Command line script name not recognized as Windows UNC path

[lrhn]

A command line like:

dart \\?\d:\something\something\lang\dart\temp\pwd.dart

gives the error:

Crash when compiling file://?/d:/something/something/lang/dart/temp/pwd.dart,
at character offset null:
Unsupported operation: Cannot extract a file path from a URI with a query component
#0      _Uri.toFilePath (dart:core/uri.dart:2713:7)
#1      new File.fromUri (dart:io/file.dart:265:49)
...

The path is a valid Windows path. It is treated as a URI, which is wrong, it should be converted to a URI explicitly in a way which preserves the ?, likely file://%25/d:/something/something/lang/dart/temp\pwd.dart or just file:///d:/something/something/lang/dart/temp/pwd.dart.

[a-siva]

This has been labelled as area-dart-cli but I presume this fails irrespective of whether dartdev is enabled or not?

[zichangg]

I think this is a problem at frontend.

\\?\ is a special prefix.

For file I/O, the "\\?\" prefix to a path string tells the Windows APIs to disable all string parsing and to send the string that follows it straight to the file system.

The path in the example is a regular path. But It can also be used together with UNC path.

The "\?" prefix can also be used with paths constructed according to the universal naming convention (UNC). To specify such a path using UNC, use the "\?\UNC" prefix. For example, "\?\UNC\server\share", where "server" is the name of the computer and "share" is the name of the shared folder.

Frontend should treat it as a regular path and Windows API is able to recognize.

Ref: https://docs.microsoft.com/en-us/windows/win32/fileio/naming-a-file#win32-file-namespaces

[johnniwinther]

@lrhn Can you provide more of the stack trace?

When it try dart \\?\c:\src\dart-repo2\temp\abstract.dart on bleeding edge I get

c:\src\dart-repo2\sdk>out\ReleaseX64\dart.exe \\?\c:\src\dart-repo2\temp\abstract.dart
Error when reading '\\?\c:\src\dart-repo2\temp\abstract.dart': No such file or directory.
Could not find a command named "\\?\c:\src\dart-repo2\temp\abstract.dart".

Usage: dart [<vm-flags>] <command|dart-file> [<arguments>]

Global options:
-h, --help                              Print this usage information.
-v, --verbose                           Show additional command output.
    --version                           Print the Dart SDK version.
    --enable-analytics                  Enable anonymous analytics.
    --disable-analytics                 Disable anonymous analytics.
    --enable-experiment=<experiment>    Enable one or more experimental features.
                                        [extension-methods, non-nullable, nonfunction-type-aliases, triple-shift, variance]

Available commands:
  analyze   Analyze the project's Dart code.
  compile   Compile Dart to various formats.
  create    Create a new project.
  format    Idiomatically formats Dart source code.
  migrate   Perform a null safety migration on a project or package.
  pub       Work with packages.
  run       Run a Dart file.
  test      Runs tests in this project.

Run "dart help <command>" for more information about a command.

and when I run dart run \\?\c:\src\dart-repo2\temp\abstract.dart I get

c:\src\dart-repo2\sdk>out\ReleaseX64\dart.exe run \\?\c:\src\dart-repo2\temp\abstract.dart
Unsupported operation: Cannot extract a file path from a URI with a query component
#0      _Uri.toFilePath (dart:core/uri.dart:2713:7)
#1      RunCommand.run (package:dartdev/src/commands/run.dart:130:10)
#2      CommandRunner.runCommand (package:args/command_runner.dart:197:27)
#3      DartdevRunner.runCommand (package:dartdev/dartdev.dart:238:24)
#4      CommandRunner.run.<anonymous closure> (package:args/command_runner.dart:112:25)
#5      new Future.sync (dart:async/future.dart:223:31)
#6      CommandRunner.run (package:args/command_runner.dart:112:14)
#7      runDartdev (package:dartdev/dartdev.dart:107:27)
#8      main (file:///c:/src/dart-repo2/sdk/pkg/dartdev/bin/dartdev.dart:12:9)
#9      _startIsolate.<anonymous closure> (dart:isolate-patch/isolate_patch.dart:297:32)
#10     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:168:12)

which doesn't match yours (at #1).

So it seems we have multiple entry points that need fixing.

[zichangg]

@johnniwinther
I'm able to repro on my gWin machine using cmd.exe.

