From 07f102c1c302226481509749d2490e1eff70eaea Mon Sep 17 00:00:00 2001
From: Douglas Raillard <douglas.raillard@arm.com>
Date: Tue, 14 Nov 2023 11:58:51 +0000
Subject: [PATCH] WIPvariance
---
tools/analysis/traceevent/src/buffer.rs | 12 +++---------
1 file changed, 3 insertions(+), 9 deletions(-)
diff --git a/tools/analysis/traceevent/src/buffer.rs b/tools/analysis/traceevent/src/buffer.rs
index 147faad6ab..ef471ec48b 100644
--- a/tools/analysis/traceevent/src/buffer.rs
+++ b/tools/analysis/traceevent/src/buffer.rs
@@ -128,6 +128,8 @@ pub struct EventVisitor<'i, 'h, 'edm, InitDescF, T = ()> {
// the only value we store back in the Cell is 'static (None) so that invariance is overkill.
// In order to stay invariant in 'h, we use *mut insteaf of &'edm mut.
desc_map: Cell<Option<*mut EventDescMap<T, InitDescF>>>,
+ _phantom_desc_map: PhantomData<&'edm mut ()>,
+
scratch: &'i ScratchAlloc,
// Unfortunately for now OnceCell<'h> makes EventVisitor invariant in 'h:
@@ -139,14 +141,6 @@ pub struct EventVisitor<'i, 'h, 'edm, InitDescF, T = ()> {
// stored when the EventVisitor is created.
event_desc: OnceCell<(*const EventDesc, *const T)>,
- _phantom: PhantomData<(
- &'h(),
- // This is a lie. In reality, we have the equivalent of an &'edm mut EventDescMap, but we
- // can't use &'edm mut (or *mut) because otherwise we conservatively become invariant in
- // 'edm, whereas covariance is appropriate given how it is used (set once, with no risk of
- // storing a value with lifetime that is too restricted).
- &'edm ()
- )>,
}
impl<'i, 'h, 'edm, InitDescF, T> EventVisitor<'i, 'h, 'edm, InitDescF, T> {
@@ -166,7 +160,7 @@ impl<'i, 'h, 'edm, InitDescF, T> EventVisitor<'i, 'h, 'edm, InitDescF, T> {
scratch,
desc_map: Cell::new(Some(desc_map)),
event_desc: OnceCell::new(),
- _phantom: PhantomData,
+ _phantom_desc_map: PhantomData,
}
}