stabilize `const_extern_fn`

9 files changed, 111 insertions, 122 deletions

diff --git a/src/tools/clippy/clippy_config/src/msrvs.rs b/src/tools/clippy/clippy_config/src/msrvs.rs
index e17458b3310..a2b4b6e256f 100644
--- a/src/tools/clippy/clippy_config/src/msrvs.rs
+++ b/src/tools/clippy/clippy_config/src/msrvs.rs
@@ -17,6 +17,7 @@ macro_rules! msrv_aliases {
 
 // names may refer to stabilized feature flags or library items
 msrv_aliases! {
+    1,83,0 { CONST_EXTERN_FN }
     1,83,0 { CONST_FLOAT_BITS_CONV }
     1,81,0 { LINT_REASONS_STABILIZATION }
     1,80,0 { BOX_INTO_ITER}
@@ -27,7 +28,7 @@ msrv_aliases! {
     1,68,0 { PATH_MAIN_SEPARATOR_STR }
     1,65,0 { LET_ELSE, POINTER_CAST_CONSTNESS }
     1,63,0 { CLONE_INTO }
-    1,62,0 { BOOL_THEN_SOME, DEFAULT_ENUM_ATTRIBUTE, CONST_EXTERN_FN }
+    1,62,0 { BOOL_THEN_SOME, DEFAULT_ENUM_ATTRIBUTE, CONST_EXTERN_C_FN }
     1,59,0 { THREAD_LOCAL_CONST_INIT }
     1,58,0 { FORMAT_ARGS_CAPTURE, PATTERN_TRAIT_CHAR_ARRAY, CONST_RAW_PTR_DEREF }
     1,56,0 { CONST_FN_UNION }
diff --git a/src/tools/clippy/clippy_lints/src/missing_const_for_fn.rs b/src/tools/clippy/clippy_lints/src/missing_const_for_fn.rs
index 052d738b2e7..859afe1b963 100644
--- a/src/tools/clippy/clippy_lints/src/missing_const_for_fn.rs
+++ b/src/tools/clippy/clippy_lints/src/missing_const_for_fn.rs
@@ -119,9 +119,7 @@ impl<'tcx> LateLintPass<'tcx> for MissingConstForFn {
                     .iter()
                     .any(|param| matches!(param.kind, GenericParamKind::Const { .. }));
 
-                if already_const(header)
-                    || has_const_generic_params
-                    || !could_be_const_with_abi(cx, &self.msrv, header.abi)
+                if already_const(header) || has_const_generic_params || !could_be_const_with_abi(&self.msrv, header.abi)
                 {
                     return;
                 }
@@ -183,13 +181,13 @@ fn already_const(header: hir::FnHeader) -> bool {
     header.constness == Constness::Const
 }
 
-fn could_be_const_with_abi(cx: &LateContext<'_>, msrv: &Msrv, abi: Abi) -> bool {
+fn could_be_const_with_abi(msrv: &Msrv, abi: Abi) -> bool {
     match abi {
         Abi::Rust => true,
         // `const extern "C"` was stabilized after 1.62.0
-        Abi::C { unwind: false } => msrv.meets(msrvs::CONST_EXTERN_FN),
+        Abi::C { unwind: false } => msrv.meets(msrvs::CONST_EXTERN_C_FN),
         // Rest ABIs are still unstable and need the `const_extern_fn` feature enabled.
-        _ => cx.tcx.features().const_extern_fn,
+        _ => msrv.meets(msrvs::CONST_EXTERN_FN),
     }
 }
 
diff --git a/src/tools/clippy/tests/ui/missing_const_for_fn/cant_be_const.rs b/src/tools/clippy/tests/ui/missing_const_for_fn/cant_be_const.rs
index 2c6e1e92da0..ca323dcf173 100644
--- a/src/tools/clippy/tests/ui/missing_const_for_fn/cant_be_const.rs
+++ b/src/tools/clippy/tests/ui/missing_const_for_fn/cant_be_const.rs
@@ -186,12 +186,6 @@ mod msrv {
     extern "C" fn c() {}
 }
 
