Merge pull request #2134 from svaarala/fix-plus-minus-number-coercion…

…-gh2019

Fix +'+' and +'-' coercion to NaN instead of 0

RELEASES.rst

@@ -3472,6 +3472,8 @@ Planned
  caused an error and Duktape.errCreate returned a callable value (such
  as Float64Array); this caused an assertion failure (GH-2061, GH-2087)
 
+* Fix coercion of +'+' and +'-' to NaN instead of 0 (GH-2019, GH-2134)
+
 * Fix possible out-of-memory in call stack unwind by preallocating the
  environment property table on creation (GH-476, GH-2021, GH-2106)
 

src-input/duk_js_ops.c

@@ -146,7 +146,8 @@ DUK_INTERNAL duk_bool_t duk_js_toboolean(duk_tval *tv) {
  * ("0x123") and infinities
  *
  * - Unlike source code literals, ToNumber() coerces empty strings
- * and strings with only whitespace to zero (not NaN).
+ * and strings with only whitespace to zero (not NaN). However,
+ * while '' coerces to 0, '+' and '-' coerce to NaN.
  */
 
 /* E5 Section 9.3.1 */

src-input/duk_numconv.c

@@ -2090,10 +2090,17 @@ DUK_INTERNAL void duk_numconv_parse(duk_hthread *thr, duk_small_int_t radix, duk
  goto parse_fail;
  }
  } else {
- /* empty ("") is allowed in some formats (e.g. Number(''), as zero */
+ /* Empty ("") is allowed in some formats (e.g. Number(''), as zero,
+ * but it must not have a leading +/- sign (GH-2019). Note that
+ * for Number(), h_str is already trimmed so we can check for zero
+ * length and still get Number(' + ') == NaN.
+ */
  if ((flags & DUK_S2N_FLAG_ALLOW_EMPTY_AS_ZERO) == 0) {
  DUK_DDD(DUK_DDDPRINT("parse failed: empty string not allowed (as zero)"));
  goto parse_fail;
+ } else if (DUK_HSTRING_GET_BYTELEN(h_str) != 0) {
+ DUK_DDD(DUK_DDDPRINT("parse failed: no digits, but not empty (had a +/- sign)"));
+ goto parse_fail;
  }
  }
  } else {

tests/ecmascript/test-bug-plus-coercion-gh2019.js

@@ -0,0 +1,73 @@
+/*
+ * https://github.com/svaarala/duktape/issues/2019
+ */
+
+/*===
+NaN
+NaN
+0
+Infinity
+0
+-Infinity
+0
+NaN
+NaN
+0
+Infinity
+0
+-Infinity
+0
+NaN
+NaN
+0
+-Infinity
+0
+Infinity
+0
+NaN
+NaN
+0
+-Infinity
+0
+Infinity
+0
+done
+===*/
+
+try {
+ print(+'+');
+ print(+'-');
+ print(+'+0');
+ print(1 / +'+0');
+ print(+'-0');
+ print(1 / +'-0');
+ print(+'');
+
+ print(+' + ');
+ print(+' - ');
+ print(+' +0 ');
+ print(1 / +' +0 ');
+ print(+' -0 ');
+ print(1 / +' -0 ');
+ print(+' ');
+
+ print(-'+');
+ print(-'-');
+ print(-'+0');
+ print(1 / -'+0');
+ print(-'-0');
+ print(1 / -'-0');
+ print(-'');
+
+ print(-' + ');
+ print(-' - ');
+ print(-' +0 ');
+ print(1 / -' +0 ');
+ print(-' -0 ');
+ print(1 / -' -0 ');
+ print(-' ');
+} catch (e) {
+ print(e.stack || e);
+}
+
+print('done');