Track which projects/solutions fail to build

csharp/autobuilder/Semmle.Autobuild.CSharp/DotNetRule.cs

@@ -17,6 +17,8 @@ namespace Semmle.Autobuild.CSharp
     {
         private IEnumerable<Project<CSharpAutobuildOptions>> notDotNetProjects;
 
+        public readonly List<IProjectOrSolution> FailedProjectsOrSolutions = new();
+
         /// <summary>
         /// A list of projects which are incompatible with DotNet.
         /// </summary>
@@ -67,7 +69,10 @@ namespace Semmle.Autobuild.CSharp
 
                         var build = GetBuildScript(builder, dotNetPath, environment, projectOrSolution.FullPath);
 
-                        ret &= BuildScript.Try(clean) & BuildScript.Try(restore) & build;
+                        ret &= BuildScript.Try(clean) & BuildScript.Try(restore) & BuildScript.OnFailure(build, ret =>
+                        {
+                            FailedProjectsOrSolutions.Add(projectOrSolution);
+                        });
                     }
                     return ret;
                 });

csharp/autobuilder/Semmle.Autobuild.Shared/BuildScript.cs

@@ -70,6 +70,9 @@ namespace Semmle.Autobuild.Shared
         /// <returns>The exit code from this build script.</returns>
         public abstract int Run(IBuildActions actions, Action<string, bool> startCallback, Action<int, string, bool> exitCallBack, BuildOutputHandler onOutput, BuildOutputHandler onError);
 
+        /// <summary>
+        /// A build script which executes an external program or script.
+        /// </summary>
         private class BuildCommand : BuildScript
         {
             private readonly string exe, arguments;
@@ -154,6 +157,9 @@ namespace Semmle.Autobuild.Shared
 
         }
 
+        /// <summary>
+        /// A build script which runs a C# function.
+        /// </summary>
         private class ReturnBuildCommand : BuildScript
         {
             private readonly Func<IBuildActions, int> func;
@@ -333,6 +339,23 @@ namespace Semmle.Autobuild.Shared
         /// </summary>
         public static BuildScript Try(BuildScript s) => s | Success;
 
+        /// <summary>
+        /// Creates a build script that runs the build script <paramref name="s" />. If
+        /// running <paramref name="s" /> fails, <paramref name="k" /> is invoked with
+        /// the exit code.
+        /// </summary>
+        /// <param name="s">The build script to run.</param>
+        /// <param name="k">
+        /// The callback that is invoked if <paramref name="s" /> failed.
+        /// </param>
+        /// <returns>The build script which implements this.</returns>
+        public static BuildScript OnFailure(BuildScript s, Action<int> k) =>
+            new BindBuildScript(s, ret => Create(actions =>
+            {
+                if (!Succeeded(ret)) k(ret);
+                return ret;
+            }));
+
         /// <summary>
         /// Creates a build script that deletes the given directory.
         /// </summary>

csharp/autobuilder/Semmle.Autobuild.Shared/MsBuildRule.cs

@@ -1,7 +1,6 @@
 using Semmle.Util.Logging;
-using System;
+using System.Collections.Generic;
 using System.Linq;
-using System.Runtime.InteropServices;
 
 namespace Semmle.Autobuild.Shared
 {
@@ -31,6 +30,11 @@ namespace Semmle.Autobuild.Shared
     /// </summary>
     public class MsBuildRule : IBuildRule<AutobuildOptionsShared>
     {
+        /// <summary>
+        /// A list of solutions or projects which failed to build.
+        /// </summary>
+        public readonly List<IProjectOrSolution> FailedProjectsOrSolutions = new();
+
         public BuildScript Analyse(IAutobuilder<AutobuildOptionsShared> builder, bool auto)
         {
             if (!builder.ProjectsOrSolutionsToBuild.Any())
@@ -128,7 +132,13 @@ namespace Semmle.Autobuild.Shared
 
                 command.Argument(builder.Options.MsBuildArguments);
 
-                ret &= command.Script;
+                // append the build script which invokes msbuild to the overall build script `ret`;
+                // we insert a check that building the current project or solution was successful:
+                // if it was not successful, we add it to `FailedProjectsOrSolutions`
+                ret &= BuildScript.OnFailure(command.Script, ret =>
+                {
+                    FailedProjectsOrSolutions.Add(projectOrSolution);
+                });
             }
 
             return ret;