-mod with_extern {
-    extern "C-unwind" fn c_unwind() {}
-    extern "system" fn system() {}
-    extern "system-unwind" fn system_unwind() {}
-}
-
 mod with_ty_alias {
     type Foo = impl std::fmt::Debug;
 
diff --git a/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const.fixed b/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const.fixed
index f54503ada97..0aef4d31fd9 100644
--- a/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const.fixed
+++ b/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const.fixed
@@ -1,5 +1,6 @@
 #![warn(clippy::missing_const_for_fn)]
 #![allow(incomplete_features, clippy::let_and_return, clippy::missing_transmute_annotations)]
+#![allow(unsupported_calling_conventions)]
 #![feature(const_mut_refs)]
 #![feature(const_trait_impl)]
 
@@ -204,3 +205,16 @@ mod with_ty_alias {
     // in this test.
     const fn alias_ty_is_projection(bar: <() as FooTrait>::Foo) {}
 }
+
+mod extern_fn {
+    const extern "C-unwind" fn c_unwind() {}
+    //~^ ERROR: this could be a `const fn`
+    const extern "system" fn system() {}
+    //~^ ERROR: this could be a `const fn`
+    const extern "system-unwind" fn system_unwind() {}
+    //~^ ERROR: this could be a `const fn`
+    pub const extern "stdcall" fn std_call() {}
+    //~^ ERROR: this could be a `const fn`
+    pub const extern "stdcall-unwind" fn std_call_unwind() {}
+    //~^ ERROR: this could be a `const fn`
+}
diff --git a/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const.rs b/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const.rs
index 2c229068e4d..4246494fe72 100644
--- a/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const.rs
+++ b/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const.rs
@@ -1,5 +1,6 @@
 #![warn(clippy::missing_const_for_fn)]
 #![allow(incomplete_features, clippy::let_and_return, clippy::missing_transmute_annotations)]
+#![allow(unsupported_calling_conventions)]
 #![feature(const_mut_refs)]
 #![feature(const_trait_impl)]
 
