Rollup merge of rust-lang#55262 - oli-obk:dangling_alloc_id_ice, r=Ra…

…lfJung

Change the ICE from rust-lang#55223 to a hard error

cc @SimonSapin

r? @RalfJung

src/librustc_mir/interpret/memory.rs

@@ -732,6 +732,11 @@ where
  if self.alloc_map.contains_key(&alloc) {
  // Not yet interned, so proceed recursively
  self.intern_static(alloc, mutability)?;
+ } else if self.dead_alloc_map.contains_key(&alloc) {
+ // danging pointer
+ return err!(ValidationFailure(
+ "encountered dangling pointer in final constant".into(),
+ ))
  }
  }
  Ok(())

src/test/ui/consts/dangling-alloc-id-ice-2.nll.stderr

@@ -0,0 +1,30 @@
+warning[E0716]: temporary value dropped while borrowed
+ --> $DIR/dangling-alloc-id-ice-2.rs:5:28
+ |
+LL | static MAP: Slice = Slice(&[
+ | ___________________________-^
+ | |___________________________|
+ | ||
+LL | || b"CloseEvent" as &'static [u8],
+LL | || ]);
+ | || -- temporary value is freed at the end of this statement
+ | ||_|
+ | |__creates a temporary which is freed while still in use
+ | cast requires that borrow lasts for `'static`
+ |
+ = warning: This error has been downgraded to a warning for backwards compatibility with previous releases.
+ It represents potential unsoundness in your code.
+ This warning will become a hard error in the future.
+
+error[E0080]: could not evaluate static initializer
+ --> $DIR/dangling-alloc-id-ice-2.rs:5:1
+ |
+LL | / static MAP: Slice = Slice(&[
+LL | | b"CloseEvent" as &'static [u8],
+LL | | ]);
+ | |___^ type validation failed: encountered dangling pointer in final constant
+
+error: aborting due to previous error
+
+Some errors occurred: E0080, E0716.
+For more information about an error, try `rustc --explain E0080`.

src/test/ui/consts/dangling-alloc-id-ice-2.rs

@@ -0,0 +1,10 @@
+// FIXME(#55223) this is just a reproduction test showing the wrong behavior
+
+struct Slice(&'static [&'static [u8]]);
+
+static MAP: Slice = Slice(&[
+ b"CloseEvent" as &'static [u8],
+]);
+
+
+fn main() {}

src/test/ui/consts/dangling-alloc-id-ice-2.stderr

@@ -0,0 +1,11 @@
+error[E0080]: could not evaluate static initializer
+ --> $DIR/dangling-alloc-id-ice-2.rs:5:1
+ |
+LL | / static MAP: Slice = Slice(&[
+LL | | b"CloseEvent" as &'static [u8],
+LL | | ]);
+ | |___^ type validation failed: encountered dangling pointer in final constant
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0080`.

src/test/ui/consts/dangling-alloc-id-ice.rs

@@ -0,0 +1,15 @@
+// https://github.com/rust-lang/rust/issues/55223
+
+#![feature(const_let)]
+
+union Foo<'a> {
+ y: &'a (),
+ long_live_the_unit: &'static (),
+}
+
+const FOO: &() = { //~ ERROR this constant cannot be used
+ let y = ();
+ unsafe { Foo { y: &y }.long_live_the_unit }
+};
+
+fn main() {}

src/test/ui/consts/dangling-alloc-id-ice.stderr

@@ -0,0 +1,13 @@
+error: this constant cannot be used
+ --> $DIR/dangling-alloc-id-ice.rs:10:1
+ |
+LL | / const FOO: &() = { //~ ERROR this constant cannot be used
+LL | | let y = ();
+LL | | unsafe { Foo { y: &y }.long_live_the_unit }
+LL | | };
+ | |__^ type validation failed: encountered dangling pointer in final constant
+ |
+ = note: #[deny(const_err)] on by default
+
+error: aborting due to previous error
+