i2pd: fix build on macOS <12

security/i2pd/Portfile

@@ -8,10 +8,11 @@ PortGroup               legacysupport 1.1
 PortGroup               openssl 1.0
 
 # on <10.15 built-in libc++ has no support for std::filesystem
+# uses number 19 due to a bug in macOS Catalina SDK
 legacysupport.use_mp_libcxx \
                         yes
 legacysupport.newest_darwin_requires_legacy \
-                        18
+                        19
 
 github.setup            PurpleI2P i2pd 2.60.0
 revision                0
@@ -33,6 +34,14 @@ depends_lib-append      port:zlib
 
 patchfiles-append       0001-i2pd.conf-adjust-for-MacPorts.patch
 
+# util.cpp:319:30: error: no viable conversion from
+# 'std::string_view' (aka 'basic_string_view<char>')
+# to 'const key_type' (aka 'const std::basic_string<char>')
+# Clang <18 on macOS <12 supports C++20, but gets stuck at this section of code
+if {${os.platform} eq "darwin" && ${os.major} < 21} {
+    patchfiles-append   0002-patch-util-cpp.patch
+}
+
 set i2pddir             ${prefix}/var/db/${name}
 
 post-patch {

security/i2pd/files/0002-patch-util-cpp.patch

@@ -0,0 +1,11 @@
+--- libi2pd/util.cpp
++++ libi2pd/util.cpp
+@@ -315,7 +315,7 @@ namespace util
+ 
+ 	bool Mapping::Contains (std::string_view param) const
+ 	{
+-#if __cplusplus >= 202002L // C++20
++#if !defined(__clang__) && (__cplusplus >= 202002L) // C++20
+ 		return m_Options.contains (param);
+ #else
+ 		auto it = m_Options.find (param);