shell: handle $((NUM++...) like bash does. Closes 10706

function                                             old     new   delta
evaluate_string                                      680     729     +49

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

4 files changed, 20 insertions, 6 deletions

diff --git a/shell/ash_test/ash-arith/arith-postinc.right b/shell/ash_test/ash-arith/arith-postinc.right
new file mode 100644
index 000000000..c95ce02bf
--- /dev/null
+++ b/shell/ash_test/ash-arith/arith-postinc.right
@@ -0,0 +1,5 @@
+1 1
+1 1
+1 1
+1 1
+Ok:0
diff --git a/shell/ash_test/ash-arith/arith-postinc.tests b/shell/ash_test/ash-arith/arith-postinc.tests
new file mode 100755
index 000000000..3fd9bfed5
--- /dev/null
+++ b/shell/ash_test/ash-arith/arith-postinc.tests
@@ -0,0 +1,5 @@
+echo 1 $((0++1))
+echo 1 $((0--1))
+x=-1; echo 1 $((0-$x))
+x=+1; echo 1 $((0+$x))
+echo Ok:$?
diff --git a/shell/ash_test/ash-arith/arith.right b/shell/ash_test/ash-arith/arith.right
index 9b9ca8e2f..6936f1269 100644
--- a/shell/ash_test/ash-arith/arith.right
+++ b/shell/ash_test/ash-arith/arith.right
@@ -126,6 +126,10 @@ ghi
 ./arith2.sub: line 5: arithmetic syntax error
 5 5
 1 1
+6 6
+2 2
+3 3
+1 1
 4 4
 0 0
 ./arith2.sub: line 42: arithmetic syntax error
diff --git a/shell/ash_test/ash-arith/arith2.sub b/shell/ash_test/ash-arith/arith2.sub
index f7e3c9235..9105059db 100755
--- a/shell/ash_test/ash-arith/arith2.sub
+++ b/shell/ash_test/ash-arith/arith2.sub
@@ -23,14 +23,14 @@
 echo 5 $(( 4 + ++a ))
 echo 1 $a
 
-# ash doesn't handle it right...
-#ash# echo 6 $(( 4+++a ))
-#ash# echo 2 $a
+# this is treated as 4 + ++a
+echo 6 $(( 4+++a ))
+echo 2 $a
       a=2
 
-# ash doesn't handle it right...
-#ash# echo 3 $(( 4---a ))
-#ash# echo 1 $a
+# this is treated as 4 - --a
+echo 3 $(( 4---a ))
+echo 1 $a
       a=1
 
 echo 4 $(( 4 - -- a ))