Make options configurable for iverilog (#1143)

ale_linters/verilog/iverilog.vim

@@ -1,6 +1,14 @@
 " Author: Masahiro H https://github.com/mshr-h
 " Description: iverilog for verilog files
 
+call ale#Set('verilog_iverilog_options', '')
+
+function! ale_linters#verilog#iverilog#GetCommand(buffer) abort
+    return 'iverilog -t null -Wall '
+    \   . ale#Var(a:buffer, 'verilog_iverilog_options')
+    \   . ' %t'
+endfunction
+
 function! ale_linters#verilog#iverilog#Handle(buffer, lines) abort
     " Look for lines like the following.
     "
@@ -30,6 +38,6 @@ call ale#linter#Define('verilog', {
 \   'name': 'iverilog',
 \   'output_stream': 'stderr',
 \   'executable': 'iverilog',
-\   'command': 'iverilog -t null -Wall %t',
+\   'command_callback': 'ale_linters#verilog#iverilog#GetCommand',
 \   'callback': 'ale_linters#verilog#iverilog#Handle',
 \})

test/test_verilog_iverilog_options.vader

@@ -0,0 +1,18 @@
+Before:
+  Save g:ale_verilog_iverilog_options
+  let g:ale_verilog_iverilog_options = ''
+
+After:
+  Restore
+  call ale#linter#Reset()
+
+Execute(Set Verilog iverilog linter additional options to `-y.`):
+  runtime! ale_linters/verilog/iverilog.vim
+
+  " Additional args for the linter
+  let g:ale_verilog_iverilog_options = '-y.'
+
+  call ale#Lint()
+
+  let g:cmd = ale_linters#verilog#iverilog#GetCommand(bufnr(''))
+  AssertEqual g:cmd, 'iverilog -t null -Wall -y. %t'