3 files changed, 109 insertions, 0 deletions
diff --git a/src/test/ui/cleanup-shortcircuit.rs b/src/test/ui/cleanup-shortcircuit.rs
index 4f5197a5ba9..fe867ce1fbd 100644
--- a/src/test/ui/cleanup-shortcircuit.rs
+++ b/src/test/ui/cleanup-shortcircuit.rs
@@ -3,6 +3,9 @@
 
 // pretty-expanded FIXME #23616
 
+#![allow(deref_nullptr)]
+
+
 use std::env;
 
 pub fn main() {
diff --git a/src/test/ui/lint/lint-deref-nullptr.rs b/src/test/ui/lint/lint-deref-nullptr.rs
new file mode 100644
index 00000000000..d052dbd9b64
--- /dev/null
+++ b/src/test/ui/lint/lint-deref-nullptr.rs
@@ -0,0 +1,38 @@
+// test the deref_nullptr lint
+
+#![deny(deref_nullptr)]
+
+use std::ptr;
+
+struct Struct {
+    field: u8,
+}
+
+fn f() {
+    unsafe {
+        let a = 1;
+        let ub = *(a as *const i32);
+        let ub = *(0 as *const i32);
+        //~^ ERROR dereferencing a null pointer
+        let ub = *ptr::null::<i32>();
+        //~^ ERROR dereferencing a null pointer
+        let ub = *ptr::null_mut::<i32>();
+        //~^ ERROR dereferencing a null pointer
+        let ub = *(ptr::null::<i16>() as *const i32);
+        //~^ ERROR dereferencing a null pointer
+        let ub = *(ptr::null::<i16>() as *mut i32 as *mut usize as *const u8);
+        //~^ ERROR dereferencing a null pointer
+        let ub = &*ptr::null::<i32>();
+        //~^ ERROR dereferencing a null pointer
+        let ub = &*ptr::null_mut::<i32>();
+        //~^ ERROR dereferencing a null pointer
+        ptr::addr_of!(*ptr::null::<i32>());
+        //~^ ERROR dereferencing a null pointer
+        ptr::addr_of_mut!(*ptr::null_mut::<i32>());
+        //~^ ERROR dereferencing a null pointer
+        let offset = ptr::addr_of!((*ptr::null::<Struct>()).field);
+        //~^ ERROR dereferencing a null pointer
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/lint/lint-deref-nullptr.stderr b/src/test/ui/lint/lint-deref-nullptr.stderr
new file mode 100644
index 00000000000..c6f432e4e42
--- /dev/null
+++ b/src/test/ui/lint/lint-deref-nullptr.stderr
@@ -0,0 +1,68 @@
+error: dereferencing a null pointer
+  --> $DIR/lint-deref-nullptr.rs:15:18
+   |
+LL |         let ub = *(0 as *const i32);
+   |                  ^^^^^^^^^^^^^^^^^^ this code causes undefined behavior when executed
+   |
+note: the lint level is defined here
+  --> $DIR/lint-deref-nullptr.rs:3:9
+   |
+LL | #![deny(deref_nullptr)]
+   |         ^^^^^^^^^^^^^
+
+error: dereferencing a null pointer
+  --> $DIR/lint-deref-nullptr.rs:17:18
+   |
+LL |         let ub = *ptr::null::<i32>();
+   |                  ^^^^^^^^^^^^^^^^^^^ this code causes undefined behavior when executed
+
+error: dereferencing a null pointer
+  --> $DIR/lint-deref-nullptr.rs:19:18
+   |
+LL |         let ub = *ptr::null_mut::<i32>();
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^ this code causes undefined behavior when executed
+
+error: dereferencing a null pointer
+  --> $DIR/lint-deref-nullptr.rs:21:18
+   |
+LL |         let ub = *(ptr::null::<i16>() as *const i32);
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ this code causes undefined behavior when executed
+
+error: dereferencing a null pointer
+  --> $DIR/lint-deref-nullptr.rs:23:18
+   |
+LL |         let ub = *(ptr::null::<i16>() as *mut i32 as *mut usize as *const u8);
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ this code causes undefined behavior when executed
+
+error: dereferencing a null pointer
+  --> $DIR/lint-deref-nullptr.rs:25:19
+   |
+LL |         let ub = &*ptr::null::<i32>();
+   |                   ^^^^^^^^^^^^^^^^^^^ this code causes undefined behavior when executed
+
+error: dereferencing a null pointer
+  --> $DIR/lint-deref-nullptr.rs:27:19
+   |
+LL |         let ub = &*ptr::null_mut::<i32>();
+   |                   ^^^^^^^^^^^^^^^^^^^^^^^ this code causes undefined behavior when executed
+
+error: dereferencing a null pointer
+  --> $DIR/lint-deref-nullptr.rs:29:23
+   |
+LL |         ptr::addr_of!(*ptr::null::<i32>());
+   |                       ^^^^^^^^^^^^^^^^^^^ this code causes undefined behavior when executed
+
+error: dereferencing a null pointer
+  --> $DIR/lint-deref-nullptr.rs:31:27
+   |
+LL |         ptr::addr_of_mut!(*ptr::null_mut::<i32>());
+   |                           ^^^^^^^^^^^^^^^^^^^^^^^ this code causes undefined behavior when executed
+
+error: dereferencing a null pointer
+  --> $DIR/lint-deref-nullptr.rs:33:36
+   |
+LL |         let offset = ptr::addr_of!((*ptr::null::<Struct>()).field);
+   |                                    ^^^^^^^^^^^^^^^^^^^^^^^^ this code causes undefined behavior when executed
+
+error: aborting due to 10 previous errors
+