Remove IsGlyphFullWidth from InputBuffer

src/host/inputBuffer.cpp

@@ -10,7 +10,6 @@
 #include "misc.h"
 #include "stream.h"
 #include "../interactivity/inc/ServiceLocator.hpp"
-#include "../types/inc/GlyphWidth.hpp"
 
 #define INPUT_BUFFER_DEFAULT_INPUT_MODE (ENABLE_LINE_INPUT | ENABLE_PROCESSED_INPUT | ENABLE_ECHO_INPUT | ENABLE_MOUSE_INPUT)
 
@@ -804,13 +803,9 @@ bool InputBuffer::_CoalesceEvent(const INPUT_RECORD& inEvent) noexcept
  (lastKey.wVirtualScanCode == inKey.wVirtualScanCode || WI_IsFlagSet(inKey.dwControlKeyState, NLS_IME_CONVERSION)) &&
  lastKey.uChar.UnicodeChar == inKey.uChar.UnicodeChar &&
  lastKey.dwControlKeyState == inKey.dwControlKeyState &&
- // TODO:GH#8000 This behavior is an import from old conhost v1 and has been broken for decades.
- // This is probably the outdated idea that any wide glyph is being represented by 2 characters (DBCS) and likely
- // resulted from conhost originally being split into a ASCII/OEM and a DBCS variant with preprocessor flags.
- // You can't update the repeat count of such a A,B pair, because they're stored as A,A,B,B (down-down, up-up).
- // I believe the proper approach is to store pairs of characters as pairs, update their combined
- // repeat count and only when they're being read de-coalesce them into their alternating form.
- !IsGlyphFullWidth(inKey.uChar.UnicodeChar))
+ // A single repeat count cannot represent two INPUT_RECORDs simultaneously,
+ // and so it cannot represent a surrogate pair either.
+ !til::is_surrogate(inKey.uChar.UnicodeChar))
  {
  lastKey.wRepeatCount += inKey.wRepeatCount;
  return true;

src/host/ut_host/InputBufferTests.cpp

@@ -219,22 +219,19 @@ class InputBufferTests
  }
  }
 
- TEST_METHOD(InputBufferDoesNotCoalesceFullWidthChars)
+ TEST_METHOD(InputBufferDoesNotCoalesceSurrogatePairs)
  {
  InputBuffer inputBuffer;
- WCHAR hiraganaA = 0x3042; // U+3042 hiragana A
- auto record = MakeKeyEvent(true, 1, hiraganaA, 0, hiraganaA, 0);
 
- // send a bunch of identical events
- inputBuffer.Flush();
- for (size_t i = 0; i < RECORD_INSERT_COUNT; ++i)
- {
- VERIFY_IS_GREATER_THAN(inputBuffer.Write(record), 0u);
- VERIFY_ARE_EQUAL(inputBuffer._storage.back(), record);
- }
+ // U+1F44D thumbs up emoji
+ inputBuffer.Write(MakeKeyEvent(true, 1, 0xD83D, 0, 0xD83D, 0));
+ inputBuffer.Write(MakeKeyEvent(true, 1, 0xDC4D, 0, 0xDC4D, 0));
+
+ // Should not coalese despite otherwise matching perfectly.
+ inputBuffer.Write(MakeKeyEvent(true, 1, 0xDC4D, 0, 0xDC4D, 0));
 
  // The events shouldn't be coalesced
- VERIFY_ARE_EQUAL(inputBuffer.GetNumberOfReadyEvents(), RECORD_INSERT_COUNT);
+ VERIFY_ARE_EQUAL(inputBuffer.GetNumberOfReadyEvents(), 3);
  }
 
  TEST_METHOD(CanFlushAllOutput)