@@ -182,8 +182,16 @@ protected Autobuilder(IBuildActions actions, TAutobuildOptions options, Diagnost
                 if (ret is not null)
                     return ret;
 
+                // Then look for language specific solution files, e.g. `.slnx` files
+                if (Options.Language.SolutionExtension is string solutionExtension)
+                {
+                    ret = FindFiles(solutionExtension, f => new Solution<TAutobuildOptions>(this, f, false))?.ToList();
+                    if (ret is not null)
+                        return ret;
+                }
+
                 // Finally look for language specific project files, e.g. `.csproj` files
-                ret = FindFiles(this.Options.Language.ProjectExtension, f => new Project<TAutobuildOptions>(this, f))?.ToList();
+                ret = FindFiles(Options.Language.ProjectExtension, f => new Project<TAutobuildOptions>(this, f))?.ToList();
                 return ret ?? new List<IProjectOrSolution>();
             });
 
 
@@ -4,12 +4,11 @@
 using System.Linq;
 using Microsoft.Build.Construction;
 using Microsoft.Build.Exceptions;
-using Semmle.Util.Logging;
 
 namespace Semmle.Autobuild.Shared
 {
     /// <summary>
-    /// A solution file, extension .sln.
+    /// A solution file, extension .sln or .slnx.
     /// </summary>
     public interface ISolution : IProjectOrSolution
     {
 
@@ -37,7 +37,7 @@ public FileProvider(DirectoryInfo sourceDir, ILogger logger)
             smallNonBinary = new Lazy<string[]>(() => ReturnAndLogFiles("small non-binary", SelectSmallFiles(allNonBinary.Value).SelectFileNames().ToArray()));
             sources = new Lazy<string[]>(() => SelectTextFileNamesByExtension("source", ".cs"));
             projects = new Lazy<string[]>(() => SelectTextFileNamesByExtension("project", ".csproj"));
-            solutions = new Lazy<string[]>(() => SelectTextFileNamesByExtension("solution", ".sln"));
+            solutions = new Lazy<string[]>(() => SelectTextFileNamesByExtension("solution", ".sln", ".slnx"));
             dlls = new Lazy<string[]>(() => SelectBinaryFileNamesByExtension("DLL", ".dll"));
             nugetConfigs = new Lazy<string[]>(() => SelectTextFileNamesByName("nuget.config"));
             globalJsons = new Lazy<string[]>(() => SelectTextFileNamesByName("global.json"));
 
@@ -6,7 +6,7 @@
 namespace Semmle.Extraction.CSharp.DependencyFetching
 {
     /// <summary>
-    /// Access data in a .sln file.
+    /// Access data in a .sln or .slnx file.
     /// </summary>
     internal class SolutionFile
     {
@@ -17,7 +17,7 @@ internal class SolutionFile
         /// <summary>
         /// Read the file.
         /// </summary>
-        /// <param name="filename">The filename of the .sln.</param>
+        /// <param name="filename">The filename of the .sln or .slnx.</param>
         public SolutionFile(string filename)
         {
             // SolutionFile.Parse() expects a rooted path.
@@ -26,7 +26,7 @@ public SolutionFile(string filename)
         }
 
         /// <summary>
-        /// Projects directly included in the .sln file.
+        /// Projects directly included in the .sln or .slnx file.
         /// </summary>
         public IEnumerable<string> MsBuildProjects
         {
 
@@ -2,21 +2,27 @@
 {
     public sealed class Language
     {
-        public static Language Cpp { get; } = new Language(".vcxproj", "CPP");
-        public static Language CSharp { get; } = new Language(".csproj", "CSHARP");
+        public static Language Cpp { get; } = new Language("CPP", ".vcxproj");
+        public static Language CSharp { get; } = new Language("CSHARP", ".csproj", ".slnx");
 
         public bool ProjectFileHasThisLanguage(string path) =>
             System.IO.Path.GetExtension(path) == ProjectExtension;
 
         public string ProjectExtension { get; }
+        public string? SolutionExtension { get; }
         public string UpperCaseName { get; }
 
-        private Language(string extension, string name)
+        private Language(string name, string projectExtension)
         {
-            ProjectExtension = extension;
+            ProjectExtension = projectExtension;
             UpperCaseName = name;
         }
 
