'if' with failing 'else' block

[Arjan van Staalduijnen]

This morning I've been busy tracking a bug in my code, for which I have
no explanation as to why it is a bug.
The situation is I have an if-else test where, in case of a match, the
if-block gets executed, but in case of a non-match, the else-block does
NOT get executed. If I turn the whole test around by adding a NOT to the
test, and swapping the if and else blocks, everything works.

This is the code which has the bug:

string key_name = "IssueID_shortname";
array qresult = myDB->Query("SHOW keys FROM
dbFinalPublicationPassive.tbIssueDetails");
if (qresult && has_value(qresult->Key_name || ({}), key_name))
        do_log("Index %O was already set", key_name);
else
{
        do_log("Adding index %O", key_name);
      myDB->Query("ALTER TABLE dbFinalPublicationPassive.tbIssueDetails"
                                " ADD INDEX IssueID_shortname (IssueID,
ShortName)");
}
        
This code does not have the bug:

string key_name = "IssueID_shortname";
array qresult = myDB->Query("SHOW keys FROM
dbFinalPublicationPassive.tbIssueDetails");
if (!(qresult && has_value(qresult->Key_name || ({}), key_name)))
{
        do_log("Adding index %O", key_name);
      myDB->Query("ALTER TABLE dbFinalPublicationPassive.tbIssueDetails"
                                " ADD INDEX IssueID_shortname (IssueID,
ShortName)");
}
else
        do_log("Index %O was already set", key_name);


Anyone has a clue? (Pike 7.4.464)


Regards,

Arjan

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