New lint: unsound_collection_transmute

CHANGELOG.md

@@ -1224,6 +1224,7 @@ Released 2018-09-13
 [`unsafe_removed_from_name`]: https://rust-lang.github.io/rust-clippy/master/index.html#unsafe_removed_from_name
 [`unsafe_vector_initialization`]: https://rust-lang.github.io/rust-clippy/master/index.html#unsafe_vector_initialization
 [`unseparated_literal_suffix`]: https://rust-lang.github.io/rust-clippy/master/index.html#unseparated_literal_suffix
+[`unsound_collection_transmute`]: https://rust-lang.github.io/rust-clippy/master/index.html#unsound_collection_transmute
 [`unstable_as_mut_slice`]: https://rust-lang.github.io/rust-clippy/master/index.html#unstable_as_mut_slice
 [`unstable_as_slice`]: https://rust-lang.github.io/rust-clippy/master/index.html#unstable_as_slice
 [`unused_collect`]: https://rust-lang.github.io/rust-clippy/master/index.html#unused_collect

README.md

@@ -6,7 +6,7 @@
 
 A collection of lints to catch common mistakes and improve your [Rust](https://github.com/rust-lang/rust) code.
 
-[There are 317 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
+[There are 318 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
 
 We have a bunch of lint categories to allow you to choose how much Clippy is supposed to ~~annoy~~ help you:
 

clippy_lints/src/lib.rs

@@ -889,6 +889,7 @@ pub fn register_plugins(reg: &mut rustc_driver::plugin::Registry<'_>, conf: &Con
         transmute::TRANSMUTE_INT_TO_FLOAT,
         transmute::TRANSMUTE_PTR_TO_PTR,
         transmute::TRANSMUTE_PTR_TO_REF,
+        transmute::UNSOUND_COLLECTION_TRANSMUTE,
         transmute::USELESS_TRANSMUTE,
         transmute::WRONG_TRANSMUTE,
         transmuting_null::TRANSMUTING_NULL,
@@ -1143,6 +1144,7 @@ pub fn register_plugins(reg: &mut rustc_driver::plugin::Registry<'_>, conf: &Con
         suspicious_trait_impl::SUSPICIOUS_ARITHMETIC_IMPL,
         suspicious_trait_impl::SUSPICIOUS_OP_ASSIGN_IMPL,
         swap::ALMOST_SWAPPED,
+        transmute::UNSOUND_COLLECTION_TRANSMUTE,
         transmute::WRONG_TRANSMUTE,
         transmuting_null::TRANSMUTING_NULL,
         types::ABSURD_EXTREME_COMPARISONS,

src/lintlist/mod.rs

@@ -6,7 +6,7 @@ pub use lint::Lint;
 pub use lint::LINT_LEVELS;
 
 // begin lint list, do not remove this comment, it’s used in `update_lints`
-pub const ALL_LINTS: [Lint; 317] = [
+pub const ALL_LINTS: [Lint; 318] = [
     Lint {
         name: "absurd_extreme_comparisons",
         group: "correctness",
@@ -2023,6 +2023,13 @@ pub const ALL_LINTS: [Lint; 317] = [
         deprecation: None,
         module: "misc_early",
     },
+    Lint {
+        name: "unsound_collection_transmute",
+        group: "correctness",
+        desc: "transmute between collections of layout-incompatible types",
+        deprecation: None,
+        module: "transmute",
+    },
     Lint {
         name: "unused_io_amount",
         group: "correctness",

tests/ui/transmute.stderr

@@ -116,6 +116,38 @@ error: transmute from a type (`std::vec::Vec<i32>`) to itself
 LL |         let _: Vec<i32> = my_transmute(my_vec());
    |                           ^^^^^^^^^^^^^^^^^^^^^^
 
+error: transmute from `std::vec::Vec<i32>` to `std::vec::Vec<u32>` with mismatched layout is unsound
+  --> $DIR/transmute.rs:83:27
+   |
+LL |         let _: Vec<u32> = core::intrinsics::transmute(my_vec());
+   |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `#[deny(clippy::unsound_collection_transmute)]` on by default
+
+error: transmute from `std::vec::Vec<i32>` to `std::vec::Vec<u32>` with mismatched layout is unsound
+  --> $DIR/transmute.rs:84:27
+   |
+LL |         let _: Vec<u32> = core::mem::transmute(my_vec());
+   |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: transmute from `std::vec::Vec<i32>` to `std::vec::Vec<u32>` with mismatched layout is unsound
+  --> $DIR/transmute.rs:85:27
+   |
+LL |         let _: Vec<u32> = std::intrinsics::transmute(my_vec());
+   |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: transmute from `std::vec::Vec<i32>` to `std::vec::Vec<u32>` with mismatched layout is unsound
+  --> $DIR/transmute.rs:86:27
+   |
+LL |         let _: Vec<u32> = std::mem::transmute(my_vec());
+   |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: transmute from `std::vec::Vec<i32>` to `std::vec::Vec<u32>` with mismatched layout is unsound
+  --> $DIR/transmute.rs:87:27
+   |
+LL |         let _: Vec<u32> = my_transmute(my_vec());
+   |                           ^^^^^^^^^^^^^^^^^^^^^^
+
 error: transmute from an integer to a pointer
   --> $DIR/transmute.rs:89:31
    |
@@ -242,5 +274,5 @@ error: transmute from a reference to a reference
 LL |         let _: &GenericParam<f32> = std::mem::transmute(&GenericParam { t: 1u32 });
    |                                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `&*(&GenericParam { t: 1u32 } as *const GenericParam<u32> as *const GenericParam<f32>)`
 
