From 59148e88c3151176e1e76daebdee92852a877f3f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Renault?= <clement@meilisearch.com>
Date: Sat, 14 Dec 2024 12:27:47 +0100
Subject: [PATCH] Fix most of the issues

---
 heed/src/cookbook.rs           |  2 +-
 heed/src/databases/database.rs |  4 ++--
 heed/src/envs/env.rs           |  6 +++++-
 heed/src/txn.rs                | 18 +++++++++++-------
 4 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/heed/src/cookbook.rs b/heed/src/cookbook.rs
index d0fd0be1..c47d5f9c 100644
--- a/heed/src/cookbook.rs
+++ b/heed/src/cookbook.rs
@@ -423,7 +423,7 @@
 //! }
 //!
 //! impl<'t> ImmutableMap<'t> {
-//!     fn from_db(rtxn: &'t RoTxn, db: Database<Str, Str>) -> heed::Result<Self> {
+//!     fn from_db<T>(rtxn: &'t RoTxn<T>, db: Database<Str, Str>) -> heed::Result<Self> {
 //!         let mut map = HashMap::new();
 //!         for result in db.iter(rtxn)? {
 //!             let (k, v) = result?;
diff --git a/heed/src/databases/database.rs b/heed/src/databases/database.rs
index c5226634..de9b31df 100644
--- a/heed/src/databases/database.rs
+++ b/heed/src/databases/database.rs
@@ -1079,7 +1079,7 @@ impl<KC, DC, C> Database<KC, DC, C> {
     /// wtxn.commit()?;
     /// # Ok(()) }
     /// ```
-    pub fn iter_mut<'txn, T>(&self, txn: &'txn mut RwTxn) -> Result<RwIter<'txn, KC, DC>> {
+    pub fn iter_mut<'txn>(&self, txn: &'txn mut RwTxn) -> Result<RwIter<'txn, KC, DC>> {
         assert_eq_env_db_txn!(self, txn);
 
         RwCursor::new(txn, self.dbi).map(|cursor| RwIter::new(cursor))
@@ -1182,7 +1182,7 @@ impl<KC, DC, C> Database<KC, DC, C> {
     /// wtxn.commit()?;
     /// # Ok(()) }
     /// ```
-    pub fn rev_iter_mut<'txn, T>(&self, txn: &'txn mut RwTxn) -> Result<RwRevIter<'txn, KC, DC>> {
+    pub fn rev_iter_mut<'txn>(&self, txn: &'txn mut RwTxn) -> Result<RwRevIter<'txn, KC, DC>> {
         assert_eq_env_db_txn!(self, txn);
 
         RwCursor::new(txn, self.dbi).map(|cursor| RwRevIter::new(cursor))
diff --git a/heed/src/envs/env.rs b/heed/src/envs/env.rs
index 52b86200..e1921388 100644
--- a/heed/src/envs/env.rs
+++ b/heed/src/envs/env.rs
@@ -22,7 +22,7 @@ use crate::mdb::lmdb_flags::AllDatabaseFlags;
 use crate::EnvOpenOptions;
 use crate::{
     CompactionOption, Database, DatabaseOpenOptions, EnvFlags, Error, Result, RoTxn, RwTxn,
-    Unspecified,
+    Unspecified, WithoutTls,
 };
 
 /// An environment handle constructed by using [`EnvOpenOptions::open`].
@@ -43,6 +43,10 @@ impl<T> Env<T> {
         self.inner.env_ptr
     }
 
+    pub(crate) unsafe fn as_without_tls(&self) -> &Env<WithoutTls> {
+        unsafe { std::mem::transmute::<&Env<T>, &Env<WithoutTls>>(self) }
+    }
+
     /// The size of the data file on disk.
     ///
     /// # Example
diff --git a/heed/src/txn.rs b/heed/src/txn.rs
index e7dfa010..18ecc4c7 100644
--- a/heed/src/txn.rs
+++ b/heed/src/txn.rs
@@ -33,15 +33,15 @@ use crate::Result;
 /// ```rust
 /// #[allow(dead_code)]
 /// trait CovariantMarker<'a>: 'static {
-///     type T: 'a;
+///     type R: 'a;
 ///
-///     fn is_covariant(&'a self) -> &'a Self::T;
+///     fn is_covariant(&'a self) -> &'a Self::R;
 /// }
 ///
-/// impl<'a> CovariantMarker<'a> for heed::RoTxn<'static> {
-///     type T = heed::RoTxn<'a>;
+/// impl<'a, T> CovariantMarker<'a> for heed::RoTxn<'static, T> {
+///     type R = heed::RoTxn<'a, T>;
 ///
-///     fn is_covariant(&'a self) -> &'a heed::RoTxn<'a> {
+///     fn is_covariant(&'a self) -> &'a heed::RoTxn<'a, T> {
 ///         self
 ///     }
 /// }
@@ -193,10 +193,12 @@ impl<'p> RwTxn<'p> {
             ))?
         };
 
+        let env_without_tls = unsafe { env.as_without_tls() };
+
         Ok(RwTxn {
             txn: RoTxn {
                 txn: NonNull::new(txn),
-                env: Cow::Borrowed(env),
+                env: Cow::Borrowed(env_without_tls),
                 _tls_marker: PhantomData,
             },
         })
@@ -210,10 +212,12 @@ impl<'p> RwTxn<'p> {
             mdb_result(ffi::mdb_txn_begin(env.env_mut_ptr().as_mut(), parent_ptr, 0, &mut txn))?
         };
 
+        let env_without_tls = unsafe { env.as_without_tls() };
+
         Ok(RwTxn {
             txn: RoTxn {
                 txn: NonNull::new(txn),
-                env: Cow::Borrowed(env),
+                env: Cow::Borrowed(env_without_tls),
                 _tls_marker: PhantomData,
             },
         })