Make NEVER_TYPE_FALLBACK_FLOWING_INTO_UNSAFE into an FCW and report it ext macros

Author: WaffleLapkin

compiler/rustc_lint_defs/src/builtin.rs

@@ -4320,7 +4320,12 @@ declare_lint! {
     /// [`()`]: https://doc.rust-lang.org/core/primitive.unit.html
     pub NEVER_TYPE_FALLBACK_FLOWING_INTO_UNSAFE,
     Warn,
-    "never type fallback affecting unsafe function calls"
+    "never type fallback affecting unsafe function calls",
+    @future_incompatible = FutureIncompatibleInfo {
+        reason: FutureIncompatibilityReason::FutureReleaseSemanticsChange,
+        reference: "issue #123748 <https://github.com/rust-lang/rust/issues/123748>",
+    };
+    report_in_external_macro
 }
 
 declare_lint! {