From 40e18460bcda85653ee5ff5989b77e1deaa21f1d Mon Sep 17 00:00:00 2001
From: yhirose <yuji.hirose.bug@gmail.com>
Date: Fri, 1 May 2026 21:46:13 +0900
Subject: [PATCH] Document str2tag_core's compile-time-only role

---
 httplib.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/httplib.h b/httplib.h
index a2de258f..4bab7bec 100644
--- a/httplib.h
+++ b/httplib.h
@@ -6361,6 +6361,10 @@ inline void get_remote_ip_and_port(socket_t sock, std::string &ip, int &port) {
   }
 }
 
+// Recursive form retained so operator""_t below can compute hashes for
+// switch-case labels at compile time (C++11 constexpr forbids loops). Do not
+// call from runtime paths with arbitrary-length inputs — use str2tag()
+// instead, which is iterative and stack-safe.
 inline constexpr unsigned int str2tag_core(const char *s, size_t l,
                                            unsigned int h) {
   return (l == 0)