Document Str.substr-eq ignorecase/ignoremark

Refs #3229

Author: stoned

doc/Type/Str.pod6

@@ -843,8 +843,8 @@ to the index of the last character.
 
 =head2 method substr-eq
 
-    multi method substr-eq(Str:D:  Str(Cool) $test-string, Int(Cool) $from --> Bool)
-    multi method substr-eq(Cool:D: Str(Cool) $test-string, Int(Cool) $from --> Bool)
+    multi method substr-eq(Str:D:  Str(Cool) $test-string, Int(Cool) $from, :i(:$ignorecase), :m(:$ignoremark) --> Bool)
+    multi method substr-eq(Cool:D: Str(Cool) $test-string, Int(Cool) $from, :i(:$ignorecase), :m(:$ignoremark) --> Bool)
 
 Returns C<True> if the C<$test-string> exactly matches the C<String> object,
 starting from the given initial index C<$from>.  For example, beginning with
@@ -864,6 +864,22 @@ Naturally, to match the entire string, one merely matches from index 0:
     my $string = "foobar";
     say $string.substr-eq("foobar", 0); # OUTPUT: «True␤»
 
+Since Rakudo version 2020.02, if the optional named parameter
+C<:ignorecase>, or C<:i>, is specified, the comparison of the invocant
+and C<$test-string> ignores the distinction between upper case,
+lower case and title case letters.
+
+    say "foobar".substr-eq("Bar", 3);              # OUTPUT: «False␤»
+    say "foobar".substr-eq("Bar", 3, :ignorecase); # OUTPUT: «True␤»
+
+Since Rakudo version 2020.02, if the optional named parameter
+C<:ignoremark>, or C<:m>, is specified, the comparison of the
+invocant and C<$test-string> only considers base characters, and
+ignores additional marks such as combining accents.
+
+    say "cliché".substr-eq("che", 3);              # OUTPUT: «False␤»
+    say "cliché".substr-eq("che", 3, :ignoremark); # OUTPUT: «True␤»
+
 Since this method is inherited from the C<Cool> type, it also works on
 integers.  Thus the integer C<42> will match the value C<342> starting from
 index 1:

xt/code.pws

@@ -144,6 +144,7 @@ cha
 childclass
 childname
 chocolatey
+cliché
 clogger
 cn
 cntrl