implement FCW for rustc_allowed_through_unstable_modules items

compiler/rustc_lint_defs/src/builtin.rs

@@ -137,6 +137,7 @@ pub mod hardwired {
             UNREACHABLE_PATTERNS,
             UNSAFE_ATTR_OUTSIDE_UNSAFE,
             UNSAFE_OP_IN_UNSAFE_FN,
+            UNSTABLE_IMPORTS,
             UNSTABLE_NAME_COLLISIONS,
             UNSTABLE_SYNTAX_PRE_EXPANSION,
             UNSUPPORTED_CALLING_CONVENTIONS,
@@ -5858,3 +5859,28 @@ declare_lint! {
     "`repr(C, align)` types nested inside `repr(C, packed)` types \
     do not always have a C-compatible layout",
 }
+
+declare_lint! {
+    /// The `unstable_imports` lints detects imports that go through unstable modules.
+    ///
+    /// ### Example
+    ///
+    /// ```rust
+    /// use core::intrinsics::transmute;
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// Previous versions of Rust accidentally allowed certain imports through unstable modules
+    /// because stability information of modules was not correctly accounted for if the imported
+    /// item was stable itself.
+    pub UNSTABLE_IMPORTS,
+    Deny,
+    "lints on accidentally allowed unstable imports",
+    @future_incompatible = FutureIncompatibleInfo {
+        reason: fcw!(FutureReleaseError # 163160),
+        report_in_deps: true,
+    };
+}

compiler/rustc_passes/src/stability.rs

@@ -19,8 +19,8 @@ use rustc_hir::{
     UsePath, Variant,
 };
 use rustc_lint_defs::builtin::{
-    DEPRECATED, DUPLICATE_FEATURES, INEFFECTIVE_UNSTABLE_REEXPORTS,
-    INEFFECTIVE_UNSTABLE_TRAIT_IMPL, STABLE_FEATURES,
+    DUPLICATE_FEATURES, INEFFECTIVE_UNSTABLE_REEXPORTS, INEFFECTIVE_UNSTABLE_TRAIT_IMPL,
+    STABLE_FEATURES, UNSTABLE_IMPORTS,
 };
 use rustc_middle::hir::nested_filter;
 use rustc_middle::middle::lib_features::{FeatureStability, LibFeatures};
@@ -1079,7 +1079,7 @@ impl<'tcx> Checker<'tcx> {
                             suggestion,
                         };
                         self.tcx.emit_node_span_lint(
-                            DEPRECATED,
+                            UNSTABLE_IMPORTS,
                             id,
                             method_span.unwrap_or(span),
                             diag,

src/tools/clippy/tests/ui/std_instead_of_core.fixed

@@ -1,7 +1,6 @@
 //@aux-build:proc_macro_derive.rs
 
 #![warn(clippy::std_instead_of_core)]
-#![expect(deprecated)]
 
 extern crate alloc;
 
@@ -77,6 +76,7 @@ mod std_in_proc_macro_derive {
 // replacing std -> core
 fn intrinsic(a: *mut u8, b: *mut u8) {
     unsafe {
+        #[allow(unstable_imports)]
         core::intrinsics::copy(a, b, 1);
         //~^ std_instead_of_core
     }

src/tools/clippy/tests/ui/std_instead_of_core.rs

@@ -1,7 +1,6 @@
 //@aux-build:proc_macro_derive.rs
 
 #![warn(clippy::std_instead_of_core)]
-#![expect(deprecated)]
 
 extern crate alloc;
 
@@ -77,6 +76,7 @@ mod std_in_proc_macro_derive {
 // replacing std -> core
 fn intrinsic(a: *mut u8, b: *mut u8) {
     unsafe {
+        #[allow(unstable_imports)]
         std::intrinsics::copy(a, b, 1);
         //~^ std_instead_of_core
     }

src/tools/clippy/tests/ui/std_instead_of_core.stderr

@@ -1,5 +1,5 @@
 error: used import from `std` instead of `core`
-  --> tests/ui/std_instead_of_core.rs:13:9
+  --> tests/ui/std_instead_of_core.rs:12:9
    |
 LL |     use std::hash::Hasher;
    |         ^^^ help: consider importing the item from `core`: `core`
@@ -8,61 +8,61 @@ LL |     use std::hash::Hasher;
    = help: to override `-D warnings` add `#[allow(clippy::std_instead_of_core)]`
 
 error: used import from `std` instead of `core`
-  --> tests/ui/std_instead_of_core.rs:16:11
+  --> tests/ui/std_instead_of_core.rs:15:11
    |
 LL |     use ::std::hash::Hash;
    |           ^^^ help: consider importing the item from `core`: `core`
 
 error: used import from `std` instead of `core`
-  --> tests/ui/std_instead_of_core.rs:22:9
+  --> tests/ui/std_instead_of_core.rs:21:9
    |
 LL |     use std::fmt::{Debug, Result};
    |         ^^^ help: consider importing the item from `core`: `core`
 
 error: used import from `std` instead of `core`
-  --> tests/ui/std_instead_of_core.rs:27:9
+  --> tests/ui/std_instead_of_core.rs:26:9
    |
 LL |     use std::{
    |         ^^^ help: consider importing the item from `core`: `core`
 
 error: used import from `std` instead of `core`
-  --> tests/ui/std_instead_of_core.rs:34:15
+  --> tests/ui/std_instead_of_core.rs:33:15
    |
 LL |     let ptr = std::ptr::null::<u32>();
    |               ^^^ help: consider importing the item from `core`: `core`
 
 error: used import from `std` instead of `core`
-  --> tests/ui/std_instead_of_core.rs:36:21
+  --> tests/ui/std_instead_of_core.rs:35:21
    |
 LL |     let ptr_mut = ::std::ptr::null_mut::<usize>();
    |                     ^^^ help: consider importing the item from `core`: `core`
 
 error: used import from `std` instead of `core`
-  --> tests/ui/std_instead_of_core.rs:40:16
+  --> tests/ui/std_instead_of_core.rs:39:16
    |
 LL |     let cell = std::cell::Cell::new(8u32);
    |                ^^^ help: consider importing the item from `core`: `core`
 
 error: used import from `std` instead of `core`
-  --> tests/ui/std_instead_of_core.rs:42:27
+  --> tests/ui/std_instead_of_core.rs:41:27
    |
 LL |     let cell_absolute = ::std::cell::Cell::new(8u32);
    |                           ^^^ help: consider importing the item from `core`: `core`
 
 error: used import from `std` instead of `core`
-  --> tests/ui/std_instead_of_core.rs:47:9
+  --> tests/ui/std_instead_of_core.rs:46:9
    |
 LL |     use std::error::Error;
    |         ^^^ help: consider importing the item from `core`: `core`
 
 error: used import from `std` instead of `core`
-  --> tests/ui/std_instead_of_core.rs:51:9
+  --> tests/ui/std_instead_of_core.rs:50:9
    |
 LL |     use std::iter::Iterator;
    |         ^^^ help: consider importing the item from `core`: `core`
 
 error: used import from `std` instead of `alloc`
-  --> tests/ui/std_instead_of_core.rs:58:9
+  --> tests/ui/std_instead_of_core.rs:57:9
    |
 LL |     use std::vec;
    |         ^^^ help: consider importing the item from `alloc`: `alloc`
@@ -71,13 +71,13 @@ LL |     use std::vec;
    = help: to override `-D warnings` add `#[allow(clippy::std_instead_of_alloc)]`
 
 error: used import from `std` instead of `alloc`
-  --> tests/ui/std_instead_of_core.rs:60:9
+  --> tests/ui/std_instead_of_core.rs:59:9
    |
 LL |     use std::vec::Vec;
    |         ^^^ help: consider importing the item from `alloc`: `alloc`
 
 error: used import from `alloc` instead of `core`
-  --> tests/ui/std_instead_of_core.rs:66:9
+  --> tests/ui/std_instead_of_core.rs:65:9
    |
 LL |     use alloc::slice::from_ref;
    |         ^^^^^ help: consider importing the item from `core`: `core`

tests/ui/stability-attribute/accidental-stable-in-unstable.rs

@@ -8,4 +8,5 @@ use core::unicode::UNICODE_VERSION; //~ ERROR use of unstable library feature `u
 // Known accidental stabilizations with known users
 // fully stable @ core::mem::transmute
 use core::intrinsics::transmute; // depended upon by rand_core
-//~^WARN deprecated
+//~^ERROR use of deprecated import through accidentally stabilized module
+//~| WARN previously accepted

tests/ui/stability-attribute/accidental-stable-in-unstable.stderr

@@ -7,19 +7,37 @@ LL | use core::unicode::UNICODE_VERSION;
    = help: add `#![feature(unicode_internals)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
-warning: use of deprecated import through accidentally stabilized module `intrinsics`
+error: use of deprecated import through accidentally stabilized module `intrinsics`
   --> $DIR/accidental-stable-in-unstable.rs:10:5
    |
 LL | use core::intrinsics::transmute; // depended upon by rand_core
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: `#[warn(deprecated)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #163160 <https://github.com/rust-lang/rust/issues/163160>
+   = note: `#[deny(unstable_imports)]` (part of `#[deny(future_incompatible)]`) on by default
 help: import this function via the `mem` module instead
    |
 LL - use core::intrinsics::transmute; // depended upon by rand_core
 LL + use core::mem::transmute; // depended upon by rand_core
    |
 