This is the stacktrace I got:

Crash when compiling file://?/C:/Users/zichangguo/dart-sdk/sdk/Junk/main.dart,
at character offset null:
Unsupported operation: Cannot extract a file path from a URI with a query component
#0      _Uri.toFilePath (dart:core/uri.dart:2713:7)
#1      new File.fromUri (dart:io/file.dart:260:49)
#2      _IoFileSystemEntity.readAsBytes (package:front_end/src/api_prototype/standard_file_system.dart:66:18)
#3      HybridFileSystemEntity.readAsBytes (package:front_end/src/fasta/hybrid_file_system.dart:54:61)
asynchronous suspension
#4      SourceLoader.tokenize (package:front_end/src/fasta/source/source_loader.dart:249:55)
#5      SourceLoader.buildOutline (package:front_end/src/fasta/source/source_loader.dart:417:26)
#6      Loader.buildOutlines (package:front_end/src/fasta/loader.dart:254:13)
#7      SourceLoader.buildOutlines (package:front_end/src/fasta/source/source_loader.dart:343:17)
#8      KernelTarget.buildOutlines.<anonymous closure> (package:front_end/src/fasta/kernel/kernel_target.dart:301:20)
#9      withCrashReporting (package:front_end/src/fasta/crash.dart:122:24)
#10     KernelTarget.buildOutlines (package:front_end/src/fasta/kernel/kernel_target.dart:300:12)
#11     generateKernelInternal.<anonymous closure> (package:front_end/src/kernel_generator_impl.dart:119:28)
asynchronous suspension
#12     generateKernelInternal.<anonymous closure> (package:front_end/src/kernel_generator_impl.dart)
#13     withCrashReporting (package:front_end/src/fasta/crash.dart:122:24)
#14     generateKernelInternal (package:front_end/src/kernel_generator_impl.dart:73:10)
#15     generateKernel.<anonymous closure> (package:front_end/src/kernel_generator_impl.dart:53:18)
#16     CompilerContext.runWithOptions.<anonymous closure> (package:front_end/src/fasta/compiler_context.dart:135:20)
asynchronous suspension
#17     CompilerContext.runWithOptions.<anonymous closure> (package:front_end/src/fasta/compiler_context.dart)
#18     CompilerContext.runInContext.<anonymous closure>.<anonymous closure> (package:front_end/src/fasta/compiler_context.dart:123:46)
#19     new Future.sync (dart:async/future.dart:223:31)
#20     CompilerContext.runInContext.<anonymous closure> (package:front_end/src/fasta/compiler_context.dart:123:19)
#21     _rootRun (dart:async/zone.dart:1190:13)
#22     _CustomZone.run (dart:async/zone.dart:1093:19)
#23     _runZoned (dart:async/zone.dart:1630:10)
#24     runZoned (dart:async/zone.dart:1550:10)
#25     CompilerContext.runInContext (package:front_end/src/fasta/compiler_context.dart:122:12)
#26     CompilerContext.runWithOptions (package:front_end/src/fasta/compiler_context.dart:133:10)
#27     generateKernel (package:front_end/src/kernel_generator_impl.dart:52:32)
#28     kernelForModule (package:front_end/src/api_prototype/kernel_generator.dart:99:17)
#29     SingleShotCompilerWrapper.compileInternal (file:///C:/Users/zichangguo/dart-sdk/sdk/pkg/vm/bin/kernel_service.dart:441:17)
#30     Compiler.compile.<anonymous closure> (file:///C:/Users/zichangguo/dart-sdk/sdk/pkg/vm/bin/kernel_service.dart:208:45)
#31     new Future.<anonymous closure> (dart:async/future.dart:175:37)
#32     _rootRun (dart:async/zone.dart:1182:47)
#33     _CustomZone.run (dart:async/zone.dart:1093:19)
#34     _CustomZone.runGuarded (dart:async/zone.dart:997:7)
#35     _CustomZone.bindCallbackGuarded.<anonymous closure> (dart:async/zone.dart:1037:23)
#36     _rootRun (dart:async/zone.dart:1190:13)
#37     _CustomZone.run (dart:async/zone.dart:1093:19)
#38     _CustomZone.bindCallback.<anonymous closure> (dart:async/zone.dart:1021:23)
#39     Timer._createTimer.<anonymous closure> (dart:async-patch/timer_patch.dart:18:15)
#40     _Timer._runTimers (dart:isolate-patch/timer_impl.dart:397:19)
#41     _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:428:5)
#42     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:168:12)