object.c: make String#to_f consistent with literal

* object.c (rb_cstr_to_dbl): stop at successive underscores, as
  well as Float literals.  [ruby-core:80098] [Bug #13105]

  * `_` should be within digits
  * only one `_` allowed between digits

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57979 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

object.c

@@ -2870,15 +2870,10 @@ rb_cstr_to_dbl(const char *p, int badcheck)
 	while (p < end && n < e) prev = *n++ = *p++;
 	while (*p) {
 	    if (*p == '_') {
-		/* remove underscores between digits */
-		if (badcheck) {
-		    if (n == buf || !ISDIGIT(prev)) goto bad;
-		    ++p;
-		    if (!ISDIGIT(*p)) goto bad;
-		}
-		else {
-		    while (*++p == '_');
-		    continue;
+		/* remove an underscore between digits */
+		if (n == buf || !ISDIGIT(prev) || (++p, !ISDIGIT(*p))) {
+		    if (badcheck) goto bad;
+		    break;
 		}
 	    }
 	    prev = *p++;

test/ruby/test_float.rb

@@ -755,6 +755,12 @@ class TestFloat < Test::Unit::TestCase
   def test_Float
     assert_in_delta(0.125, Float("0.1_2_5"), 0.00001)
     assert_in_delta(0.125, "0.1_2_5__".to_f, 0.00001)
+    assert_in_delta(0.0, "0_.125".to_f, 0.00001)
+    assert_in_delta(0.0, "0._125".to_f, 0.00001)
+    assert_in_delta(0.1, "0.1__2_5".to_f, 0.00001)
+    assert_in_delta(0.1, "0.1_e10".to_f, 0.00001)
+    assert_in_delta(0.1, "0.1e_10".to_f, 0.00001)
+    assert_in_delta(1.0, "0.1e1__0".to_f, 0.00001)
     assert_equal(1, suppress_warning {Float(([1] * 10000).join)}.infinite?)
     assert_not_predicate(Float(([1] * 10000).join("_")), :infinite?) # is it really OK?
     assert_raise(ArgumentError) { Float("1.0\x001") }