Adding upstream version 1.76.0+dfsg1.upstream/1.76.0+dfsg1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 619 insertions, 0 deletions

diff --git a/vendor/gix-diff/src/blob/platform.rs b/vendor/gix-diff/src/blob/platform.rs
new file mode 100644
index 000000000..fb37b735c
--- /dev/null
+++ b/vendor/gix-diff/src/blob/platform.rs
@@ -0,0 +1,619 @@
+use std::{io::Write, process::Stdio};
+
+use bstr::{BStr, BString, ByteSlice};
+
+use super::Algorithm;
+use crate::blob::{pipeline, Pipeline, Platform, ResourceKind};
+
+/// A key to uniquely identify either a location in the worktree, or in the object database.
+#[derive(Clone)]
+pub(crate) struct CacheKey {
+    id: gix_hash::ObjectId,
+    location: BString,
+    /// If `true`, this is an `id` based key, otherwise it's location based.
+    use_id: bool,
+    /// Only relevant when `id` is not null, to further differentiate content and allow us to
+    /// keep track of both links and blobs with the same content (rare, but possible).
+    is_link: bool,
+}
+
+/// A stored value representing a diffable resource.
+#[derive(Clone, Eq, PartialEq, Ord, PartialOrd, Debug)]
+pub(crate) struct CacheValue {
+    /// The outcome of converting a resource into a diffable format using [Pipeline::convert_to_diffable()].
+    conversion: pipeline::Outcome,
+    /// The kind of the resource we are looking at. Only possible values are `Blob`, `BlobExecutable` and `Link`.
+    mode: gix_object::tree::EntryKind,
+    /// A possibly empty buffer, depending on `conversion.data` which may indicate the data is considered binary.
+    buffer: Vec<u8>,
+}
+
+impl std::hash::Hash for CacheKey {
+    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
+        if self.use_id {
+            self.id.hash(state);
+            self.is_link.hash(state)
+        } else {
+            self.location.hash(state)
+        }
+    }
+}
+
+impl PartialEq for CacheKey {
+    fn eq(&self, other: &Self) -> bool {
+        match (self.use_id, other.use_id) {
+            (false, false) => self.location.eq(&other.location),
+            (true, true) => self.id.eq(&other.id) && self.is_link.eq(&other.is_link),
+            _ => false,
+        }
+    }
+}
+
+impl Eq for CacheKey {}
+
+impl Default for CacheKey {
+    fn default() -> Self {
+        CacheKey {
+            id: gix_hash::Kind::Sha1.null(),
+            use_id: false,
+            is_link: false,
+            location: BString::default(),
+        }
+    }
+}
+
+impl CacheKey {
+    fn set_location(&mut self, rela_path: &BStr) {
+        self.location.clear();
+        self.location.extend_from_slice(rela_path);
+    }
+}
+
+/// A resource ready to be diffed in one way or another.
+#[derive(Debug, Copy, Clone, Ord, PartialOrd, Eq, PartialEq, Hash)]
+pub struct Resource<'a> {
+    /// If available, an index into the `drivers` field to access more diff-related information of the driver for items
+    /// at the given path, as previously determined by git-attributes.
+    ///
+    /// Note that drivers are queried even if there is no object available.
+    pub driver_index: Option<usize>,
+    /// The data itself, suitable for diffing, and if the object or worktree item is present at all.
+    pub data: resource::Data<'a>,
+    /// The kind of the resource we are looking at. Only possible values are `Blob`, `BlobExecutable` and `Link`.
+    pub mode: gix_object::tree::EntryKind,
+    /// The location of the resource, relative to the working tree.
+    pub rela_path: &'a BStr,
+    /// The id of the content as it would be stored in `git`, or `null` if the content doesn't exist anymore at
+    /// `rela_path` or if it was never computed. This can happen with content read from the worktree, which has to
+    /// go through a filter to be converted back to what `git` would store.
