[osh-language] Decay arrays to strings for indirect expansion

- For string ref '*' which is like $*
- For string ref 'a[*]' which is like ${a[*]}

Preparing to address issue #964

osh/word_eval.py

@@ -612,9 +612,9 @@ def _ApplyTestOp(self,
     else:
       raise NotImplementedError(tok.id)
 
-  def _EvalIndirectArrayExpansion(self, name, index):
+  def _EvalIndirectArrayExpansion(self, name, index, box):
     # type: (str, str) -> Optional[value_t]
-    """Expands ${!ref} when $ref has the form `name[index]`.
+    """Expands ${!ref} when $ref has the form 'name[index]'.
 
     Args:
       name, index: arbitrary strings
@@ -636,9 +636,13 @@ def _EvalIndirectArrayExpansion(self, name, index):
 
       elif case(value_e.MaybeStrArray):
         val = cast(value__MaybeStrArray, UP_val)
-        if index in ('@', '*'):
-          # TODO: maybe_decay_array
+        if index == '@':
+          return value.MaybeStrArray(val.strs)
+
+        elif index == '*':
+          box[0] = True  # maybe_decay_array
           return value.MaybeStrArray(val.strs)
+
         try:
           index_num = int(index)
         except ValueError:
@@ -734,8 +738,8 @@ def _Keys(self, val, token):
       else:
         raise AssertionError()
 
-  def _IndirectExpansion(self, val, token):
-    # type: (value_t, Token) -> value_t
+  def _IndirectExpansion(self, val, token, box):
+    # type: (value_t, Token, List[bool]) -> value_t
     """Handles indirect expansion ${!var} and ${!a[0]}."""
     UP_val = val
     with tagswitch(val) as case:
@@ -754,8 +758,11 @@ def _IndirectExpansion(self, val, token):
         except ValueError:
           pass
 
-        if val.s in ('@', '*'):
-          # TODO: maybe_decay_array
+        if val.s == '@':
+          return value.MaybeStrArray(self.mem.GetArgv())
+
+        elif val.s == '*':
+          box[0] = True  # maybe_decay_array
           return value.MaybeStrArray(self.mem.GetArgv())
 
         if 1:
@@ -765,7 +772,7 @@ def _IndirectExpansion(self, val, token):
           if i >= 0 and val.s[-1] == ']':
             name = val.s[:i]
             index = val.s[i+1:-1]
-            result = self._EvalIndirectArrayExpansion(name, index)
+            result = self._EvalIndirectArrayExpansion(name, index, box)
             if result is not None:
               return result
 
@@ -1266,7 +1273,10 @@ def _EvalBracedVarSub(self, part, part_vals, quoted):
         else:
           # Process ${!ref}.  SURPRISE: ${!a[0]} is an indirect expansion unlike
           # ${!a[@]} !
-          val = self._IndirectExpansion(val, part.token)
+          box = [False]
+          val = self._IndirectExpansion(val, part.token, box)
+          if box[0]:
+            maybe_decay_array = True
 
           if not suffix_is_test:  # undef -> '' AFTER indirection
             val = self._EmptyStrOrError(val, part.token)

spec/var-ref.test.sh

@@ -118,7 +118,7 @@ ref1=one
 ref2=two
 ## END
 
-#### var ref with 1 and @ and *
+#### var ref: 1, @, *
 set -- x y
 ref=1; argv.py "${!ref}"
 ref=@; argv.py "${!ref}"
@@ -247,8 +247,8 @@ f() {
 f a[0]
 b=(x y)
 f b[0]
-f b[@]
-f "b[*]"
+f 'b[@]'
+f 'b[*]'
 # Also associative arrays.
 ## STDOUT:
 ['']

test/spec.sh

@@ -729,7 +729,7 @@ nocasematch-match() {
 # ${!var} syntax -- oil should replace this with associative arrays.
 # mksh has completely different behavior for this syntax.  Not worth testing.
 var-ref() {
-  sh-spec spec/var-ref.test.sh --osh-failures-allowed 4 \
+  sh-spec spec/var-ref.test.sh --osh-failures-allowed 2 \
     $BASH $OSH_LIST "$@"
 }