Mark `never_type_fallback_flowing_into_unsafe` as a semantic change

...rather than a future error

6 files changed, 49 insertions, 32 deletions

diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
index 7f3f31843f5..efdb4b077e9 100644
--- a/compiler/rustc_lint_defs/src/builtin.rs
+++ b/compiler/rustc_lint_defs/src/builtin.rs
@@ -4185,7 +4185,7 @@ declare_lint! {
     Warn,
     "never type fallback affecting unsafe function calls",
     @future_incompatible = FutureIncompatibleInfo {
-        reason: FutureIncompatibilityReason::EditionAndFutureReleaseError(Edition::Edition2024),
+        reason: FutureIncompatibilityReason::EditionAndFutureReleaseSemanticsChange(Edition::Edition2024),
         reference: "issue #123748 <https://github.com/rust-lang/rust/issues/123748>",
     };
     @edition Edition2024 => Deny;
diff --git a/compiler/rustc_lint_defs/src/lib.rs b/compiler/rustc_lint_defs/src/lib.rs
index 1bf5d9e5098..eac4afee050 100644
--- a/compiler/rustc_lint_defs/src/lib.rs
+++ b/compiler/rustc_lint_defs/src/lib.rs
@@ -432,6 +432,17 @@ pub enum FutureIncompatibilityReason {
     /// [`EditionError`]: FutureIncompatibilityReason::EditionError
     /// [`FutureReleaseErrorDontReportInDeps`]: FutureIncompatibilityReason::FutureReleaseErrorDontReportInDeps
     EditionAndFutureReleaseError(Edition),
+    /// This will change meaning in the provided edition *and* in a future
+    /// release.
+    ///
+    /// This variant a combination of [`FutureReleaseSemanticsChange`]
+    /// and [`EditionSemanticsChange`]. This is useful in rare cases when we
+    /// want to have "preview" of a breaking change in an edition, but do a
+    /// breaking change later on all editions anyway.
+    ///
+    /// [`EditionSemanticsChange`]: FutureIncompatibilityReason::EditionSemanticsChange
+    /// [`FutureReleaseSemanticsChange`]: FutureIncompatibilityReason::FutureReleaseSemanticsChange
+    EditionAndFutureReleaseSemanticsChange(Edition),
     /// A custom reason.
     ///
     /// Choose this variant if the built-in text of the diagnostic of the
@@ -446,7 +457,8 @@ impl FutureIncompatibilityReason {
         match self {
             Self::EditionError(e)
             | Self::EditionSemanticsChange(e)
-            | Self::EditionAndFutureReleaseError(e) => Some(e),
+            | Self::EditionAndFutureReleaseError(e)
+            | Self::EditionAndFutureReleaseSemanticsChange(e) => Some(e),
 
             FutureIncompatibilityReason::FutureReleaseErrorDontReportInDeps
             | FutureIncompatibilityReason::FutureReleaseErrorReportInDeps
diff --git a/compiler/rustc_middle/src/lint.rs b/compiler/rustc_middle/src/lint.rs
index 1bcdbe33286..92ba6ceee93 100644
--- a/compiler/rustc_middle/src/lint.rs
+++ b/compiler/rustc_middle/src/lint.rs
@@ -388,6 +388,11 @@ pub fn lint_level(
                          it will become a hard error in Rust {edition} and in a future release in all editions!"
                     )
                 }
+                FutureIncompatibilityReason::EditionAndFutureReleaseSemanticsChange(edition) => {
+                    format!(
+                        "this changes meaning in Rust {edition} and in a future release in all editions!"
+                    )
+                }
                 FutureIncompatibilityReason::Custom(reason) => reason.to_owned(),
             };
 
