Fix #1186 - Use -w by default for Perl, which does not execute code

ale_linters/perl/perl.vim

@@ -1,18 +1,15 @@
 " Author: Vincent Lequertier <https://github.com/SkySymbol>
 " Description: This file adds support for checking perl syntax
 
-let g:ale_perl_perl_executable =
-\   get(g:, 'ale_perl_perl_executable', 'perl')
-
-let g:ale_perl_perl_options =
-\   get(g:, 'ale_perl_perl_options', '-c -Mwarnings -Ilib')
+call ale#Set('perl_perl_executable', 'perl')
+call ale#Set('perl_perl_options', '-w -Mwarnings -Ilib')
 
 function! ale_linters#perl#perl#GetExecutable(buffer) abort
     return ale#Var(a:buffer, 'perl_perl_executable')
 endfunction
 
 function! ale_linters#perl#perl#GetCommand(buffer) abort
-    return ale_linters#perl#perl#GetExecutable(a:buffer)
+    return ale#Escape(ale_linters#perl#perl#GetExecutable(a:buffer))
     \   . ' ' . ale#Var(a:buffer, 'perl_perl_options')
     \   . ' %t'
 endfunction

doc/ale-perl.txt

@@ -16,11 +16,15 @@ g:ale_perl_perl_executable                         *g:ale_perl_perl_executable*
 g:ale_perl_perl_options                               *g:ale_perl_perl_options*
                                                       *b:ale_perl_perl_options*
   Type: |String|
-  Default: `'-c -Mwarnings -Ilib'`
+  Default: `'-w -Mwarnings -Ilib'`
 
   This variable can be changed to alter the command-line arguments to the perl
   invocation.
 
+  Perl code is checked with `-w` by default, because `-c` can execute
+  malicious code. You can use the `-c` option at your own risk. See
+  |g:ale_pattern_options| for changing the option only for specific files.
+
 
 ===============================================================================
 perlcritic                                                *ale-perl-perlcritic*

test/command_callback/test_perl_command_callback.vader

@@ -0,0 +1,37 @@
+Before:
+  Save g:ale_perl_perl_executable
+  Save g:ale_perl_perl_options
+
+  unlet! g:ale_perl_perl_executable
+  unlet! g:ale_perl_perl_options
+
+  runtime ale_linters/perl/perl.vim
+
+After:
+  Restore
+
+  unlet! b:ale_perl_perl_executable
+  unlet! b:ale_perl_perl_options
+
+  call ale#linter#Reset()
+
+Execute(The default Perl command callback should be correct):
+  AssertEqual
+  \ 'perl',
+  \ ale_linters#perl#perl#GetExecutable(bufnr(''))
+
+  AssertEqual
+  \ ale#Escape('perl') . ' -w -Mwarnings -Ilib %t',
+  \ ale_linters#perl#perl#GetCommand(bufnr(''))
+
+Execute(Overriding the executable and command should work):
+  let b:ale_perl_perl_executable = 'foobar'
+  let b:ale_perl_perl_options = '-c'
+
+  AssertEqual
+  \ 'foobar',
+  \ ale_linters#perl#perl#GetExecutable(bufnr(''))
+
+  AssertEqual
+  \ ale#Escape('foobar') . ' -c %t',
+  \ ale_linters#perl#perl#GetCommand(bufnr(''))