add sanity test for inferred lifetimes in PhantomData

Author: Lukas Markeffsky

src/test/ui/rfc-2093-infer-outlives/phatom-data.rs

@@ -0,0 +1,60 @@
+// Sanity check that `PhantomData<&'a T>` infers `T: 'a`.
+
+use std::marker::PhantomData;
+use std::ptr;
+
+struct InferredBound<'a, T> {
+    ptr: *const T,
+    phantom: PhantomData<&'a T>,
+}
+
+struct RedundantBound<'a, T: 'a> {
+    ptr: *const T,
+    phantom: PhantomData<&'a T>,
+}
+
+struct ManualBound<'a, T: 'a> {
+    ptr: *const T,
+    phantom: PhantomData<&'a ()>,
+}
+
+struct NoBound<'a, T> {
+    ptr: *const T,
+    phantom: PhantomData<&'a ()>,
+}
+
+fn inferred_bound<'a>(_: &'a u8) -> InferredBound<'static, &'a u8> {
+    InferredBound {
+        ptr: ptr::null(),
+        phantom: PhantomData,
+    }
+}
+
+fn redundant_bound<'a>(_: &'a u8) -> RedundantBound<'static, &'a u8> {
+    RedundantBound {
+        ptr: ptr::null(),
+        phantom: PhantomData,
+    }
+}
+
+fn manual_bound<'a>(_: &'a u8) -> ManualBound<'static, &'a u8> {
+    ManualBound {
+        ptr: ptr::null(),
+        phantom: PhantomData,
+    }
+}
+
+fn no_bound<'a>(_: &'a u8) -> NoBound<'static, &'a u8> {
+    NoBound {
+        ptr: ptr::null(),
+        phantom: PhantomData,
+    }
+}
+
+fn main() {
+    let local = 0;
+    inferred_bound(&local); //~ ERROR: `local` does not live long enough [E0597]
+    redundant_bound(&local); //~ ERROR: `local` does not live long enough [E0597]
+    manual_bound(&local); //~ ERROR: `local` does not live long enough [E0597]
+    no_bound(&local); // OK
+}

src/test/ui/rfc-2093-infer-outlives/phatom-data.stderr

@@ -0,0 +1,39 @@
+error[E0597]: `local` does not live long enough
+  --> $DIR/phatom-data.rs:56:20
+   |
+LL |     inferred_bound(&local);
+   |     ---------------^^^^^^-
+   |     |              |
+   |     |              borrowed value does not live long enough
+   |     argument requires that `local` is borrowed for `'static`
+...
+LL | }
+   | - `local` dropped here while still borrowed
+
+error[E0597]: `local` does not live long enough
+  --> $DIR/phatom-data.rs:57:21
+   |
+LL |     redundant_bound(&local);
+   |     ----------------^^^^^^-
+   |     |               |
+   |     |               borrowed value does not live long enough
+   |     argument requires that `local` is borrowed for `'static`
+...
+LL | }
+   | - `local` dropped here while still borrowed
+
+error[E0597]: `local` does not live long enough
+  --> $DIR/phatom-data.rs:58:18
+   |
+LL |     manual_bound(&local);
+   |     -------------^^^^^^-
+   |     |            |
+   |     |            borrowed value does not live long enough
+   |     argument requires that `local` is borrowed for `'static`
+LL |     no_bound(&local); // OK
+LL | }
+   | - `local` dropped here while still borrowed
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0597`.