Process C# directives in file-based programs (#47702)

Author: jjonescz

documentation/general/dotnet-run-file.md

@@ -183,15 +183,14 @@ Directives `sdk`, `package`, and `property` are translated into `<Project Sdk=".
 Other directives result in a warning, reserving them for future use.
 
 ```cs
-#:sdk      Microsoft.NET.Sdk.Web
-#:property TargetFramework=net11.0
-#:property LangVersion=preview
-#:package  System.CommandLine=2.0.0-*
+#:sdk Microsoft.NET.Sdk.Web
+#:property TargetFramework net11.0
+#:property LangVersion preview
+#:package System.CommandLine 2.0.0-*
 ```
 
 The value must be separated from the name of the directive by white space and any leading and trailing white space is not considered part of the value.
-Any value can optionally have two parts separated by `=` or `/`
-(the former is consistent with how properties are usually passed, e.g., `/p:Prop=Value`, and the latter is what the `<Project Sdk="Name/Version">` attribute uses).
+Any value can optionally have two parts separated by a space (more whitespace characters could be allowed in the future).
 The value of the first `#:sdk` is injected into `<Project Sdk="{0}">` with the separator (if any) replaced with `/`,
 and the subsequent `#:sdk` directive values are split by the separator and injected as `<Sdk Name="{0}" Version="{1}" />` elements (or without the `Version` attribute if there is no separator).
 It is an error if the first part (name) is empty (the version is allowed to be empty, but that results in empty `Version=""`).

src/Cli/dotnet/Commands/Project/Convert/ProjectConvertCommand.cs

@@ -3,7 +3,9 @@
 
 #nullable enable
 
+using System.Collections.Immutable;
 using System.CommandLine;
+using System.IO;
 using Microsoft.DotNet.Cli;
 using Microsoft.DotNet.Cli.Utils;
 using Microsoft.TemplateEngine.Cli.Commands;
@@ -35,13 +37,29 @@ public override int Execute()
             throw new GracefulException(LocalizableStrings.DirectoryAlreadyExists, targetDirectory);
         }
 
+        // Find directives (this can fail, so do this before creating the target directory).
+        var sourceFile = VirtualProjectBuildingCommand.LoadSourceFile(file);
+        var directives = VirtualProjectBuildingCommand.FindDirectives(sourceFile);
+
         Directory.CreateDirectory(targetDirectory);
 
-        string projectFile = Path.Join(targetDirectory, Path.GetFileNameWithoutExtension(file) + ".csproj");
-        string projectFileText = VirtualProjectBuildingCommand.GetNonVirtualProjectFileText();
-        File.WriteAllText(path: projectFile, contents: projectFileText);
+        var targetFile = Path.Join(targetDirectory, Path.GetFileName(file));
+
+        // If there were any directives, remove them from the file.
+        if (directives.Length != 0)
+        {
+            VirtualProjectBuildingCommand.RemoveDirectivesFromFile(directives, sourceFile.Text, targetFile);
+            File.Delete(file);
+        }
+        else
+        {
+            File.Move(file, targetFile);
+        }
 
-        File.Move(file, Path.Join(targetDirectory, Path.GetFileName(file)));
+        string projectFile = Path.Join(targetDirectory, Path.GetFileNameWithoutExtension(file) + ".csproj");
+        using var stream = File.Open(projectFile, FileMode.Create, FileAccess.Write);
+        using var writer = new StreamWriter(stream, Encoding.UTF8);
+        VirtualProjectBuildingCommand.WriteProjectFile(writer, directives);
 
         return 0;
     }

src/Cli/dotnet/Commands/Run/LocalizableStrings.resx

@@ -244,4 +244,20 @@ Make the profile names distinct.</value>
   <data name="LaunchProfileDoesNotExist" xml:space="preserve">
     <value>A launch profile with the name '{0}' doesn't exist.</value>
   </data>
+  <data name="UnrecognizedDirective" xml:space="preserve">
+    <value>Unrecognized directive '{0}' at {1}.</value>
+    <comment>{0} is the directive name like 'package' or 'sdk', {1} is the file path and line number.</comment>
+  </data>
+  <data name="MissingDirectiveName" xml:space="preserve">
+    <value>Missing name of '{0}' at {1}.</value>
+    <comment>{0} is the directive name like 'package' or 'sdk', {1} is the file path and line number.</comment>
+  </data>
+  <data name="PropertyDirectiveMissingParts" xml:space="preserve">
+    <value>The property directive needs to have two parts separated by '=' like 'PropertyName=PropertyValue': {0}</value>
+    <comment>{0} is the file path and line number. {Locked="="}</comment>
+  </data>
+  <data name="PropertyDirectiveInvalidName" xml:space="preserve">
+    <value>Invalid property name at {0}. {1}</value>
+    <comment>{0} is the file path and line number. {1} is an inner exception message.</comment>
+  </data>
 </root>

src/Cli/dotnet/Commands/Run/RunCommand.cs

@@ -110,7 +110,7 @@ public int Execute()
             projectFactory = new VirtualProjectBuildingCommand
             {
                 EntryPointFileFullPath = EntryPointFileFullPath,
-            }.CreateProjectInstance;
+            }.PrepareProjectInstance().CreateProjectInstance;
         }
 
         try