+    pub id: &'a gix_hash::oid,
+}
+
+///
+pub mod resource {
+    use crate::blob::{
+        pipeline,
+        platform::{CacheKey, CacheValue, Resource},
+    };
+
+    impl<'a> Resource<'a> {
+        pub(crate) fn new(key: &'a CacheKey, value: &'a CacheValue) -> Self {
+            Resource {
+                driver_index: value.conversion.driver_index,
+                data: value.conversion.data.map_or(Data::Missing, |data| match data {
+                    pipeline::Data::Buffer => Data::Buffer(&value.buffer),
+                    pipeline::Data::Binary { size } => Data::Binary { size },
+                }),
+                mode: value.mode,
+                rela_path: key.location.as_ref(),
+                id: &key.id,
+            }
+        }
+
+        /// Produce an iterator over lines, separated by LF or CRLF, suitable to create tokens using
+        /// [`imara_diff::intern::InternedInput`].
+        pub fn intern_source(&self) -> imara_diff::sources::ByteLines<'a, true> {
+            crate::blob::sources::byte_lines_with_terminator(self.data.as_slice().unwrap_or_default())
+        }
+    }
+
+    /// The data of a diffable resource, as it could be determined and computed previously.
+    #[derive(Debug, Copy, Clone, Ord, PartialOrd, Eq, PartialEq, Hash)]
+    pub enum Data<'a> {
+        /// The object is missing, either because it didn't exist in the working tree or because its `id` was null.
+        Missing,
+        /// The textual data as processed to be in a diffable state.
+        Buffer(&'a [u8]),
+        /// The size that the binary blob had at the given revision, without having applied filters, as it's either
+        /// considered binary or above the big-file threshold.
+        ///
+        /// In this state, the binary file cannot be diffed.
+        Binary {
+            /// The size of the object prior to performing any filtering or as it was found on disk.
+            ///
+            /// Note that technically, the size isn't always representative of the same 'state' of the
+            /// content, as once it can be the size of the blob in git, and once it's the size of file
+            /// in the worktree.
+            size: u64,
+        },
+    }
+
+    impl<'a> Data<'a> {
+        /// Return ourselves as slice of bytes if this instance stores data.
+        pub fn as_slice(&self) -> Option<&'a [u8]> {
+            match self {
+                Data::Buffer(d) => Some(d),
+                Data::Binary { .. } | Data::Missing => None,
+            }
+        }
+    }
+}
+
+///
+pub mod set_resource {
+    use bstr::BString;
+
+    use crate::blob::{pipeline, ResourceKind};
+
+    /// The error returned by [Platform::set_resource](super::Platform::set_resource).
+    #[derive(Debug, thiserror::Error)]
+    #[allow(missing_docs)]
+    pub enum Error {
+        #[error("Can only diff blobs and links, not {mode:?}")]
+        InvalidMode { mode: gix_object::tree::EntryKind },
+        #[error("Failed to read {kind} worktree data from '{rela_path}'")]
+        Io {
+            rela_path: BString,
+            kind: ResourceKind,
+            source: std::io::Error,
+        },
+        #[error("Failed to obtain attributes for {kind} resource at '{rela_path}'")]
+        Attributes {
+            rela_path: BString,
+            kind: ResourceKind,
+            source: std::io::Error,
+        },
+        #[error(transparent)]
+        ConvertToDiffable(#[from] pipeline::convert_to_diffable::Error),
+    }
+}
+
+///
+pub mod prepare_diff {
+    use bstr::BStr;
+
+    use crate::blob::platform::Resource;
+
+    /// The kind of operation that was performed during the [`diff`](super::Platform::prepare_diff()) operation.
+    #[derive(Debug, Copy, Clone, Eq, PartialEq)]
+    pub enum Operation<'a> {
+        /// The [internal diff algorithm](imara_diff::diff) should be called with the provided arguments.
+        /// This only happens if none of the resources are binary, and if there is no external diff program configured via git-attributes
+        /// *or* [Options::skip_internal_diff_if_external_is_configured](super::Options::skip_internal_diff_if_external_is_configured)
+        /// is `false`.
+        ///
+        /// Use [`Outcome::interned_input()`] to easily obtain an interner for use with [`imara_diff::diff()`], or maintain one yourself
+        /// for greater re-use.
+        InternalDiff {
+            /// The algorithm we determined should be used, which is one of (in order, first set one wins):
+            ///
+            /// * the driver's override
+            /// * the platforms own configuration (typically from git-config)
+            /// * the default algorithm
+            algorithm: imara_diff::Algorithm,
+        },
+        /// Run the external diff program according as configured in the `source`-resources driver.
+        /// This only happens if [Options::skip_internal_diff_if_external_is_configured](super::Options::skip_internal_diff_if_external_is_configured)
+        /// was `true`, preventing the usage of the internal diff implementation.
