Problem

When using crystal i (interpreter/REPL) on Windows MinGW UCRT64, any use of regular expressions raises:

undefined reference to `pcre2_compile_8' (Crystal::Loader::LoadError)

The same code works correctly with crystal run or crystal build.

Fixes #16794

Root Cause

Two bugs were found:

1. interpreter/[context.cr](http://context.cr/) — lazy loader initialization

The loader is initialized once (lazy getter) using program.lib_flags at the first c_function call. In REPL mode, pcre2 is not in lib_flags at loader init time because Regex is defined in prelude but not yet used. When the user types the first regex, pcre2 is added to lib_flags but the loader is already cached. File mode works because prelude and file are analyzed together.

2. loader/[mingw.cr](http://mingw.cr/) — LoadLibraryExW handle issue

LoadLibraryExW with a bare DLL name returns a handle for already-loaded process DLLs where GetProcAddress subsequently fails. Using GetModuleHandleExW first returns the canonical handle that works correctly.

Fix

• src/compiler/crystal/loader/[mingw.cr](http://mingw.cr/): load_dll? now uses GetModuleHandleExW first, falls back to full-path LoadLibraryExW; added resolve_dll_full_path to find the DLL in search paths and sibling bin/ directories.

• src/compiler/crystal/interpreter/[context.cr](http://context.cr/): added dll_search_paths for Windows MinGW, tracks lib_flags at loader init time, added update_loader to dynamically load new -l libraries when lib_flags changes.

Test Case

result = "hello world" =~ /world/
puts result         # should print 6
m = /(\w+)/.match("hello")
puts m.try(&.[1])   # should print "hello"
puts "OK"