since Unreal never actually links with MDd on its own, we can configure libraries to use MD in debug builds as well. override is possible when necessary

Author: microdee

README.md

@@ -623,11 +623,7 @@ public partial class TpModule : ModuleRules
 		var VisionOS =    target.Platform == UnrealTargetPlatform.VisionOS;
 		var Independent = true;
 
-		var Debug = target is
-		{
-			Configuration: UnrealTargetConfiguration.Debug,
-			bDebugBuildsActuallyUseDebugCRT: true
-		};
+		var Debug = Target.Configuration <= UnrealTargetConfiguration.DebugGame;
 		var Release = !Debug;
 		var All = true;
 

docs/Manual/RuntimeDeps.md

@@ -164,11 +164,7 @@ public partial class TpModule : ModuleRules
 		var VisionOS =    target.Platform == UnrealTargetPlatform.VisionOS;
 		var Independent = true;
 
-		var Debug = target is
-		{
-			Configuration: UnrealTargetConfiguration.Debug,
-			bDebugBuildsActuallyUseDebugCRT: true
-		};
+		var Debug = Target.Configuration <= UnrealTargetConfiguration.DebugGame;
 		var Release = !Debug;
 		var All = true;
 

src/Nuke.Unreal/BoilerplateGenerators/LibraryGenerator.cs

@@ -41,7 +41,7 @@ public class LibraryType : Enumeration
     public Func<string, LibrarySpec> ParseSpec { get; private set; } = s => new LibrarySpec(s, s);
 }
 
-public record LibrarySpec(
+public record class LibrarySpec(
     string Spec,
     string Name,
     string? Version = null,
@@ -55,12 +55,12 @@ public record LibrarySpec(
         .Pascalize();
 }
 
-public record SuffixRecord(string? Text, string? Us, string? Dot)
+public record class SuffixRecord(string? Text, string? Us, string? Dot)
 {
     public SuffixRecord(string? suffix) : this(suffix, suffix.PrependNonEmpty("_"), suffix.PrependNonEmpty(".")) {}
 }
 
-public record LibraryModel(
+public record class LibraryModel(
     LibrarySpec Spec,
     string? Copyright,
     SuffixRecord Suffix,

src/Nuke.Unreal/BoilerplateGenerators/XRepo/XRepoLibrary.cs

@@ -12,6 +12,9 @@
 
 namespace Nuke.Unreal.BoilerplateGenerators.XRepo;
 
+/// <summary>
+/// Utility classes for working with XRepo (or XMake) packages
+/// </summary>
 public static partial class XRepoLibrary
 {
     [GeneratedRegex(
@@ -34,6 +37,9 @@ public static partial class XRepoLibrary
     )]
     private static partial Regex SpecRegex();
 
+    /// <summary>
+    /// Parses an input library spec string as a record
+    /// </summary>
     public static LibrarySpec ParseSpec(string spec)
     {
         var matches = spec.Parse(SpecRegex(), forceNullOnWhitespce: true);
@@ -47,13 +53,10 @@ public static LibrarySpec ParseSpec(string spec)
         );
     }
 
-    internal static IEnumerable<XRepoLibraryRecord> InstallXRepoLibrary(UnrealBuild self, LibrarySpec spec, string options, AbsolutePath targetPath, bool debug)
+    internal static IEnumerable<XRepoLibraryRecord> InstallXRepoLibrary(UnrealBuild self, LibrarySpec spec, string options, AbsolutePath targetPath, bool debug, string runtime = "MD")
     {
         var libraryFiles = targetPath / "LibraryFiles";
-        options = options.AppendNonEmpty(",") + (debug
-            ? "runtimes='MDd'"
-            : "runtimes='MD'"
-        );
+        options = options.AppendNonEmpty(",") + $"runtimes='{runtime}'";
         var xrepoPlatArch = self.Platform.GetXRepoPlatformArch();
 
         var extraArgs =
@@ -136,7 +139,17 @@ string[] ProcessPaths(string? paths, AbsolutePath dstDir)
             .ToArray();
     }
 