@@ -204,3 +205,16 @@ mod with_ty_alias {
     // in this test.
     fn alias_ty_is_projection(bar: <() as FooTrait>::Foo) {}
 }
+
+mod extern_fn {
+    extern "C-unwind" fn c_unwind() {}
+    //~^ ERROR: this could be a `const fn`
+    extern "system" fn system() {}
+    //~^ ERROR: this could be a `const fn`
+    extern "system-unwind" fn system_unwind() {}
+    //~^ ERROR: this could be a `const fn`
+    pub extern "stdcall" fn std_call() {}
+    //~^ ERROR: this could be a `const fn`
+    pub extern "stdcall-unwind" fn std_call_unwind() {}
+    //~^ ERROR: this could be a `const fn`
+}
diff --git a/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const.stderr b/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const.stderr
index fb4db703103..6bc71e29840 100644
--- a/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const.stderr
+++ b/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const.stderr
@@ -1,5 +1,5 @@
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:14:5
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:15:5
    |
 LL | /     pub fn new() -> Self {
 LL | |
@@ -16,7 +16,7 @@ LL |     pub const fn new() -> Self {
    |         +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:20:5
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:21:5
    |
 LL | /     fn const_generic_params<'a, T, const N: usize>(&self, b: &'a [T; N]) -> &'a [T; N] {
 LL | |
@@ -30,7 +30,7 @@ LL |     const fn const_generic_params<'a, T, const N: usize>(&self, b: &'a [T;
    |     +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:27:1
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:28:1
    |
 LL | / fn one() -> i32 {
 LL | |
@@ -44,7 +44,7 @@ LL | const fn one() -> i32 {
    | +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:33:1
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:34:1
    |
 LL | / fn two() -> i32 {
 LL | |
@@ -59,7 +59,7 @@ LL | const fn two() -> i32 {
    | +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:40:1
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:41:1
    |
 LL | / fn string() -> String {
 LL | |
@@ -73,7 +73,7 @@ LL | const fn string() -> String {
    | +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:46:1
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:47:1
    |
 LL | / unsafe fn four() -> i32 {
 LL | |
@@ -87,7 +87,7 @@ LL | const unsafe fn four() -> i32 {
    | +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:52:1
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:53:1
    |
 LL | / fn generic<T>(t: T) -> T {
 LL | |
@@ -101,7 +101,7 @@ LL | const fn generic<T>(t: T) -> T {
    | +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:61:1
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:62:1
    |
 LL | / fn generic_arr<T: Copy>(t: [T; 1]) -> T {
 LL | |
@@ -115,7 +115,7 @@ LL | const fn generic_arr<T: Copy>(t: [T; 1]) -> T {
    | +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:75:9
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:76:9
    |
 LL | /         pub fn b(self, a: &A) -> B {
 LL | |
@@ -129,7 +129,7 @@ LL |         pub const fn b(self, a: &A) -> B {
    |             +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:85:5
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:86:5
    |
 LL | /     fn const_fn_stabilized_before_msrv(byte: u8) {
 LL | |
@@ -143,7 +143,7 @@ LL |     const fn const_fn_stabilized_before_msrv(byte: u8) {
    |     +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:97:1
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:98:1
    |
 LL | / fn msrv_1_46() -> i32 {
 LL | |
@@ -157,7 +157,7 @@ LL | const fn msrv_1_46() -> i32 {
    | +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:117:1
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:118:1
    |
 LL | fn d(this: D) {}
    | ^^^^^^^^^^^^^^^^
@@ -168,7 +168,7 @@ LL | const fn d(this: D) {}
    | +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:125:9
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:126:9
    |
 LL | /         fn deref_ptr_can_be_const(self) -> usize {
 LL | |
@@ -182,7 +182,7 @@ LL |         const fn deref_ptr_can_be_const(self) -> usize {
    |         +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:130:9
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:131:9
    |
 LL | /         fn deref_copied_val(self) -> usize {
 LL | |
@@ -196,7 +196,7 @@ LL |         const fn deref_copied_val(self) -> usize {
    |         +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:141:5
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:142:5
    |
 LL | /     fn union_access_can_be_const() {
 LL | |
@@ -211,7 +211,7 @@ LL |     const fn union_access_can_be_const() {
    |     +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:149:9
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:150:9
    |
 LL |         extern "C" fn c() {}
    |         ^^^^^^^^^^^^^^^^^^^^
@@ -222,7 +222,7 @@ LL |         const extern "C" fn c() {}
    |         +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:153:9
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:154:9
    |
 LL |         extern fn implicit_c() {}
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -233,7 +233,7 @@ LL |         const extern fn implicit_c() {}
    |         +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:170:9
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:171:9
    |
 LL | /         pub fn new(strings: Vec<String>) -> Self {
 LL | |             Self { strings }
@@ -246,7 +246,7 @@ LL |         pub const fn new(strings: Vec<String>) -> Self {
    |             +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:175:9
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:176:9
    |
 LL | /         pub fn empty() -> Self {
 LL | |             Self { strings: Vec::new() }
@@ -259,7 +259,7 @@ LL |         pub const fn empty() -> Self {
    |             +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:186:9
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:187:9
    |
 LL | /         pub fn new(text: String) -> Self {
 LL | |             let vec = Vec::new();
@@ -273,7 +273,7 @@ LL |         pub const fn new(text: String) -> Self {
    |             +++++
 
 error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const.rs:205:5
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:206:5
    |
 LL |     fn alias_ty_is_projection(bar: <() as FooTrait>::Foo) {}
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -283,5 +283,60 @@ help: make the function `const`
 LL |     const fn alias_ty_is_projection(bar: <() as FooTrait>::Foo) {}
    |     +++++
 
-error: aborting due to 21 previous errors
+error: this could be a `const fn`
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:210:5
+   |
+LL |     extern "C-unwind" fn c_unwind() {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: make the function `const`
+   |
+LL |     const extern "C-unwind" fn c_unwind() {}
+   |     +++++
+
+error: this could be a `const fn`
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:212:5
+   |
+LL |     extern "system" fn system() {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: make the function `const`
+   |
+LL |     const extern "system" fn system() {}
+   |     +++++
+
+error: this could be a `const fn`
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:214:5
+   |
+LL |     extern "system-unwind" fn system_unwind() {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: make the function `const`
+   |
+LL |     const extern "system-unwind" fn system_unwind() {}
+   |     +++++
+
+error: this could be a `const fn`
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:216:5
+   |
+LL |     pub extern "stdcall" fn std_call() {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: make the function `const`
+   |
+LL |     pub const extern "stdcall" fn std_call() {}
+   |         +++++
+
+error: this could be a `const fn`
+  --> tests/ui/missing_const_for_fn/could_be_const.rs:218:5
+   |
+LL |     pub extern "stdcall-unwind" fn std_call_unwind() {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: make the function `const`
+   |
+LL |     pub const extern "stdcall-unwind" fn std_call_unwind() {}
+   |         +++++
+
+error: aborting due to 26 previous errors
 