diff --git a/tests/ui/never_type/lint-never-type-fallback-flowing-into-unsafe.e2015.stderr b/tests/ui/never_type/lint-never-type-fallback-flowing-into-unsafe.e2015.stderr
index d178a7fc299..03bb0ca5f3a 100644
--- a/tests/ui/never_type/lint-never-type-fallback-flowing-into-unsafe.e2015.stderr
+++ b/tests/ui/never_type/lint-never-type-fallback-flowing-into-unsafe.e2015.stderr
@@ -4,7 +4,7 @@ warning: never type fallback affects this call to an `unsafe` function
 LL |         unsafe { mem::zeroed() }
    |                  ^^^^^^^^^^^^^
    |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+   = warning: this changes meaning in Rust 2024 and in a future release in all editions!
    = note: for more information, see issue #123748 <https://github.com/rust-lang/rust/issues/123748>
    = help: specify the type explicitly
    = note: `#[warn(never_type_fallback_flowing_into_unsafe)]` on by default
@@ -19,7 +19,7 @@ warning: never type fallback affects this call to an `unsafe` function
 LL |             core::mem::transmute(Zst)
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+   = warning: this changes meaning in Rust 2024 and in a future release in all editions!
    = note: for more information, see issue #123748 <https://github.com/rust-lang/rust/issues/123748>
    = help: specify the type explicitly
 help: use `()` annotations to avoid fallback changes
@@ -33,7 +33,7 @@ warning: never type fallback affects this union access
 LL |         unsafe { Union { a: () }.b }
    |                  ^^^^^^^^^^^^^^^^^
    |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+   = warning: this changes meaning in Rust 2024 and in a future release in all editions!
    = note: for more information, see issue #123748 <https://github.com/rust-lang/rust/issues/123748>
    = help: specify the type explicitly
 
@@ -43,7 +43,7 @@ warning: never type fallback affects this raw pointer dereference
 LL |         unsafe { *ptr::from_ref(&()).cast() }
    |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+   = warning: this changes meaning in Rust 2024 and in a future release in all editions!
    = note: for more information, see issue #123748 <https://github.com/rust-lang/rust/issues/123748>
    = help: specify the type explicitly
 help: use `()` annotations to avoid fallback changes
@@ -57,7 +57,7 @@ warning: never type fallback affects this call to an `unsafe` function
 LL |         unsafe { internally_create(x) }
    |                  ^^^^^^^^^^^^^^^^^^^^
    |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+   = warning: this changes meaning in Rust 2024 and in a future release in all editions!
    = note: for more information, see issue #123748 <https://github.com/rust-lang/rust/issues/123748>
    = help: specify the type explicitly
 help: use `()` annotations to avoid fallback changes
@@ -71,7 +71,7 @@ warning: never type fallback affects this call to an `unsafe` function
 LL |         unsafe { zeroed() }
    |                  ^^^^^^^^
    |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+   = warning: this changes meaning in Rust 2024 and in a future release in all editions!
    = note: for more information, see issue #123748 <https://github.com/rust-lang/rust/issues/123748>
    = help: specify the type explicitly
 help: use `()` annotations to avoid fallback changes
@@ -85,7 +85,7 @@ warning: never type fallback affects this `unsafe` function
 LL |         let zeroed = mem::zeroed;
    |                      ^^^^^^^^^^^
    |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+   = warning: this changes meaning in Rust 2024 and in a future release in all editions!
    = note: for more information, see issue #123748 <https://github.com/rust-lang/rust/issues/123748>
    = help: specify the type explicitly
 help: use `()` annotations to avoid fallback changes
@@ -99,7 +99,7 @@ warning: never type fallback affects this `unsafe` function
 LL |         let f = internally_create;
    |                 ^^^^^^^^^^^^^^^^^
    |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+   = warning: this changes meaning in Rust 2024 and in a future release in all editions!
    = note: for more information, see issue #123748 <https://github.com/rust-lang/rust/issues/123748>
    = help: specify the type explicitly
 help: use `()` annotations to avoid fallback changes
@@ -113,7 +113,7 @@ warning: never type fallback affects this call to an `unsafe` method
 LL |             S(marker::PhantomData).create_out_of_thin_air()
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+   = warning: this changes meaning in Rust 2024 and in a future release in all editions!
    = note: for more information, see issue #123748 <https://github.com/rust-lang/rust/issues/123748>
    = help: specify the type explicitly
 
