Checking for VS pathing when import not found

src/Build.UnitTests/Evaluation/Evaluator_Tests.cs

@@ -914,6 +914,31 @@ public void MultipleImportsVerifyImportsIncludingDuplicates()
             }
         }
 
+        [DotNetOnlyFact("Tests .NET SDK-only error")]
+        public void ImportWithVSPathThrowsCorrectError()
+        {
+            string importPath = null;
+
+            using (TestEnvironment env = TestEnvironment.Create())
+            {
+                // Does not matter that the file or folder does not exist, we are checking for the VS pathing here
+                importPath = "path\\that\\does\\not\\exist\\Microsoft\\VisualStudio\\FileName.txt";
+
+                var content = env.CreateTestProjectWithFiles(@"
+                    <Project ToolsVersion=""msbuilddefaulttoolsversion"" xmlns='msbuildnamespace' >
+                        <Import Project='" + importPath + @"'/>
+                    </Project>
+                ");
+
+                InvalidProjectFileException ex = Assert.Throws<InvalidProjectFileException>(() =>
+                {
+                        Project project = new Project(content.ProjectFile, null, null);
+                });
+
+                Assert.Contains("MSB4278", ex.ErrorCode);
+            }
+        }
+
         /// <summary>
         /// RecordDuplicateButNotCircularImports should not record circular imports (which do come under the category of "duplicate imports".
         /// </summary>

src/Build/Evaluation/Evaluator.cs

@@ -2304,6 +2304,8 @@ private LoadImportsResult ExpandAndLoadImportsFromUnescapedImportExpression(stri
                                 continue;
                             }
 
+                            VerifyVSDistributionPath(importElement.Project, importLocationInProject);
+
                             ProjectErrorUtilities.ThrowInvalidProject(importLocationInProject, "ImportedProjectNotFound",
                                                                       importFileUnescaped, importExpressionEscaped);
                         }
@@ -2577,6 +2579,8 @@ private void ThrowForImportedProjectWithSearchPathsNotFound(ProjectImportPathMat
 
             string stringifiedListOfSearchPaths = StringifyList(onlyFallbackSearchPaths);
 
+            VerifyVSDistributionPath(importElement.Project, importElement.ProjectLocation);
+
 #if FEATURE_SYSTEM_CONFIGURATION
             string configLocation = AppDomain.CurrentDomain.SetupInformation.ConfigurationFile;
 
@@ -2640,6 +2644,16 @@ private void SetAllProjectsProperty()
                     mayBeReserved: false);
             }
         }
+
+        [Conditional("FEATURE_GUIDE_TO_VS_ON_UNSUPPORTED_PROJECTS")]
+        private void VerifyVSDistributionPath(string path, ElementLocation importLocationInProject)
+        {
+            if (path.IndexOf("Microsoft\\VisualStudio", StringComparison.OrdinalIgnoreCase) >= 0
+                || path.IndexOf("Microsoft/VisualStudio", StringComparison.OrdinalIgnoreCase) >= 0)
+            {
+                ProjectErrorUtilities.ThrowInvalidProject(importLocationInProject, "ImportedProjectFromVSDistribution", path);
+            }
+        }
     }
 
     /// <summary>

src/Build/Resources/Strings.resx

@@ -527,6 +527,10 @@
     <value>MSB4019: The imported project "{0}" was not found. Confirm that the expression in the Import declaration "{1}" is correct, and that the file exists on disk.</value>
     <comment>{StrBegin="MSB4019: "}LOCALIZATION: &lt;Import&gt; should not be localized.</comment>
   </data>
+  <data name="ImportedProjectFromVSDistribution" xml:space="preserve">
+    <value>MSB4278: The imported file "{0}" does not exist and appears to be part of a Visual Studio component. This file may require MSBuild.exe in order to be imported successfully, and so may fail to build in the dotnet CLI. </value>
+    <comment>{StrBegin="MSB4278: "}LOCALIZATION: &lt;Import&gt; should not be localized.</comment>
+  </data>
   <data name="ImportedProjectFromExtensionsPathNotFoundFromAppConfig" xml:space="preserve">
     <value>MSB4226: The imported project "{0}" was not found. Also, tried to find "{1}" in the fallback search path(s) for {2} - {3} . These search paths are defined in "{4}". Confirm that the path in the &lt;Import&gt; declaration is correct, and that the file exists on disk in one of the search paths.</value>
     <comment>{StrBegin="MSB4226: "}LOCALIZATION: &lt;Import&gt; should not be localized.</comment>
@@ -2013,7 +2017,7 @@ Utilization:          {0} Average Utilization: {1:###.0}</value>
   <!--
         The Build message bucket is: MSB4000 - MSB4999
 
-        Next message code should be MSB4278
+        Next message code should be MSB4279
 
         Don't forget to update this comment after using a new code.
   -->