+        ExternalCommand {
+            /// The command as extracted from [Driver::command](super::super::Driver::command).
+            /// Use it in [`Platform::prepare_diff_command`](super::Platform::prepare_diff_command()) to easily prepare a compatible invocation.
+            command: &'a BStr,
+        },
+        /// One of the involved resources, [`old`](Outcome::old) or [`new`](Outcome::new), were binary and thus no diff
+        /// cannot be performed.
+        SourceOrDestinationIsBinary,
+    }
+
+    /// The outcome of a [`prepare_diff`](super::Platform::prepare_diff()) operation.
+    #[derive(Debug, Copy, Clone, Eq, PartialEq)]
+    pub struct Outcome<'a> {
+        /// The kind of diff that was actually performed. This may include skipping the internal diff as well.
+        pub operation: Operation<'a>,
+        /// The old or source of the diff operation.
+        pub old: Resource<'a>,
+        /// The new or destination of the diff operation.
+        pub new: Resource<'a>,
+    }
+
+    impl<'a> Outcome<'a> {
+        /// Produce an instance of an interner which `git` would use to perform diffs.
+        pub fn interned_input(&self) -> imara_diff::intern::InternedInput<&'a [u8]> {
+            crate::blob::intern::InternedInput::new(self.old.intern_source(), self.new.intern_source())
+        }
+    }
+
+    /// The error returned by [Platform::prepare_diff()](super::Platform::prepare_diff()).
+    #[derive(Debug, thiserror::Error)]
+    #[allow(missing_docs)]
+    pub enum Error {
+        #[error("Either the source or the destination of the diff operation were not set")]
+        SourceOrDestinationUnset,
+        #[error("Tried to diff resources that are both considered removed")]
+        SourceAndDestinationRemoved,
+    }
+}
+
+///
+pub mod prepare_diff_command {
+    use std::ops::{Deref, DerefMut};
+
+    use bstr::BString;
+
+    /// The error returned by [Platform::prepare_diff_command()](super::Platform::prepare_diff_command()).
+    #[derive(Debug, thiserror::Error)]
+    #[allow(missing_docs)]
+    pub enum Error {
+        #[error("Either the source or the destination of the diff operation were not set")]
+        SourceOrDestinationUnset,
+        #[error("Binary resources can't be diffed with an external command (as we don't have the data anymore)")]
+        SourceOrDestinationBinary,
+        #[error(
+            "Tempfile to store content of '{rela_path}' for passing to external diff command could not be created"
+        )]
+        CreateTempfile { rela_path: BString, source: std::io::Error },
+        #[error("Could not write content of '{rela_path}' to tempfile for passing to external diff command")]
+        WriteTempfile { rela_path: BString, source: std::io::Error },
+    }
+
+    /// The outcome of a [`prepare_diff_command`](super::Platform::prepare_diff_command()) operation.
+    ///
+    /// This type acts like [`std::process::Command`], ready to run, with `stdin`, `stdout` and `stderr` set to *inherit*
+    /// all handles as this is expected to be for visual inspection.
+    pub struct Command {
+        pub(crate) cmd: std::process::Command,
+        /// Possibly a tempfile to be removed after the run, or `None` if there is no old version.
+        pub(crate) old: Option<gix_tempfile::Handle<gix_tempfile::handle::Closed>>,
+        /// Possibly a tempfile to be removed after the run, or `None` if there is no new version.
+        pub(crate) new: Option<gix_tempfile::Handle<gix_tempfile::handle::Closed>>,
+    }
+
+    impl Deref for Command {
+        type Target = std::process::Command;
+
+        fn deref(&self) -> &Self::Target {
+            &self.cmd
+        }
+    }
+
+    impl DerefMut for Command {
+        fn deref_mut(&mut self) -> &mut Self::Target {
+            &mut self.cmd
+        }
+    }
+}
+
+/// Options for use in [Platform::new()].
+#[derive(Default, Copy, Clone)]
+pub struct Options {
+    /// The algorithm to use when diffing.
+    /// If unset, it uses the [default algorithm](Algorithm::default()).
+    pub algorithm: Option<Algorithm>,
+    /// If `true`, default `false`, then an external `diff` configured using gitattributes and drivers,
+    /// will cause the built-in diff [to be skipped](prepare_diff::Operation::ExternalCommand).
