compiler/Generator.cs

@@ -5,21 +5,21 @@ namespace Compiler;
 
 public class Generator
 {
-    public static string Emit(List<TypedNodeDefinitionFunc> functions, ModuleGraph moduleGraph, bool compileLib)
+    public static string Emit(List<TypedNodeDefinitionFunc> functions, ModuleGraph moduleGraph, string? entryPoint)
     {
-        return new Generator(functions, moduleGraph, compileLib).Emit();
+        return new Generator(functions, moduleGraph, entryPoint).Emit();
     }
 
-    private Generator(List<TypedNodeDefinitionFunc> functions, ModuleGraph moduleGraph, bool compileLib)
+    private Generator(List<TypedNodeDefinitionFunc> functions, ModuleGraph moduleGraph, string? entryPoint)
     {
         this.functions = functions;
         this.moduleGraph = moduleGraph;
-        this.compileLib = compileLib;
+        this.entryPoint = entryPoint;
     }
 
     private readonly List<TypedNodeDefinitionFunc> functions;
     private readonly ModuleGraph moduleGraph;
-    private readonly bool compileLib;
+    private readonly string? entryPoint;
     private IndentedTextWriter writer = new();
     private HashSet<NubType> referencedTypes = new();
     private readonly HashSet<NubType> emittedTypes = new();
@@ -28,15 +28,12 @@ public class Generator
 
     private string Emit()
     {
-        if (!compileLib)
+        if (entryPoint != null)
         {
-            if (!moduleGraph.TryResolveIdentifier("main", "main", true, out var info))
-                throw new UnreachableException("func main::main() is not defined. This should have been caught earlier");
-
             writer.WriteLine($$"""
                              int main(int argc, char *argv[])
                              {
-                                return {{info.MangledName}}();
+                                return {{entryPoint}}();
                              }
                              """);
 
@@ -604,7 +601,6 @@ public class Generator
                 writer.WriteLine("{");
                 using (writer.Indent())
                 {
-                    writer.WriteLine("puts(\"free\");");
                     writer.WriteLine($"free({value});");
                 }
                 writer.WriteLine("}");

compiler/Program.cs

@@ -128,7 +128,32 @@ else
     Directory.CreateDirectory(".build");
 }
 
-var output = Generator.Emit(functions, moduleGraph, compileLib);
+string? entryPoint = null;
+
+if (!compileLib)
+{
+    if (!moduleGraph.TryResolveIdentifier("main", "main", true, out var info) || info.Type is not NubTypeFunc entryPointType)
+    {
+        DiagnosticFormatter.Print(Diagnostic.Error("func main::main(): i32 is not defined. If you wanted to compile as a library, specify --type=lib").Build(), Console.Error);
+        return 1;
+    }
+
+    if (!entryPointType.ReturnType.IsAssignableTo(NubTypeSInt.Get(32)))
+    {
+        DiagnosticFormatter.Print(Diagnostic.Error($"Entrypoint must return an i32 (currently '{entryPointType.ReturnType}')").Build(), Console.Error);
+        return 1;
+    }
+
+    if (entryPointType.Parameters.Any())
+    {
+        DiagnosticFormatter.Print(Diagnostic.Error($"Entrypoint must not take any parameters").Build(), Console.Error);
+        return 1;
+    }
+
+    entryPoint = info.MangledName;
+}
+
+var output = Generator.Emit(functions, moduleGraph, entryPoint);
 File.WriteAllText(".build/out.c", output);
 
 if (compileLib)

examples/program/main.nub

@@ -1,5 +1,6 @@
 module main
 
 func main(): i32 {
+    core::print("Your mom")
     return 0
 }