Dont allow top level names start with '//'

src/fun/parser.rs

@@ -812,6 +812,9 @@ pub trait ParserCommons<'a>: Parser<'a> {
     if nam.contains("__") {
       let msg = "Top-level names are not allowed to contain \"__\".".to_string();
       self.with_ctx(Err(msg), ini_idx, end_idx)
+    } else if nam.starts_with("//") {
+      let msg = "Top-level names are not allowed to start with \"//\".".to_string();
+      self.with_ctx(Err(msg), ini_idx, end_idx)
     } else {
       Ok(nam)
     }

src/imp/parser.rs

@@ -912,7 +912,7 @@ impl<'a> PyParser<'a> {
     }
 
     self.skip_trivia_inline();
-    let name = self.parse_bend_name()?;
+    let name = self.parse_top_level_name()?;
     self.skip_trivia_inline();
     let params = if self.starts_with("(") {
       self.list_like(|p| p.parse_bend_name(), "(", ")", ",", true, 0)?

tests/golden_tests/compile_file/top_level_name_slashslash.bend

@@ -0,0 +1,8 @@
+def random//constant():
+  return 3.14
+
+def //thisshouldfail():
+  return random//constant()
+
+def main:
+  return //thisshouldfail()

tests/snapshots/compile_file__top_level_name_slashslash.bend.snap

@@ -0,0 +1,8 @@
+---
+source: tests/golden_tests.rs
+input_file: tests/golden_tests/compile_file/top_level_name_slashslash.bend
+---
+Errors:
+In tests/golden_tests/compile_file/top_level_name_slashslash.bend :
+Top-level names are not allowed to start with "//".
+  4 | def //thisshouldfail():