Reduce false positives for @hsh{$s} and @ary[$s] warnings

This resolves tickets #28380 and #114024.

Commit 95a31aad5 did something similar to this for the new %hash{...}
syntax.  This commit extends it to @ slices and combines the two
code paths.

The heuristics in toke.c can easily produce false positives.  So the
op is flagged as being a candidate for the warning.  Then when op.c
has the op tree available, it examines it to see whether the heuristic
may have been a false positive.

This avoids bugs with qw "foo bar baz" and sub calls triggering
the warning.

The source code is no longer available for the warning, so we recon-
struct it from the op tree, skipping the subscript if it is anything
other than a const op.

This means that @hash{$foo} comes out as @hash{...} and @hash{foo} as
@hash{"foo"}.  It also meeans that @hash{"]"} is displayed correctly
instead of as @hash{"].

Commit 95a31aad5 also modified the heuristic for %hash{...} to exempt
qw altogether.  But it did not exempt it if it was preceded by a tab.
So this commit rectifies that.

This commit also improves the false positive detection by exempting
any ops returning lists that can get past toke.c’s heuristic.  I went
through the entire list of ops, but I may have missed some.

Also, @ slices on the lhs of = are exempt, as they change the context
and are hence actually useful.

1 files changed, 58 insertions, 51 deletions

diff --git a/perly.act b/perly.act
index 67596ca2a9..f6e1365c64 100644
--- a/perly.act
+++ b/perly.act
@@ -1422,13 +1422,16 @@ case 2:
 				    newLISTOP(OP_ASLICE, 0,
 					list((ps[(3) - (4)].val.opval)),
 					ref((ps[(1) - (4)].val.opval), OP_ASLICE)));
+			  if ((yyval.opval) && (ps[(1) - (4)].val.opval))
+			      (yyval.opval)->op_private |=
+				  (ps[(1) - (4)].val.opval)->op_private & OPpSLICEWARNING;
 			  TOKEN_GETMAD((ps[(2) - (4)].val.i_tkval),(yyval.opval),'[');
 			  TOKEN_GETMAD((ps[(4) - (4)].val.i_tkval),(yyval.opval),']');
 			;}
     break;
 
   case 176:
-#line 1208 "perly.y"
+#line 1211 "perly.y"
     { (yyval.opval) = op_prepend_elem(OP_KVASLICE,
 				newOP(OP_PUSHMARK, 0),
 				    newLISTOP(OP_KVASLICE, 0,
@@ -1443,12 +1446,15 @@ case 2:
     break;
 
   case 177:
-#line 1220 "perly.y"
+#line 1223 "perly.y"
     { (yyval.opval) = op_prepend_elem(OP_HSLICE,
 				newOP(OP_PUSHMARK, 0),
 				    newLISTOP(OP_HSLICE, 0,
 					list((ps[(3) - (5)].val.opval)),
 					ref(oopsHV((ps[(1) - (5)].val.opval)), OP_HSLICE)));
+			  if ((yyval.opval) && (ps[(1) - (5)].val.opval))
+			      (yyval.opval)->op_private |=
+				  (ps[(1) - (5)].val.opval)->op_private & OPpSLICEWARNING;
 			    PL_parser->expect = XOPERATOR;
 			  TOKEN_GETMAD((ps[(2) - (5)].val.i_tkval),(yyval.opval),'{');
 			  TOKEN_GETMAD((ps[(4) - (5)].val.i_tkval),(yyval.opval),';');
@@ -1457,7 +1463,7 @@ case 2:
     break;
 
   case 178:
-#line 1231 "perly.y"
+#line 1237 "perly.y"
     { (yyval.opval) = op_prepend_elem(OP_KVHSLICE,
 				newOP(OP_PUSHMARK, 0),
 				    newLISTOP(OP_KVHSLICE, 0,
@@ -1474,17 +1480,17 @@ case 2:
     break;
 
   case 179:
-#line 1245 "perly.y"
+#line 1251 "perly.y"
     { (yyval.opval) = (ps[(1) - (1)].val.opval); ;}
     break;
 
