fix: error reporting sometimes used token position instead of code position

src/syntax/functions/params_list.rs

@@ -4,7 +4,10 @@ use crate::{
         ErrorContainer, ErrorLabel,
     },
     lexic::token::{Token, TokenType},
-    syntax::{utils::parse_token_type, ParsingError, ParsingResult},
+    syntax::{
+        utils::{parse_token_type, Tokenizer},
+        ParsingError, ParsingResult,
+    },
 };
 
 use super::super::{
@@ -93,14 +96,15 @@ pub fn parse_params_list(tokens: &Vec<Token>, pos: usize) -> ParsingResult<Param
                     start: opening_paren.position,
                     end: opening_paren.get_end_position(),
                 };
+                let label_2_pos = tokens.code_position_from_idx(current_pos);
                 let label_2 = ErrorLabel {
                     message: String::from("The code ends here without closing the parameter list"),
-                    start: current_pos,
-                    end: current_pos + 1,
+                    start: label_2_pos,
+                    end: label_2_pos + 1,
                 };
                 let econtainer = ErrorContainer {
                     error_code: SYNTAX_INCOMPLETE_PARAMETER_LIST,
-                    error_offset: current_pos,
+                    error_offset: tokens.code_position_from_idx(current_pos),
                     labels: vec![label_1, label_2],
                     note: None,
                     help: None,
@@ -172,7 +176,7 @@ fn parse_param_definition(tokens: &Vec<Token>, pos: usize) -> ParsingResult<Para
                 };
                 let econtainer = ErrorContainer {
                     error_code: SYNTAX_INVALID_PARAMETER_DECLARATION,
-                    error_offset: datatype_token.position,
+                    error_offset: datatype_token.get_end_position(),
                     labels: vec![label],
                     note: None,
                     help: None,
@@ -290,4 +294,126 @@ mod tests {
         assert_eq!(second_param.datatype, "String");
         assert_eq!(second_param.identifier, "y");
     }
+
+    #[test]
+    fn should_fail_on_incomplete_params_list() {
+        let tokens = get_tokens(&String::from("   (   ")).unwrap();
+        let result = parse_params_list(&tokens, 0);
+
+        match result {
+            Err(ParsingError::Err(err)) => {
+                assert_eq!(SYNTAX_INCOMPLETE_PARAMETER_LIST, err.error_code);
+                assert_eq!(err.error_offset, 4);
+
+                let label = &err.labels[0];
+                assert_eq!(label.message, "The parameter list starts here");
+                assert_eq!(label.start, 3);
+                assert_eq!(label.end, 4);
+
+                let label = &err.labels[1];
+                assert_eq!(
+                    label.message,
+                    "The code ends here without closing the parameter list"
+                );
+                assert_eq!(label.start, 4);
+                assert_eq!(label.end, 5);
+            }
+            _ => panic!("Expected a ParsingError::Err"),
+        }
+    }
+
+    #[test]
+    fn should_fail_on_invalid_params_closing() {
+        let tokens = get_tokens(&String::from("   (   &")).unwrap();
+        let result = parse_params_list(&tokens, 0);
+
+        match result {
+            Err(ParsingError::Err(err)) => {
+                assert_eq!(SYNTAX_INCOMPLETE_PARAMETER_LIST, err.error_code);
+                assert_eq!(err.error_offset, 7);
+
+                let label = &err.labels[0];
+                assert_eq!(label.message, "The parameter list starts here");
+                assert_eq!(label.start, 3);
+                assert_eq!(label.end, 4);
+
+                let label = &err.labels[1];
+                assert_eq!(label.message, "Expected a closing paren `)` here");
+                assert_eq!(label.start, 7);
+                assert_eq!(label.end, 8);
+            }
+            _ => panic!("Expected a ParsingError::Err"),
+        }
+    }
+
+    #[test]
+    fn should_fail_on_invalid_params_closing_2() {
+        let tokens = get_tokens(&String::from("   (   Int i &")).unwrap();
+        let result = parse_params_list(&tokens, 0);
+
+        match result {
+            Err(ParsingError::Err(err)) => {
+                assert_eq!(SYNTAX_INCOMPLETE_PARAMETER_LIST, err.error_code);
+                assert_eq!(err.error_offset, 13);
+
+                let label = &err.labels[0];
+                assert_eq!(label.message, "The parameter list starts here");
+                assert_eq!(label.start, 3);
+                assert_eq!(label.end, 4);
+
+                let label = &err.labels[1];
+                assert_eq!(label.message, "Expected a closing paren `)` here");
+                assert_eq!(label.start, 13);
+                assert_eq!(label.end, 14);
+            }
+            _ => panic!("Expected a ParsingError::Err"),
+        }
+    }
+}
+
+#[cfg(test)]
+mod params_tests {
+    use super::*;
+    use crate::lexic::get_tokens;
+
+    #[test]
+    fn should_fail_on_missing_identifier() {
+        let tokens = get_tokens(&String::from("  Int ")).unwrap();
+        let result = parse_param_definition(&tokens, 0);
+
+        match result {
+            Err(ParsingError::Err(err)) => {
+                assert_eq!(SYNTAX_INVALID_PARAMETER_DECLARATION, err.error_code);
+                assert_eq!(err.error_offset, 5);
+
+                let label = &err.labels[0];
+                assert_eq!(label.message, "Expected an identifier after this datatype");
+                assert_eq!(label.start, 2);
+                assert_eq!(label.end, 5);
+            }
+            _ => panic!("Expected a ParsingError::Err"),
+        }
+    }
+
+    #[test]
+    fn should_fail_on_wrong_identifier() {
+        let tokens = get_tokens(&String::from("  Int 322")).unwrap();
+        let result = parse_param_definition(&tokens, 0);
+
+        match result {
+            Err(ParsingError::Err(err)) => {
+                assert_eq!(SYNTAX_INVALID_PARAMETER_DECLARATION, err.error_code);
+                assert_eq!(err.error_offset, 6);
+
+                let label = &err.labels[0];
+                assert_eq!(
+                    label.message,
+                    "Expected an identifier here, found this instead"
+                );
+                assert_eq!(label.start, 6);
+                assert_eq!(label.end, 9);
+            }
+            _ => panic!("Expected a ParsingError::Err"),
+        }
+    }
 }

