Do not suggest to use implicit `DerefMut` on `ManuallyDrop` reached through unions (#14387)

This requires making the `deref_addrof` lint a late lint instead of an
early lint to check for types.

changelog: [`deref_addrof`]: do not suggest implicit `DerefMut` on
`ManuallyDrop` union fields

Fix rust-lang/rust-clippy#14386

3 files changed, 191 insertions, 41 deletions

diff --git a/tests/ui/deref_addrof.fixed b/tests/ui/deref_addrof.fixed
index 35dbd790e89..ffe7f7d1440 100644
--- a/tests/ui/deref_addrof.fixed
+++ b/tests/ui/deref_addrof.fixed
@@ -1,11 +1,11 @@
-//@aux-build:proc_macros.rs
-
-#![allow(clippy::return_self_not_must_use, clippy::useless_vec)]
+#![allow(
+    dangerous_implicit_autorefs,
+    clippy::explicit_auto_deref,
+    clippy::return_self_not_must_use,
+    clippy::useless_vec
+)]
 #![warn(clippy::deref_addrof)]
 
-extern crate proc_macros;
-use proc_macros::inline_macros;
-
 fn get_number() -> usize {
     10
 }
@@ -56,19 +56,75 @@ fn main() {
     //~^ deref_addrof
     // do NOT lint for array as semantic differences with/out `*&`.
     let _arr = *&[0, 1, 2, 3, 4];
+
+    // Do not lint when text comes from macro
+    macro_rules! mac {
+        (dr) => {
+            *&0
+        };
+        (dr $e:expr) => {
+            *&$e
+        };
+        (r $e:expr) => {
+            &$e
+        };
+    }
+    let b = mac!(dr);
+    let b = mac!(dr a);
+    let b = *mac!(r a);
 }
 
-#[derive(Copy, Clone)]
-pub struct S;
-#[inline_macros]
-impl S {
-    pub fn f(&self) -> &Self {
-        inline!($(@expr self))
-        //~^ deref_addrof
+fn issue14386() {
+    use std::mem::ManuallyDrop;
+
+    #[derive(Copy, Clone)]
+    struct Data {
+        num: u64,
     }
-    #[allow(unused_mut)] // mut will be unused, once the macro is fixed
-    pub fn f_mut(mut self) -> Self {
-        inline!($(@expr self))
+
+    #[derive(Clone, Copy)]
+    struct M {
+        md: ManuallyDrop<[u8; 4]>,
+    }
+
+    union DataWithPadding<'lt> {
+        data: ManuallyDrop<Data>,
+        prim: ManuallyDrop<u64>,
+        padding: [u8; size_of::<Data>()],
+        tup: (ManuallyDrop<Data>, ()),
+        indirect: M,
+        indirect_arr: [M; 2],
+        indirect_ref: &'lt mut M,
+    }
+
+    let mut a = DataWithPadding {
+        padding: [0; size_of::<DataWithPadding>()],
+    };
+    unsafe {
+        a.padding = [1; size_of::<DataWithPadding>()];
         //~^ deref_addrof
+        a.tup.1 = ();
+        //~^ deref_addrof
+        *a.prim = 0;
+        //~^ deref_addrof
+
+        (*a.data).num = 42;
+        //~^ deref_addrof
+        (*a.indirect.md)[3] = 1;
+        //~^ deref_addrof
+        (*a.indirect_arr[1].md)[3] = 1;
+        //~^ deref_addrof
+        (*a.indirect_ref.md)[3] = 1;
+        //~^ deref_addrof
+
+        // Check that raw pointers are properly considered as well
+        *a.prim = 0;
+        //~^ deref_addrof
+        (*a.data).num = 42;
+        //~^ deref_addrof
+
+        // Do not lint, as the dereference happens later, we cannot
+        // just remove `&mut`
+        (*&mut a.tup).0.num = 42;
     }
 }
diff --git a/tests/ui/deref_addrof.rs b/tests/ui/deref_addrof.rs
index 96d1b92ef7b..bc253716aff 100644
--- a/tests/ui/deref_addrof.rs
+++ b/tests/ui/deref_addrof.rs
@@ -1,11 +1,11 @@
-//@aux-build:proc_macros.rs
-
-#![allow(clippy::return_self_not_must_use, clippy::useless_vec)]
+#![allow(
+    dangerous_implicit_autorefs,
+    clippy::explicit_auto_deref,
+    clippy::return_self_not_must_use,
+    clippy::useless_vec
+)]
 #![warn(clippy::deref_addrof)]
 
-extern crate proc_macros;
-use proc_macros::inline_macros;
-
 fn get_number() -> usize {
     10
 }
@@ -56,19 +56,75 @@ fn main() {
     //~^ deref_addrof
     // do NOT lint for array as semantic differences with/out `*&`.
     let _arr = *&[0, 1, 2, 3, 4];
+
+    // Do not lint when text comes from macro
+    macro_rules! mac {
+        (dr) => {
+            *&0
+        };
+        (dr $e:expr) => {
+            *&$e
+        };
+        (r $e:expr) => {
+            &$e
+        };
+    }
+    let b = mac!(dr);
+    let b = mac!(dr a);
+    let b = *mac!(r a);
 }
 
