Original Redmine Comment
Author Name: Usha Priyadharshini
Original Date: 2010-09-16T17:25:50Z

Updating since the code segment does not show up as expected:

Trying to expand the following macro definition:

`define FRAME_TYPE sonet 
`define JOIN(__arg1, __arg2) __arg1``__arg2 
`define XACTION `JOIN(`FRAME_TYPE, _frame)

`XACTION

I would expect the last XACTION call expanding to sonet_frame. However output of preprocessor shows FRAME_TYPE_frame. Parsing this in VCS produces the expected output: sonet_frame.

As the macro is expanded, the arguments are fully expanded before the next expansion, I would expect the following steps:

`XACTION 
`JOIN(`FRAME_TYPE, _frame)
`JOIN(sonet, _frame) 
sonet``_frame 
sonet_frame

Original Redmine Comment
Author Name: Wilson Snyder (@wsnyder)
Original Date: 2010-09-16T17:37:32Z

Unfortunately the specification doesn't clearly specify the order of expansion, so the results depends on the simulator.
I think you're interpretation makes more sense, but let me try more simulators to see what the majority believe.

Original Redmine Comment
Author Name: Wilson Snyder (@wsnyder)
Original Date: 2010-09-16T17:39:44Z

Misspoke above, the order of expansion is specified, just not when `` is done during expansion.

Original Redmine Comment
Author Name: Wilson Snyder (@wsnyder)
Original Date: 2010-09-20T19:20:34Z

First, I did some research, and only 3 of four simulators surveyed support this ordering. If you want to be maximally compliant, you may not want to do that.

However, majority rules. I further discovered that the majority believes:

`define QA_b qindirect
`define Q1 `QA``_b
//-> qindirect

`define QA a
//-> a_b

which is amazing, as I just wrote a paper that discovered a ton of odd stuff, but missed this!

Anyhow, fixed in git, for 3.303.

Original Redmine Comment
Author Name: Wilson Snyder (@wsnyder)
Original Date: 2010-09-20T19:32:18Z

In 3.303