From 2a9b44d97d55779b3758a1f0558b22de3a6572ea Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Sat, 31 Jul 2021 11:52:59 +0200
Subject: [PATCH] add a test
---
.../const-eval/partial_ptr_overwrite.rs | 15 ++++++++++++++
.../const-eval/partial_ptr_overwrite.stderr | 20 +++++++++++++++++++
2 files changed, 35 insertions(+)
create mode 100644 src/test/ui/consts/const-eval/partial_ptr_overwrite.rs
create mode 100644 src/test/ui/consts/const-eval/partial_ptr_overwrite.stderr
diff --git a/src/test/ui/consts/const-eval/partial_ptr_overwrite.rs b/src/test/ui/consts/const-eval/partial_ptr_overwrite.rs
new file mode 100644
index 00000000000..5371f9f1749
--- /dev/null
+++ b/src/test/ui/consts/const-eval/partial_ptr_overwrite.rs
@@ -0,0 +1,15 @@
+// Test for the behavior described in <https://github.com/rust-lang/rust/issues/87184>.
+#![feature(const_mut_refs, const_raw_ptr_deref)]
+
+const PARTIAL_OVERWRITE: () = {
+ let mut p = &42;
+ unsafe {
+ let ptr: *mut _ = &mut p;
+ *(ptr as *mut u8) = 123; //~ ERROR any use of this value
+ //~| unable to overwrite parts of a pointer
+ //~| WARN previously accepted
+ }
+ let x = *p;
+};
+
+fn main() {}
diff --git a/src/test/ui/consts/const-eval/partial_ptr_overwrite.stderr b/src/test/ui/consts/const-eval/partial_ptr_overwrite.stderr
new file mode 100644
index 00000000000..a18c7e78d95
--- /dev/null
+++ b/src/test/ui/consts/const-eval/partial_ptr_overwrite.stderr
@@ -0,0 +1,20 @@
+error: any use of this value will cause an error
+ --> $DIR/partial_ptr_overwrite.rs:8:9
+ |
+LL | / const PARTIAL_OVERWRITE: () = {
+LL | | let mut p = &42;
+LL | | unsafe {
+LL | | let ptr: *mut _ = &mut p;
+LL | | *(ptr as *mut u8) = 123;
+ | | ^^^^^^^^^^^^^^^^^^^^^^^ unable to overwrite parts of a pointer in memory at alloc4
+... |
+LL | | let x = *p;
+LL | | };
+ | |__-
+ |
+ = note: `#[deny(const_err)]` 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 #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+error: aborting due to previous error
+