Mark never_type_fallback_flowing_into_unsafe as a semantic change

...rather than a future error

Author: WaffleLapkin

Diff for: 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 for: 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 for: 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 for: 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 for: 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)