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[Bug tapsets/13450] get rid of most/all probe-alias "?" (optional) markup


http://sourceware.org/bugzilla/show_bug.cgi?id=13450

Josh Stone <jistone at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jistone at redhat dot com

--- Comment #1 from Josh Stone <jistone at redhat dot com> 2011-11-29 17:18:48 UTC ---
(In reply to comment #0)
> It quietly fails when the underlying bar probe point is not present.

That's not true:

$ stap -e 'probe foo = bar ? {}  probe foo {}' -p2
semantic error: no match while resolving probe point foo
Pass 2: analysis failed.  Try again with another '--vp 01' option.

The optional tag on the alias allows a user to possibly match the probe with a
wildcard, but carry on if it doesn't resolve.

$ stap -e 'probe bar = foo ? {}  probe b* {}' -p2 -u
# probes
begin /* <- b* */

vs. 

$ stap -e 'probe bar = foo {}  probe b* {}' -p2 -u
semantic error: probe point mismatch at position 0  (alternatives: __nfs
__scheduler __signal __tcpmib __vm _linuxmib _signal _sunrpc _syscall _vfs bar
begin begin(number) end end(number) error error(number) generic ioblock
ioblock_trace ioscheduler ioscheduler_trace ipmib irq_handler kernel kprobe
kprocess linuxmib module(string) nd_syscall netdev never nfs nfsd perf process
process(number) process(string) procfs procfs(string) scheduler scsi signal
socket softirq stap staprun sunrpc syscall tcp tcpmib timer tty udp vfs vm
workqueue): identifier 'foo' at <input>:1:13 while resolving probe point foo
        source: probe bar = foo {}  probe b* {}
                            ^
Pass 2: analysis failed.  Try again with another '--vp 01' option.

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