangle]
+   |     ------------ help: remove this attribute
+LL |     fn foo2<U>() {}
+   |     ^^^^^^^^^^^^^^^
+
+error: functions generic over types or consts must be mangled
+  --> $DIR/generic-no-mangle.rs:70:5
+   |
+LL |     #[no_mangle]
+   |     ------------ help: remove this attribute
+LL |     extern "C" fn bar() {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+
+error: functions generic over types or consts must be mangled
+  --> $DIR/generic-no-mangle.rs:73:5
+   |
+LL |     #[no_mangle]
+   |     ------------ help: remove this attribute
+LL |     fn baz(x: &i32) -> &i32 { x }
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: functions generic over types or consts must be mangled
+  --> $DIR/generic-no-mangle.rs:76:5
+   |
+LL |     #[no_mangle]
+   |     ------------ help: remove this attribute
+LL |     fn qux<'a>(x: &'a i32) -> &i32 { x }
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: functions generic over types or consts must be mangled
+  --> $DIR/generic-no-mangle.rs:83:5
+   |
+LL |     #[no_mangle]
+   |     ------------ help: remove this attribute
+LL |     pub fn foo() {}
+   |     ^^^^^^^^^^^^^^^
+
+error: functions generic over types or consts must be mangled
+  --> $DIR/generic-no-mangle.rs:86:5
+   |
+LL |     #[no_mangle]
+   |     ------------ help: remove this attribute
+LL |     pub extern "C" fn bar() {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: functions generic over types or consts must be mangled
+  --> $DIR/generic-no-mangle.rs:89:5
+   |
+LL |     #[no_mangle]
+   |     ------------ help: remove this attribute
+LL |     pub fn baz<U>() {}
+   |     ^^^^^^^^^^^^^^^^^^
+
+error: functions generic over types or consts must be mangled
+  --> $DIR/generic-no-mangle.rs:105:5
+   |
+LL |     #[no_mangle]
+   |     ------------ help: remove this attribute
+LL |     fn foo() {}
+   |     ^^^^^^^^^^^
+
+error: functions generic over types or consts must be mangled
+  --> $DIR/generic-no-mangle.rs:108:5
+   |
+LL |     #[no_mangle]
+   |     ------------ help: remove this attribute
+LL |     extern "C" fn bar() {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+
+error: functions generic over types or consts must be mangled
+  --> $DIR/generic-no-mangle.rs:111:5
+   |
+LL |     #[no_mangle]
+   |     ------------ help: remove this attribute
+LL |     fn baz<U>() {}
+   |     ^^^^^^^^^^^^^^
+
+error: aborting due to 17 previous errors
 

src/test/ui/lint/issue-31924-non-snake-ffi.rs

@@ -5,4 +5,11 @@
 #[no_mangle]
 pub extern "C" fn SparklingGenerationForeignFunctionInterface() {} // OK
 
+pub struct Foo;
+
+impl Foo {
+    #[no_mangle]
+    pub extern "C" fn SparklingGenerationForeignFunctionInterface() {} // OK
+}
+
 fn main() {}

src/test/ui/lint/lint-unsafe-code.rs

@@ -31,9 +31,33 @@ macro_rules! unsafe_in_macro {
 #[no_mangle] fn foo() {} //~ ERROR: declaration of a `no_mangle` function
 #[no_mangle] static FOO: u32 = 5; //~ ERROR: declaration of a `no_mangle` static
 
+trait AssocFnTrait {
+    fn foo();
+}
+
+struct AssocFnFoo;
+
+impl AssocFnFoo {
+    #[no_mangle] fn foo() {} //~ ERROR: declaration of a `no_mangle` method
+}
+
+impl AssocFnTrait for AssocFnFoo {
+    #[no_mangle] fn foo() {} //~ ERROR: declaration of a `no_mangle` method
+}
+
 #[export_name = "bar"] fn bar() {} //~ ERROR: declaration of a function with `export_name`
 #[export_name = "BAR"] static BAR: u32 = 5; //~ ERROR: declaration of a static with `export_name`
 
+struct AssocFnBar;
+
+impl AssocFnBar {
+    #[export_name = "bar"] fn bar() {} //~ ERROR: declaration of a method with `export_name`
+}
+
+impl AssocFnTrait for AssocFnBar {
+    #[export_name = "bar"] fn foo() {} //~ ERROR: declaration of a method with `export_name`
+}
+
 unsafe fn baz() {} //~ ERROR: declaration of an `unsafe` function
 unsafe trait Foo {} //~ ERROR: declaration of an `unsafe` trait
 unsafe impl Foo for Bar {} //~ ERROR: implementation of an `unsafe` trait

src/test/ui/lint/lint-unsafe-code.stderr

@@ -19,8 +19,24 @@ LL | #[no_mangle] static FOO: u32 = 5;
    |
    = note: the linker's behavior with multiple libraries exporting duplicate symbol names is undefined and Rust cannot provide guarantees when you manually override them
 
