Avoid the issue outlined in #2289 where the @if or @else is taken as the
statement of an `if`, `for` or `while` by rejecting such constructs.
Effectively this means the following scripts are now rejected:
# Print's "cond true" with Zeek 5.0 even though the `if ( F )`
# should be in effect.
if ( F )
@if ( T )
print "cond true";
@else
print "cond false";
@endif
or
# Print's "hello" once with Zeek 5.0
local v = vector( 1, 2, 3 );
for ( i in v )
@if ( T )
print("hello")
@endif
To make above work as intended, additional braces can be used.
if ( T )
{
@if ( cond )
print "cond true";
@else
print "cond false";
@endif
}
for ( i in v )
{
@if ( T )
print("hello")
@endif
}
