From 6f1c37dc2dc1fba055b08c29f8373618e9bf0613 Mon Sep 17 00:00:00 2001
From: XiaoBaiYun <71159641+littlewhitecloud@users.noreply.github.com>
Date: Thu, 23 Mar 2023 23:44:23 +0800
Subject: [PATCH] Improve missing self error (#345)

Co-authored-by: Akuli <akuviljanen17@gmail.com>
---
 self_hosted/parser.jou              |  7 +++++++
 src/parse.c                         | 14 +++++++++++---
 tests/syntax_error/missing_self.jou |  8 ++++++++
 3 files changed, 26 insertions(+), 3 deletions(-)
 create mode 100644 tests/syntax_error/missing_self.jou

diff --git a/self_hosted/parser.jou b/self_hosted/parser.jou
index abf5859a..802883e7 100644
--- a/self_hosted/parser.jou
+++ b/self_hosted/parser.jou
@@ -78,6 +78,7 @@ def parse_name_type_value(tokens: Token**, expected_what_for_name: byte*) -> Ast
 
 def parse_function_or_method_signature(tokens: Token**, is_method: bool) -> AstSignature:
     # TODO: change error messages to say method, when it is a method (#243)
+    used_self: bool = False
     if (*tokens)->kind != TokenKind::Name:
         (*tokens)->fail_expected_got("a function name")
 
@@ -108,6 +109,7 @@ def parse_function_or_method_signature(tokens: Token**, is_method: bool) -> AstS
                 name_location = (*tokens)->location,
             }
             ++*tokens
+            used_self = True
 
         else:
             arg = parse_name_type_value(tokens, "an argument name")
@@ -144,6 +146,11 @@ def parse_function_or_method_signature(tokens: Token**, is_method: bool) -> AstS
         (*tokens)->fail_expected_got("a '->'")
     ++*tokens
 
+    if not used_self and is_method:
+        throwerror: byte[300]
+        snprintf(throwerror, sizeof throwerror, "missing self, should be 'def %s(self, ...)'", result.name)
+        fail((*tokens)->location, throwerror)
+
     result.return_type = parse_type(tokens)
     return result
 
diff --git a/src/parse.c b/src/parse.c
index e5f22a8c..a18f83ec 100644
--- a/src/parse.c
+++ b/src/parse.c
@@ -127,7 +127,7 @@ static AstNameTypeValue parse_name_type_value(const Token **tokens, const char *
 static AstSignature parse_function_signature(const Token **tokens, bool accept_self)
 {
     AstSignature result = {0};
-
+	bool used_self = false;
     if ((*tokens)->type != TOKEN_NAME)
         fail_with_parse_error(*tokens, "a function name");
     result.name_location = (*tokens)->location;
@@ -150,6 +150,7 @@ static AstSignature parse_function_signature(const Token **tokens, bool accept_s
                 fail_with_error((*tokens)->location, "'self' cannot be used here");
             AstNameTypeValue self_arg = { .name="self", .name_location=(*tokens)++->location };
             Append(&result.args, self_arg);
+            used_self = true;
         } else {
             AstNameTypeValue arg = parse_name_type_value(tokens, "an argument name");
 
@@ -167,7 +168,6 @@ static AstSignature parse_function_signature(const Token **tokens, bool accept_s
         else
             break;
     }
-
     if (!is_operator(*tokens, ")"))
         fail_with_parse_error(*tokens, "a ')'");
     ++*tokens;
@@ -184,7 +184,15 @@ static AstSignature parse_function_signature(const Token **tokens, bool accept_s
         fail_with_parse_error(*tokens, "a '->'");
     }
     ++*tokens;
-
+	
+	if (!used_self && accept_self) {
+        fail_with_error(
+            (*tokens)->location,
+            "missing self, should be 'def %s(self, ...)'",
+            result.name
+        );
+	}
+	
     result.returntype = parse_type(tokens);
     return result;
 }
diff --git a/tests/syntax_error/missing_self.jou b/tests/syntax_error/missing_self.jou
new file mode 100644
index 00000000..bc9d53b1
--- /dev/null
+++ b/tests/syntax_error/missing_self.jou
@@ -0,0 +1,8 @@
+class Foo:
+    def bar() -> void: # Error: missing self, should be 'def bar(self, ...)'
+        return
+
+def main() -> int:
+    f = Foo{}
+    f.bar()
+    return 0