+error: declaration of a `no_mangle` method
+  --> $DIR/lint-unsafe-code.rs:41:5
+   |
+LL |     #[no_mangle] fn foo() {}
+   |     ^^^^^^^^^^^^
+   |
+   = note: the linker's behavior with multiple libraries exporting duplicate symbol names is undefined and Rust cannot provide guarantees when you manually override them
+
+error: declaration of a `no_mangle` method
+  --> $DIR/lint-unsafe-code.rs:45:5
+   |
+LL |     #[no_mangle] fn foo() {}
+   |     ^^^^^^^^^^^^
+   |
+   = note: the linker's behavior with multiple libraries exporting duplicate symbol names is undefined and Rust cannot provide guarantees when you manually override them
+
 error: declaration of a function with `export_name`
-  --> $DIR/lint-unsafe-code.rs:34:1
+  --> $DIR/lint-unsafe-code.rs:48:1
    |
 LL | #[export_name = "bar"] fn bar() {}
    | ^^^^^^^^^^^^^^^^^^^^^^
@@ -28,61 +44,59 @@ LL | #[export_name = "bar"] fn bar() {}
    = note: the linker's behavior with multiple libraries exporting duplicate symbol names is undefined and Rust cannot provide guarantees when you manually override them
 
 error: declaration of a static with `export_name`
-  --> $DIR/lint-unsafe-code.rs:35:1
+  --> $DIR/lint-unsafe-code.rs:49:1
    |
 LL | #[export_name = "BAR"] static BAR: u32 = 5;
    | ^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: the linker's behavior with multiple libraries exporting duplicate symbol names is undefined and Rust cannot provide guarantees when you manually override them
 
+error: declaration of a method with `export_name`
+  --> $DIR/lint-unsafe-code.rs:54:5
+   |
+LL |     #[export_name = "bar"] fn bar() {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the linker's behavior with multiple libraries exporting duplicate symbol names is undefined and Rust cannot provide guarantees when you manually override them
+
+error: declaration of a method with `export_name`
+  --> $DIR/lint-unsafe-code.rs:58:5
+   |
+LL |     #[export_name = "bar"] fn foo() {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the linker's behavior with multiple libraries exporting duplicate symbol names is undefined and Rust cannot provide guarantees when you manually override them
+
 error: declaration of an `unsafe` function
-  --> $DIR/lint-unsafe-code.rs:37:1
+  --> $DIR/lint-unsafe-code.rs:61:1
    |
 LL | unsafe fn baz() {}
    | ^^^^^^^^^^^^^^^^^^
 
 error: declaration of an `unsafe` trait
-  --> $DIR/lint-unsafe-code.rs:38:1
+  --> $DIR/lint-unsafe-code.rs:62:1
    |
 LL | unsafe trait Foo {}
    | ^^^^^^^^^^^^^^^^^^^
 
 error: implementation of an `unsafe` trait
-  --> $DIR/lint-unsafe-code.rs:39:1
+  --> $DIR/lint-unsafe-code.rs:63:1
    |
 LL | unsafe impl Foo for Bar {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: declaration of an `unsafe` method
-  --> $DIR/lint-unsafe-code.rs:42:5
+  --> $DIR/lint-unsafe-code.rs:66:5
    |
 LL |     unsafe fn baz(&self);
    |     ^^^^^^^^^^^^^^^^^^^^^
 
