[word_eval] Implement 'shopt -s compat_array'.

osh/sh_expr_eval.py

@@ -331,7 +331,7 @@ def _EvalLhsAndLookupArith(self, node):
     # BASH_LINENO, etc.
     if val.tag_() in (value_e.MaybeStrArray, value_e.AssocArray) and lval.tag_() == lvalue_e.Named:
       named_lval = cast(lvalue__Named, lval)
-      if word_eval.CheckCompatArray(named_lval.name):
+      if word_eval.CheckCompatArray(named_lval.name, self.exec_opts):
         val = word_eval.ResolveCompatArray(val)
 
     # This error message could be better, but we already have one
@@ -358,7 +358,7 @@ def EvalToInt(self, node):
     # BASH_LINENO, etc.
     if val.tag_() in (value_e.MaybeStrArray, value_e.AssocArray) and node.tag_() == arith_expr_e.VarRef:
       tok = cast(Token, node)
-      if word_eval.CheckCompatArray(tok.val):
+      if word_eval.CheckCompatArray(tok.val, self.exec_opts):
         val = word_eval.ResolveCompatArray(val)
 
     # TODO: Can we avoid the runtime cost of adding location info?

osh/word_eval.py

@@ -61,9 +61,9 @@
 # For compatibility, ${BASH_SOURCE} and ${BASH_SOURCE[@]} are both valid.
 # ${FUNCNAME} and ${BASH_LINENO} are also the same type of of special variables.
 _STRING_AND_ARRAY = ['BASH_SOURCE', 'FUNCNAME', 'BASH_LINENO']
-def CheckCompatArray(var_name):
-  # type: (str) -> bool
-  return var_name in _STRING_AND_ARRAY
+def CheckCompatArray(var_name, opts):
+  # type: (str, optview.Exec) -> bool
+  return opts.compat_array() or var_name in _STRING_AND_ARRAY
 
 def ResolveCompatArray(val):
   # type: (value_t) -> value_t
@@ -990,7 +990,7 @@ def _EvalBracedVarSub(self, part, part_vals, quoted):
           # ${array@a} is a string
           # TODO: An IR for ${} might simplify these lengthy conditions
           pass
-        elif CheckCompatArray(var_name):
+        elif CheckCompatArray(var_name, self.exec_opts):
           # for ${BASH_SOURCE}, etc.
           val = ResolveCompatArray(val)
         else:
@@ -1219,7 +1219,7 @@ def _EvalSimpleVarSub(self, token, part_vals, quoted):
       # TODO: Special case for LINENO
       val = self.mem.GetVar(var_name)
       if val.tag_() in (value_e.MaybeStrArray, value_e.AssocArray):
-        if CheckCompatArray(var_name):
+        if CheckCompatArray(var_name, self.exec_opts):
           # for $BASH_SOURCE, etc.
           val = ResolveCompatArray(val)
         else: