[sh-options] Turn strict-arith on by default.

Adjusted spec tests.

This behavior is unsafe/annoying and slightly incompatible with bash.
Consider:

x=foo

- echo $(( x )) turned to 0 in OSH because 'foo' doesn't look like an
  integer.
- echo $(( x )) in bash would be 42 if the variable 'foo' is 42.  It
  happened to be 0 because in many cases 'foo' is undefined.

The user can still 'shopt -u strict-arith', and I've done that in many
of the tests.

osh/expr_eval.py

@@ -36,30 +36,28 @@
 def _StringToInteger(s, span_id=const.NO_INTEGER):
   """Use bash-like rules to coerce a string to an integer.
 
+  Runtime parsing enables silly stuff like $(( $(echo 1)$(echo 2) + 1 )) => 13
+
   0xAB -- hex constant
-  010 -- octable constant
+  042  -- octal constant
+  42   -- decimal constant
   64#z -- arbitary base constant
-  bare word: variable
-  quoted word: string
 
-  Dumb stuff like $(( $(echo 1)$(echo 2) + 1 ))  =>  13  is possible.
+  bare word: variable
+  quoted word: string (not done?)
   """
-  # TODO: In non-strict mode, empty string becomes zero.  In strict mode, it's
-  # a runtime error.
-
   if s.startswith('0x'):
     try:
       integer = int(s, 16)
     except ValueError:
-      # TODO: Show line number
       e_die('Invalid hex constant %r', s, span_id=span_id)
     return integer
 
   if s.startswith('0'):
     try:
       integer = int(s, 8)
     except ValueError:
-      e_die('Invalid octal constant %r', s, span_id=span_id)  # TODO: Show line number
+      e_die('Invalid octal constant %r', s, span_id=span_id)
     return integer
 
   if '#' in s:
@@ -92,7 +90,7 @@ def _StringToInteger(s, span_id=const.NO_INTEGER):
       n *= base
     return integer
 
-  # Plain integer
+  # Normal base 10 integer
   try:
     integer = int(s)
   except ValueError:
@@ -220,13 +218,12 @@ def _ValToArith(self, val, span_id, int_coerce=True):
       if val.tag == value_e.Undef:  # 'nounset' already handled before got here
         # Happens upon a[undefined]=42, which unfortunately turns into a[0]=42.
         #log('blame_word %s   arena %s', blame_word, self.arena)
-        e_die('Coercing undefined value to 0 in arithmetic context',
-              span_id=span_id)
+        e_die('Undefined value in arithmetic context '
+              '(0 if shopt -u strict-arith)', span_id=span_id)
         return 0
 
       if val.tag == value_e.Str:
-        # may raise FatalRuntimeError
-        return _StringToInteger(val.s, span_id=span_id)
+        return _StringToInteger(val.s, span_id=span_id)  # calls e_die
 
       if val.tag == value_e.StrArray:  # array is valid on RHS, but not on left
         return val.strs

osh/state.py

@@ -113,28 +113,22 @@ def Disable(self):
 
     # NOTE: strict-errexit CANNOT be on by default.
     # - some are PARSING:
-    #   - strict-glob-parse
-    #   - strict-backslash-parse
+    #   - strict-glob
+    #   - strict-backslash
     # - some are runtime:
-    #   - strict-arith-eval
+    #   - strict-arith
     #   - strict-word-eval
-    #
-    # Syntax idea:
-    # shopt -s 'strict-*' 2>/dev/null || true
-    # You could apply LooksLikeGlob to the argument and then match it against
-    # SHOPT_OPTION_NAMES.
 
     'strict-argv',  # empty argv not allowed
     'strict-arith',  # string to integer conversions
     'strict-array',  # no implicit conversion between string and array
-    'strict-backslash',  # BadBackslash
     'strict-control-flow',  # break/continue at top level is fatal
     'strict-errexit',  # inherited to command subs, etc.
-    'strict-glob',  # GlobParser
-
-    # strict-arith-eval?
-    # TODO: strict-array could be in here?  And turn it on by default?
     'strict-word-eval',  # negative slices, unicode
+
+    # Not implemented
+    'strict-backslash',  # BadBackslash
+    'strict-glob',  # GlobParser
 )
 
 
@@ -167,10 +161,11 @@ def __init__(self, mem, readline):
 
     # OSH-specific options.
 
-    self.strict_argv = False
-
+    # The only one that's ON by default.
     # e.g. $(( x )) where x doesn't look like integer is fatal
-    self.strict_arith = False
+    self.strict_arith = True
+
+    self.strict_argv = False
 