+    /// Otherwise, the internal diff is called despite the configured external diff, which is
+    /// typically what callers expect by default.
+    pub skip_internal_diff_if_external_is_configured: bool,
+}
+
+/// Lifecycle
+impl Platform {
+    /// Create a new instance with `options`, and a way to `filter` data from the object database to data that is diff-able.
+    /// `filter_mode` decides how to do that specifically.
+    /// Use `attr_stack` to access attributes pertaining worktree filters and diff settings.
+    pub fn new(
+        options: Options,
+        filter: Pipeline,
+        filter_mode: pipeline::Mode,
+        attr_stack: gix_worktree::Stack,
+    ) -> Self {
+        Platform {
+            old: None,
+            new: None,
+            diff_cache: Default::default(),
+            options,
+            filter,
+            filter_mode,
+            attr_stack,
+        }
+    }
+}
+
+/// Conversions
+impl Platform {
+    /// Store enough information about a resource to eventually diff it, where…
+    ///
+    /// * `id` is the hash of the resource. If it [is null](gix_hash::ObjectId::is_null()), it should either
+    ///   be a resource in the worktree, or it's considered a non-existing, deleted object.
+    ///   If an `id` is known, as the hash of the object as (would) be stored in `git`, then it should be provided
+    ///   for completeness.
+    /// * `mode` is the kind of object (only blobs and links are allowed)
+    /// * `rela_path` is the relative path as seen from the (work)tree root.
+    /// * `kind` identifies the side of the diff this resource will be used for.
+    ///    A diff needs both `OldOrSource` *and* `NewOrDestination`.
+    /// * `objects` provides access to the object database in case the resource can't be read from a worktree.
+    ///
+    /// Note that it's assumed that either `id + mode (` or `rela_path` can serve as unique identifier for the resource,
+    /// depending on whether or not a [worktree root](pipeline::WorktreeRoots) is set for the resource of `kind`,
+    /// with resources with worktree roots using the `rela_path` as unique identifier.
+    ///
+    /// ### Important
+    ///
+    /// If an error occours, the previous resource of `kind` will be cleared, preventing further diffs
+    /// unless another attempt succeeds.
+    pub fn set_resource(
+        &mut self,
+        id: gix_hash::ObjectId,
+        mode: gix_object::tree::EntryKind,
+        rela_path: &BStr,
+        kind: ResourceKind,
+        objects: &impl gix_object::FindObjectOrHeader, // TODO: make this `dyn` once https://github.com/rust-lang/rust/issues/65991 is stable, then also make tracker.rs `objects` dyn
+    ) -> Result<(), set_resource::Error> {
+        let res = self.set_resource_inner(id, mode, rela_path, kind, objects);
+        if res.is_err() {
+            *match kind {
+                ResourceKind::OldOrSource => &mut self.old,
+                ResourceKind::NewOrDestination => &mut self.new,
+            } = None;
+        }
+        res
+    }
+
+    /// Given `diff_command` and `context`, typically obtained from git-configuration, and the currently set diff-resources,
+    /// prepare the invocation and temporary files needed to launch it according to protocol.
+    /// `count` / `total` are used for progress indication passed as environment variables `GIT_DIFF_PATH_(COUNTER|TOTAL)`
+    /// respectively (0-based), so the first path has `count=0` and `total=1` (assuming there is only one path).
+    /// Returns `None` if at least one resource is unset, see [`set_resource()`](Self::set_resource()).
+    ///
+    /// Please note that this is an expensive operation this will always create up to two temporary files to hold the data
+    /// for the old and new resources.
+    ///
+    /// ### Deviation
+    ///
+    /// If one of the resources is binary, the operation reports an error as such resources don't make their data available
+    /// which is required for the external diff to run.
