[simpleqt]

Root cause

ListIter in src/de/simple_type.rs:363 searched for the space byte only:

const DELIMITER: u8 = b' ';
...
return match memchr(DELIMITER, string.as_bytes()) {

The XML Schema specification defines the items of an xs:list as separated by white space (#x20, #x9, #xD, #xA, collapsed), and the doc comment of SimpleTypeDeserializer says the items "should be delimited by a space ( , \t, \r, or \n)", so tab, carriage return and line feed have to be delimiters too. They were not, and the skip of the leading and trailing delimiters (src/de/simple_type.rs:387) had the same problem.

Repro

#[derive(Deserialize)]
struct List {
    item: [Vec<String>; 1],
}

from_str::<List>("<root><item>first\tsecond</item></root>").unwrap();

gives item: [vec!["first\tsecond"]] instead of [vec!["first", "second"]]. The same happens with \n, with \r, and through a character reference, because the reader reports the contents of 	 as a tab:

from_str::<List>("<root><item a=\"first&#9;second\"/></root>")  // 1 item, 2 expected

An attribute value behaves the same way. The character reference form matters because it is the form the writer itself produces: escape_item escapes \t, \r and \n of a list item (src/se/simple_type.rs:100), so a list written by Serializer is read back as a single item containing that character.

Leading and trailing delimiters were affected as well: <item>\tfirst</item> produced the item "\tfirst" instead of "first", and <item>\t</item> produced one empty item instead of an empty list.

Fix

Use utils::is_whitespace - the definition of XML whitespace used in the rest of the crate - for both the search and the skip, instead of the space byte. AtomicDeserializer already used the same set of characters when trimming an item.

Tests

Added each_delimiter_is_a_separator, mixed_delimiters and only_delimiters to the list unit tests, and whitespace_delimiters to tests/serde-de-seq.rs.

RED on master (the fix stashed, the tests kept):

test de::simple_type::tests::list::each_delimiter_is_a_separator ... FAILED
test de::simple_type::tests::list::mixed_delimiters ... FAILED
test de::simple_type::tests::list::only_delimiters ... FAILED
assertion failed: `(left == right)`: "abc\tdef"

and the integration test:

---- fixed_name::fixed_size::xs_list::whitespace_delimiters stdout ----
assertion failed: `(left == right)`: "<root><item>first\tlist</item></root>"

GREEN with the fix: cargo test --all-features - 1473 lib tests and all 18 integration test binaries pass, cargo fmt -- --check is clean.

Impact

ListIter only ever receives decoded text, so no document that was deserialized correctly before is deserialized differently now, except that a tab, a carriage return or a line feed that is surrounded by item characters used to be kept inside the item and is now a delimiter, as the specification requires.

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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 53.88%. Comparing base (4a56631) to head (2256444).
⚠️ Report is 23 commits behind head on master.
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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1034      +/-   ##
==========================================
+ Coverage   53.71%   53.88%   +0.16%     
==========================================
  Files          51       51              
  Lines       19412    19541     +129     
==========================================
+ Hits        10428    10529     +101     
- Misses       8984     9012      +28     

Flag	Coverage Δ
unittests	53.88% <100.00%> (+0.16%)	⬆️

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