 error: implementation of an `unsafe` method
-  --> $DIR/lint-unsafe-code.rs:43:5
+  --> $DIR/lint-unsafe-code.rs:67:5
    |
 LL |     unsafe fn provided(&self) {}
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: implementation of an `unsafe` method
-  --> $DIR/lint-unsafe-code.rs:44:5
-   |
-LL |     unsafe fn provided_override(&self) {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-error: implementation of an `unsafe` method
-  --> $DIR/lint-unsafe-code.rs:48:5
-   |
-LL |     unsafe fn baz(&self) {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^
-
-error: implementation of an `unsafe` method
-  --> $DIR/lint-unsafe-code.rs:49:5
-   |
-LL |     unsafe fn provided_override(&self) {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
 error: implementation of an `unsafe` method
   --> $DIR/lint-unsafe-code.rs:68:5
    |
@@ -90,25 +104,43 @@ LL |     unsafe fn provided_override(&self) {}
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: implementation of an `unsafe` method
-  --> $DIR/lint-unsafe-code.rs:79:5
+  --> $DIR/lint-unsafe-code.rs:72:5
+   |
+LL |     unsafe fn baz(&self) {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^^
+
+error: implementation of an `unsafe` method
+  --> $DIR/lint-unsafe-code.rs:73:5
+   |
+LL |     unsafe fn provided_override(&self) {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: implementation of an `unsafe` method
+  --> $DIR/lint-unsafe-code.rs:92:5
+   |
+LL |     unsafe fn provided_override(&self) {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: implementation of an `unsafe` method
+  --> $DIR/lint-unsafe-code.rs:103:5
    |
 LL |     unsafe fn provided(&self) {}
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: implementation of an `unsafe` method
-  --> $DIR/lint-unsafe-code.rs:85:5
+  --> $DIR/lint-unsafe-code.rs:109:5
    |
 LL |     unsafe fn provided(&self) {}
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: implementation of an `unsafe` method
-  --> $DIR/lint-unsafe-code.rs:89:5
+  --> $DIR/lint-unsafe-code.rs:113:5
    |
 LL |     unsafe fn baz(&self) {}
    |     ^^^^^^^^^^^^^^^^^^^^^^^
 
 error: usage of an `unsafe` block
-  --> $DIR/lint-unsafe-code.rs:100:5
+  --> $DIR/lint-unsafe-code.rs:124:5
    |
 LL |     unsafe {}
    |     ^^^^^^^^^
@@ -172,5 +204,5 @@ LL |     unsafe_in_macro!()
    |
    = note: this error originates in the macro `unsafe_in_macro` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: aborting due to 22 previous errors
+error: aborting due to 26 previous errors
 

src/test/ui/no-mangle-associated-fn.rs

@@ -0,0 +1,37 @@
+// aux-build: no-mangle-associated-fn.rs
+// run-pass
+
+extern crate no_mangle_associated_fn;
+
+struct Foo;
+
+impl Foo {
+    #[no_mangle]
+    fn foo() -> u8 {
+        1
+    }
+}
+
+trait Bar {
+    fn qux() -> u8;
+}
+
+impl Bar for Foo {
+    #[no_mangle]
+    fn qux() -> u8 {
+        4
+    }
+}
+
+fn main() {
+    extern "Rust" {
+        fn foo() -> u8;
+        fn bar() -> u8;
+        fn baz() -> u8;
+        fn qux() -> u8;
+    }
+    assert_eq!(unsafe { foo() }, 1);
+    assert_eq!(unsafe { bar() }, 2);
+    assert_eq!(unsafe { baz() }, 3);
+    assert_eq!(unsafe { qux() }, 4);
+}

src/test/ui/rfc-2457/no_mangle_nonascii_forbidden.rs

@@ -1,4 +1,20 @@
 #[no_mangle]
 pub fn řųśť() {}  //~ `#[no_mangle]` requires ASCII identifier
 
+pub struct Foo;
+
+impl Foo {
+    #[no_mangle]
+    pub fn řųśť() {}  //~ `#[no_mangle]` requires ASCII identifier
+}
+
+trait Bar {
+    fn řųśť();
+}
+
+impl Bar for Foo {
+    #[no_mangle]
+    fn řųśť() {}  //~ `#[no_mangle]` requires ASCII identifier
+}
+
 fn main() {}

src/test/ui/rfc-2457/no_mangle_nonascii_forbidden.stderr

@@ -4,6 +4,18 @@ error[E0754]: `#[no_mangle]` requires ASCII identifier
 LL | pub fn řųśť() {}
    | ^^^^^^^^^^^^^
 
-error: aborting due to previous error
+error[E0754]: `#[no_mangle]` requires ASCII identifier
+  --> $DIR/no_mangle_nonascii_forbidden.rs:8:5
+   |
+LL |     pub fn řųśť() {}
+   |     ^^^^^^^^^^^^^
+
+error[E0754]: `#[no_mangle]` requires ASCII identifier
+  --> $DIR/no_mangle_nonascii_forbidden.rs:17:5
+   |
+LL |     fn řųśť() {}
+   |     ^^^^^^^^^
+
+error: aborting due to 3 previous errors
 
 For more information about this error, try `rustc --explain E0754`.