From e8af6134a1eb292b97819e12a899747571af8b0c Mon Sep 17 00:00:00 2001
From: Michael Dyck <jmdyck@ibiblio.org>
Date: Mon, 19 Jul 2021 11:22:53 -0700
Subject: [PATCH 1/2] Editorial: Remove ToNumber's note re surrogates (#1554)

The note says that "the result of ToNumber will be *NaN*
if the string contains any [surrogate] code units,
whether paired or unpaired."

However, if Unicode were to define a non-BMP code point
with General_Category=Zs, that would qualify as <USP>
and thus WhiteSpace and StrWhiteSpaceChar, in which case
the note would be rendered false. That is, the ToNumber
procedure would continue to work, and would result in
non-NaN values for some strings containing surrogates.

(And if you think that the ES spec doesn't need to concern itself
with such future possibilities, note that ES 6 (2015) changed/clarified
the semantics of String.p.trim et al for precisely this case,
to say how they would deal with non-BMP white space.)

Given that the note could be invalidated by a future
edition of Unicode, I think it's a bit risky to keep it in.
---
 spec.html | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/spec.html b/spec.html
index c61653bf38..ac02a6a2df 100644
--- a/spec.html
+++ b/spec.html
@@ -4831,9 +4831,6 @@ <h1>
       <emu-clause id="sec-tonumber-applied-to-the-string-type">
         <h1>ToNumber Applied to the String Type</h1>
         <p>ToNumber applied to Strings applies the following grammar to the input String interpreted as a sequence of UTF-16 encoded code points (<emu-xref href="#sec-ecmascript-language-types-string-type"></emu-xref>). If the grammar cannot interpret the String as an expansion of |StringNumericLiteral|, then the result of ToNumber is *NaN*.</p>
-        <emu-note>
-          <p>The terminal symbols of this grammar are all composed of characters in the Unicode Basic Multilingual Plane (BMP). Therefore, the result of ToNumber will be *NaN* if the string contains any <emu-xref href="#leading-surrogate"></emu-xref> or <emu-xref href="#trailing-surrogate"></emu-xref> code units, whether paired or unpaired.</p>
-        </emu-note>
         <h2>Syntax</h2>
         <emu-grammar type="definition">
           StringNumericLiteral :::

From 37d6204945862d0a1379e771b1352a1eb158618e Mon Sep 17 00:00:00 2001
From: Michael Dyck <jmdyck@ibiblio.org>
Date: Mon, 19 Jul 2021 11:23:04 -0700
Subject: [PATCH 2/2] Editorial: Define + use StringToNumber (#1554)

Introduce the abstract operation StringToNumber
to replace the prose that expressed the procedure
for applying ToNumber to String values.
---
 spec.html | 24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/spec.html b/spec.html
index ac02a6a2df..cb67acb432 100644
--- a/spec.html
+++ b/spec.html
@@ -4793,7 +4793,7 @@ <h1>
               String
             </td>
             <td>
-              See grammar and conversion algorithm below.
+              Return ! StringToNumber(_argument_).
             </td>
           </tr>
           <tr>
@@ -4830,7 +4830,7 @@ <h1>
 
       <emu-clause id="sec-tonumber-applied-to-the-string-type">
         <h1>ToNumber Applied to the String Type</h1>
-        <p>ToNumber applied to Strings applies the following grammar to the input String interpreted as a sequence of UTF-16 encoded code points (<emu-xref href="#sec-ecmascript-language-types-string-type"></emu-xref>). If the grammar cannot interpret the String as an expansion of |StringNumericLiteral|, then the result of ToNumber is *NaN*.</p>
+        <p>The abstract operation StringToNumber specifies how to convert a String value to a Number value, using the following grammar.</p>
         <h2>Syntax</h2>
         <emu-grammar type="definition">
           StringNumericLiteral :::
@@ -4884,9 +4884,27 @@ <h2>Syntax</h2>
           </ul>
         </emu-note>
 
+        <emu-clause id="sec-stringtonumber" type="abstract operation">
+          <h1>
+            StringToNumber (
+              _str_: a String,
+            )
+          </h1>
+          <dl class="header">
+            <dt>description</dt>
+            <dd>It returns a Number.</dd>
+          </dl>
+          <emu-alg>
+            1. Let _text_ be ! StringToCodePoints(_str_).
+            1. Let _literal_ be ParseText(_text_, |StringNumericLiteral|).
+            1. If _literal_ is a List of errors, return *NaN*.
+            1. Return StringNumericValue of _literal_.
+          </emu-alg>
+        </emu-clause>
+
         <emu-clause id="sec-runtime-semantics-stringnumericvalue" type="sdo" aoid="StringNumericValue" oldids="sec-runtime-semantics-mv-s">
           <h1>Runtime Semantics: StringNumericValue</h1>
-          <p>The conversion of a String to a Number value is similar overall to the determination of the Number value for a numeric literal (see <emu-xref href="#sec-literals-numeric-literals"></emu-xref>), but some of the details are different, so the process for converting a String numeric literal to a value of the Number type is given here.</p>
+          <p>The conversion of a |StringNumericLiteral| to a Number value is similar overall to the determination of the NumericValue of a |NumericLiteral| (see <emu-xref href="#sec-literals-numeric-literals"></emu-xref>), but some of the details are different.</p>
           <emu-grammar>StringNumericLiteral ::: StrWhiteSpace?</emu-grammar>
           <emu-alg>
             1. Return *+0*<sub>𝔽</sub>.