Flutter preview device depends on VS debug dlls

[christopherfujino]

When running the dumpbin.exe tool on a compiled flutter_preview.exe to determine dynamically linked dependencies:

PS D:\git\flutter> & "C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.37.32822\bin\Hostx64\x64\dumpbin.exe" /dependents .\bin\cache\artifacts\flutter_preview\flutter_preview.exe
Microsoft (R) COFF/PE Dumper Version 14.37.32825.0
Copyright (C) Microsoft Corporation.  All rights reserved.

Dump of file .\bin\cache\artifacts\flutter_preview\flutter_preview.exe

File Type: EXECUTABLE IMAGE

  Image has the following dependencies:

    dwmapi.dll
    flutter_windows.dll
    KERNEL32.dll
    USER32.dll
    SHELL32.dll
    ole32.dll
    ADVAPI32.dll
    MSVCP140D.dll
    VCRUNTIME140D.dll
    VCRUNTIME140_1D.dll
    ucrtbased.dll

Of these, the following are commonly available on new Windows installation:

• dwmapi.dll
• KERNEL32.dll
• USER32.dll
• SHELL32.dll
• ole32.dll
• ADVAPI32.dll

flutter_windows.dll is explicitly provided by the flutter tool. The following are not part of a new Windows installation, however, and are C/C++ debug libraries:

• MSVCP140D.dll
• VCRUNTIME140D.dll
• VCRUNTIME140_1D.dll
• ucrtbased.dll

The first three of these are distributed with Visual Studio, in a directory marked "debug_nondredist" (see https://learn.microsoft.com/en-us/visualstudio/releases/2022/redistribution#visual-c-runtime-files).

The last, ucrtbased.dll, I found under C:\Program Files (x86)\WIndows Kits\10\bin...

[christopherfujino]

I attempted to link a release build of a Flutter C++ entrypoint to a debug engine, but got the following linker errors:

[        ] "D:\git\tmp\delete_me_flutter\build\windows\x64\INSTALL.vcxproj" (default target) (1) ->
[        ] "D:\git\tmp\delete_me_flutter\build\windows\x64\ALL_BUILD.vcxproj" (default target) (3) ->
[        ] "D:\git\tmp\delete_me_flutter\build\windows\x64\runner\delete_me_flutter.vcxproj" (default target) (4) ->
[        ] (Link target) ->
[        ]   flutter_wrapper_app.lib(core_implementations.obj) : error LNK2001: unresolved external symbol __imp__invalid_parameter [D:\git\tmp\delete_me_flutter\build\windows\x64\runner\delete_me_flutter.vcxproj]
[        ]   flutter_window.obj : error LNK2001: unresolved external symbol __imp__invalid_parameter [D:\git\tmp\delete_me_flutter\build\windows\x64\runner\delete_me_flutter.vcxproj]
[        ]   main.obj : error LNK2001: unresolved external symbol __imp__invalid_parameter [D:\git\tmp\delete_me_flutter\build\windows\x64\runner\delete_me_flutter.vcxproj]
[        ]   utils.obj : error LNK2001: unresolved external symbol __imp__invalid_parameter [D:\git\tmp\delete_me_flutter\build\windows\x64\runner\delete_me_flutter.vcxproj]
[        ]   flutter_wrapper_app.lib(flutter_engine.obj) : error LNK2001: unresolved external symbol __imp__invalid_parameter [D:\git\tmp\delete_me_flutter\build\windows\x64\runner\delete_me_flutter.vcxproj]
[        ]   flutter_wrapper_app.lib(core_implementations.obj) : error LNK2001: unresolved external symbol __imp__CrtDbgReport [D:\git\tmp\delete_me_flutter\build\windows\x64\runner\delete_me_flutter.vcxproj]
[        ]   flutter_window.obj : error LNK2001: unresolved external symbol __imp__CrtDbgReport [D:\git\tmp\delete_me_flutter\build\windows\x64\runner\delete_me_flutter.vcxproj]
[        ]   main.obj : error LNK2001: unresolved external symbol __imp__CrtDbgReport [D:\git\tmp\delete_me_flutter\build\windows\x64\runner\delete_me_flutter.vcxproj]
[        ]   utils.obj : error LNK2001: unresolved external symbol __imp__CrtDbgReport [D:\git\tmp\delete_me_flutter\build\windows\x64\runner\delete_me_flutter.vcxproj]
[        ]   flutter_wrapper_app.lib(flutter_engine.obj) : error LNK2001: unresolved external symbol __imp__CrtDbgReport [D:\git\tmp\delete_me_flutter\build\windows\x64\runner\delete_me_flutter.vcxproj]
[        ]   D:\git\tmp\delete_me_flutter\build\windows\x64\runner\Debug\delete_me_flutter.exe : fatal error LNK1120: 2 unresolved externals [D:\git\tmp\delete_me_flutter\build\windows\x64\runner\delete_me_flutter.vcxproj]
[        ]     0 Warning(s)
[        ]     11 Error(s)

Loic got similar errors with https://github.com/loic-sharma/flutter_raw_cpp, which is a pure C++/Visual Studio project that links to the debug flutter engine (link). This project succeeds in debug mode, but fails to link in release mode.

[mkustermann]

From a brief look:

The Dart dependencies on windows are listed here, they are due to process wide memory allocators, sockets, etc.

Flutter seems to have a copy_dlls step in the build root that copies various dlls (see here - which includes those non-dist dlls). This code in the buildroot is very old and therfore unclear for what it's needed (if it's still needed).

I don't know what "flutter preview device" is how how it's built, but it may be that it's build is linked against all those dlls that are copied by the build root scripts.

[christopherfujino]

I don't know what "flutter preview device" is how how it's built, but it may be that it's build is linked against all those dlls that are copied by the build root scripts.

Right, this is not (directly) related to the engine or Dart VM, but the way we build the preview device's main.cc entrypoint. The Preview Device is essentially a debug build of the Flutter counter app for Windows, so we use the open source toolchain (CMake, MSBuild, VS compiler).

[flutter-triage-bot[bot]]

This issue is marked P1 but has had no recent status updates.

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