New experimental feature: allow skipping FastBuild projects from the …

…solution when they are not really necessary

The new behavior is activated by setting IncludeOnlyNeededFastBuildProjects to true in solution configure methods

By default, we'll add FastBuildAll, the fastbuild projects that output executables, those where VcxprojUserFile was set, and those we must build will be added to the sln
The user code can tweak the rules by setting AddFastBuildProjectToSolutionCallback to a method returning whether we want the project to be added or not, in project configure methods

Sharpmake/Project.Configuration.cs

@@ -2156,6 +2156,37 @@ internal void AddMasterBff(string masterBff)
             // If true, remove the source files from a FastBuild project's associated vcxproj file.
             public bool StripFastBuildSourceFiles = true;
 
+            /// <summary>
+            /// Override this delegate with a method returning a bool letting sharpmake know if it needs to add the
+            /// project containing this FastBuild conf to the solution.
+            /// By default, sharpmake will only add it if the Output is executable, or if <see cref="VcxprojUserFile"/>
+            /// is not null.
+            /// </summary>
+            public Func<bool> AddFastBuildProjectToSolutionCallback => DefaultAddFastBuildProjectToSolution;
+
+            /// <summary>
+            /// Default method returning whether sharpmake will add the project containing this FastBuild conf to the solution
+            /// </summary>
+            public bool DefaultAddFastBuildProjectToSolution()
+            {
+                if (!IsFastBuild)
+                    return true;
+
+                if (Project.IsFastBuildAll)
+                    return true;
+
+                if (!DoNotGenerateFastBuild)
+                {
+                    if (Output == OutputType.Exe)
+                        return true;
+
+                    if (VcxprojUserFile != null)
+                        return true;
+                }
+
+                return false;
+            }
+
             private Dictionary<KeyValuePair<Type, ITarget>, DependencySetting> _dependenciesSetting = new Dictionary<KeyValuePair<Type, ITarget>, DependencySetting>();
 
             // These dependencies will not be propagated to other projects that depend on us

Sharpmake/Solution.Configuration.cs

@@ -101,6 +101,13 @@ public string PlatformName
                 }
             }
 
+            /// <summary>
+            /// Experimental: only add to the solution the FastBuild projects that are really needed, or where
+            /// <see cref="Project.Configuration.AddFastBuildProjectToSolutionCallback"/> returned true.
+            /// Set to false to add all of them.
+            /// </summary>
+            public bool IncludeOnlyNeededFastBuildProjects = false;
+
             public bool IncludeOnlyFilterProject = false;
 
             public string CompileCommandLine = string.Empty;

Sharpmake/Solution.cs

@@ -177,6 +177,17 @@ public IEnumerable<ResolvedProject> GetResolvedProjects(IEnumerable<Configuratio
                         projectsWereFiltered = true;
                         continue;
                     }
+                    else if (solutionConfiguration.IncludeOnlyNeededFastBuildProjects)
+                    {
+                        if (!includedProjectInfo.Project.IsFastBuildAll &&
+                            (includedProjectInfo.ToBuild == Solution.Configuration.IncludedProjectInfo.Build.No || includedProjectInfo.ToBuild == Solution.Configuration.IncludedProjectInfo.Build.YesThroughDependency) &&
+                            includedProjectInfo.Configuration.IsFastBuild && !includedProjectInfo.Configuration.DoNotGenerateFastBuild &&
+                            !(includedProjectInfo.Configuration.AddFastBuildProjectToSolutionCallback?.Invoke() ?? false))
+                        {
+                            projectsWereFiltered = true;
+                            continue;
+                        }
+                    }
 
                     ResolvedProject resolvedProject = result.GetValueOrAdd(
                         includedProjectInfo.Configuration.ProjectFullFileName,