awk: fix 'delete array[var--]' decrementing var twice

function                                             old     new   delta
evaluate                                            3395    3390      -5

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 50 insertions, 23 deletions

diff --git a/editors/awk.c b/editors/awk.c
index d40c7816a..8f523ea28 100644
--- a/editors/awk.c
+++ b/editors/awk.c
@@ -2514,6 +2514,32 @@ static var *evaluate(node *op, var *res)
                 op1 = op->l.n;
                 debug_printf_eval("opinfo:%08x opn:%08x\n", opinfo, opn);
 
+                /* "delete" is special:
+                 * "delete array[var--]" must evaluate index expr only once,
+                 * must not evaluate it in "execute inevitable things" part.
+                 */
+                if (XC(opinfo & OPCLSMASK) == XC(OC_DELETE)) {
+                        uint32_t info = op1->info & OPCLSMASK;
+                        var *v;
+
+                        debug_printf_eval("DELETE\n");
+                        if (info == OC_VAR) {
+                                v = op1->l.v;
+                        } else if (info == OC_FNARG) {
+                                v = &fnargs[op1->l.aidx];
+                        } else {
+                                syntax_error(EMSG_NOT_ARRAY);
+                        }
+                        if (op1->r.n) { /* array ref? */
+                                const char *s;
+                                s = getvar_s(evaluate(op1->r.n, v1));
+                                hash_remove(iamarray(v), s);
+                        } else {
+                                clear_array(iamarray(v));
+                        }
+                        goto next;
+                }
+
                 /* execute inevitable things */
                 if (opinfo & OF_RES1)
                         L.v = evaluate(op1, v1);
@@ -2621,28 +2647,7 @@ static var *evaluate(node *op, var *res)
                         break;
                 }
 
-                case XC( OC_DELETE ): {
-                        uint32_t info = op1->info & OPCLSMASK;
-                        var *v;
-
-                        if (info == OC_VAR) {
-                                v = op1->l.v;
-                        } else if (info == OC_FNARG) {
-                                v = &fnargs[op1->l.aidx];
-                        } else {
-                                syntax_error(EMSG_NOT_ARRAY);
-                        }
-
-                        if (op1->r.n) {
-                                const char *s;
-                                clrvar(L.v);
-                                s = getvar_s(evaluate(op1->r.n, v1));
-                                hash_remove(iamarray(v), s);
-                        } else {
-                                clear_array(iamarray(v));
-                        }
-                        break;
-                }
+                /* case XC( OC_DELETE ): - moved to happen before arg evaluation */
 
                 case XC( OC_NEWSOURCE ):
                         g_progname = op->l.new_progname;
@@ -2666,12 +2671,14 @@ static var *evaluate(node *op, var *res)
                 /* -- recursive node type -- */
 
                 case XC( OC_VAR ):
+                        debug_printf_eval("VAR\n");
                         L.v = op->l.v;
                         if (L.v == intvar[NF])
                                 split_f0();
                         goto v_cont;
 
                 case XC( OC_FNARG ):
+                        debug_printf_eval("FNARG[%d]\n", op->l.aidx);
                         L.v = &fnargs[op->l.aidx];
  v_cont:
                         res = op->r.n ? findvar(iamarray(L.v), R.s) : L.v;
@@ -3035,7 +3042,8 @@ static var *evaluate(node *op, var *res)
 
                 default:
                         syntax_error(EMSG_POSSIBLE_ERROR);
-                }
+                } /* switch */
+ next:
                 if ((opinfo & OPCLSMASK) <= SHIFT_TIL_THIS)
                         op = op->a.n;
                 if ((opinfo & OPCLSMASK) >= RECUR_FROM_THIS)
diff --git a/testsuite/awk.tests b/testsuite/awk.tests
index 82937bc10..ad0583afb 100755
--- a/testsuite/awk.tests
+++ b/testsuite/awk.tests
@@ -261,6 +261,25 @@ end d
 " \
         "" ""
 
+prg='
+BEGIN{
+cnt = 0
+a[cnt] = "zeroth"
+a[++cnt] = "first"
+delete a[cnt--]
+print cnt
+print "[0]:" a[0]
+print "[1]:" a[1]
+}'
+testing "awk 'delete a[v--]' evaluates v-- once" \
+        "awk '$prg'" \
+        "\
+0
+[0]:zeroth
+[1]:
+" \
+        "" ""
+
 testing "awk handles empty ()" \
         "awk 'BEGIN {print()}' 2>&1" "awk: cmd. line:1: Empty sequence\n" "" ""