format: slice entry points for the facade's hot *_in calls (local listing back to main's speed)

Since the M2 merge the facade handed in-memory files to the generic
`*_in` parsers as `&[u8]` (`with_bytes!`), which instantiates them in
the facade crate, where the format crate's private helpers do not
inline without LTO: listing a 400-group v1 file through `File::open`
was 7-10% slower than main. `ObjectHeader::parse_in`,
`group_v2::{resolve_child_in, resolve_group_children_in,
resolve_path_any_in}` and `attribute::{extract_attributes_tolerant_in,
find_attribute_in}` now pass a storage with `as_contiguous()` to their
non-generic slice entry point, compiled once in the format crate; other
storages reach the same generic core as before.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

crates/clawhdf5-format/src/attribute.rs

@@ -470,16 +470,31 @@ pub fn extract_attributes_tolerant(
     offset_size: u8,
     length_size: u8,
 ) -> Result<(Vec<AttributeMessage>, Vec<FormatError>), FormatError> {
-    extract_attributes_tolerant_in(file_data, header, offset_size, length_size)
+    extract_attributes_tolerant_core(file_data, header, offset_size, length_size)
 }
 
 /// [`extract_attributes_tolerant`] over any [`Storage`] (see
-/// [`extract_attributes_full_in`] for dense storage).
+/// [`extract_attributes_full_in`] for dense storage). One with the whole
+/// file in memory is read as the slice, by code compiled in this crate (see
+/// [`crate::storage`], "Slice entry points").
+#[inline]
 pub fn extract_attributes_tolerant_in<S: Storage + ?Sized>(
     file_data: &S,
     header: &ObjectHeader,
     offset_size: u8,
     length_size: u8,
+) -> Result<(Vec<AttributeMessage>, Vec<FormatError>), FormatError> {
+    match file_data.as_contiguous() {
+        Some(all) => extract_attributes_tolerant(all, header, offset_size, length_size),
+        None => extract_attributes_tolerant_core(file_data, header, offset_size, length_size),
+    }
+}
+
+fn extract_attributes_tolerant_core<S: Storage + ?Sized>(
+    file_data: &S,
+    header: &ObjectHeader,
+    offset_size: u8,
+    length_size: u8,
 ) -> Result<(Vec<AttributeMessage>, Vec<FormatError>), FormatError> {
     let mut errors = Vec::new();
     let attrs = extract_attributes_with(file_data, header, offset_size, length_size, &mut |e| {
@@ -561,18 +576,34 @@ pub fn find_attribute_in_file(
     offset_size: u8,
     length_size: u8,
 ) -> Result<Option<AttributeMessage>, FormatError> {
-    find_attribute_in(file_data, header, name, offset_size, length_size)
+    find_attribute_core(file_data, header, name, offset_size, length_size)
 }
 
 /// [`find_attribute_in_file`] over any [`Storage`] (see
 /// [`extract_attributes_full_in`] for dense storage, whose name index still
-/// needs the whole file in memory).
+/// needs the whole file in memory). One with the whole file in memory is
+/// read as the slice, by code compiled in this crate (see
+/// [`crate::storage`], "Slice entry points").
+#[inline]
 pub fn find_attribute_in<S: Storage + ?Sized>(
     file_data: &S,
     header: &ObjectHeader,
     name: &str,
     offset_size: u8,
     length_size: u8,
+) -> Result<Option<AttributeMessage>, FormatError> {
+    match file_data.as_contiguous() {
+        Some(all) => find_attribute_in_file(all, header, name, offset_size, length_size),
+        None => find_attribute_core(file_data, header, name, offset_size, length_size),
+    }
+}
+
+fn find_attribute_core<S: Storage + ?Sized>(
+    file_data: &S,
+    header: &ObjectHeader,
+    name: &str,
+    offset_size: u8,
+    length_size: u8,
 ) -> Result<Option<AttributeMessage>, FormatError> {
     let attr_info = find_attribute_info(header, offset_size)?;
     let dense = attr_info