From 6be28381d6081dfb3a1dc9d1ec15062b67ba1ef9 Mon Sep 17 00:00:00 2001
From: Tolmachev Igor <me@igorek.dev>
Date: Sat, 9 May 2026 19:04:27 +0300
Subject: Implement fmt::Display for Error

Replaces the todo!() stub. InvalidFloatLiteral and InvalidIntegerLiteral now also take the original
string.
---
 compiler/src/ast/error.rs  | 33 +++++++++++++++++----------------
 compiler/src/ast/parser.rs | 16 ++++++++++------
 compiler/src/ast/tests.rs  |  8 ++++----
 3 files changed, 31 insertions(+), 26 deletions(-)

(limited to 'compiler/src')

diff --git a/compiler/src/ast/error.rs b/compiler/src/ast/error.rs
index c3283f4..8117513 100644
--- a/compiler/src/ast/error.rs
+++ b/compiler/src/ast/error.rs
@@ -7,8 +7,8 @@ use std::{
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub enum Error {
     // Number
-    InvalidFloatLiteral(ParseFloatError),
-    InvalidIntegerLiteral(ParseIntError),
+    InvalidFloatLiteral(Rc<str>, ParseFloatError),
+    InvalidIntegerLiteral(Rc<str>, ParseIntError),
 
     // String
     UnclosedString(Rc<str>),
@@ -23,21 +23,22 @@ pub enum Error {
     RecursionLimit,
 }
 
-impl From<ParseFloatError> for Error {
-    fn from(value: ParseFloatError) -> Self {
-        Self::InvalidFloatLiteral(value)
-    }
-}
-
-impl From<ParseIntError> for Error {
-    fn from(value: ParseIntError) -> Self {
-        Self::InvalidIntegerLiteral(value)
-    }
-}
-
 impl fmt::Display for Error {
-    fn fmt(&self, _f: &mut fmt::Formatter) -> fmt::Result {
-        todo!()
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Error::InvalidFloatLiteral(number, err) => {
+                write!(f, "invalid float literal {number}: {err}")
+            }
+            Error::InvalidIntegerLiteral(number, err) => {
+                write!(f, "invalid integer literal {number}: {err}")
+            }
+            Error::UnclosedString(string) => write!(f, "unclosed string {string:?}"),
+            Error::UnexpectedEscapeChar(ch) => write!(f, "unexpected escape char {ch:?}"),
+            Error::UnexpectedRightPar => write!(f, "unexpected right par"),
+            Error::UnclosedLeftPar => write!(f, "unclosed left par"),
+            Error::UnexpectedEof => write!(f, "unexpected eof"),
+            Error::RecursionLimit => write!(f, "recursion limit"),
+        }
     }
 }
 
diff --git a/compiler/src/ast/parser.rs b/compiler/src/ast/parser.rs
index 83e48b8..263e5b7 100644
--- a/compiler/src/ast/parser.rs
+++ b/compiler/src/ast/parser.rs
@@ -12,13 +12,17 @@ fn parse_number(number: &str) -> Result<Atom, Error> {
     let is_float = number.bytes().any(|b| matches!(b, b'.' | b'e' | b'E'))
         || matches!(number, "inf" | "+inf" | "-inf" | "nan");
 
-    let atom = if is_float {
-        Atom::Float(number.parse()?)
+    if is_float {
+        match number.parse() {
+            Ok(ok) => Ok(Atom::Float(ok)),
+            Err(err) => Err(Error::InvalidFloatLiteral(number.into(), err)),
+        }
     } else {
-        Atom::Integer(number.parse()?)
-    };
-
-    Ok(atom)
+        match number.parse() {
+            Ok(ok) => Ok(Atom::Integer(ok)),
+            Err(err) => Err(Error::InvalidIntegerLiteral(number.into(), err)),
+        }
+    }
 }
 
 fn parse_string(string: &str) -> Result<Atom, Error> {
diff --git a/compiler/src/ast/tests.rs b/compiler/src/ast/tests.rs
index 708e788..c6d8c38 100644
--- a/compiler/src/ast/tests.rs
+++ b/compiler/src/ast/tests.rs
@@ -415,7 +415,7 @@ fn test_invalid_integer() {
         let error = number.parse::<i64>().unwrap_err();
         assert_eq!(
             parse_err(tokens.clone()),
-            Error::InvalidIntegerLiteral(error),
+            Error::InvalidIntegerLiteral(number.into(), error),
             "input: {tokens:?}",
         );
     }
@@ -445,7 +445,7 @@ fn test_invalid_float() {
         let error = number.parse::<f64>().unwrap_err();
         assert_eq!(
             parse_err(tokens.clone()),
-            Error::InvalidFloatLiteral(error),
+            Error::InvalidFloatLiteral(number.into(), error),
             "input: {tokens:?}",
         );
     }
@@ -639,7 +639,7 @@ fn test_error_span_invalid_float() {
     let err = parse_sp_err(tokens.clone());
 
     assert!(
-        matches!(err.inner, Error::InvalidFloatLiteral(_)),
+        matches!(err.inner, Error::InvalidFloatLiteral(..)),
         "input: {tokens:?}, got: {:?}",
         err.inner,
     );
@@ -725,7 +725,7 @@ fn test_error_span_deep_nested() {
     let err = parse_sp_err(tokens.clone());
 
     assert!(
-        matches!(err.inner, Error::InvalidIntegerLiteral(_)),
+        matches!(err.inner, Error::InvalidIntegerLiteral(..)),
         "input: {tokens:?}, got: {:?}",
         err.inner,
     );
-- 
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