Add a new warning, "State variable %s will be reinitialized"

p4raw-id: //depot/perl@28496

diff --git a/op.c b/op.c
index 370a01f..4716788 100644 (file)
--- a/op.c
+++ b/op.c
@@ -3800,10 +3800,16 @@ Perl_newASSIGNOP(pTHX_ I32 flags, OP *left, I32 optype, OP *right)
                             curop->op_type == OP_PADHV ||
                             curop->op_type == OP_PADANY)
                    {
-                       if ((left->op_private & OPpLVAL_INTRO) && (curop->op_private & OPpPAD_STATE)) {
-                           o->op_private |= OPpASSIGN_STATE;
-                           /* hijacking PADSTALE for uninitialized state variables */
-                           SvPADSTALE_on(PAD_SVl(curop->op_targ));
+                       if (curop->op_private & OPpPAD_STATE) {
+                           if (left->op_private & OPpLVAL_INTRO) {
+                               o->op_private |= OPpASSIGN_STATE;
+                               /* hijacking PADSTALE for uninitialized state variables */
+                               SvPADSTALE_on(PAD_SVl(curop->op_targ));
+                           }
+                           else if (ckWARN(WARN_MISC)) {
+                               Perl_warner(aTHX_ packWARN(WARN_MISC), "State variable %s will be reinitialized",
+                                       PAD_COMPNAME_PV(curop->op_targ));
+                           }
                        }
                        if (PAD_COMPNAME_GEN(curop->op_targ)
                                                    == (STRLEN)PL_generation)

diff --git a/pod/perldiag.pod b/pod/perldiag.pod
index 8228cf9..d9aa877 100644 (file)
--- a/pod/perldiag.pod
+++ b/pod/perldiag.pod
@@ -3745,6 +3745,16 @@ L<perlfunc/splice>.
 iterate more times than there are characters of input, which is what
 happened.) See L<perlfunc/split>.
 
+=item State variable %s will be reinitialized
+
+(W misc) You're declaring a C<state> variable inside a list. The list
+assignment will be treated by perl as a regular assignment, which means
+that the C<state> variable will be reinitialized each time the statement
+is run. The solution to have it initialized twice is to write the
+assignment on its own line, as in:
+
+    state $var = 42;
+
 =item Statement unlikely to be reached
 
 (W exec) You did an exec() with some statement after it other than a

diff --git a/t/lib/warnings/op b/t/lib/warnings/op
index 891677f..3c10751 100644 (file)
--- a/t/lib/warnings/op
+++ b/t/lib/warnings/op
@@ -1081,3 +1081,20 @@ Deprecated use of my() in false conditional at - line 6.
 Deprecated use of my() in false conditional at - line 7.
 Deprecated use of my() in false conditional at - line 8.
 Deprecated use of my() in false conditional at - line 9.
+########
+# op.c
+use feature 'state';
+use warnings 'misc';
+state($x) = 1;
+(state $y) = 2;
+(state $z, my $t) = (3, 4);
+(state $foo, state $bar) = (5, 6);
+no warnings 'misc';
+state($x) = 1;
+(state $y) = 2;
+(state $z, my $t) = (3, 4);
+(state $foo, state $bar) = (5, 6);
+EXPECT
+State variable $z will be reinitialized at - line 6.
+State variable $foo will be reinitialized at - line 7.
+State variable $bar will be reinitialized at - line 7.