-error: aborting due to 38 previous errors
+error: aborting due to 43 previous errors
 

tests/ui/transmute_collection.rs

@@ -0,0 +1,47 @@
+#![warn(clippy::unsound_collection_transmute)]
+
+use std::collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, VecDeque};
+use std::mem::transmute;
+
+fn main() {
+    unsafe {
+        // wrong size
+        let _ = transmute::<_, Vec<u32>>(vec![0u8]);
+        // wrong layout
+        let _ = transmute::<_, Vec<[u8; 4]>>(vec![1234u32]);
+
+        // wrong size
+        let _ = transmute::<_, VecDeque<u32>>(VecDeque::<u8>::new());
+        // wrong layout
+        let _ = transmute::<_, VecDeque<u32>>(VecDeque::<[u8; 4]>::new());
+
+        // wrong size
+        let _ = transmute::<_, BinaryHeap<u32>>(BinaryHeap::<u8>::new());
+        // wrong layout
+        let _ = transmute::<_, BinaryHeap<u32>>(BinaryHeap::<[u8; 4]>::new());
+
+        // wrong size
+        let _ = transmute::<_, BTreeSet<u32>>(BTreeSet::<u8>::new());
+        // wrong layout
+        let _ = transmute::<_, BTreeSet<u32>>(BTreeSet::<[u8; 4]>::new());
+
+        // wrong size
+        let _ = transmute::<_, HashSet<u32>>(HashSet::<u8>::new());
+        // wrong layout
+        let _ = transmute::<_, HashSet<u32>>(HashSet::<[u8; 4]>::new());
+
+        // wrong size
+        let _ = transmute::<_, BTreeMap<u8, u32>>(BTreeMap::<u8, u8>::new());
+        let _ = transmute::<_, BTreeMap<u8, u32>>(BTreeMap::<u32, u32>::new());
+        // wrong layout
+        let _ = transmute::<_, BTreeMap<u8, u32>>(BTreeMap::<u8, [u8; 4]>::new());
+        let _ = transmute::<_, BTreeMap<u32, u32>>(BTreeMap::<[u8; 4], u32>::new());
+
+        // wrong size
+        let _ = transmute::<_, HashMap<u8, u32>>(HashMap::<u8, u8>::new());
+        let _ = transmute::<_, HashMap<u8, u32>>(HashMap::<u32, u32>::new());
+        // wrong layout
+        let _ = transmute::<_, HashMap<u8, u32>>(HashMap::<u8, [u8; 4]>::new());
+        let _ = transmute::<_, HashMap<u32, u32>>(HashMap::<[u8; 4], u32>::new());
+    }
+}

