Performance: `extract_field_name` in proc-macro is O(n²) due to unnecessary iterator clone

[ZialeHub]

Description

In pulsync-derive/src/lib.rs, extract_field_name checks for the "self." prefix by cloning the entire remaining character iterator and collecting it into a String on every { encountered:

  // line 126 — allocates a new String of all remaining chars on every '{'
  if chars.clone().collect::<String>().as_str().starts_with("self.") {

For a format string with K fields and average remaining length L, this is O(K × L) allocations — quadratic in the number of characters in the worst case.

Affected file

• pulsync-derive/src/lib.rs — line 126

Fix

std::str::Chars exposes the remaining string slice via .as_str(), which avoids any allocation:

  // O(5), zero allocation
  if chars.as_str().starts_with("self.") {
      for _ in 0..5 { chars.next(); }
  }

This is a one-line change that makes the method O(n) overall.