suggest better for !($foo == $bar) (same for eq, != and ne)

2 files changed, 14 insertions, 0 deletions

diff --git a/perl_checker.src/parser_helper.ml b/perl_checker.src/parser_helper.ml
index 8a81bda..727f956 100644
--- a/perl_checker.src/parser_helper.ml
+++ b/perl_checker.src/parser_helper.ml
@@ -439,12 +439,22 @@ let check_scalar_subscripted esp =
   | Deref(I_scalar, Deref _) -> warn_rule "for complex dereferencing, use \"->\""
   | _ -> ()
 
+let negatable_ops = collect (fun (a, b) -> [ a, b ; b, a ]) [
+  "==", "!=" ; 
+  "eq", "ne" ;
+]
+
 let check_negatable_expr esp =
   match un_parenthesize_full esp.any.expr with
   | Call_op("m//", var :: _, _) when not (is_var_dollar_ var) ->
       warn_rule "!($var =~ /.../) is better written $var !~ /.../"
   | Call_op("!m//", var :: _, _) when not (is_var_dollar_ var) ->
       warn_rule "!($var !~ /.../) is better written $var =~ /.../"
+  | Call_op(op, _, _) ->
+      (try
+	let neg_op = List.assoc op negatable_ops in
+        warn_rule (Printf.sprintf "!($foo %s $bar) is better written $foo %s $bar" op neg_op)
+      with Not_found -> ())
   | _ -> ()
 
 let check_ternary_paras(cond, a, b) =
diff --git a/perl_checker.src/test/suggest_better.t b/perl_checker.src/test/suggest_better.t
index 58a1308..caa3677 100644
--- a/perl_checker.src/test/suggest_better.t
+++ b/perl_checker.src/test/suggest_better.t
@@ -62,6 +62,10 @@ member($xxx, keys %h)                    you can replace "member($xxx, keys %yyy
 
 !($xxx =~ /.../)                         !($var =~ /.../) is better written $var !~ /.../
 
+!($xxx == 1)                             !($foo == $bar) is better written $foo != $bar
+
+!($xxx eq 'foo')                         !($foo eq $bar) is better written $foo ne $bar
+
 foreach (@l) {                           use "push @l2, grep { ... } ..." instead of "foreach (...) { push @l2, $_ if ... }"
   push @l2, $_ if yyy($_);                 or sometimes "@l2 = grep { ... } ..."
 }