refactor(pcre): hand back the match instead of copying it out

Preg::match4 and Preg::replace_callback gave callers a
PregMatchedGroups: an IndexMap rebuilt from the match with an owned
String per group, plus a second String for a named group's name key.
That is the copy PregMatches shed when it started wrapping
regex::Captures, reinstated one layer up -- and nearly every regex call
in the tree goes through Preg rather than the shim's preg_* directly, so
almost nothing saw the borrow.

PregMatchedGroups existed only to drop the null (unmatched) groups the
old PregMatches held as Option<String> values. PregMatches::get reports
a non-participating group as None on its own, so the two read alike and
the type collapses into it. Call sites still reach groups through
get(&CaptureKey::ByIndex(N)); what changes is that the value arrives as
a &str borrowed from the subject, which the signatures now carry as a
lifetime.

Three places needed the borrow reckoned with rather than a mechanical
rewrite: PhpFileCleaner::clean and Problem::get_messages read their
groups out before mutating what the match borrows, and
Git::get_authentication_failure names the lifetime of its url argument,
which the result borrows instead of self.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

1 files changed, 5 insertions, 6 deletions

diff --git a/crates/shirabe/src/io/buffer_io.rs b/crates/shirabe/src/io/buffer_io.rs
index a3311129..ce67c7eb 100644
--- a/crates/shirabe/src/io/buffer_io.rs
+++ b/crates/shirabe/src/io/buffer_io.rs
@@ -76,21 +76,20 @@ impl BufferIO {
         loop {
             let next = Preg::replace_callback(
                 php_regex!(r"{(^|\n|\x08)(.+?)(\x08+)}"),
-                |matches: &shirabe_pcre::PregMatchedGroups| -> String {
-                    let empty = String::new();
+                |matches: &shirabe_pcre::PregMatches| -> String {
                     let g1 = matches
                         .get(&shirabe_pcre::CaptureKey::ByIndex(1))
-                        .unwrap_or(&empty);
+                        .unwrap_or("");
                     let g2 = matches
                         .get(&shirabe_pcre::CaptureKey::ByIndex(2))
-                        .unwrap_or(&empty);
+                        .unwrap_or("");
                     let g3 = matches
                         .get(&shirabe_pcre::CaptureKey::ByIndex(3))
-                        .unwrap_or(&empty);
+                        .unwrap_or("");
                     let pre = strip_tags(g2);
 
                     if pre.len() == g3.len() {
-                        return g1.clone();
+                        return g1.to_string();
                     }
 
                     // TODO reverse parse the string, skipping span tags and \033\[([0-9;]+)m(.*?)\033\[0m style blobs