util,readline: NFC-normalize strings before getStringWidth

The assumption here is that decomposed characters render like their
composed character equivalents, and that working with the former
comes with a risk of over-estimating string widths given that
we compute them on a per-code-point basis. The regression test
added here (한글 vs 한글) is an example of that happening.
PR-URL: #33052
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: addaleax

lib/internal/util/inspect.js

@@ -1917,6 +1917,13 @@ function formatWithOptionsInternal(inspectOptions, ...args) {
 returnstr;
 }
 
+functionprepareStringForGetStringWidth(str,removeControlChars){
+str=str.normalize('NFC');
+if(removeControlChars)
+str=stripVTControlCharacters(str);
+returnstr;
+}
+
 if(internalBinding('config').hasIntl){
 consticu=internalBinding('icu');
 // icu.getStringWidth(string, ambiguousAsFullWidth, expandEmojiSequence)
@@ -1926,8 +1933,8 @@ if (internalBinding('config').hasIntl) {
 // the receiving end supports.
 getStringWidth=functiongetStringWidth(str,removeControlChars=true){
 letwidth=0;
-if(removeControlChars)
-str=stripVTControlCharacters(str);
+
+str=prepareStringForGetStringWidth(str,removeControlChars);
 for(leti=0;i<str.length;i++){
 // Try to avoid calling into C++ by first handling the ASCII portion of
 // the string. If it is fully ASCII, we skip the C++ part.
@@ -1947,9 +1954,7 @@ if (internalBinding('config').hasIntl) {
 getStringWidth=functiongetStringWidth(str,removeControlChars=true){
 letwidth=0;
 
-if(removeControlChars)
-str=stripVTControlCharacters(str);
-
+str=prepareStringForGetStringWidth(str,removeControlChars);
 for(constcharofstr){
 constcode=char.codePointAt(0);
 if(isFullWidthCodePoint(code)){

test/parallel/test-icu-stringwidth.js

@@ -87,3 +87,12 @@ for (let i = 0; i < 256; i++) {
 assert.strictEqual(getStringWidth(char),1);
 }
 }
+
+{
+consta='한글'.normalize('NFD');// 한글
+constb='한글'.normalize('NFC');// 한글
+assert.strictEqual(a.length,6);
+assert.strictEqual(b.length,2);
+assert.strictEqual(getStringWidth(a),4);
+assert.strictEqual(getStringWidth(b),4);
+}