   case 180:
-#line 1247 "perly.y"
+#line 1253 "perly.y"
     { (yyval.opval) = newUNOP(OP_ENTERSUB, 0, scalar((ps[(1) - (1)].val.opval))); ;}
     break;
 
   case 181:
-#line 1249 "perly.y"
+#line 1255 "perly.y"
     { (yyval.opval) = newUNOP(OP_ENTERSUB, OPf_STACKED, scalar((ps[(1) - (3)].val.opval)));
 			  TOKEN_GETMAD((ps[(2) - (3)].val.i_tkval),(yyval.opval),'(');
 			  TOKEN_GETMAD((ps[(3) - (3)].val.i_tkval),(yyval.opval),')');
@@ -1492,7 +1498,7 @@ case 2:
     break;
 
   case 182:
-#line 1254 "perly.y"
+#line 1260 "perly.y"
     {
 			  (yyval.opval) = newUNOP(OP_ENTERSUB, OPf_STACKED,
 				op_append_elem(OP_LIST, (ps[(3) - (4)].val.opval), scalar((ps[(1) - (4)].val.opval))));
@@ -1508,7 +1514,7 @@ case 2:
     break;
 
   case 183:
-#line 1267 "perly.y"
+#line 1273 "perly.y"
     { (yyval.opval) = newUNOP(OP_ENTERSUB, OPf_STACKED,
 			    op_append_elem(OP_LIST, (ps[(3) - (3)].val.opval), scalar((ps[(2) - (3)].val.opval))));
 			  TOKEN_GETMAD((ps[(1) - (3)].val.i_tkval),(yyval.opval),'o');
@@ -1516,7 +1522,7 @@ case 2:
     break;
 
   case 184:
-#line 1272 "perly.y"
+#line 1278 "perly.y"
     { (yyval.opval) = newOP(IVAL((ps[(1) - (1)].val.i_tkval)), OPf_SPECIAL);
 			    PL_hints |= HINT_BLOCK_SCOPE;
 			  TOKEN_GETMAD((ps[(1) - (1)].val.i_tkval),(yyval.opval),'o');
@@ -1524,74 +1530,74 @@ case 2:
     break;
 
   case 185:
-#line 1277 "perly.y"
+#line 1283 "perly.y"
     { (yyval.opval) = newLOOPEX(IVAL((ps[(1) - (2)].val.i_tkval)),(ps[(2) - (2)].val.opval));
 			  TOKEN_GETMAD((ps[(1) - (2)].val.i_tkval),(yyval.opval),'o');
 			;}
     break;
 
   case 186:
-#line 1281 "perly.y"
+#line 1287 "perly.y"
     { (yyval.opval) = newUNOP(OP_NOT, 0, scalar((ps[(2) - (2)].val.opval)));
 			  TOKEN_GETMAD((ps[(1) - (2)].val.i_tkval),(yyval.opval),'o');
 			;}
     break;
 
   case 187:
-#line 1285 "perly.y"
+#line 1291 "perly.y"
     { (yyval.opval) = newOP(IVAL((ps[(1) - (1)].val.i_tkval)), 0);
 			  TOKEN_GETMAD((ps[(1) - (1)].val.i_tkval),(yyval.opval),'o');
 			;}
     break;
 
   case 188:
-#line 1289 "perly.y"
+#line 1295 "perly.y"
     { (yyval.opval) = newUNOP(IVAL((ps[(1) - (2)].val.i_tkval)), 0, (ps[(2) - (2)].val.opval));
 			  TOKEN_GETMAD((ps[(1) - (2)].val.i_tkval),(yyval.opval),'o');
 			;}
     break;
 
   case 189:
-#line 1293 "perly.y"
+#line 1299 "perly.y"
     { (yyval.opval) = newUNOP(IVAL((ps[(1) - (2)].val.i_tkval)), 0, (ps[(2) - (2)].val.opval));
 			  TOKEN_GETMAD((ps[(1) - (2)].val.i_tkval),(yyval.opval),'o');
 			;}
     break;
 
