changes based on review

3 files changed, 34 insertions, 66 deletions

diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index 905a808f51f..f19572550eb 100644
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -2972,10 +2972,10 @@ declare_lint! {
     ///
     /// ```rust,no_run
     /// # #![allow(unused)]
+    /// use std::ptr;
     /// unsafe {
-    ///     let x = &*core::ptr::null::<i32>();
-    ///     let x = core::ptr::addr_of!(*std::ptr::null::<i32>());
-    ///     let x = *core::ptr::null::<i32>();
+    ///     let x = &*ptr::null::<i32>();
+    ///     let x = ptr::addr_of!(*ptr::null::<i32>());
     ///     let x = *(0 as *const i32);
     /// }
     /// ```
@@ -3036,9 +3036,7 @@ impl<'tcx> LateLintPass<'tcx> for DerefNullPtr {
             if let rustc_hir::UnOp::Deref = un_op {
                 if is_null_ptr(cx, expr_deref) {
                     cx.struct_span_lint(DEREF_NULLPTR, expr.span, |lint| {
-                        let mut err =
-                            lint.build("Dereferencing a null pointer causes undefined behavior");
-                        err.span_label(expr.span, "a null pointer is dereferenced");
+                        let mut err = lint.build("dereferencing a null pointer");
                         err.span_label(
                             expr.span,
                             "this code causes undefined behavior when executed",
diff --git a/src/test/ui/lint/lint-deref-nullptr.rs b/src/test/ui/lint/lint-deref-nullptr.rs
index 7b10e711c27..a5aee735140 100644
--- a/src/test/ui/lint/lint-deref-nullptr.rs
+++ b/src/test/ui/lint/lint-deref-nullptr.rs
@@ -7,25 +7,25 @@ fn f() {
         let a = 1;
         let ub = *(a as *const i32);
         let ub = *(0 as *const i32);
-        //~^ ERROR Dereferencing a null pointer causes undefined behavior
+        //~^ ERROR dereferencing a null pointer
         let ub = *core::ptr::null::<i32>();
-        //~^ ERROR Dereferencing a null pointer causes undefined behavior
+        //~^ ERROR dereferencing a null pointer
         let ub = *core::ptr::null_mut::<i32>();
-        //~^ ERROR Dereferencing a null pointer causes undefined behavior
+        //~^ ERROR dereferencing a null pointer
         let ub = *(core::ptr::null::<i16>() as *const i32);
-        //~^ ERROR Dereferencing a null pointer causes undefined behavior
+        //~^ ERROR dereferencing a null pointer
         let ub = *(core::ptr::null::<i16>() as *mut i32 as *mut usize as *const u8);
-        //~^ ERROR Dereferencing a null pointer causes undefined behavior
+        //~^ ERROR dereferencing a null pointer
         let ub = &*core::ptr::null::<i32>();
-        //~^ ERROR Dereferencing a null pointer causes undefined behavior
+        //~^ ERROR dereferencing a null pointer
         core::ptr::addr_of!(*core::ptr::null::<i32>());
-        //~^ ERROR Dereferencing a null pointer causes undefined behavior
+        //~^ ERROR dereferencing a null pointer
         std::ptr::addr_of_mut!(*core::ptr::null_mut::<i32>());
-        //~^ ERROR Dereferencing a null pointer causes undefined behavior
+        //~^ ERROR dereferencing a null pointer
         let ub = *std::ptr::null::<i32>();
-        //~^ ERROR Dereferencing a null pointer causes undefined behavior
+        //~^ ERROR dereferencing a null pointer
         let ub = *std::ptr::null_mut::<i32>();
-        //~^ ERROR Dereferencing a null pointer causes undefined behavior
+        //~^ ERROR dereferencing a null pointer
     }
 }
 
diff --git a/src/test/ui/lint/lint-deref-nullptr.stderr b/src/test/ui/lint/lint-deref-nullptr.stderr
index 4fc6c54e197..ba27d2c45fc 100644
--- a/src/test/ui/lint/lint-deref-nullptr.stderr
+++ b/src/test/ui/lint/lint-deref-nullptr.stderr
@@ -1,11 +1,8 @@
-error: Dereferencing a null pointer causes undefined behavior
+error: dereferencing a null pointer
   --> $DIR/lint-deref-nullptr.rs:9:18
    |
 LL |         let ub = *(0 as *const i32);
-   |                  ^^^^^^^^^^^^^^^^^^
-   |                  |
-   |                  a null pointer is dereferenced
-   |                  this code causes undefined behavior when executed
+   |                  ^^^^^^^^^^^^^^^^^^ this code causes undefined behavior when executed
    |
 note: the lint level is defined here
   --> $DIR/lint-deref-nullptr.rs:3:9
@@ -13,86 +10,59 @@ note: the lint level is defined here
 LL | #![deny(deref_nullptr)]
    |         ^^^^^^^^^^^^^
 
