warn on !=~

Message-ID: <20040319062035.GA3768@efn.org>

with an improvement suggested by Ton Hospel.

p4raw-id: //depot/perl@22542

diff --git a/pod/perldiag.pod b/pod/perldiag.pod
index e74984c..3132242 100644 (file)
--- a/pod/perldiag.pod
+++ b/pod/perldiag.pod
@@ -3444,6 +3444,12 @@ world, because the world might have written on it already.
 
 (F) You don't have System V shared memory IPC on your system.
 
+=item !=~ should be !~
+
+(W syntax) The non-matching operator is !~, not !=~.  !=~ will be
+interpreted as the != (numeric not equal) and ~ (1's complement)
+operators: probably not what you intended.
+
 =item <> should be quotes
 
 (F) You wrote C<< require <file> >> when you should have written

diff --git a/t/lib/warnings/toke b/t/lib/warnings/toke
index e49376c..f9072ab 100644 (file)
--- a/t/lib/warnings/toke
+++ b/t/lib/warnings/toke
@@ -816,4 +816,22 @@ eval q/5 6/;
 EXPECT
 Number found where operator expected at (eval 1) line 1, near "5 6"
        (Missing operator before  6?)
-
+########
+# toke.c
+use warnings "syntax";
+$_ = $a = 1;
+$a !=~  /1/;
+$a !=~ m#1#;
+$a !=~/1/;
+$a !=~ ?/?;
+$a != ~/1/;
+no warnings "syntax";
+$a !=~  /1/;
+$a !=~ m#1#;
+$a !=~/1/;
+$a !=~ ?/?;
+EXPECT
+!=~ should be !~ at - line 4.
+!=~ should be !~ at - line 5.
+!=~ should be !~ at - line 6.
+!=~ should be !~ at - line 7.

diff --git a/toke.c b/toke.c
index a26c724..46aa3aa 100644 (file)
--- a/toke.c
+++ b/toke.c
@@ -3382,8 +3382,20 @@ Perl_yylex(pTHX)
     case '!':
        s++;
        tmp = *s++;
-       if (tmp == '=')
+       if (tmp == '=') {
+            /* was this !=~ where !~ was meant? */
+            if (*s == '~' && ckWARN(WARN_SYNTAX)) {
+                char *t = s+1;
+
+                while (t < PL_bufend && isSPACE(*t))
+                    ++t;
+
+                if (*t == '/' || (*t == 'm' && !isALNUM(t[1])) || *t == '?')
+                    Perl_warner(aTHX_ packWARN(WARN_SYNTAX),
+                                "!=~ should be !~");
+            }
            Eop(OP_NE);
+        }
        if (tmp == '~')
            PMop(OP_NOT);
        s--;