From c02a0f90df8f45e3cda4b320acaa3989745118f1 Mon Sep 17 00:00:00 2001
From: Henrixounez <30901439+Henrixounez@users.noreply.github.com>
Date: Fri, 18 Sep 2020 01:14:14 +0200
Subject: [PATCH] checker: prompt error on script expression while inside a
 file with main (#6400)

---
 vlib/v/checker/checker.v                     | 3 +++
 vlib/v/checker/tests/main_and_script_err.out | 5 +++++
 vlib/v/checker/tests/main_and_script_err.vv  | 4 ++++
 3 files changed, 12 insertions(+)
 create mode 100644 vlib/v/checker/tests/main_and_script_err.out
 create mode 100644 vlib/v/checker/tests/main_and_script_err.vv

diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index cf4330f83d..199700dbd4 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -191,6 +191,9 @@ fn (mut c Checker) check_file_in_main(file ast.File) bool {
 			}
 			ast.FnDecl {
 				if stmt.name == 'main.main' {
+					if has_main_fn {
+						c.error('function `main` is already defined', stmt.pos)
+					}
 					has_main_fn = true
 					if stmt.is_pub {
 						c.error('function `main` cannot be declared public', stmt.pos)
diff --git a/vlib/v/checker/tests/main_and_script_err.out b/vlib/v/checker/tests/main_and_script_err.out
new file mode 100644
index 0000000000..71b5f75084
--- /dev/null
+++ b/vlib/v/checker/tests/main_and_script_err.out
@@ -0,0 +1,5 @@
+vlib/v/checker/tests/main_and_script_err.vv:1:1: error: function `main` is already defined
+    1 | fn main() {
+      | ^
+    2 |     println('main')
+    3 | }
diff --git a/vlib/v/checker/tests/main_and_script_err.vv b/vlib/v/checker/tests/main_and_script_err.vv
new file mode 100644
index 0000000000..e746460bd9
--- /dev/null
+++ b/vlib/v/checker/tests/main_and_script_err.vv
@@ -0,0 +1,4 @@
+fn main() {
+	println('main')
+}
+println('out')