ADDITIONAL SYSTEM INFORMATION :
javac 22-ea, javac 21.0.1

A DESCRIPTION OF THE PROBLEM :
This does not compile:

{code:java}
public class WithFinal {
record ARecord(String aComponent) {}

public String match(Object o) {
return switch(o) {
case ARecord(final String s) -> s;
default -> "No match";
};
}
}
{code}

javac outputs the following errors:

{noformat}
./WithFinal.java:6: error: illegal start of expression
case ARecord(final String s) -> s;
^
./WithFinal.java:6: error: ';' expected
case ARecord(final String s) -> s;
^
./WithFinal.java:6: error: not a statement
case ARecord(final String s) -> s;
^
3 errors
{noformat}

According to chapter 14.30.1. of the JLS, {{final}} is allowed as a _VariableModifier_. Without {{final}}, mutating the pattern variable is valid:

{code:java}
public class NotEffectivelyFinal {
record ARecord(String aComponent) {}

public String match(Object o) {
return switch(o) {
case ARecord(String s) -> {
s = "";
yield s;
}
default -> "No match";
};
}
}
{code}