code review feedback

src/EditorFeatures/Test2/IntelliSense/CSharpCompletionCommandHandlerTests.vb

@@ -3066,28 +3066,6 @@ class C
             Using New CultureContext(New CultureInfo("tr-TR", useUserOverride:=False))
                 Using state = TestStateFactory.CreateCSharpTestState(
                                <Document><![CDATA[
-        class İFADE {}
-        class ifTest {}
-        class C
-        {
-            void goo(int x)
-            {
-              İFADE ifade = null;
-                $$]]></Document>, extraExportedTypes:={GetType(CSharpEditorFormattingService)}.ToList())
-                    state.SendTypeChars("if")
-                    Await state.WaitForAsynchronousOperationsAsync()
-                    Await state.AssertSelectedCompletionItem("if")
-                End Using
-            End Using
-
-        End Function
-
-        <WorkItem(29938, "https://github.com/dotnet/roslyn/issues/29938")>
-        <WpfFact, Trait(Traits.Feature, Traits.Features.Completion)>
-        Public Async Function TestMatchWithTurkishIWorkaround6() As Task
-            Using New CultureContext(New CultureInfo("tr-TR", useUserOverride:=False))
-                Using state = TestStateFactory.CreateCSharpTestState(
-                               <Document><![CDATA[
         class TARİFE { }
         class C
         {
@@ -3104,7 +3082,7 @@ class C
 
         <WorkItem(29938, "https://github.com/dotnet/roslyn/issues/29938")>
         <WpfFact, Trait(Traits.Feature, Traits.Features.Completion)>
-        Public Async Function TestMatchWithTurkishIWorkaround7() As Task
+        Public Async Function TestMatchWithTurkishIWorkaround6() As Task
             Using New CultureContext(New CultureInfo("tr-TR", useUserOverride:=False))
                 Using state = TestStateFactory.CreateCSharpTestState(
                                <Document><![CDATA[
@@ -3125,7 +3103,7 @@ class C
 
         <WorkItem(29938, "https://github.com/dotnet/roslyn/issues/29938")>
         <WpfFact, Trait(Traits.Feature, Traits.Features.Completion)>
-        Public Async Function TestMatchWithTurkishIWorkaround8() As Task
+        Public Async Function TestMatchWithTurkishIWorkaround7() As Task
             Using New CultureContext(New CultureInfo("tr-TR", useUserOverride:=False))
                 Using state = TestStateFactory.CreateCSharpTestState(
                                <Document><![CDATA[
@@ -3146,7 +3124,7 @@ class C
 
         <WorkItem(29938, "https://github.com/dotnet/roslyn/issues/29938")>
         <WpfFact, Trait(Traits.Feature, Traits.Features.Completion)>
-        Public Async Function TestMatchWithTurkishIWorkaround9() As Task
+        Public Async Function TestMatchWithTurkishIWorkaround8() As Task
             Using New CultureContext(New CultureInfo("tr-TR", useUserOverride:=False))
                 Using state = TestStateFactory.CreateCSharpTestState(
                                <Document><![CDATA[
@@ -3168,7 +3146,7 @@ class C
 
         <WorkItem(29938, "https://github.com/dotnet/roslyn/issues/29938")>
         <WpfFact, Trait(Traits.Feature, Traits.Features.Completion)>
-        Public Async Function TestMatchWithTurkishIWorkaround10() As Task
+        Public Async Function TestMatchWithTurkishIWorkaround9() As Task
             Using New CultureContext(New CultureInfo("tr-TR", useUserOverride:=False))
                 Using state = TestStateFactory.CreateCSharpTestState(
                                <Document><![CDATA[

src/Features/Core/Portable/Completion/CompletionHelper.cs

@@ -87,7 +87,11 @@ public bool MatchesPattern(string text, string pattern, CultureInfo culture)
             var patternMatcher = GetPatternMatcher(pattern, culture, includeMatchSpans);
             var match = patternMatcher.GetFirstMatch(completionItemText);
 
-            if (culture.Equals(EnUSCultureInfo))
+            // We still have making checks for language having different to English capitalization,
+            // for example, for Turkish with dotted and dotless i capitalization totally diferent from English.
+            // Now we escaping from the second check for English languages.
+            // Maybe we can escape as well for more similar languages in case if we meet performance issues.
+            if (culture.ThreeLetterWindowsLanguageName.Equals(EnUSCultureInfo.ThreeLetterWindowsLanguageName))
             {
                 return match;
             }