+    pub fn prepare_diff_command(
+        &self,
+        diff_command: BString,
+        context: gix_command::Context,
+        count: usize,
+        total: usize,
+    ) -> Result<prepare_diff_command::Command, prepare_diff_command::Error> {
+        fn add_resource(
+            cmd: &mut std::process::Command,
+            res: Resource<'_>,
+        ) -> Result<Option<gix_tempfile::Handle<gix_tempfile::handle::Closed>>, prepare_diff_command::Error> {
+            let tmpfile = match res.data {
+                resource::Data::Missing => {
+                    cmd.args(["/dev/null", ".", "."]);
+                    None
+                }
+                resource::Data::Buffer(buf) => {
+                    let mut tmp = gix_tempfile::new(
+                        std::env::temp_dir(),
+                        gix_tempfile::ContainingDirectory::Exists,
+                        gix_tempfile::AutoRemove::Tempfile,
+                    )
+                    .map_err(|err| prepare_diff_command::Error::CreateTempfile {
+                        rela_path: res.rela_path.to_owned(),
+                        source: err,
+                    })?;
+                    tmp.write_all(buf)
+                        .map_err(|err| prepare_diff_command::Error::WriteTempfile {
+                            rela_path: res.rela_path.to_owned(),
+                            source: err,
+                        })?;
+                    tmp.with_mut(|f| {
+                        cmd.arg(f.path());
+                    })
+                    .map_err(|err| prepare_diff_command::Error::WriteTempfile {
+                        rela_path: res.rela_path.to_owned(),
+                        source: err,
+                    })?;
+                    cmd.arg(res.id.to_string()).arg(res.mode.as_octal_str().to_string());
+                    let tmp = tmp.close().map_err(|err| prepare_diff_command::Error::WriteTempfile {
+                        rela_path: res.rela_path.to_owned(),
+                        source: err,
+                    })?;
+                    Some(tmp)
+                }
+                resource::Data::Binary { .. } => return Err(prepare_diff_command::Error::SourceOrDestinationBinary),
+            };
+            Ok(tmpfile)
+        }
+
+        let (old, new) = self
+            .resources()
+            .ok_or(prepare_diff_command::Error::SourceOrDestinationUnset)?;
+        let mut cmd: std::process::Command = gix_command::prepare(gix_path::from_bstring(diff_command))
+            .with_context(context)
+            .env("GIT_DIFF_PATH_COUNTER", (count + 1).to_string())
+            .env("GIT_DIFF_PATH_TOTAL", total.to_string())
+            .stdin(Stdio::inherit())
+            .stdout(Stdio::inherit())
+            .stderr(Stdio::inherit())
+            .into();
+
+        cmd.arg(gix_path::from_bstr(old.rela_path).into_owned());
+        let mut out = prepare_diff_command::Command {
+            cmd,
+            old: None,
+            new: None,
+        };
+
+        out.old = add_resource(&mut out.cmd, old)?;
+        out.new = add_resource(&mut out.cmd, new)?;
+
+        if old.rela_path != new.rela_path {
+            out.cmd.arg(gix_path::from_bstr(new.rela_path).into_owned());
+        }
+
+        Ok(out)
+    }
+
+    /// Returns the resource of the given kind if it was set.
+    pub fn resource(&self, kind: ResourceKind) -> Option<Resource<'_>> {
+        let key = match kind {
+            ResourceKind::OldOrSource => self.old.as_ref(),
+            ResourceKind::NewOrDestination => self.new.as_ref(),
+        }?;
+        Resource::new(key, self.diff_cache.get(key)?).into()
+    }
+
+    /// Obtain the two resources that were previously set as `(OldOrSource, NewOrDestination)`, if both are set and available.
+    ///
+    /// This is useful if one wishes to manually prepare the diff, maybe for invoking external programs, instead of relying on
+    /// [`Self::prepare_diff()`].
+    pub fn resources(&self) -> Option<(Resource<'_>, Resource<'_>)> {
+        let key = &self.old.as_ref()?;
+        let value = self.diff_cache.get(key)?;
+        let old = Resource::new(key, value);
+
+        let key = &self.new.as_ref()?;
+        let value = self.diff_cache.get(key)?;
+        let new = Resource::new(key, value);
+        Some((old, new))
+    }
+
+    /// Prepare a diff operation on the [previously set](Self::set_resource()) [old](ResourceKind::OldOrSource) and
+    /// [new](ResourceKind::NewOrDestination) resources.
+    ///
+    /// The returned outcome allows to easily perform diff operations, based on the [`prepare_diff::Outcome::operation`] field,
+    /// which hints at what should be done.
