[osh-language] Do additional type checks for arithmetic.

Fixes unhandled Python exception with +, etc.

osh/expr_eval.py

@@ -521,6 +521,12 @@ def Eval(self, node, int_coerce=True):
       if op_id == Id.Arith_Comma:
         return rhs
 
+      # Do additional type checking after indexing and comma.
+      if not isinstance(lhs, int):
+        e_die('LHS should be an integer, got %s', lhs)
+      if not isinstance(rhs, int):
+        e_die('RHS should be an integer, got %s', rhs)
+
       if op_id == Id.Arith_Plus:
         return lhs + rhs
       if op_id == Id.Arith_Minus:

spec/arith.test.sh

@@ -130,7 +130,7 @@ echo "[$undef1][$undef2]"
 ## stdout: [1][1]
 ## N-I dash stdout: [][]
 
-#### Increment and decrement array
+#### Increment and decrement array elements
 shopt -u strict-arith || true
 a=(5 6 7 8)
 (( a[0]++, ++a[1], a[2]--, --a[3] ))
@@ -393,3 +393,25 @@ echo [$a]
 []
 ## END
 ## OK bash status: 0
+
+#### Can't add integer to indexed array
+declare -a array=(1 2 3)
+echo $((array + 5))
+## status: 1
+## stdout-json: ""
+## BUG bash status: 0
+## BUG bash STDOUT:
+6
+## END
+## N-I dash status: 2
+
+#### Can't add integer to associative array
+typeset -A assoc
+assoc[0]=42
+echo $((assoc + 5))
+## status: 1
+## stdout-json: ""
+## BUG bash/mksh/zsh status: 0
+## BUG bash/mksh/zsh stdout: 47
+## BUG dash status: 0
+## BUG dash stdout: 5

spec/assoc.test.sh

@@ -195,7 +195,10 @@ a["aa"]=b
 a["foo"]=bar
 a['a+1']=c
 echo "${a[a+1]}"
-## stdout: c
+## stdout-json: ""
+## status: 1
+## BUG bash stdout: c
+## BUG bash status: 0
 
 #### lookup by unquoted string as arithmetic
 

test/spec.sh

@@ -575,7 +575,7 @@ append() {
 
 # associative array -- mksh and zsh implement different associative arrays.
 assoc() {
-  sh-spec spec/assoc.test.sh --osh-failures-allowed 9 \
+  sh-spec spec/assoc.test.sh --osh-failures-allowed 8 \
     $BASH $OSH_LIST "$@"
 }