-error: Dereferencing a null pointer causes undefined behavior
+error: dereferencing a null pointer
   --> $DIR/lint-deref-nullptr.rs:11:18
    |
 LL |         let ub = *core::ptr::null::<i32>();
-   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^
-   |                  |
-   |                  a null pointer is dereferenced
-   |                  this code causes undefined behavior when executed
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^ this code causes undefined behavior when executed
 
-error: Dereferencing a null pointer causes undefined behavior
+error: dereferencing a null pointer
   --> $DIR/lint-deref-nullptr.rs:13:18
    |
 LL |         let ub = *core::ptr::null_mut::<i32>();
-   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |                  |
-   |                  a null pointer is dereferenced
-   |                  this code causes undefined behavior when executed
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ this code causes undefined behavior when executed
 
-error: Dereferencing a null pointer causes undefined behavior
+error: dereferencing a null pointer
   --> $DIR/lint-deref-nullptr.rs:15:18
    |
 LL |         let ub = *(core::ptr::null::<i16>() as *const i32);
-   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |                  |
-   |                  a null pointer is dereferenced
-   |                  this code causes undefined behavior when executed
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ this code causes undefined behavior when executed
 
-error: Dereferencing a null pointer causes undefined behavior
+error: dereferencing a null pointer
   --> $DIR/lint-deref-nullptr.rs:17:18
    |
 LL |         let ub = *(core::ptr::null::<i16>() as *mut i32 as *mut usize as *const u8);
-   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |                  |
-   |                  a null pointer is dereferenced
-   |                  this code causes undefined behavior when executed
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ this code causes undefined behavior when executed
 
-error: Dereferencing a null pointer causes undefined behavior
+error: dereferencing a null pointer
   --> $DIR/lint-deref-nullptr.rs:19:19
    |
 LL |         let ub = &*core::ptr::null::<i32>();
-   |                   ^^^^^^^^^^^^^^^^^^^^^^^^^
-   |                   |
-   |                   a null pointer is dereferenced
-   |                   this code causes undefined behavior when executed
+   |                   ^^^^^^^^^^^^^^^^^^^^^^^^^ this code causes undefined behavior when executed
 
-error: Dereferencing a null pointer causes undefined behavior
+error: dereferencing a null pointer
   --> $DIR/lint-deref-nullptr.rs:21:29
    |
 LL |         core::ptr::addr_of!(*core::ptr::null::<i32>());
-   |                             ^^^^^^^^^^^^^^^^^^^^^^^^^
-   |                             |
-   |                             a null pointer is dereferenced
-   |                             this code causes undefined behavior when executed
+   |                             ^^^^^^^^^^^^^^^^^^^^^^^^^ this code causes undefined behavior when executed
 
-error: Dereferencing a null pointer causes undefined behavior
+error: dereferencing a null pointer
   --> $DIR/lint-deref-nullptr.rs:23:32
    |
 LL |         std::ptr::addr_of_mut!(*core::ptr::null_mut::<i32>());
-   |                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |                                |
-   |                                a null pointer is dereferenced
-   |                                this code causes undefined behavior when executed
+   |                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ this code causes undefined behavior when executed
 
-error: Dereferencing a null pointer causes undefined behavior
+error: dereferencing a null pointer
   --> $DIR/lint-deref-nullptr.rs:25:18
    |
 LL |         let ub = *std::ptr::null::<i32>();
-   |                  ^^^^^^^^^^^^^^^^^^^^^^^^
-   |                  |
-   |                  a null pointer is dereferenced
-   |                  this code causes undefined behavior when executed
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^ this code causes undefined behavior when executed
 
-error: Dereferencing a null pointer causes undefined behavior
+error: dereferencing a null pointer
   --> $DIR/lint-deref-nullptr.rs:27:18
    |
 LL |         let ub = *std::ptr::null_mut::<i32>();
-   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |                  |
-   |                  a null pointer is dereferenced
-   |                  this code causes undefined behavior when executed
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ this code causes undefined behavior when executed
 
 error: aborting due to 10 previous errors