@@ -126,7 +126,7 @@ LL |             match send_message::<_ /* ?0 */>() {
 LL |         msg_send!();
    |         ----------- in this macro invocation
    |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+   = warning: this changes meaning in Rust 2024 and in a future release in all editions!
    = note: for more information, see issue #123748 <https://github.com/rust-lang/rust/issues/123748>
    = help: specify the type explicitly
    = note: this warning originates in the macro `msg_send` (in Nightly builds, run with -Z macro-backtrace for more info)
diff --git a/tests/ui/never_type/lint-never-type-fallback-flowing-into-unsafe.e2024.stderr b/tests/ui/never_type/lint-never-type-fallback-flowing-into-unsafe.e2024.stderr
index 7fb6a484b33..cf12d699f2e 100644
--- a/tests/ui/never_type/lint-never-type-fallback-flowing-into-unsafe.e2024.stderr
+++ b/tests/ui/never_type/lint-never-type-fallback-flowing-into-unsafe.e2024.stderr
@@ -4,7 +4,7 @@ error: never type fallback affects this call to an `unsafe` function
 LL |         unsafe { mem::zeroed() }
    |                  ^^^^^^^^^^^^^
    |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+   = warning: this changes meaning in Rust 2024 and in a future release in all editions!
    = note: for more information, see issue #123748 <https://github.com/rust-lang/rust/issues/123748>
    = help: specify the type explicitly
    = note: `#[deny(never_type_fallback_flowing_into_unsafe)]` on by default
@@ -19,7 +19,7 @@ error: never type fallback affects this call to an `unsafe` function
 LL |             core::mem::transmute(Zst)
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+   = warning: this changes meaning in Rust 2024 and in a future release in all editions!
    = note: for more information, see issue #123748 <https://github.com/rust-lang/rust/issues/123748>
    = help: specify the type explicitly
 help: use `()` annotations to avoid fallback changes
@@ -33,7 +33,7 @@ error: never type fallback affects this union access
 LL |         unsafe { Union { a: () }.b }
    |                  ^^^^^^^^^^^^^^^^^
    |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+   = warning: this changes meaning in Rust 2024 and in a future release in all editions!
    = note: for more information, see issue #123748 <https://github.com/rust-lang/rust/issues/123748>
    = help: specify the type explicitly
 
@@ -43,7 +43,7 @@ error: never type fallback affects this raw pointer dereference
 LL |         unsafe { *ptr::from_ref(&()).cast() }
    |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+   = warning: this changes meaning in Rust 2024 and in a future release in all editions!
    = note: for more information, see issue #123748 <https://github.com/rust-lang/rust/issues/123748>
    = help: specify the type explicitly
 help: use `()` annotations to avoid fallback changes
@@ -57,7 +57,7 @@ error: never type fallback affects this call to an `unsafe` function
 LL |         unsafe { internally_create(x) }
    |                  ^^^^^^^^^^^^^^^^^^^^
    |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+   = warning: this changes meaning in Rust 2024 and in a future release in all editions!
    = note: for more information, see issue #123748 <https://github.com/rust-lang/rust/issues/123748>
    = help: specify the type explicitly
 help: use `()` annotations to avoid fallback changes
@@ -71,7 +71,7 @@ error: never type fallback affects this call to an `unsafe` function
 LL |         unsafe { zeroed() }
    |                  ^^^^^^^^
    |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+   = warning: this changes meaning in Rust 2024 and in a future release in all editions!
    = note: for more information, see issue #123748 <https://github.com/rust-lang/rust/issues/123748>
    = help: specify the type explicitly
 help: use `()` annotations to avoid fallback changes
@@ -85,7 +85,7 @@ error: never type fallback affects this `unsafe` function
 LL |         let zeroed = mem::zeroed;
    |                      ^^^^^^^^^^^
    |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+   = warning: this changes meaning in Rust 2024 and in a future release in all editions!
    = note: for more information, see issue #123748 <https://github.com/rust-lang/rust/issues/123748>
    = help: specify the type explicitly
 help: use `()` annotations to avoid fallback changes
@@ -99,7 +99,7 @@ error: never type fallback affects this `unsafe` function
 LL |         let f = internally_create;
    |                 ^^^^^^^^^^^^^^^^^
    |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+   = warning: this changes meaning in Rust 2024 and in a future release in all editions!
    = note: for more information, see issue #123748 <https://github.com/rust-lang/rust/issues/123748>
    = help: specify the type explicitly
 help: use `()` annotations to avoid fallback changes
@@ -113,7 +113,7 @@ error: never type fallback affects this call to an `unsafe` method
 LL |             S(marker::PhantomData).create_out_of_thin_air()
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+   = warning: this changes meaning in Rust 2024 and in a future release in all editions!
    = note: for more information, see issue #123748 <https://github.com/rust-lang/rust/issues/123748>
    = help: specify the type explicitly
 
