Merge pull request #9159 from Microsoft/code_completion_escaping

Code completion escaping

src/harness/fourslash.ts

@@ -717,6 +717,8 @@ namespace FourSlash {
         public verifyCompletionEntryDetails(entryName: string, expectedText: string, expectedDocumentation?: string, kind?: string) {
             const details = this.getCompletionEntryDetails(entryName);
 
+            assert(details, "no completion entry available");
+
             assert.equal(ts.displayPartsToString(details.displayParts), expectedText, this.assertionMessageAtLastKnownMarker("completion entry details text"));
 
             if (expectedDocumentation !== undefined) {

src/services/services.ts

@@ -4141,7 +4141,7 @@ namespace ts {
 
                     if (!uniqueNames[name]) {
                         uniqueNames[name] = name;
-                        const displayName = getCompletionEntryDisplayName(name, target, /*performCharacterChecks*/ true);
+                        const displayName = getCompletionEntryDisplayName(unescapeIdentifier(name), target, /*performCharacterChecks*/ true);
                         if (displayName) {
                             const entry = {
                                 name: displayName,

tests/cases/fourslash/codeCompletionEscaping.ts

@@ -0,0 +1,9 @@
+/// <reference path="fourslash.ts" />
+
+// @Filename: a.js
+// @allowJs: true
+////___foo; __foo;/**/
+
+goTo.marker();
+verify.completionListContains("__foo", undefined, undefined, "warning");
+verify.completionListContains("___foo", undefined, undefined, "warning");