[macOS] Entering text at a cursor position is broken when using some non-English language inputs

[blono]

Steps to Reproduce

1. Run git clone https://github.com/blono/flutter_test_field_test.git (I really wanted to name it test_field_text, but it's mistakenly named test_field_test...😭)
2. Run cd flutter_test_field_test
3. Run flutter run -d macos
4. See attached movie

flutter_text_field_bug.mov

flutter doctor -v
[✓] Flutter (Channel master, 2.1.0-11.0.pre.180, on macOS 11.2.3 20D91
    darwin-x64, locale ja-JP)
    • Flutter version 2.1.0-11.0.pre.180 at /usr/local/flutter
    • Framework revision be8989f185 (3 hours ago), 2021-03-09 23:31:02 -0800
    • Engine revision 7764b5c55f
    • Dart version 2.13.0 (build 2.13.0-116.0.dev)

[✗] Android toolchain - develop for Android devices
    ✗ Unable to locate Android SDK.
      Install Android Studio from:
      https://developer.android.com/studio/index.html
      On first launch it will assist you in installing the Android SDK
      components.
      (or visit https://flutter.dev/docs/get-started/install/macos#android-setup
      for detailed instructions).
      If the Android SDK has been installed to a custom location, please use
      `flutter config --android-sdk` to update to that location.


[✓] Xcode - develop for iOS and macOS
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 12.4, Build version 12D4e
    • CocoaPods version 1.10.0

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[!] Android Studio (not installed)
    • Android Studio not found; download from
      https://developer.android.com/studio/index.html
      (or visit https://flutter.dev/docs/get-started/install/macos#android-setup
      for detailed instructions).

[✓] VS Code (version 1.54.1)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.20.0

[✓] Connected device (2 available)
    • macOS (desktop) • macos  • darwin-x64     • macOS 11.2.3 20D91 darwin-x64
    • Chrome (web)    • chrome • web-javascript • Google Chrome 89.0.4389.82

! Doctor found issues in 2 categories.

[blono]

This bug has been occurring for about a month now, though I can't remember it very well.
It was working fine a couple of months ago.

[TahaTesser]

Hi @blono
Thanks for filing the issue, I can reproduce with Japanese and Arabic as well and sometimes with Korean too, tested tons of times to be sure

dev and master

Screen.Recording.2021-03-10.at.6.43.04.PM.mov

stable and beta　(input style a little bit different here when using the method on macOS, first you type then hit the return key to insert text) but no issue when testing

flutter doctor -v

[✓] Flutter (Channel stable, 2.0.1, on macOS 11.2.3 20D91 darwin-x64, locale
    en-GB)
    • Flutter version 2.0.1 at /Users/tahatesser/Code/flutter_stable
    • Framework revision c5a4b4029c (6 days ago), 2021-03-04 09:47:48 -0800
    • Engine revision 40441def69
    • Dart version 2.12.0

[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
    • Android SDK at /Volumes/Extreme/SDK
    • Platform android-30, build-tools 30.0.3
    • ANDROID_HOME = /Volumes/Extreme/SDK
    • Java binary at: /Applications/Android
      Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build
      1.8.0_242-release-1644-b3-6915495)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS
    • Xcode at /Volumes/Extreme/Xcode.app/Contents/Developer
    • Xcode 12.4, Build version 12D4e
    • CocoaPods version 1.10.1

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 4.1)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build
      1.8.0_242-release-1644-b3-6915495)

[✓] VS Code (version 1.54.1)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.20.0

[✓] Connected device (4 available)
    • SM M025F (mobile)    • R9ZR205XX0A               • android-arm    •
      Android 10 (API 29)
    • Taha’s iPad (mobile) • 00008020-000255113EE8402E • ios            • iOS
      14.4.1
    • macOS (desktop)      • macos                     • darwin-x64     • macOS
      11.2.3 20D91 darwin-x64
    • Chrome (web)         • chrome                    • web-javascript • Google
      Chrome 89.0.4389.82
    ! Error: Taha’s iPad is busy: Copying cache files from device. Xcode will
      continue when Taha’s iPad is finished. (code -10)

• No issues found!