     # No implicit conversions between string and array.
     # Several problems (not all implemented):

spec/arith.test.sh

@@ -32,8 +32,9 @@ echo $((i+1))
 ## stdout: 2
 
 #### SimpleVarSub within arith
-echo $(($j + 1))
-## stdout: 1
+j=0
+echo $(($j + 42))
+## stdout: 42
 
 #### BracedVarSub within ArithSub
 echo $((${j:-5} + 1))
@@ -68,6 +69,7 @@ echo $((`echo 1` + 2))
 
 #### Invalid string to int
 # bash, mksh, and zsh all treat strings that don't look like numbers as zero.
+shopt -u strict-arith || true
 s=foo
 echo $((s+5))
 ## OK dash stdout-json: ""
@@ -121,13 +123,15 @@ echo $a
 ## N-I dash stdout-json: ""
 
 #### Increment undefined variables
+shopt -u strict-arith || true
 (( undef1++ ))
 (( ++undef2 ))
 echo "[$undef1][$undef2]"
 ## stdout: [1][1]
-## N-I dash stdout-json: "[][]\n"
+## N-I dash stdout: [][]
 
 #### Increment and decrement array
+shopt -u strict-arith || true
 a=(5 6 7 8)
 (( a[0]++, ++a[1], a[2]--, --a[3] ))
 (( undef[0]++, ++undef[1], undef[2]--, --undef[3] ))
@@ -261,7 +265,8 @@ foo=5
 x=oo
 echo $(( foo + f$x + 1 ))
 ## stdout: 11
-## OK osh stdout: 6
+## OK osh stdout-json: ""
+## OK osh status: 1
 
 #### Bizarre recursive name evaluation - result of runtime parse/eval
 foo=5
@@ -270,7 +275,8 @@ spam=bar
 eggs=spam
 echo $((foo+1)) $((bar+1)) $((spam+1)) $((eggs+1))
 ## stdout: 6 6 6 6
-## OK osh stdout: 6 1 1 1
+## OK osh stdout-json: ""
+## OK osh status: 1
 ## N-I dash stdout-json: ""
 ## N-I dash status: 2
 

spec/dbracket.test.sh

@@ -87,15 +87,20 @@ fi
 # http://tldp.org/LDP/abs/html/testconstructs.html#DBLBRACKETS
 
 #### Octal literals with -eq
+shopt -u strict-arith || true
 decimal=15
 octal=017   # = 15 (decimal)
 [[ $decimal -eq $octal ]] && echo true
 [[ $decimal -eq ZZZ$octal ]] || echo false
-## stdout-json: "true\nfalse\n"
+## STDOUT:
+true
+false
+## END
 ## N-I mksh stdout: false
 # mksh doesn't implement this syntax for literals.
 
 #### Hex literals with -eq
+shopt -u strict-arith || true
 decimal=15
 hex=0x0f    # = 15 (decimal)
 [[ $decimal -eq $hex ]] && echo true
@@ -122,10 +127,13 @@ hex=0x0f    # = 15 (decimal)
 
 #### -eq on strings 
 # This is lame behavior: it does a conversion to 0 first for any string
+shopt -u strict-arith || true
 [[ a -eq a ]] && echo true
 [[ a -eq b ]] && echo true
-## stdout-json: "true\ntrue\n"
-## OK bash/mksh stdout-json: "true\ntrue\n"
+## STDOUT: 
+true
+true
+## END
 
 #### [[ compare with literal -f (compare with test-builtin.test.sh)
 var=-f
@@ -214,6 +222,7 @@ true
 ## N-I osh status: 1
 
 #### -eq coercion produces weird results
+shopt -u strict-arith || true
 [[ '' -eq 0 ]] && echo true
 ## stdout: true
 

spec/sh-options.test.sh

@@ -460,7 +460,7 @@ shopt -u all:strict
 show-strict
 ## STDOUT:
 shopt -u strict-argv
-shopt -u strict-arith
+shopt -s strict-arith
 -
 shopt -s strict-argv
 shopt -s strict-arith

spec/strict-options.test.sh

@@ -206,6 +206,7 @@ argv "${undef[@]}"
 ## N-I dash stdout-json: ""
 
 #### automatically creating arrays are INDEXED, not associative
+shopt -u strict-arith || true
 
 undef[2]=x
 undef[3]=y