Fix parsing of for (( )) loops.

We weren't properly accounting for spaces in the conditions.

This was caught by a 'bashdb' source file with an empty initial
condition.

Added tests.

osh/word_parse.py

@@ -846,33 +846,38 @@ def ReadDParen(self):
 
     return anode
 
+  def _NextNonSpace(self):
+    """Same logic as _ReadWord, but for ReadForExpresion."""
+    while True:
+      self._Next(lex_mode_e.ARITH)
+      self._Peek()
+      if self.token_kind not in (Kind.Ignored, Kind.WS):
+        break
+
   def ReadForExpression(self):
     """Read ((i=0; i<5; ++i)) -- part of command context."""
-    # No PushHint because we're in arith state.
-    #self.lexer.PushHint(Id.Op_RParen, Id.Op_DRightParen)
-
-    self._Next(lex_mode_e.ARITH)  # skip over ((
+    self._NextNonSpace()  # skip over ((
 
     self._Peek()
     if self.token_type == Id.Arith_Semi:  # for (( ; i < 10; i++ ))
       init_node = None
     else:
       init_node = self._ReadArithExpr(do_next=False)
-    self._Next(lex_mode_e.ARITH)
+    self._NextNonSpace()
 
     self._Peek()
     if self.token_type == Id.Arith_Semi:  # for (( ; ; i++ ))
       cond_node = None
     else:
       cond_node = self._ReadArithExpr(do_next=False)
-    self._Next(lex_mode_e.ARITH)
+    self._NextNonSpace()
 
     self._Peek()
     if self.token_type == Id.Arith_RParen:  # for (( ; ; ))
       update_node = None
     else:
       update_node = self._ReadArithExpr(do_next=False)
-    self._Next(lex_mode_e.ARITH)
+    self._NextNonSpace()
 
     self._Peek()
     if self.token_type != Id.Arith_RParen:

spec/for-expr.test.sh

@@ -14,23 +14,22 @@ do
     break
   fi
   echo $a
-done  # A construct borrowed from ksh93.
+done
 ## status: 0
 ## STDOUT:
 1
 2
 4
 5
-## N-I mksh status: 1
-## N-I mksh stdout-json: ""
+## END
 
 #### For loop with and without semicolon
 for ((a=1; a <= 3; a++)); do
   echo $a
-done  # A construct borrowed from ksh93.
+done
 for ((a=1; a <= 3; a++)) do
   echo $a
-done  # A construct borrowed from ksh93.
+done
 ## status: 0
 ## STDOUT:
 1
@@ -39,21 +38,46 @@ done  # A construct borrowed from ksh93.
 1
 2
 3
-## N-I mksh status: 1
-## N-I mksh stdout-json: ""
+## END
 
-#### For loop with empty head
+#### Empty init
+i=1
+for ((  ;i < 4;  i++ )); do
+  echo $i
+done
+## status: 0
+## STDOUT:
+1
+2
+3
+## END
+
+#### Empty init and cond
+i=1
+for ((  ; ;  i++ )); do
+  if test $i = 4; then
+    break
+  fi
+  echo $i
+done
+## status: 0
+## STDOUT:
+1
+2
+3
+## END
+
+#### Infinite loop with ((;;))
 a=1
-for ((;;)); do
+for ((  ;  ;  )); do
   if test $a = 4; then
     break
   fi
   echo $((a++))
-done  # A construct borrowed from ksh93.
+done
 ## status: 0
 ## STDOUT:
 1
 2
 3
-## N-I mksh status: 1
-## N-I mksh stdout-json: ""
+## END

test/spec.sh

@@ -591,7 +591,7 @@ let() {
 
 for-expr() {
   sh-spec spec/for-expr.test.sh \
-    $MKSH $BASH $OSH "$@"
+    $BASH $ZSH $OSH "$@"
 }
 
 empty-bodies() {