From 9a15c392db4bfa66fc1bd2c578d5072b8152b610 Mon Sep 17 00:00:00 2001
From: Adam Mulvany <amulvany@gitlab.com>
Date: Tue, 9 Jul 2024 13:07:39 +1000
Subject: [PATCH 1/4] Updating lints page to reflect recent changes
---
src/doc/rustc/src/lints/index.md | 37 ++++++++++++++++++++++----------
1 file changed, 26 insertions(+), 11 deletions(-)
diff --git a/src/doc/rustc/src/lints/index.md b/src/doc/rustc/src/lints/index.md
index 029c9edc1b5fe..4fa91ea654341 100644
--- a/src/doc/rustc/src/lints/index.md
+++ b/src/doc/rustc/src/lints/index.md
@@ -39,19 +39,34 @@ provides detailed information and an opportunity for feedback. This gives
users some time to fix the code to accommodate the change. After some time,
the warning may become an error.
-The following is an example of what a future-incompatible looks like:
+The following is an example of what future-incompatible code looks like:
+
+```rust
+#[repr(packed)]
+struct Packed {
+ f1: u8,
+ f2: u16,
+}
+
+fn main() {
+ let packed = Packed { f1: 1, f2: 2 };
+ let _ = &packed.f2; // This line triggers the warning
+}
+```
+
+This code would produce a warning like:
```text
-warning: borrow of packed field is unsafe and requires unsafe function or block (error E0133)
- --> lint_example.rs:11:13
- |
-11 | let y = &x.data.0;
- | ^^^^^^^^^
- |
- = note: `#[warn(safe_packed_borrows)]` 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 #46043 <https://github.com/rust-lang/rust/issues/46043>
- = note: fields of packed structs might be misaligned: dereferencing a misaligned pointer or even just creating a misaligned reference is undefined behavior
+warning: reference to packed field is unaligned
+ --> src/main.rs:8:13
+ |
+8 | let _ = &packed.f2;
+ | ^^^^^^^^^^
+ |
+ = note: `#[warn(unaligned_references)]` 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 #82523 <https://github.com/rust-lang/rust/issues/82523>
+ = help: copy the field contents to a local variable, or use `core::ptr::addr_of!` to create a reference that is guaranteed to be aligned
```
For more information about the process and policy of future-incompatible
From 3638ad02ac33e5d364a30b15f3bb0794f98e5531 Mon Sep 17 00:00:00 2001
From: Adam Mulvany <amulvany@gitlab.com>
Date: Tue, 9 Jul 2024 13:14:01 +1000
Subject: [PATCH 2/4] Updating lints page to reflect recent changes
---
src/doc/rustc/src/lints/index.md | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/src/doc/rustc/src/lints/index.md b/src/doc/rustc/src/lints/index.md
index 4fa91ea654341..9bfa5584abbb7 100644
--- a/src/doc/rustc/src/lints/index.md
+++ b/src/doc/rustc/src/lints/index.md
@@ -57,16 +57,16 @@ fn main() {
This code would produce a warning like:
```text
-warning: reference to packed field is unaligned
- --> src/main.rs:8:13
+error[E0793]: reference to packed field is unaligned
+ --> src/main.rs:9:13
|
-8 | let _ = &packed.f2;
+9 | let _ = &packed.f2; // This line triggers the warning
| ^^^^^^^^^^
|
- = note: `#[warn(unaligned_references)]` 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 #82523 <https://github.com/rust-lang/rust/issues/82523>
- = help: copy the field contents to a local variable, or use `core::ptr::addr_of!` to create a reference that is guaranteed to be aligned
+ = note: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses
+ = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced)
+ = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers)
+
```
For more information about the process and policy of future-incompatible
From 952e4642db818c7282cb5e56221cfd4cd16bf205 Mon Sep 17 00:00:00 2001
From: Adam Mulvany <amulvany@gitlab.com>
Date: Tue, 9 Jul 2024 14:51:34 +1000
Subject: [PATCH 3/4] Updating lints page to reflect recent changes
---
src/doc/rustc/src/lints/index.md | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/src/doc/rustc/src/lints/index.md b/src/doc/rustc/src/lints/index.md
index 9bfa5584abbb7..c84a35c871dd6 100644
--- a/src/doc/rustc/src/lints/index.md
+++ b/src/doc/rustc/src/lints/index.md
@@ -41,7 +41,8 @@ the warning may become an error.
The following is an example of what future-incompatible code looks like:
-```rust
+```bash
+$ cat main.rs
#[repr(packed)]
struct Packed {
f1: u8,
@@ -52,11 +53,9 @@ fn main() {
let packed = Packed { f1: 1, f2: 2 };
let _ = &packed.f2; // This line triggers the warning
}
-```
-This code would produce a warning like:
+$ rustc main.rs
-```text
error[E0793]: reference to packed field is unaligned
--> src/main.rs:9:13
|
@@ -66,7 +65,6 @@ error[E0793]: reference to packed field is unaligned
= note: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses
= note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced)
= help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers)
-
```
For more information about the process and policy of future-incompatible
From 18652477c31acb61f1909246278e656b4888c670 Mon Sep 17 00:00:00 2001
From: Adam Mulvany <amulvany@gitlab.com>
Date: Wed, 10 Jul 2024 08:42:04 +1000
Subject: [PATCH 4/4] example future incompat instead of error
---
src/doc/rustc/src/lints/index.md | 42 ++++++++++++++++++--------------
1 file changed, 24 insertions(+), 18 deletions(-)
diff --git a/src/doc/rustc/src/lints/index.md b/src/doc/rustc/src/lints/index.md
index c84a35c871dd6..0566bf631cf9e 100644
--- a/src/doc/rustc/src/lints/index.md
+++ b/src/doc/rustc/src/lints/index.md
@@ -41,30 +41,36 @@ the warning may become an error.
The following is an example of what future-incompatible code looks like:
-```bash
-$ cat main.rs
-#[repr(packed)]
-struct Packed {
- f1: u8,
- f2: u16,
+```rust,compile_fail
+#![allow(unused)]
+enum E {
+ A,
+}
+impl Drop for E {
+ fn drop(&mut self) {
+ println!("Drop");
+ }
}
+#[allow(cenum_impl_drop_cast)]
fn main() {
- let packed = Packed { f1: 1, f2: 2 };
- let _ = &packed.f2; // This line triggers the warning
+ let e = E::A;
+ let i = e as u32;
}
+```
-$ rustc main.rs
+This will produce the following warning:
-error[E0793]: reference to packed field is unaligned
- --> src/main.rs:9:13
- |
-9 | let _ = &packed.f2; // This line triggers the warning
- | ^^^^^^^^^^
- |
- = note: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses
- = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced)
- = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers)
+```text
+> warning: cannot cast enum `E` into integer `u32` because it implements `Drop`
+> --> src/main.rs:14:13
+> |
+> 14 | let i = e as u32;
+> | ^^^^^^^^
+> |
+> = 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 #73333 <https://github.com/rust-lang/rust/issues/73333>
+>
```
For more information about the process and policy of future-incompatible