"test" instruction with "ina" as first operand does not work

[rstemmer]

I once again spent days of debugging a problem a simple warning or an error could have avoided.

Description of the Problem

I had the following code in a function that should read data from an SPI device:

test    ina,  :pin_miso   WZ

My problem was that I got no data from that device, I always received 0-Bytes.
I then connected an FPGA between the SPI Device and the Propeller to observe the communication and figured out, that the whole communication worked.
After flipping the operands I finally got the valid response in the Propeller:

test    :pin_miso,  ina   WZ

Investigation of the Problems Origin

The documentation explicitly writes about the test command that it does not perform writing, so I was not concerned about the order of operands.:

Explanation
TEST is similar to AND except it doesn’t write a result to Value1; [..]

Anyway, in the description of the ina register, the following warning was spoken:

[..] Do not use INA as the destination operand; that only results in reading and modifying the shadow register whose address INA occupies. [..]

Suggestion as Solution

Obviously the assembler knows that this was an invalid use of the test instruction to access the ina register.
A warning like: "WARNING: Invalid use of ina register. ina should only be used as source register." would have helped a lot.

Environment

Version 1.00.81 Compiled on Jul  5 2019 09:30:36

[PropGit]

Thank you for the report @rstemmer.

I agree, this is something we should improve. It should be a warning and will require a proper warning system to be implemented in the compiler first before implementing this (and other) warnings. It should not be an error because it actually does perform a task, though it is utilizing an odd behavior that is not typically utilized and certainly not what you intended.

[drawkula]

Just for having a reference:
—▷ Add warning system #44