[✓] Flutter (Channel beta, 2.0.1, on macOS 11.2.3 20D91 darwin-x64, locale
    en-GB)
    • Flutter version 2.0.1 at /Users/tahatesser/Code/flutter_beta
    • Framework revision c5a4b4029c (6 days ago), 2021-03-04 09:47:48 -0800
    • Engine revision 40441def69
    • Dart version 2.12.0

[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
    • Android SDK at /Volumes/Extreme/SDK
    • Platform android-30, build-tools 30.0.3
    • ANDROID_HOME = /Volumes/Extreme/SDK
    • Java binary at: /Applications/Android
      Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build
      1.8.0_242-release-1644-b3-6915495)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS
    • Xcode at /Volumes/Extreme/Xcode.app/Contents/Developer
    • Xcode 12.4, Build version 12D4e
    • CocoaPods version 1.10.1

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 4.1)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build
      1.8.0_242-release-1644-b3-6915495)

[✓] VS Code (version 1.54.1)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.20.0

[✓] Connected device (4 available)
    • SM M025F (mobile)    • R9ZR205XX0A               • android-arm    •
      Android 10 (API 29)
    • Taha’s iPad (mobile) • 00008020-000255113EE8402E • ios            • iOS
      14.4.1
    • macOS (desktop)      • macos                     • darwin-x64     • macOS
      11.2.3 20D91 darwin-x64
    • Chrome (web)         • chrome                    • web-javascript • Google
      Chrome 89.0.4389.82
    ! Error: Taha’s iPad is busy: Copying cache files from device. Xcode will
      continue when Taha’s iPad is finished. (code -10)

• No issues found!

[✓] Flutter (Channel dev, 2.1.0-10.0.pre, on macOS 11.2.3 20D91 darwin-x64,
    locale en-GB)
    • Flutter version 2.1.0-10.0.pre at /Users/tahatesser/Code/flutter_dev
    • Framework revision cc9b78fc5c (13 days ago), 2021-02-25 13:26:03 -0800
    • Engine revision a252ec09b7
    • Dart version 2.13.0 (build 2.13.0-77.0.dev)

[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
    • Android SDK at /Volumes/Extreme/SDK
    • Platform android-30, build-tools 30.0.3
    • ANDROID_HOME = /Volumes/Extreme/SDK
    • Java binary at: /Applications/Android
      Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build
      1.8.0_242-release-1644-b3-6915495)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS
    • Xcode at /Volumes/Extreme/Xcode.app/Contents/Developer
    • Xcode 12.4, Build version 12D4e
    • CocoaPods version 1.10.1

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 4.1)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build
      1.8.0_242-release-1644-b3-6915495)

[✓] VS Code (version 1.54.1)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.20.0

[✓] Connected device (4 available)
    • SM M025F (mobile)    • R9ZR205XX0A               • android-arm    •
      Android 10 (API 29)
    • Taha’s iPad (mobile) • 00008020-000255113EE8402E • ios            • iOS
      14.4.1
    • macOS (desktop)      • macos                     • darwin-x64     • macOS
      11.2.3 20D91 darwin-x64
    • Chrome (web)         • chrome                    • web-javascript • Google
      Chrome 89.0.4389.82
    ! Error: Taha’s iPad is busy: Copying cache files from device. Xcode will
      continue when Taha’s iPad is finished. (code -10)

• No issues found!

[✓] Flutter (Channel master, 2.1.0-11.0.pre.180, on macOS 11.2.3 20D91
    darwin-x64, locale en-GB)
    • Flutter version 2.1.0-11.0.pre.180 at
      /Users/tahatesser/Code/flutter_master
    • Framework revision be8989f185 (6 hours ago), 2021-03-09 23:31:02 -0800
    • Engine revision 7764b5c55f
    • Dart version 2.13.0 (build 2.13.0-116.0.dev)

[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
    • Android SDK at /Volumes/Extreme/SDK
    • Platform android-30, build-tools 30.0.3
    • ANDROID_HOME = /Volumes/Extreme/SDK
    • Java binary at: /Applications/Android
      Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build
      1.8.0_242-release-1644-b3-6915495)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS
    • Xcode at /Volumes/Extreme/Xcode.app/Contents/Developer
    • Xcode 12.4, Build version 12D4e
    • CocoaPods version 1.10.1

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 4.1)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build
      1.8.0_242-release-1644-b3-6915495)

[✓] VS Code (version 1.54.1)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.20.0

[✓] Connected device (4 available)
    • SM M025F (mobile)    • R9ZR205XX0A               • android-arm    •
      Android 10 (API 29)
    • Taha’s iPad (mobile) • 00008020-000255113EE8402E • ios            • iOS
      14.4.1
    • macOS (desktop)      • macos                     • darwin-x64     • macOS
      11.2.3 20D91 darwin-x64
    • Chrome (web)         • chrome                    • web-javascript • Google
      Chrome 89.0.4389.82
    ! Error: Taha’s iPad is busy: Copying cache files from device. Xcode will
      continue when Taha’s iPad is finished. (code -10)

• No issues found!

Thank you