+        private Language(string name, string projectExtension, string solutionExtension) : this(name, projectExtension)
+        {
+            SolutionExtension = solutionExtension;
+        }
+
         public override string ToString() =>
             ProjectExtension == Cpp.ProjectExtension ? "C/C++" : "C#";
     }
Original file line number	Diff line number	Diff line change
`@@ -4,12 +4,11 @@`
`4`	`4`	`using System.Linq;`
`5`	`5`	`using Microsoft.Build.Construction;`
`6`	`6`	`using Microsoft.Build.Exceptions;`
`7`		`-using Semmle.Util.Logging;`
`8`	`7`
`9`	`8`	`namespace Semmle.Autobuild.Shared`
`10`	`9`	`{`
`11`	`10`	`/// <summary>`
`12`		`- /// A solution file, extension .sln.`
	`11`	`+ /// A solution file, extension .sln or .slnx.`
`13`	`12`	`/// </summary>`
`14`	`13`	`public interface ISolution : IProjectOrSolution`
`15`	`14`	`{`
Original file line number	Diff line number	Diff line change
`@@ -6,7 +6,7 @@`
`6`	`6`	`namespace Semmle.Extraction.CSharp.DependencyFetching`
`7`	`7`	`{`
`8`	`8`	`/// <summary>`
`9`		`- /// Access data in a .sln file.`
	`9`	`+ /// Access data in a .sln or .slnx file.`
`10`	`10`	`/// </summary>`
`11`	`11`	`internal class SolutionFile`
`12`	`12`	`{`
`@@ -17,7 +17,7 @@ internal class SolutionFile`
`17`	`17`	`/// <summary>`
`18`	`18`	`/// Read the file.`
`19`	`19`	`/// </summary>`
`20`		`- /// <param name="filename">The filename of the .sln.</param>`
	`20`	`+ /// <param name="filename">The filename of the .sln or .slnx.</param>`
`21`	`21`	`public SolutionFile(string filename)`
`22`	`22`	`{`
`23`	`23`	`// SolutionFile.Parse() expects a rooted path.`
`@@ -26,7 +26,7 @@ public SolutionFile(string filename)`
`26`	`26`	`}`
`27`	`27`
`28`	`28`	`/// <summary>`
`29`		`- /// Projects directly included in the .sln file.`
	`29`	`+ /// Projects directly included in the .sln or .slnx file.`
`30`	`30`	`/// </summary>`
`31`	`31`	`public IEnumerable<string> MsBuildProjects`
`32`	`32`	`{`
Original file line number	Diff line number	Diff line change
`@@ -2,21 +2,27 @@`
`2`	`2`	`{`
`3`	`3`	`public sealed class Language`
`4`	`4`	`{`
`5`		`- public static Language Cpp { get; } = new Language(".vcxproj", "CPP");`
`6`		`- public static Language CSharp { get; } = new Language(".csproj", "CSHARP");`
	`5`	`+ public static Language Cpp { get; } = new Language("CPP", ".vcxproj");`
	`6`	`+ public static Language CSharp { get; } = new Language("CSHARP", ".csproj", ".slnx");`
`7`	`7`
`8`	`8`	`public bool ProjectFileHasThisLanguage(string path) =>`
`9`	`9`	`System.IO.Path.GetExtension(path) == ProjectExtension;`
`10`	`10`
`11`	`11`	`public string ProjectExtension { get; }`
	`12`	`+ public string? SolutionExtension { get; }`
`12`	`13`	`public string UpperCaseName { get; }`
`13`	`14`
`14`		`- private Language(string extension, string name)`
	`15`	`+ private Language(string name, string projectExtension)`
`15`	`16`	`{`
`16`		`- ProjectExtension = extension;`
	`17`	`+ ProjectExtension = projectExtension;`
`17`	`18`	`UpperCaseName = name;`
`18`	`19`	`}`
`19`	`20`
	`21`	`+ private Language(string name, string projectExtension, string solutionExtension) : this(name, projectExtension)`
	`22`	`+ {`
	`23`	`+ SolutionExtension = solutionExtension;`
	`24`	`+ }`
	`25`	`+`
`20`	`26`	`public override string ToString() =>`
`21`	`27`	`ProjectExtension == Cpp.ProjectExtension ? "C/C++" : "C#";`
`22`	`28`	`}`