   case 190:
-#line 1297 "perly.y"
+#line 1303 "perly.y"
     { (yyval.opval) = newOP(OP_REQUIRE, (ps[(1) - (1)].val.i_tkval) ? OPf_SPECIAL : 0);
 			  TOKEN_GETMAD((ps[(1) - (1)].val.i_tkval),(yyval.opval),'o');
 			;}
     break;
 
   case 191:
-#line 1301 "perly.y"
+#line 1307 "perly.y"
     { (yyval.opval) = newUNOP(OP_REQUIRE, (ps[(1) - (2)].val.i_tkval) ? OPf_SPECIAL : 0, (ps[(2) - (2)].val.opval));
 			  TOKEN_GETMAD((ps[(1) - (2)].val.i_tkval),(yyval.opval),'o');
 			;}
     break;
 
   case 192:
-#line 1305 "perly.y"
+#line 1311 "perly.y"
     { (yyval.opval) = newUNOP(OP_ENTERSUB, OPf_STACKED, scalar((ps[(1) - (1)].val.opval))); ;}
     break;
 
   case 193:
-#line 1307 "perly.y"
+#line 1313 "perly.y"
     { (yyval.opval) = newUNOP(OP_ENTERSUB, OPf_STACKED,
 			    op_append_elem(OP_LIST, (ps[(2) - (2)].val.opval), scalar((ps[(1) - (2)].val.opval)))); ;}
     break;
 
   case 194:
-#line 1310 "perly.y"
+#line 1316 "perly.y"
     { (yyval.opval) = newOP(IVAL((ps[(1) - (1)].val.i_tkval)), 0);
 			  TOKEN_GETMAD((ps[(1) - (1)].val.i_tkval),(yyval.opval),'o');
 			;}
     break;
 
   case 195:
-#line 1314 "perly.y"
+#line 1320 "perly.y"
     { (yyval.opval) = newOP(IVAL((ps[(1) - (3)].val.i_tkval)), 0);
 			  TOKEN_GETMAD((ps[(1) - (3)].val.i_tkval),(yyval.opval),'o');
 			  TOKEN_GETMAD((ps[(2) - (3)].val.i_tkval),(yyval.opval),'(');
@@ -1600,12 +1606,12 @@ case 2:
     break;
 
   case 196:
-#line 1320 "perly.y"
+#line 1326 "perly.y"
     { (yyval.opval) = (ps[(1) - (1)].val.opval); ;}
     break;
 
   case 197:
-#line 1322 "perly.y"
+#line 1328 "perly.y"
     { (yyval.opval) = (ps[(1) - (3)].val.opval);
 			  TOKEN_GETMAD((ps[(2) - (3)].val.i_tkval),(yyval.opval),'(');
 			  TOKEN_GETMAD((ps[(3) - (3)].val.i_tkval),(yyval.opval),')');
@@ -1613,13 +1619,13 @@ case 2:
     break;
 
   case 198:
-#line 1327 "perly.y"
+#line 1333 "perly.y"
     { (yyval.opval) = newUNOP(OP_ENTERSUB, OPf_STACKED,
 				scalar((ps[(1) - (1)].val.opval))); ;}
     break;
 
   case 199:
-#line 1330 "perly.y"
+#line 1336 "perly.y"
     { (yyval.opval) = (IVAL((ps[(1) - (3)].val.i_tkval)) == OP_NOT)
 			    ? newUNOP(IVAL((ps[(1) - (3)].val.i_tkval)), 0, newSVOP(OP_CONST, 0, newSViv(0)))
 			    : newOP(IVAL((ps[(1) - (3)].val.i_tkval)), OPf_SPECIAL);
@@ -1631,7 +1637,7 @@ case 2:
     break;
 
   case 200:
-#line 1339 "perly.y"
+#line 1345 "perly.y"
     { (yyval.opval) = newUNOP(IVAL((ps[(1) - (4)].val.i_tkval)), 0, (ps[(3) - (4)].val.opval));
 			  TOKEN_GETMAD((ps[(1) - (4)].val.i_tkval),(yyval.opval),'o');
 			  TOKEN_GETMAD((ps[(2) - (4)].val.i_tkval),(yyval.opval),'(');
@@ -1640,7 +1646,7 @@ case 2:
     break;
 
