// The mail below doesn't appear to have made it to the
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Hey Gavin,
In a switch expression, I believe it should be legal for every
`case`/`default` arm to complete abruptly _for a reason other than a
break with value_.
That is, a legal switch expression may have zero rules like `case a ->
5;` (completes normally) or `case b -> { break 6; }` (completes abruptly
for reason of break with value). Instead, it only has rules like `case c
-> { throw new Exc(); }` or `case d -> throw new Exc();`, both of which
complete abruptly for reason othan than break with value. (Extend to
switch labeled statement groups.)
I suspect that the strong rule flagged by Manoj:
It is a compile-time error if a switch expression has no result
expressions.
is trying to require a value `break` statement being present in every
switch labeled block, because a rule earlier in 15.28.1 did not quite go
that far:
If the switch block consists of switch labeled rules, then any
switch labeled block (14.11.1) must complete abruptly.
Alex
On 3/14/2019 4:14 PM, Manoj Palat wrote:
Hi Alex, Gavin,
One more clarification of the spec:
Consider the following code:
public class X {
@SuppressWarnings("preview")
public static int foo(int i) throws MyException {
int v = switch (i) {
default -> throw new MyException(); // error or no error?
};
return v;
}
public static void main(String argv[]) {
try {
System.out.println(X.foo(1));
} catch (MyException e) {
System.out.println("Exception thrown as expected");
}
}
}
class MyException extends Exception {
private static final long serialVersionUID = 3461899582505930473L;
}
As per spec, JLS 15.28.1
It is a compile-time error if a switch expression has no result expressions.
------------------------
Throw statement is not a result expression and hence as per the spec we
should be giving this error.
Is this an omission in the spec? Should we be flagging an error?
In Eclipse ECJ we are flagging an error but I observed javac does not -
Want to get clarity on what does the spec mean.
Regards,
Manoj
Eclipse Java Dev,
IBM.
