Allow collection of C#/VB command line without actually invoking the compiler

src/Compilers/Core/MSBuildTask/ManagedCompiler.cs

@@ -72,6 +72,13 @@ public int CodePage
             get { return _store.GetOrDefault(nameof(CodePage), 0); }
         }
 
+        [Output]
+        public string CommandLineInvocation
+        {
+            set { _store[nameof(CommandLineInvocation)] = value; }
+            get { return _store.GetOrDefault(nameof(CommandLineInvocation), string.Empty); }
+        }
+
         public string DebugType
         {
             set { _store[nameof(DebugType)] = value; }
@@ -187,6 +194,12 @@ public bool Prefer32Bit
             get { return _store.GetOrDefault(nameof(Prefer32Bit), false); }
         }
 
+        public bool ProvideCommandLineInvocation
+        {
+            set { _store[nameof(ProvideCommandLineInvocation)] = value; }
+            get { return _store.GetOrDefault(nameof(ProvideCommandLineInvocation), false); }
+        }
+
         public ITaskItem[] References
         {
             set { _store[nameof(References)] = value; }
@@ -211,6 +224,12 @@ public ITaskItem[] ResponseFiles
             get { return (ITaskItem[])_store[nameof(ResponseFiles)]; }
         }
 
+        public bool SkipCompilerExecution
+        {
+            set { _store[nameof(SkipCompilerExecution)] = value; }
+            get { return _store.GetOrDefault(nameof(SkipCompilerExecution), false); }
+        }
+
         public ITaskItem[] Sources
         {
             set
@@ -312,6 +331,16 @@ protected override Encoding StandardOutputEncoding
 
         protected override int ExecuteTool(string pathToTool, string responseFileCommands, string commandLineCommands)
         {
+            if (ProvideCommandLineInvocation)
+            {
+                CommandLineInvocation = GenerateResponseFileContents();
+            }
+
+            if (SkipCompilerExecution)
+            {
+                return 0;
+            }
+
             if (!UseSharedCompilation || !String.IsNullOrEmpty(this.ToolPath))
             {
                 return base.ExecuteTool(pathToTool, responseFileCommands, commandLineCommands);

src/Compilers/Core/MSBuildTask/Microsoft.CSharp.Core.targets

@@ -19,7 +19,7 @@
                  @(_DebugSymbolsIntermediatePath);
                  $(NonExistentFile);
                  @(CustomAdditionalCompileOutputs)"
-          Returns=""
+          Returns="$(CscCommandLineInvocation)"
           DependsOnTargets="$(CoreCompileDependsOn)"
     >
     <!-- These two compiler warnings are raised when a reference is bound to a different version
@@ -105,10 +105,12 @@
           Platform="$(PlatformTarget)"
           Prefer32Bit="$(Prefer32Bit)"
           PreferredUILang="$(PreferredUILang)"
+          ProvideCommandLineInvocation="$(ProvideCommandLineInvocation)"
           References="@(ReferencePath)"
           ReportAnalyzer="$(ReportAnalyzer)"
           Resources="@(_CoreCompileResourceInputs);@(CompiledLicenseFile)"
           ResponseFiles="$(CompilerResponseFile)"
+          SkipCompilerExecution="$(SkipCompilerExecution)"
           Sources="@(Compile)"
           SubsystemVersion="$(SubsystemVersion)"
           TargetType="$(OutputType)"
@@ -125,7 +127,9 @@
           Win32Icon="$(ApplicationIcon)"
           Win32Manifest="$(Win32Manifest)"
           Win32Resource="$(Win32Resource)"
-              />
+          >
+      <Output TaskParameter="CommandLineInvocation" PropertyName="CscCommandLineInvocation" />
+    </Csc>
 
     <ItemGroup>
       <_CoreCompileResourceInputs Remove="@(_CoreCompileResourceInputs)" />

src/Compilers/Core/MSBuildTask/Microsoft.VisualBasic.Core.targets

@@ -19,7 +19,7 @@
                  @(_DebugSymbolsIntermediatePath);
                  $(NonExistentFile);
                  @(CustomAdditionalCompileOutputs)"
-          Returns=""
+          Returns="$(VbcCommandLineInvocation)"
           DependsOnTargets="$(CoreCompileDependsOn)"
     >
     <PropertyGroup>
@@ -97,6 +97,7 @@
           Platform="$(PlatformTarget)"
           Prefer32Bit="$(Prefer32Bit)"
           PreferredUILang="$(PreferredUILang)"
+          ProvideCommandLineInvocation="$(ProvideCommandLineInvocation)"
           References="@(ReferencePath)"
           RemoveIntegerChecks="$(RemoveIntegerChecks)"
           ReportAnalyzer="$(ReportAnalyzer)"
@@ -104,6 +105,7 @@
           ResponseFiles="$(CompilerResponseFile)"
           RootNamespace="$(RootNamespace)"
           SdkPath="$(FrameworkPathOverride)"
+          SkipCompilerExecution="$(SkipCompilerExecution)"
           Sources="@(Compile)"
           SubsystemVersion="$(SubsystemVersion)"
           TargetCompactFramework="$(TargetCompactFramework)"
@@ -123,8 +125,9 @@
           Win32Manifest="$(Win32Manifest)"
           Win32Resource="$(Win32Resource)"
           VBRuntime="$(VBRuntime)"
-          />
-
+          >
+      <Output TaskParameter="CommandLineInvocation" PropertyName="CscCommandLineInvocation" />
+    </Vbc>
     <ItemGroup>
       <_CoreCompileResourceInputs Remove="@(_CoreCompileResourceInputs)" />
     </ItemGroup>