diff --git a/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const_with_const_extern_fn.fixed b/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const_with_const_extern_fn.fixed
deleted file mode 100644
index c103db536ab..00000000000
--- a/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const_with_const_extern_fn.fixed
+++ /dev/null
@@ -1,14 +0,0 @@
-#![warn(clippy::missing_const_for_fn)]
-#![allow(unsupported_calling_conventions)]
-#![feature(const_extern_fn)]
-
-const extern "C-unwind" fn c_unwind() {}
-//~^ ERROR: this could be a `const fn`
-const extern "system" fn system() {}
-//~^ ERROR: this could be a `const fn`
-const extern "system-unwind" fn system_unwind() {}
-//~^ ERROR: this could be a `const fn`
-pub const extern "stdcall" fn std_call() {}
-//~^ ERROR: this could be a `const fn`
-pub const extern "stdcall-unwind" fn std_call_unwind() {}
-//~^ ERROR: this could be a `const fn`
diff --git a/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const_with_const_extern_fn.rs b/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const_with_const_extern_fn.rs
deleted file mode 100644
index 0f7020ae559..00000000000
--- a/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const_with_const_extern_fn.rs
+++ /dev/null
@@ -1,14 +0,0 @@
-#![warn(clippy::missing_const_for_fn)]
-#![allow(unsupported_calling_conventions)]
-#![feature(const_extern_fn)]
-
-extern "C-unwind" fn c_unwind() {}
-//~^ ERROR: this could be a `const fn`
-extern "system" fn system() {}
-//~^ ERROR: this could be a `const fn`
-extern "system-unwind" fn system_unwind() {}
-//~^ ERROR: this could be a `const fn`
-pub extern "stdcall" fn std_call() {}
-//~^ ERROR: this could be a `const fn`
-pub extern "stdcall-unwind" fn std_call_unwind() {}
-//~^ ERROR: this could be a `const fn`
diff --git a/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const_with_const_extern_fn.stderr b/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const_with_const_extern_fn.stderr
deleted file mode 100644
index 036094a367b..00000000000
--- a/src/tools/clippy/tests/ui/missing_const_for_fn/could_be_const_with_const_extern_fn.stderr
+++ /dev/null
@@ -1,59 +0,0 @@
-error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const_with_const_extern_fn.rs:5:1
-   |
-LL | extern "C-unwind" fn c_unwind() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `-D clippy::missing-const-for-fn` implied by `-D warnings`
-   = help: to override `-D warnings` add `#[allow(clippy::missing_const_for_fn)]`
-help: make the function `const`
-   |
-LL | const extern "C-unwind" fn c_unwind() {}
-   | +++++
-
-error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const_with_const_extern_fn.rs:7:1
-   |
-LL | extern "system" fn system() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-help: make the function `const`
-   |
-LL | const extern "system" fn system() {}
-   | +++++
-
-error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const_with_const_extern_fn.rs:9:1
-   |
-LL | extern "system-unwind" fn system_unwind() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-help: make the function `const`
-   |
-LL | const extern "system-unwind" fn system_unwind() {}
-   | +++++
-
-error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const_with_const_extern_fn.rs:11:1
-   |
-LL | pub extern "stdcall" fn std_call() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-help: make the function `const`
-   |
-LL | pub const extern "stdcall" fn std_call() {}
-   |     +++++
-
-error: this could be a `const fn`
-  --> tests/ui/missing_const_for_fn/could_be_const_with_const_extern_fn.rs:13:1
-   |
-LL | pub extern "stdcall-unwind" fn std_call_unwind() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-help: make the function `const`
-   |
-LL | pub const extern "stdcall-unwind" fn std_call_unwind() {}
-   |     +++++
-
-error: aborting due to 5 previous errors
-