fixup correct handling of non-ASCII parameter names

Author: leonerd

pp.c

@@ -7995,8 +7995,9 @@ PP(pp_multiparam)
                 val = svp ? *svp : &PL_sv_undef;
             }
 
+            /* namepv / namelen are always UTF-8 */
             STRLEN namelen;
-            const char *namepv = SvPV(name, namelen);
+            const char *namepv = SvPVutf8(name, namelen);
 
             U32 namehash;
             PERL_HASH(namehash, namepv, namelen);
@@ -8059,8 +8060,8 @@ PP(pp_multiparam)
             else {
                 // TODO: Consider collecting up all the names of unrecognised
                 // in one string
-                croak_caller("Unrecognized named parameter '%s' to subroutine '%" SVf "'",
-                    namepv, S_find_runcv_name());
+                croak_caller("Unrecognized named parameter '%" UTF8f "' to subroutine '%" SVf "'",
+                    UTF8fARG(true, namelen, namepv), S_find_runcv_name());
             }
         }
 
@@ -8071,8 +8072,8 @@ PP(pp_multiparam)
 
             // TODO: Consider collecting up all the names of missing
             // parameters in one string
-            croak_caller("Missing required named parameter '%s' to subroutine '%" SVf "'",
-                    named->namepv, S_find_runcv_name());
+            croak_caller("Missing required named parameter '%" UTF8f "' to subroutine '%" SVf "'",
+                    UTF8fARG(true, named->namelen, named->namepv), S_find_runcv_name());
         }
     }
 

t/op/signatures.t

@@ -965,6 +965,30 @@ sub tnamed07 (:$x, :$y, %) { "x=$x y=$y"; }
 is prototype(\&tnamed07), undef;
 is eval("tnamed07(w => 'W', x => 'X', y => 'Y', z => 'Z')"), "x=X y=Y";
 
+# Unicode handling of parameter names
+{
+    use utf8;
+
+    sub tnamed08 (:$ĉevaloj) { return "$ĉevaloj horses"; }
+
+    is eval("tnamed08(ĉevaloj => 1)"), "1 horses";
+
+    is eval("tnamed08()"), undef;
+    like $@, qr/^Missing required named parameter 'ĉevaloj' to subroutine 'main::tnamed08' at /;
+
+    is eval("tnamed08(ŝafoj => 5)"), undef;
+    like $@, qr/^Unrecognized named parameter 'ŝafoj' to subroutine 'main::tnamed08' at /;
+}
+
+# Handling of Unicode parameter names from non-utf8 contexts
+{
+    use utf8;
+
+    sub tnamed09 (:$café) { return $café; }
+}
+# "café" = "caf\x{e9}"
+is eval('tnamed09("caf\x{e9}", "Ritz")'), "Ritz";
+
 sub t085
     (
     $