+    pub fn prepare_diff(&mut self) -> Result<prepare_diff::Outcome<'_>, prepare_diff::Error> {
+        let old_key = &self.old.as_ref().ok_or(prepare_diff::Error::SourceOrDestinationUnset)?;
+        let old = self
+            .diff_cache
+            .get(old_key)
+            .ok_or(prepare_diff::Error::SourceOrDestinationUnset)?;
+        let new_key = &self.new.as_ref().ok_or(prepare_diff::Error::SourceOrDestinationUnset)?;
+        let new = self
+            .diff_cache
+            .get(new_key)
+            .ok_or(prepare_diff::Error::SourceOrDestinationUnset)?;
+        let mut out = prepare_diff::Outcome {
+            operation: prepare_diff::Operation::SourceOrDestinationIsBinary,
+            old: Resource::new(old_key, old),
+            new: Resource::new(new_key, new),
+        };
+
+        match (old.conversion.data, new.conversion.data) {
+            (None, None) => return Err(prepare_diff::Error::SourceAndDestinationRemoved),
+            (Some(pipeline::Data::Binary { .. }), _) | (_, Some(pipeline::Data::Binary { .. })) => return Ok(out),
+            _either_missing_or_non_binary => {
+                if let Some(command) = old
+                    .conversion
+                    .driver_index
+                    .and_then(|idx| self.filter.drivers[idx].command.as_deref())
+                    .filter(|_| self.options.skip_internal_diff_if_external_is_configured)
+                {
+                    out.operation = prepare_diff::Operation::ExternalCommand {
+                        command: command.as_bstr(),
+                    };
+                    return Ok(out);
+                }
+            }
+        }
+
+        out.operation = prepare_diff::Operation::InternalDiff {
+            algorithm: old
+                .conversion
+                .driver_index
+                .and_then(|idx| self.filter.drivers[idx].algorithm)
+                .or(self.options.algorithm)
+                .unwrap_or_default(),
+        };
+        Ok(out)
+    }
+
+    /// Every call to [set_resource()](Self::set_resource()) will keep the diffable data in memory, and that will never be cleared.
+    ///
+    /// Use this method to clear the cache, releasing memory. Note that this will also loose all information about resources
+    /// which means diffs would fail unless the resources are set again.
+    ///
+    /// Note that this also has to be called if the same resource is going to be diffed in different states, i.e. using different
+    /// `id`s, but the same `rela_path`.
+    pub fn clear_resource_cache(&mut self) {
+        self.old = None;
+        self.new = None;
+        self.diff_cache.clear();
+    }
+}
+
+impl Platform {
+    fn set_resource_inner(
+        &mut self,
+        id: gix_hash::ObjectId,
+        mode: gix_object::tree::EntryKind,
+        rela_path: &BStr,
+        kind: ResourceKind,
+        objects: &impl gix_object::FindObjectOrHeader,
+    ) -> Result<(), set_resource::Error> {
+        if matches!(
+            mode,
+            gix_object::tree::EntryKind::Commit | gix_object::tree::EntryKind::Tree
+        ) {
+            return Err(set_resource::Error::InvalidMode { mode });
+        }
+        let storage = match kind {
+            ResourceKind::OldOrSource => &mut self.old,
+            ResourceKind::NewOrDestination => &mut self.new,
+        }
+        .get_or_insert_with(Default::default);
+
+        storage.id = id;
+        storage.set_location(rela_path);
+        storage.is_link = matches!(mode, gix_object::tree::EntryKind::Link);
+        storage.use_id = self.filter.roots.by_kind(kind).is_none();
+
+        if self.diff_cache.contains_key(storage) {
+            return Ok(());
+        }
+        let entry = self
+            .attr_stack
+            .at_entry(rela_path, Some(false), objects)
+            .map_err(|err| set_resource::Error::Attributes {
+                source: err,
+                kind,
+                rela_path: rela_path.to_owned(),
+            })?;
+        let mut buf = Vec::new();
+        let out = self.filter.convert_to_diffable(
+            &id,
+            mode,
+            rela_path,
+            kind,
+            &mut |_, out| {
+                let _ = entry.matching_attributes(out);
+            },
+            objects,
+            self.filter_mode,
+            &mut buf,
+        )?;
+        let key = storage.clone();
+        assert!(
+            self.diff_cache
+                .insert(
+                    key,
+                    CacheValue {
+                        conversion: out,
+                        mode,
+                        buffer: buf,
+                    },
+                )
+                .is_none(),
+            "The key impl makes clashes impossible with our usage"
+        );
+        Ok(())
+    }
+}