PATCH Re: 5.0.8 regression regarding $() in arithmetic for-loops

[Bart Schaefer <schaefer@brasslantern.com>]

This turns out to be a recursive-descent parsing error, we weren't saving
enough state when entering command substitution from inside math parsing.

I'm not sure whether the "infor" stuff is actually necessary but it seemed
to make sense.  The real meat is dbparens = 0 when leaving math context.


diff --git a/Src/lex.c b/Src/lex.c
index b0cd963..70f3d14 100644
--- a/Src/lex.c
+++ b/Src/lex.c
@@ -1388,7 +1388,7 @@ dquote_parse(char endchar, int sub)
 {
     int pct = 0, brct = 0, bct = 0, intick = 0, err = 0;
     int c;
-    int math = endchar == ')' || endchar == ']';
+    int math = endchar == ')' || endchar == ']' || infor;
     int zlemath = math && zlemetacs > zlemetall + addedx - inbufct;
 
     while (((c = hgetc()) != endchar || bct ||
@@ -1995,8 +1995,10 @@ skipcomm(void)
 #else
     char *new_tokstr;
     int new_lexstop, new_lex_add_raw;
+    int save_infor = infor;
     struct lexbufstate new_lexbuf;
 
+    infor = 0;
     cmdpush(CS_CMDSUBST);
     SETPARBEGIN
     add(Inpar);
@@ -2065,6 +2067,7 @@ skipcomm(void)
      * the recursive parsing.
      */
     lexflags &= ~LEXFLAGS_ZLE;
+    dbparens = 0;	/* restored by zcontext_restore_partial() */
 
     if (!parse_event(OUTPAR) || tok != OUTPAR)
 	lexstop = 1;
@@ -2111,6 +2114,7 @@ skipcomm(void)
     if (!lexstop)
 	SETPAREND
     cmdpop();
+    infor = save_infor;
 
     return lexstop;
 #endif
diff --git a/Test/A01grammar.ztst b/Test/A01grammar.ztst
index 59f87fa..7eedfa6 100644
--- a/Test/A01grammar.ztst
+++ b/Test/A01grammar.ztst
@@ -182,6 +182,12 @@
 >1
 >2
 
+  for (( $(true); ; )); do break; done
+  for (( ; $(true); )); do break; done
+  for (( ; ; $(true) )); do break; done
+  for (( ; $((1)); )); do break; done
+0:regression test, nested cmdsubst in arithmetic `for' loop
+
   for keyvar valvar in key1 val1 key2 val2; do
      print key=$keyvar val=$valvar
   done