Validate main() argument types

self_hosted/typecheck.jou

@@ -389,10 +389,19 @@ def handle_signature(ft: FileTypes*, astsig: AstSignature*, self_type: Type*) ->
     else:
         sig.return_type = type_from_ast(ft, &astsig->return_type)
 
-    # TODO: validate main() parameters
-    # TODO: test main() taking parameters
-    if self_type == NULL and strcmp(sig.name, "main") == 0 and sig.return_type != int_type:
-        fail(astsig->return_type.location, "the main() function must return int")
+    if self_type == NULL and strcmp(sig.name, "main") == 0:
+        # special main() function checks
+        if sig.return_type != int_type:
+            fail(astsig->return_type.location, "the main() function must return int")
+        if sig.nargs != 0 and not (
+            sig.nargs == 2
+            and sig.argtypes[0] == int_type
+            and sig.argtypes[1] == byte_type->get_pointer_type()->get_pointer_type()
+        ):
+            fail(
+                astsig->args[0].type.location,
+                "if the main() function takes parameters, it should be defined like this: def main(argc: int, argv: byte**) -> int"
+            )
 
     return sig
 

src/typecheck.c

@@ -245,10 +245,20 @@ static Signature handle_signature(FileTypes *ft, const AstSignature *astsig, con
     else
         sig.returntype = type_from_ast(ft, &astsig->returntype);
 
-    // TODO: validate main() parameters
-    // TODO: test main() taking parameters
-    if (!self_type && !strcmp(sig.name, "main") && sig.returntype != intType) {
-        fail(astsig->returntype.location, "the main() function must return int");
+    if (!self_type && !strcmp(sig.name, "main")) {
+        // special main() function checks
+        if (sig.returntype != intType)
+            fail(astsig->returntype.location, "the main() function must return int");
+        if (sig.nargs != 0 && !(
+                sig.nargs == 2
+                && sig.argtypes[0] == intType
+                && sig.argtypes[1] == get_pointer_type(get_pointer_type(byteType))))
+        {
+            fail(
+                astsig->args.ptr[0].type.location,
+                "if the main() function takes parameters, it should be defined like this: def main(argc: int, argv: byte**) -> int"
+            );
+        }
     }
 
     sig.returntype_location = astsig->returntype.location;

tests/should_succeed/main_funny_arg_names.jou

@@ -0,0 +1,6 @@
+import "stdlib/io.jou"
+
+# Usually the args are named "argc" and "argv", but you can name them whatever you want.
+def main(lol: int, wat: byte**) -> int:
+    printf("lol = %d\n", lol)  # Output: lol = 1
+    return 0

tests/wrong_type/main_1_arg.jou

@@ -0,0 +1,4 @@
+def main(
+    argc: int  # Error: if the main() function takes parameters, it should be defined like this: def main(argc: int, argv: byte**) -> int
+) -> int:
+    return 0

tests/wrong_type/main_3_args.jou

@@ -0,0 +1,4 @@
+def main(
+    argc: int, argv: byte**, lol: int  # Error: if the main() function takes parameters, it should be defined like this: def main(argc: int, argv: byte**) -> int
+) -> int:
+    return 0

tests/wrong_type/main_argc.jou

@@ -0,0 +1,4 @@
+def main(
+    argc: long, argv: byte**  # Error: if the main() function takes parameters, it should be defined like this: def main(argc: int, argv: byte**) -> int
+) -> int:
+    return 0

tests/wrong_type/main_argv.jou

@@ -0,0 +1,4 @@
+def main(
+    argc: int, argv: byte*  # Error: if the main() function takes parameters, it should be defined like this: def main(argc: int, argv: byte**) -> int
+) -> int:
+    return 0