src/syntax/utils.rs

@@ -4,6 +4,7 @@ use super::{ParsingError, ParsingResult};
 
 pub trait Tokenizer {
     fn get_significant<'a>(&'a self, index: usize) -> Option<(&'a Token, usize)>;
+    fn code_position_from_idx(&self, idx: usize) -> usize;
 }
 
 impl Tokenizer for Vec<Token> {
@@ -30,6 +31,30 @@ impl Tokenizer for Vec<Token> {
             }
         }
     }
+
+    /// Returns the position in the code from the token idx.
+    ///
+    /// If the token at `idx` exists, returns `tokens[idx].position`.
+    ///
+    /// Otherwise returns `tokens[idx - 1].get_end_position()`
+    fn code_position_from_idx(&self, idx: usize) -> usize {
+        // try to get the token at idx
+        match self.get(idx) {
+            Some(t) if t.token_type == TokenType::EOF => {
+                // If idx points at EOF, return the end position of the previous token
+                // This shouldnt fail
+                self[idx - 1].get_end_position()
+            }
+            Some(t) => t.position,
+            None => {
+                // this should never happen.
+                // the token stream always ends with an EOF token,
+                // and the parser should never be able to go
+                // to a position after that EOF token
+                unreachable!("Compiler error: Tried to get an out of bound token. This means that somewhere a token beyond EOF was requested.")
+            }
+        }
+    }
 }
 
 /// Expects the token at `pos` to be an operator of value `operator`. Doesn't ignore whitespace or newlines