   case 201:
-#line 1345 "perly.y"
+#line 1351 "perly.y"
     {
 			    if (   (ps[(1) - (1)].val.opval)->op_type != OP_TRANS
 			        && (ps[(1) - (1)].val.opval)->op_type != OP_TRANSR
@@ -1654,7 +1660,7 @@ case 2:
     break;
 
   case 202:
-#line 1356 "perly.y"
+#line 1362 "perly.y"
     { (yyval.opval) = pmruntime((ps[(1) - (5)].val.opval), (ps[(4) - (5)].val.opval), 1, (ps[(2) - (5)].val.ival));
 			  TOKEN_GETMAD((ps[(3) - (5)].val.i_tkval),(yyval.opval),'(');
 			  TOKEN_GETMAD((ps[(5) - (5)].val.i_tkval),(yyval.opval),')');
@@ -1662,7 +1668,7 @@ case 2:
     break;
 
   case 205:
-#line 1363 "perly.y"
+#line 1369 "perly.y"
     {
 			  (yyval.opval) = newLISTOP(OP_DIE, 0, newOP(OP_PUSHMARK, 0),
 				newSVOP(OP_CONST, 0, newSVpvs("Unimplemented")));
@@ -1671,7 +1677,7 @@ case 2:
     break;
 
   case 207:
-#line 1373 "perly.y"
+#line 1379 "perly.y"
     { (yyval.opval) = my_attrs((ps[(2) - (3)].val.opval),(ps[(3) - (3)].val.opval));
 			  DO_MAD(
 			      token_getmad((ps[(1) - (3)].val.i_tkval),(yyval.opval),'d');
@@ -1682,14 +1688,14 @@ case 2:
     break;
 
   case 208:
-#line 1381 "perly.y"
+#line 1387 "perly.y"
     { (yyval.opval) = localize((ps[(2) - (2)].val.opval),IVAL((ps[(1) - (2)].val.i_tkval)));
 			  TOKEN_GETMAD((ps[(1) - (2)].val.i_tkval),(yyval.opval),'d');
 			;}
     break;
 
   case 209:
-#line 1388 "perly.y"
+#line 1394 "perly.y"
     { (yyval.opval) = sawparens((ps[(2) - (3)].val.opval));
 			  TOKEN_GETMAD((ps[(1) - (3)].val.i_tkval),(yyval.opval),'(');
 			  TOKEN_GETMAD((ps[(3) - (3)].val.i_tkval),(yyval.opval),')');
@@ -1697,7 +1703,7 @@ case 2:
     break;
 
   case 210:
-#line 1393 "perly.y"
+#line 1399 "perly.y"
     { (yyval.opval) = sawparens(newNULLLIST());
 			  TOKEN_GETMAD((ps[(1) - (2)].val.i_tkval),(yyval.opval),'(');
 			  TOKEN_GETMAD((ps[(2) - (2)].val.i_tkval),(yyval.opval),')');
@@ -1705,68 +1711,69 @@ case 2:
     break;
 
   case 211:
-#line 1398 "perly.y"
+#line 1404 "perly.y"
     { (yyval.opval) = (ps[(1) - (1)].val.opval); ;}
     break;
 
   case 212:
-#line 1400 "perly.y"
+#line 1406 "perly.y"
     { (yyval.opval) = (ps[(1) - (1)].val.opval); ;}
     break;
 
   case 213:
-#line 1402 "perly.y"
+#line 1408 "perly.y"
     { (yyval.opval) = (ps[(1) - (1)].val.opval); ;}
     break;
 
   case 214:
-#line 1407 "perly.y"
+#line 1413 "perly.y"
     { (yyval.opval) = (OP*)NULL; ;}
     break;
 
   case 215:
-#line 1409 "perly.y"
+#line 1415 "perly.y"
     { (yyval.opval) = (ps[(1) - (1)].val.opval); ;}
     break;
 
