[Varnish] #1800: PRIV_TASK in a vmod object method leads to code that cannot be compiled/linked

[Varnish]

#1800: PRIV_TASK in a vmod object method leads to code that cannot be
compiled/linked
--------------------+--------------------
 Reporter:  geoff   |       Owner:
     Type:  defect  |      Status:  new
 Priority:  normal  |   Milestone:  Later
Component:  vmod    |     Version:  4.1.0
 Severity:  normal  |  Resolution:
 Keywords:          |
--------------------+--------------------

Comment (by geoff):

 OK, I've attached a patch to demonstrate the problem, which matches the
 problem with my own VMOD.

 The patch adds these two methods to the object "obj" in vmod debug:

 {{{
 $Method VOID .task_set(PRIV_TASK, INT)

 $Method INT .task_get(PRIV_TASK, INT fallback=-1)
 }}}

 Set an integer in task scope, and retrieve it in the same scope.
 m00000.vtc tests it:

 {{{
 sub vcl_init {
         new foo = debug.obj("foo");
 }

 sub vcl_deliver {
         # ...
         foo.task_set(4711);
         set resp.http.task = foo.task_get();
 }
 }}}

 The generated code fails to compile with this message:

 {{{
 **** v1    0.2 CLI RX| Message from C-compiler:\n
 **** v1    0.2 CLI RX| vgc.c: In function
 \xe2\x80\x98VGC_function_vcl_deliver\xe2\x80\x99:\n
 **** v1    0.2 CLI RX| vgc.c:1352:29: error:
 \xe2\x80\x98VGC_vmod_foo\xe2\x80\x99 undeclared (first use in this
 function)\n
 **** v1    0.2 CLI RX|          VRT_priv_task(ctx, &VGC_vmod_foo),\n
 **** v1    0.2 CLI RX|                              ^\n
 **** v1    0.2 CLI RX| vgc.c:1352:29: note: each undeclared identifier is
 reported only once for each function it appears in\n
 **** v1    0.2 CLI RX| Running C-compiler failed, exited with 1\n
 **** v1    0.2 CLI RX| VCL compilation failed
 ---- v1    0.2 FAIL VCL does not compile
 }}}

 So please try to forget what I said about linking (duh), the problem is in
 the generated C code. A symbol `VGC_vmod_<object name>` is used for the
 priv object, but is not declared.

 As I said above, the uncompilable code is the immediate problem, but it
 also seems intuitive that object methods should be able to make use of
 task scope -- in other words, rather than having the vmodtool generate an
 error, it would be better to make PRIV_TASK possible in a method.

-- 
Ticket URL: <https://www.varnish-cache.org/trac/ticket/1800#comment:3>
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