@@ -126,7 +126,7 @@ LL |             match send_message::<_ /* ?0 */>() {
 LL |         msg_send!();
    |         ----------- in this macro invocation
    |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+   = warning: this changes meaning in Rust 2024 and in a future release in all editions!
    = note: for more information, see issue #123748 <https://github.com/rust-lang/rust/issues/123748>
    = help: specify the type explicitly
    = note: this error originates in the macro `msg_send` (in Nightly builds, run with -Z macro-backtrace for more info)
diff --git a/tests/ui/never_type/lint-never-type-fallback-flowing-into-unsafe.rs b/tests/ui/never_type/lint-never-type-fallback-flowing-into-unsafe.rs
index 651892d7b51..19b51eea2f5 100644
--- a/tests/ui/never_type/lint-never-type-fallback-flowing-into-unsafe.rs
+++ b/tests/ui/never_type/lint-never-type-fallback-flowing-into-unsafe.rs
@@ -13,7 +13,7 @@ fn _zero() {
         unsafe { mem::zeroed() }
         //[e2015]~^ warn: never type fallback affects this call to an `unsafe` function
         //[e2024]~^^ error: never type fallback affects this call to an `unsafe` function
-        //~| warn: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+        //~| warn: this changes meaning in Rust 2024 and in a future release in all editions!
         //[e2024]~| warning: the type `!` does not permit zero-initialization
     } else {
         return;
@@ -30,7 +30,7 @@ fn _trans() {
             core::mem::transmute(Zst)
             //[e2015]~^ warn: never type fallback affects this call to an `unsafe` function
             //[e2024]~^^ error: never type fallback affects this call to an `unsafe` function
-            //~| warn: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+            //~| warn: this changes meaning in Rust 2024 and in a future release in all editions!
         }
     } else {
         return;
@@ -47,7 +47,7 @@ fn _union() {
         unsafe { Union { a: () }.b }
         //[e2015]~^ warn: never type fallback affects this union access
         //[e2024]~^^ error: never type fallback affects this union access
-        //~| warn: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+        //~| warn: this changes meaning in Rust 2024 and in a future release in all editions!
     } else {
         return;
     };
@@ -58,7 +58,7 @@ fn _deref() {
         unsafe { *ptr::from_ref(&()).cast() }
         //[e2015]~^ warn: never type fallback affects this raw pointer dereference
         //[e2024]~^^ error: never type fallback affects this raw pointer dereference
-        //~| warn: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+        //~| warn: this changes meaning in Rust 2024 and in a future release in all editions!
     } else {
         return;
     };
@@ -79,7 +79,7 @@ fn _only_generics() {
         unsafe { internally_create(x) }
         //[e2015]~^ warn: never type fallback affects this call to an `unsafe` function
         //[e2024]~^^ error: never type fallback affects this call to an `unsafe` function
-        //~| warn: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+        //~| warn: this changes meaning in Rust 2024 and in a future release in all editions!
 
         x.unwrap()
     } else {
@@ -92,12 +92,12 @@ fn _stored_function() {
         let zeroed = mem::zeroed;
         //[e2015]~^ warn: never type fallback affects this `unsafe` function
         //[e2024]~^^ error: never type fallback affects this `unsafe` function
-        //~| warn: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+        //~| warn: this changes meaning in Rust 2024 and in a future release in all editions!
 
         unsafe { zeroed() }
         //[e2015]~^ warn: never type fallback affects this call to an `unsafe` function
         //[e2024]~^^ error: never type fallback affects this call to an `unsafe` function
-        //~| warn: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+        //~| warn: this changes meaning in Rust 2024 and in a future release in all editions!
     } else {
         return;
     };
@@ -115,7 +115,7 @@ fn _only_generics_stored_function() {
         let f = internally_create;
         //[e2015]~^ warn: never type fallback affects this `unsafe` function
         //[e2024]~^^ error: never type fallback affects this `unsafe` function
-        //~| warn: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+        //~| warn: this changes meaning in Rust 2024 and in a future release in all editions!
 
         unsafe { f(x) }
 
@@ -140,7 +140,7 @@ fn _method() {
             S(marker::PhantomData).create_out_of_thin_air()
             //[e2015]~^ warn: never type fallback affects this call to an `unsafe` method
             //[e2024]~^^ error: never type fallback affects this call to an `unsafe` method
-            //~| warn: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+            //~| warn: this changes meaning in Rust 2024 and in a future release in all editions!
         }
     } else {
         return;
@@ -158,7 +158,7 @@ fn _objc() {
             match send_message::<_ /* ?0 */>() {
                 //[e2015]~^ warn: never type fallback affects this call to an `unsafe` function
                 //[e2024]~^^ error: never type fallback affects this call to an `unsafe` function
-                //~| warn: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
+                //~| warn: this changes meaning in Rust 2024 and in a future release in all editions!
                 Ok(x) => x,
                 Err(_) => loop {},
             }