-#[derive(Copy, Clone)]
-pub struct S;
-#[inline_macros]
-impl S {
-    pub fn f(&self) -> &Self {
-        inline!(*& $(@expr self))
-        //~^ deref_addrof
+fn issue14386() {
+    use std::mem::ManuallyDrop;
+
+    #[derive(Copy, Clone)]
+    struct Data {
+        num: u64,
     }
-    #[allow(unused_mut)] // mut will be unused, once the macro is fixed
-    pub fn f_mut(mut self) -> Self {
-        inline!(*&mut $(@expr self))
+
+    #[derive(Clone, Copy)]
+    struct M {
+        md: ManuallyDrop<[u8; 4]>,
+    }
+
+    union DataWithPadding<'lt> {
+        data: ManuallyDrop<Data>,
+        prim: ManuallyDrop<u64>,
+        padding: [u8; size_of::<Data>()],
+        tup: (ManuallyDrop<Data>, ()),
+        indirect: M,
+        indirect_arr: [M; 2],
+        indirect_ref: &'lt mut M,
+    }
+
+    let mut a = DataWithPadding {
+        padding: [0; size_of::<DataWithPadding>()],
+    };
+    unsafe {
+        (*&mut a.padding) = [1; size_of::<DataWithPadding>()];
         //~^ deref_addrof
+        (*&mut a.tup).1 = ();
+        //~^ deref_addrof
+        **&mut a.prim = 0;
+        //~^ deref_addrof
+
+        (*&mut a.data).num = 42;
+        //~^ deref_addrof
+        (*&mut a.indirect.md)[3] = 1;
+        //~^ deref_addrof
+        (*&mut a.indirect_arr[1].md)[3] = 1;
+        //~^ deref_addrof
+        (*&mut a.indirect_ref.md)[3] = 1;
+        //~^ deref_addrof
+
+        // Check that raw pointers are properly considered as well
+        **&raw mut a.prim = 0;
+        //~^ deref_addrof
+        (*&raw mut a.data).num = 42;
+        //~^ deref_addrof
+
+        // Do not lint, as the dereference happens later, we cannot
+        // just remove `&mut`
+        (*&mut a.tup).0.num = 42;
     }
 }
diff --git a/tests/ui/deref_addrof.stderr b/tests/ui/deref_addrof.stderr
index 81414b625b2..65dd904a8f7 100644
--- a/tests/ui/deref_addrof.stderr
+++ b/tests/ui/deref_addrof.stderr
@@ -56,20 +56,58 @@ LL |     let _repeat = *&[0; 64];
    |                   ^^^^^^^^^ help: try: `[0; 64]`
 
 error: immediately dereferencing a reference
-  --> tests/ui/deref_addrof.rs:66:17
+  --> tests/ui/deref_addrof.rs:104:9
    |
-LL |         inline!(*& $(@expr self))
-   |                 ^^^^^^^^^^^^^^^^ help: try: `$(@expr self)`
+LL |         (*&mut a.padding) = [1; size_of::<DataWithPadding>()];
+   |         ^^^^^^^^^^^^^^^^^ help: try: `a.padding`
+
+error: immediately dereferencing a reference
+  --> tests/ui/deref_addrof.rs:106:9
+   |
+LL |         (*&mut a.tup).1 = ();
+   |         ^^^^^^^^^^^^^ help: try: `a.tup`
+
+error: immediately dereferencing a reference
+  --> tests/ui/deref_addrof.rs:108:10
    |
-   = note: this error originates in the macro `__inline_mac_impl` (in Nightly builds, run with -Z macro-backtrace for more info)
+LL |         **&mut a.prim = 0;
+   |          ^^^^^^^^^^^^ help: try: `a.prim`
 
 error: immediately dereferencing a reference
-  --> tests/ui/deref_addrof.rs:71:17
+  --> tests/ui/deref_addrof.rs:111:9
    |
-LL |         inline!(*&mut $(@expr self))
-   |                 ^^^^^^^^^^^^^^^^^^^ help: try: `$(@expr self)`
+LL |         (*&mut a.data).num = 42;
+   |         ^^^^^^^^^^^^^^ help: try: `(*a.data)`
+
+error: immediately dereferencing a reference
+  --> tests/ui/deref_addrof.rs:113:9
+   |
+LL |         (*&mut a.indirect.md)[3] = 1;
+   |         ^^^^^^^^^^^^^^^^^^^^^ help: try: `(*a.indirect.md)`
+
+error: immediately dereferencing a reference
+  --> tests/ui/deref_addrof.rs:115:9
+   |
+LL |         (*&mut a.indirect_arr[1].md)[3] = 1;
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `(*a.indirect_arr[1].md)`
+
+error: immediately dereferencing a reference
+  --> tests/ui/deref_addrof.rs:117:9
+   |
+LL |         (*&mut a.indirect_ref.md)[3] = 1;
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `(*a.indirect_ref.md)`
+
+error: immediately dereferencing a reference
+  --> tests/ui/deref_addrof.rs:121:10
+   |
+LL |         **&raw mut a.prim = 0;
+   |          ^^^^^^^^^^^^^^^^ help: try: `a.prim`
+
+error: immediately dereferencing a reference
+  --> tests/ui/deref_addrof.rs:123:9
    |
-   = note: this error originates in the macro `__inline_mac_impl` (in Nightly builds, run with -Z macro-backtrace for more info)
+LL |         (*&raw mut a.data).num = 42;
+   |         ^^^^^^^^^^^^^^^^^^ help: try: `(*a.data)`
 
-error: aborting due to 11 previous errors
+error: aborting due to 18 previous errors