tests/ui/transmute_collection.stderr

@@ -0,0 +1,112 @@
+error: transmute from `std::vec::Vec<u8>` to `std::vec::Vec<u32>` with mismatched layout is unsound
+  --> $DIR/transmute_collection.rs:9:17
+   |
+LL |         let _ = transmute::<_, Vec<u32>>(vec![0u8]);
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::unsound-collection-transmute` implied by `-D warnings`
+
+error: transmute from `std::vec::Vec<u32>` to `std::vec::Vec<[u8; 4]>` with mismatched layout is unsound
+  --> $DIR/transmute_collection.rs:11:17
+   |
+LL |         let _ = transmute::<_, Vec<[u8; 4]>>(vec![1234u32]);
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: transmute from `std::collections::VecDeque<u8>` to `std::collections::VecDeque<u32>` with mismatched layout is unsound
+  --> $DIR/transmute_collection.rs:14:17
+   |
+LL |         let _ = transmute::<_, VecDeque<u32>>(VecDeque::<u8>::new());
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: transmute from `std::collections::VecDeque<[u8; 4]>` to `std::collections::VecDeque<u32>` with mismatched layout is unsound
+  --> $DIR/transmute_collection.rs:16:17
+   |
+LL |         let _ = transmute::<_, VecDeque<u32>>(VecDeque::<[u8; 4]>::new());
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: transmute from `std::collections::BinaryHeap<u8>` to `std::collections::BinaryHeap<u32>` with mismatched layout is unsound
+  --> $DIR/transmute_collection.rs:19:17
+   |
+LL |         let _ = transmute::<_, BinaryHeap<u32>>(BinaryHeap::<u8>::new());
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: transmute from `std::collections::BinaryHeap<[u8; 4]>` to `std::collections::BinaryHeap<u32>` with mismatched layout is unsound
+  --> $DIR/transmute_collection.rs:21:17
+   |
+LL |         let _ = transmute::<_, BinaryHeap<u32>>(BinaryHeap::<[u8; 4]>::new());
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: transmute from `std::collections::BTreeSet<u8>` to `std::collections::BTreeSet<u32>` with mismatched layout is unsound
+  --> $DIR/transmute_collection.rs:24:17
+   |
+LL |         let _ = transmute::<_, BTreeSet<u32>>(BTreeSet::<u8>::new());
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: transmute from `std::collections::BTreeSet<[u8; 4]>` to `std::collections::BTreeSet<u32>` with mismatched layout is unsound
+  --> $DIR/transmute_collection.rs:26:17
+   |
+LL |         let _ = transmute::<_, BTreeSet<u32>>(BTreeSet::<[u8; 4]>::new());
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: transmute from `std::collections::HashSet<u8>` to `std::collections::HashSet<u32>` with mismatched layout is unsound
+  --> $DIR/transmute_collection.rs:29:17
+   |
+LL |         let _ = transmute::<_, HashSet<u32>>(HashSet::<u8>::new());
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: transmute from `std::collections::HashSet<[u8; 4]>` to `std::collections::HashSet<u32>` with mismatched layout is unsound
+  --> $DIR/transmute_collection.rs:31:17
+   |
+LL |         let _ = transmute::<_, HashSet<u32>>(HashSet::<[u8; 4]>::new());
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: transmute from `std::collections::BTreeMap<u8, u8>` to `std::collections::BTreeMap<u8, u32>` with mismatched layout is unsound
+  --> $DIR/transmute_collection.rs:34:17
+   |
+LL |         let _ = transmute::<_, BTreeMap<u8, u32>>(BTreeMap::<u8, u8>::new());
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: transmute from `std::collections::BTreeMap<u32, u32>` to `std::collections::BTreeMap<u8, u32>` with mismatched layout is unsound
+  --> $DIR/transmute_collection.rs:35:17
+   |
+LL |         let _ = transmute::<_, BTreeMap<u8, u32>>(BTreeMap::<u32, u32>::new());
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: transmute from `std::collections::BTreeMap<u8, [u8; 4]>` to `std::collections::BTreeMap<u8, u32>` with mismatched layout is unsound
+  --> $DIR/transmute_collection.rs:37:17
+   |
+LL |         let _ = transmute::<_, BTreeMap<u8, u32>>(BTreeMap::<u8, [u8; 4]>::new());
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: transmute from `std::collections::BTreeMap<[u8; 4], u32>` to `std::collections::BTreeMap<u32, u32>` with mismatched layout is unsound
+  --> $DIR/transmute_collection.rs:38:17
+   |
+LL |         let _ = transmute::<_, BTreeMap<u32, u32>>(BTreeMap::<[u8; 4], u32>::new());
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: transmute from `std::collections::HashMap<u8, u8>` to `std::collections::HashMap<u8, u32>` with mismatched layout is unsound
+  --> $DIR/transmute_collection.rs:41:17
+   |
+LL |         let _ = transmute::<_, HashMap<u8, u32>>(HashMap::<u8, u8>::new());
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: transmute from `std::collections::HashMap<u32, u32>` to `std::collections::HashMap<u8, u32>` with mismatched layout is unsound
+  --> $DIR/transmute_collection.rs:42:17
+   |
+LL |         let _ = transmute::<_, HashMap<u8, u32>>(HashMap::<u32, u32>::new());
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: transmute from `std::collections::HashMap<u8, [u8; 4]>` to `std::collections::HashMap<u8, u32>` with mismatched layout is unsound
+  --> $DIR/transmute_collection.rs:44:17
+   |
+LL |         let _ = transmute::<_, HashMap<u8, u32>>(HashMap::<u8, [u8; 4]>::new());
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: transmute from `std::collections::HashMap<[u8; 4], u32>` to `std::collections::HashMap<u32, u32>` with mismatched layout is unsound
+  --> $DIR/transmute_collection.rs:45:17
+   |
+LL |         let _ = transmute::<_, HashMap<u32, u32>>(HashMap::<[u8; 4], u32>::new());
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 18 previous errors
+