   case 216:
-#line 1413 "perly.y"
+#line 1419 "perly.y"
     { (yyval.opval) = (OP*)NULL; ;}
     break;
 
   case 217:
-#line 1415 "perly.y"
+#line 1421 "perly.y"
     { (yyval.opval) = (ps[(1) - (1)].val.opval); ;}
     break;
 
   case 218:
-#line 1421 "perly.y"
+#line 1427 "perly.y"
     { PL_parser->in_my = 0; (yyval.opval) = my((ps[(1) - (1)].val.opval)); ;}
     break;
 
   case 219:
-#line 1425 "perly.y"
+#line 1431 "perly.y"
     { (yyval.opval) = newCVREF(IVAL((ps[(1) - (2)].val.i_tkval)),(ps[(2) - (2)].val.opval));
 			  TOKEN_GETMAD((ps[(1) - (2)].val.i_tkval),(yyval.opval),'&');
 			;}
     break;
 
   case 220:
-#line 1431 "perly.y"
+#line 1437 "perly.y"
     { (yyval.opval) = newSVREF((ps[(2) - (2)].val.opval));
 			  TOKEN_GETMAD((ps[(1) - (2)].val.i_tkval),(yyval.opval),'$');
 			;}
     break;
 
   case 221:
-#line 1437 "perly.y"
+#line 1443 "perly.y"
     { (yyval.opval) = newAVREF((ps[(2) - (2)].val.opval));
+			  if ((yyval.opval)) (yyval.opval)->op_private |= IVAL((ps[(1) - (2)].val.i_tkval));
 			  TOKEN_GETMAD((ps[(1) - (2)].val.i_tkval),(yyval.opval),'@');
 			;}
     break;
 
   case 222:
-#line 1443 "perly.y"
+#line 1450 "perly.y"
     { (yyval.opval) = newHVREF((ps[(2) - (2)].val.opval));
 			  if ((yyval.opval)) (yyval.opval)->op_private |= IVAL((ps[(1) - (2)].val.i_tkval));
 			  TOKEN_GETMAD((ps[(1) - (2)].val.i_tkval),(yyval.opval),'%');
@@ -1774,36 +1781,36 @@ case 2:
     break;
 
   case 223:
-#line 1450 "perly.y"
+#line 1457 "perly.y"
     { (yyval.opval) = newAVREF((ps[(2) - (2)].val.opval));
 			  TOKEN_GETMAD((ps[(1) - (2)].val.i_tkval),(yyval.opval),'l');
 			;}
     break;
 
   case 224:
-#line 1456 "perly.y"
+#line 1463 "perly.y"
     { (yyval.opval) = newGVREF(0,(ps[(2) - (2)].val.opval));
 			  TOKEN_GETMAD((ps[(1) - (2)].val.i_tkval),(yyval.opval),'*');
 			;}
     break;
 
   case 225:
-#line 1463 "perly.y"
+#line 1470 "perly.y"
     { (yyval.opval) = scalar((ps[(1) - (1)].val.opval)); ;}
     break;
 
   case 226:
-#line 1465 "perly.y"
+#line 1472 "perly.y"
     { (yyval.opval) = scalar((ps[(1) - (1)].val.opval)); ;}
     break;
 
   case 227:
-#line 1467 "perly.y"
+#line 1474 "perly.y"
     { (yyval.opval) = op_scope((ps[(1) - (1)].val.opval)); ;}
     break;
 
   case 228:
-#line 1470 "perly.y"
+#line 1477 "perly.y"
     { (yyval.opval) = (ps[(1) - (1)].val.opval); ;}
     break;
 
@@ -1814,6 +1821,6 @@ case 2:
     
 
 /* Generated from:
- * 80609b739b642fa427503886445869dfd47021624a1977b902211b38043ed9f1 perly.y
+ * 5b290f371f373fb17e073f602c676e436e9d457a1d4db67d192e3cfa0eeb36d7 perly.y
  * 5c9d2a0262457fe9b70073fc8ad6c188f812f38ad57712b7e2f53daa01b297cc regen_perly.pl
  * ex: set ro: */