CAPI2 Syntax Gotcha: fileset_append existing fileset

[ArkoshEternal]

Background

While converting to VCS 3-Step recently, I ran into a few file already defined error, despite the file only being defined once in the relevant fileset. I realized someone had extended a target and then appended a fileset that already existed in the base target. This was a simple syntax fix, but seems like it could be incorrect behavior.

Proposed Fix

I plan to implement either a parse error if this occurs, or a system which removes fileset duplication from within one core file. Will see which one fits better with the codebase, and if I automatically fix, add a warning that it occurred.

Example "Problem"

CAPI=2: 

name: my:test:core 

filesets: 
  files_rtl: 
    - dut.sv
  file_type: systemVerilogSource

  files_dv: 
    - tb.sv
  file_type: systemVerilogSource 

targets:
  default: &default
    filesets: [files_rtl]
  
  sim_base: &sim_base: 
    <<: *default
    filesets_append: [files_dv]
    flow: sim
    flow_options: 
      tool: vcs
    toplevel: tb

  unit_test: 
    <<: *sim_base
   # issue occurs on next line
   filesets_append: [files_dv]
   parameters: 
     TESTNAME=unit_test

parameters: 
   TESTNAME: 
     datatype: string
     paramtype: plusarg

[olofk]

I see how this can happen. Deduplication and a warning would be my preferred solution for this rather than a parse error, but I guess it's mostly a matter of taste.