Fix SEARCH position when text contains a char with multi-char lowercase (#571)

crates/functions/src/criteria.rs

@@ -168,19 +168,25 @@ fn tokenize(pattern: &str) -> Vec<Tok> {
     while let Some(c) = it.next() {
         match c {
             '~' => match it.next() {
-                Some(n) => out.extend(n.to_lowercase().map(Tok::Char)),
+                Some(n) => out.extend(std::iter::once(lower_char(n)).map(Tok::Char)),
                 None => out.push(Tok::Char('~')),
             },
             '*' => out.push(Tok::Star),
             '?' => out.push(Tok::Any),
-            c => out.extend(c.to_lowercase().map(Tok::Char)),
+            c => out.extend(std::iter::once(lower_char(c)).map(Tok::Char)),
         }
     }
     out
 }
 
+/// Lowercase one char to exactly one char, so positions in the lowered text match the original
+/// (U+0130 `İ` folds to `i`, like `fold` in text.rs).
+fn lower_char(c: char) -> char {
+    c.to_lowercase().next().unwrap_or(c)
+}
+
 fn lower_chars(s: &str) -> Vec<char> {
-    s.chars().flat_map(char::to_lowercase).collect()
+    s.chars().map(lower_char).collect()
 }
 
 /// Whether the pattern contains an unescaped wildcard.
@@ -317,6 +323,8 @@ mod tests {
         assert_eq!(wildcard_find("b?d", "abxxd bcd", 0), Some(6));
         assert_eq!(wildcard_find("c*", "abcd", 0), Some(2));
         assert_eq!(wildcard_find("z", "abcd", 0), None);
+        assert_eq!(wildcard_find("b", "a\u{130}bc", 0), Some(2));
+        assert!(wildcard_match("i*", "\u{130}stanbul"));
         assert!(has_wildcards("a*"));
         assert!(!has_wildcards("abc"));
     }

crates/functions/src/text.rs

@@ -1032,6 +1032,11 @@ mod tests {
         close(ev("SEARCH", vec![t("~*"), t("a*b")]), 2.0);
         is_err(ev("SEARCH", vec![t("z"), t("abc")]), CellError::Value);
         is_err(ev("SEARCH", vec![t("a"), t("abc"), n(5.0)]), CellError::Value);
+        close(ev("SEARCH", vec![t("b"), t("\u{130}b")]), 2.0);
+        close(ev("SEARCH", vec![t("B"), t("\u{130}b")]), 2.0);
+        close(ev("SEARCH", vec![t("b?"), t("a\u{130}bc")]), 3.0);
+        close(ev("SEARCH", vec![t("i"), t("a\u{130}bc")]), 2.0);
+        is_err(ev("SEARCH", vec![t("b"), t("a\u{130}bc"), n(4.0)]), CellError::Value);
         assert_eq!(ev("EXACT", vec![t("a"), t("A")]), Value::Bool(false));
         assert_eq!(ev("EXACT", vec![t("a"), t("a")]), Value::Bool(true));
     }