From 72f5e82196d95008ed12c12de6bdccf24361e106 Mon Sep 17 00:00:00 2001
From: Eugen Wissner <belka@caraus.de>
Date: Mon, 7 Sep 2026 22:02:15 +0200
Subject: Make module entry point more procedure like

---
 include/elna/boot/ast.h        |  7 +++++++
 include/elna/boot/dependency.h | 34 +++++++++++++++++++++++++++++-----
 include/elna/boot/type_check.h |  5 +++++
 3 files changed, 41 insertions(+), 5 deletions(-)

(limited to 'include')

diff --git a/include/elna/boot/ast.h b/include/elna/boot/ast.h
index c485dc7..4919510 100644
--- a/include/elna/boot/ast.h
+++ b/include/elna/boot/ast.h
@@ -292,6 +292,10 @@ namespace elna::boot
         void visit(literal<std::uint32_t> *) override;
         void visit(literal<std::nullptr_t> *) override;
         void visit(literal<std::string> *) override;
+
+    protected:
+        /// Passes needing the entry point's scope override this.
+        virtual void visit_entry_point(unit *unit);
     };
 
     /**
@@ -951,6 +955,7 @@ namespace elna::boot
         const std::vector<variable_declaration *> variables;
         const std::optional<procedure_body> entry_point;
         const std::vector<identifier> parameters;
+        const std::optional<source_position> entry_position;
 
         unit(const source_position position,
                 std::vector<import_declaration *>&& imports,
@@ -962,6 +967,8 @@ namespace elna::boot
                 std::vector<type_declaration *>&& types,
                 std::vector<variable_declaration *>&& variables,
                 std::vector<procedure_declaration *>&& procedures,
+                std::vector<identifier>&& parameters,
+                const source_position entry_position,
                 std::optional<procedure_body>&& body);
 
         void accept(parser_visitor *visitor) override;
diff --git a/include/elna/boot/dependency.h b/include/elna/boot/dependency.h
index 9bc1adf..195d37a 100644
--- a/include/elna/boot/dependency.h
+++ b/include/elna/boot/dependency.h
@@ -104,16 +104,27 @@ namespace elna::boot
     };
 
     /**
-     * An import that closes a cycle, e.g. a module importing itself.
+     * A module that cannot be imported.
      */
-    class circular_import_error final : public diagnostic
+    class import_error final : public diagnostic
     {
         const std::string module_name;
 
     public:
-        circular_import_error(const source_position position, const std::string& module_name);
+        enum class kind
+        {
+            /// An import that closes a cycle, e.g. a module importing itself.
+            circular,
+            /// A program has an entry point and is not importable.
+            program
+        };
+
+        import_error(const source_position position, const std::string& module_name, kind payload);
 
         std::string what() const override;
+
+    private:
+        const kind m_payload;
     };
 
     /**
@@ -249,6 +260,19 @@ namespace elna::boot
             std::vector<std::shared_ptr<symbol_table>> imports;
             diagnostic_list circular;
 
+            if (imported && tree->entry_point.has_value())
+            {
+                diagnostic_list entry_point;
+
+                entry_point.push_back(std::make_unique<import_error>(tree->entry_position.value(),
+                        key.stem().string(), import_error::kind::program));
+                result.append(key, std::move(entry_point));
+                this->cache.insert({ key, symbol_bag({}, this->globals) });
+                this->in_progress.erase(key);
+
+                return result;
+            }
+
             for (const import_declaration* sub_tree : tree->imports)
             {
                 const std::filesystem::path module_path = loader.resolve(
@@ -256,8 +280,8 @@ namespace elna::boot
 
                 if (this->in_progress.contains(module_path))
                 {
-                    circular.push_back(std::make_unique<circular_import_error>(sub_tree->position(),
-                            module_path.stem().string()));
+                    circular.push_back(std::make_unique<import_error>(sub_tree->position(),
+                            module_path.stem().string(), import_error::kind::circular));
                     continue;
                 }
                 dependency sub = this->compile(module_path, loader, target, true);
diff --git a/include/elna/boot/type_check.h b/include/elna/boot/type_check.h
index 345ef9d..50b9225 100644
--- a/include/elna/boot/type_check.h
+++ b/include/elna/boot/type_check.h
@@ -214,6 +214,11 @@ namespace elna::boot
         static bool is_equality_compatible(const type& left, const type& right);
 
         void visit_and_validate_condition(expression& condition);
+        void check_return(const procedure_body& body, const source_position position,
+                const std::string& name);
+
+    protected:
+        void visit_entry_point(unit *unit) override;
 
     public:
         explicit type_analysis_visitor(symbol_bag bag, const target_info& target);
-- 
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