-error: aborting due to 1 previous error; 1 warning emitted
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0658`.
+Future incompatibility report: Future breakage diagnostic:
+error: use of deprecated import through accidentally stabilized module `intrinsics`
+  --> $DIR/accidental-stable-in-unstable.rs:10:5
+   |
+LL | use core::intrinsics::transmute; // depended upon by rand_core
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #163160 <https://github.com/rust-lang/rust/issues/163160>
+   = note: `#[deny(unstable_imports)]` (part of `#[deny(future_incompatible)]`) on by default
+help: import this function via the `mem` module instead
+   |
+LL - use core::intrinsics::transmute; // depended upon by rand_core
+LL + use core::mem::transmute; // depended upon by rand_core
+   |
+

tests/ui/stability-attribute/accidentally-stable-intrinsics.fixed

@@ -1,26 +1,32 @@
 //@ run-rustfix
 #![crate_type = "lib"]
 #![allow(unnecessary_transmutes, unused_imports)]
-#![deny(deprecated)]
 
 extern crate core;
 
 use std::mem::transmute as _;
 //~^ ERROR use of deprecated import through accidentally stabilized module `intrinsics`
+//~| WARN previously accepted
 use core::ptr::copy as _;
 //~^ ERROR use of deprecated import through accidentally stabilized module `intrinsics`
+//~| WARN previously accepted
 use std::ptr::copy_nonoverlapping as _;
 //~^ ERROR use of deprecated import through accidentally stabilized module `intrinsics`
+//~| WARN previously accepted
 use core::ptr::write_bytes as _;
 //~^ ERROR use of deprecated import through accidentally stabilized module `intrinsics`
+//~| WARN previously accepted
 
 use core::ptr::{
     copy as _,
     //~^ ERROR use of deprecated import through accidentally stabilized module `intrinsics`
+    //~| WARN previously accepted
     copy_nonoverlapping as _,
     //~^ ERROR use of deprecated import through accidentally stabilized module `intrinsics`
+    //~| WARN previously accepted
     write_bytes as _,
     //~^ ERROR use of deprecated import through accidentally stabilized module `intrinsics`
+    //~| WARN previously accepted
 };
 
 pub fn what() {
@@ -29,11 +35,15 @@ pub fn what() {
         let mut dst = 0;
         let _ = std::mem::transmute::<u8, i8>(value);
         //~^ ERROR use of deprecated import through accidentally stabilized module `intrinsics`
+        //~| WARN previously accepted
         core::ptr::copy(&value, &mut dst, 1);
         //~^ ERROR use of deprecated import through accidentally stabilized module `intrinsics`
+        //~| WARN previously accepted
         core::ptr::copy_nonoverlapping(&value, &mut dst, 1);
         //~^ ERROR use of deprecated import through accidentally stabilized module `intrinsics`
+        //~| WARN previously accepted
         std::ptr::write_bytes(&mut dst, value, 1)
         //~^ ERROR use of deprecated import through accidentally stabilized module `intrinsics`
+        //~| WARN previously accepted
     }
 }

tests/ui/stability-attribute/accidentally-stable-intrinsics.rs

@@ -1,26 +1,32 @@
 //@ run-rustfix
 #![crate_type = "lib"]
 #![allow(unnecessary_transmutes, unused_imports)]
-#![deny(deprecated)]
 
 extern crate core;
 
 use std::intrinsics::transmute as _;
 //~^ ERROR use of deprecated import through accidentally stabilized module `intrinsics`
+//~| WARN previously accepted
 use core::intrinsics::copy as _;
 //~^ ERROR use of deprecated import through accidentally stabilized module `intrinsics`
+//~| WARN previously accepted
 use std::intrinsics::copy_nonoverlapping as _;
 //~^ ERROR use of deprecated import through accidentally stabilized module `intrinsics`
+//~| WARN previously accepted
 use core::intrinsics::write_bytes as _;
 //~^ ERROR use of deprecated import through accidentally stabilized module `intrinsics`
+//~| WARN previously accepted
 
 use core::intrinsics::{
     copy as _,
     //~^ ERROR use of deprecated import through accidentally stabilized module `intrinsics`
+    //~| WARN previously accepted
     copy_nonoverlapping as _,
     //~^ ERROR use of deprecated import through accidentally stabilized module `intrinsics`
+    //~| WARN previously accepted
     write_bytes as _,
     //~^ ERROR use of deprecated import through accidentally stabilized module `intrinsics`
+    //~| WARN previously accepted
 };
 
 pub fn what() {
@@ -29,11 +35,15 @@ pub fn what() {
         let mut dst = 0;
         let _ = std::intrinsics::transmute::<u8, i8>(value);
         //~^ ERROR use of deprecated import through accidentally stabilized module `intrinsics`
+        //~| WARN previously accepted
         core::intrinsics::copy(&value, &mut dst, 1);
         //~^ ERROR use of deprecated import through accidentally stabilized module `intrinsics`
+        //~| WARN previously accepted
         core::intrinsics::copy_nonoverlapping(&value, &mut dst, 1);
         //~^ ERROR use of deprecated import through accidentally stabilized module `intrinsics`
+        //~| WARN previously accepted
         std::intrinsics::write_bytes(&mut dst, value, 1)
         //~^ ERROR use of deprecated import through accidentally stabilized module `intrinsics`
+        //~| WARN previously accepted
     }
 }