-    public static void InstallXRepoLibrary(this UnrealBuild self, string specIn, string options, AbsolutePath targetPath, string? suffix = null)
+    /// <summary>
+    /// Prepare a third-party library from an XRepo library spec for Unreal engine's consumption
+    /// </summary>
+    /// <param name="self">The build context</param>
+    /// <param name="specIn">The library spec specified here (without the options) https://mcro.de/Nuke.Unreal/d2/d84/CppLibraries.html</param>
+    /// <param name="options">Comma separated '=' delimited key-value pairs. Space is not allowed around commas</param>
+    /// <param name="targetPath">Where library files should be organized</param>
+    /// <param name="suffix">Optional addition to the name of library name exposed to Unreal</param>
+    /// <param name="releaseRuntime">Windows CRT linkage for release versions (default is MD)</param>
+    /// <param name="debugRuntime">Windows CRT linkage for debug versions (default is MD)</param>
+    public static void InstallXRepoLibrary(this UnrealBuild self, string specIn, string options, AbsolutePath targetPath, string? suffix = null, string releaseRuntime = "MD", string debugRuntime = "MD")
     {
         Log.Information("Installing library {0} via xrepo", specIn);
         var spec = ParseSpec(specIn) with { Options = options };
@@ -147,10 +160,10 @@ public static void InstallXRepoLibrary(this UnrealBuild self, string specIn, str
         Log.Information("    Features: {0}", spec.Features);
 
         Log.Information("Installing debug build");
-        var debugLibs = InstallXRepoLibrary(self, spec, options, targetPath, true);
+        var debugLibs = InstallXRepoLibrary(self, spec, options, targetPath, true, debugRuntime);
 
         Log.Information("Installing release build (metadata will be used from release build)");
-        var releaseLibs = InstallXRepoLibrary(self, spec, options, targetPath, false);
+        var releaseLibs = InstallXRepoLibrary(self, spec, options, targetPath, false, releaseRuntime);
 
         Log.Information("Generating partial module rule class for {0}", self.Platform);
         new XRepoLibraryModuleGenerator().Generate(

src/Nuke.Unreal/templates/AutoRuntimeDependency/{{ module_name }}.Rtd.Build.sbncs

@@ -29,11 +29,7 @@ public partial class {{ module_name }} : ModuleRules
 		var VisionOS =    target.Platform == UnrealTargetPlatform.VisionOS;
 		var Independent = true;
 
-		var Debug = target is
-		{
-			Configuration: UnrealTargetConfiguration.Debug,
-			bDebugBuildsActuallyUseDebugCRT: true
-		};
+		var Debug = Target.Configuration <= UnrealTargetConfiguration.DebugGame;
 		var Release = !Debug;
 		var All = true;
 

src/Nuke.Unreal/templates/CMakeLibrary/{{ spec.unreal_name }}{{ suffix.us }}/{{ spec.unreal_name }}{{ suffix.us }}.Build.sbncs

@@ -10,7 +10,7 @@ public class {{ cap_name }}{{ suffix.us }} : ModuleRules
 		Type = ModuleType.External;
 		PublicIncludePaths.Add($"{ModuleDirectory}/Include");
 
-		var isDebug = target.Configuration == UnrealTargetConfiguration.Debug && target.bDebugBuildsActuallyUseDebugCRT;
+		var isDebug = Target.Configuration <= UnrealTargetConfiguration.DebugGame;
 		var config = isDebug ? "Debug" : "Release";
 
 		PublicAdditionalLibraries.AddRange(new []

src/Nuke.Unreal/templates/XRepoLibrary/{{ spec.unreal_name }}{{ suffix.us }}/{{ spec.unreal_name }}{{ suffix.us }}.Build.sbncs

@@ -20,7 +20,7 @@ public partial class {{ cap_name }}{{ suffix.us }} : ModuleRules
 		// auto generated when the library is prepared on/for a specific platform.
 
 		Type = ModuleType.External;
-		IsDebug = target.Configuration == UnrealTargetConfiguration.Debug && target.bDebugBuildsActuallyUseDebugCRT;
+		IsDebug = Target.Configuration <= UnrealTargetConfiguration.DebugGame;
 		LibraryConfig = IsDebug ? "Debug" : "Release";
 		LibraryPlatform = target.Platform.ToString();