fix formatting of doubly negated literal ints

Author: giacomocavalieri

compiler-core/src/format.rs

@@ -2548,7 +2548,7 @@ impl<'comments> Formatter<'comments> {
     fn negate_int<'a>(&mut self, expr: &'a UntypedExpr) -> Document<'a> {
         match expr {
             UntypedExpr::NegateInt { value, .. } => self.expr(value),
-            UntypedExpr::Int { value, .. } if value.starts_with('-') => self.int(value),
+            UntypedExpr::Int { value, .. } if value.starts_with('-') => self.int(&value[1..]),
             UntypedExpr::BinOp { .. } => "- ".to_doc().append(self.expr(expr)),
 
             _ => docvec!["-", self.expr(expr)],

compiler-core/src/format/tests.rs

@@ -6733,3 +6733,46 @@ fn format_panic_as_with_block_message() {
 "#
     );
 }
+
+// https://github.com/gleam-lang/gleam/issues/5056
+#[test]
+fn remove_redundant_negation_from_literal_int_1() {
+    assert_format_rewrite!(
+        "pub fn main() {
+  --1
+}
+",
+        "pub fn main() {
+  1
+}
+"
+    );
+}
+
+#[test]
+fn remove_redundant_negation_from_literal_int_2() {
+    assert_format_rewrite!(
+        "pub fn main() {
+  ---1
+}
+",
+        "pub fn main() {
+  -1
+}
+"
+    );
+}
+
+#[test]
+fn remove_redundant_negation_from_literal_int_3() {
+    assert_format_rewrite!(
+        "pub fn main() {
+  ----1
+}
+",
+        "pub fn main() {
+  1
+}
+"
+    );
+}