dc: execute shouldn't pop if stack head is not a string

This matches the behaviour of both GNU dc (as specified in
its man page), and BSD dc (where stack_popstring() pops
only if the head is a string.)

Add a couple of tests to verify this behavior.

function                                             old     new   delta
zxc_vm_process                                      6882    6884      +2

Signed-off-by: Brian Foley <bpfoley@google.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/testsuite/dc.tests b/testsuite/dc.tests
index 8c3af4156..f74e3f0f5 100755
--- a/testsuite/dc.tests
+++ b/testsuite/dc.tests
@@ -44,6 +44,16 @@ testing "dc complex without spaces (multiple args)" \
 optional FEATURE_DC_BIG
 # All tests below depend on FEATURE_DC_BIG
 
+testing "dc: x should execute strings" \
+        "dc -e'[40 2 +] x f'" \
+        "42\n" \
+        "" ""
+
+testing "dc: x should not execute or pop non-strings" \
+        "dc -e'42 x f'" \
+        "42\n" \
+        "" ""
+
 testing "dc read" \
         "dc -finput" \
         "2\n9\n1\n" \