46079: Ignore double quotes in math expressions.

Treat as white space.

This is required for compatibility and previously had no use in zsh
as it generated an error.

Author: Peter Stephenson

ChangeLog

@@ -1,3 +1,8 @@
+2020-06-22  Peter Stephenson  <p.stephenson@samsung.com>
+
+	* 46079: Src/math.c, Test/C01arith.ztst: Ignore double quotes in
+	math expression: treat as white space.
+
 2020-06-22  Manuel Jacob  <me@manueljacob.de>
 
 	* 46091: Doc/Zsh/contrib.yo,

Src/math.c

@@ -831,6 +831,8 @@ zzlex(void)
 	case ' ': /* Fall through! */
 	case '\t':
 	case '\n':
+	case '"': /* POSIX says ignore these */
+	case Dnull:
 	    break;
 	default:
 	    if (idigit(*--ptr) || *ptr == '.')

Test/C01arith.ztst

@@ -180,9 +180,10 @@
 1:bases beyond 36 don't work
 ?(eval):1: invalid base (must be 2 to 36 inclusive): 37
 
+  fail=39
   print $(( 3 + "fail" ))
-1:parse failure in arithmetic
-?(eval):1: bad math expression: operand expected at `"fail" '
+0:Double quotes are not treated specially in arithmetic
+>42
 
   alias 3=echo
   print $(( 3 + "OK"); echo "Worked")
@@ -487,3 +488,8 @@
   let noexist==0 )
 1:Arithmetic, NO_UNSET part 3
 ?(eval):2: noexist: parameter not set
+
+  print $(( "6+2" / "1+3" ))
+0:Double quotes are not treated specially in arithmetic (POSIX)
+# and do not do grouping!  this is 6 + (2/1) + 3
+>11