fix(seq): handle 0e... scientific notation without padding (#6934)

* fix(seq): handle 0e... scientific notation without padding

- Updated the parse_exponent_no_decimal function to treat 0e... as zero.
- Added test cases to verify correct behavior for 0e15 and -w 0e15.

Fix: #6926

* fix(seq): improved parse for accurate BigDecimal handling

* apply missing cargo fmt formatting adjustments

src/uu/seq/src/numberparse.rs

@@ -102,7 +102,16 @@ fn parse_exponent_no_decimal(s: &str, j: usize) -> Result<PreciseNumber, ParseNu
     // displayed in decimal notation. For example, "1e-2" will be
     // displayed as "0.01", but "1e2" will be displayed as "100",
     // without a decimal point.
-    let x: BigDecimal = s.parse().map_err(|_| ParseNumberError::Float)?;
+    let x: BigDecimal = {
+        let parsed_decimal = s
+            .parse::<BigDecimal>()
+            .map_err(|_| ParseNumberError::Float)?;
+        if parsed_decimal == BigDecimal::zero() {
+            BigDecimal::zero()
+        } else {
+            parsed_decimal
+        }
+    };
 
     let num_integral_digits = if is_minus_zero_float(s, &x) {
         if exponent > 0 {
@@ -204,7 +213,16 @@ fn parse_decimal_and_exponent(
     // Because of the match guard, this subtraction will not underflow.
     let num_digits_between_decimal_point_and_e = (j - (i + 1)) as i64;
     let exponent: i64 = s[j + 1..].parse().map_err(|_| ParseNumberError::Float)?;
-    let val: BigDecimal = s.parse().map_err(|_| ParseNumberError::Float)?;
+    let val: BigDecimal = {
+        let parsed_decimal = s
+            .parse::<BigDecimal>()
+            .map_err(|_| ParseNumberError::Float)?;
+        if parsed_decimal == BigDecimal::zero() {
+            BigDecimal::zero()
+        } else {
+            parsed_decimal
+        }
+    };
 
     let num_integral_digits = {
         let minimum: usize = {

tests/by-util/test_seq.rs

@@ -842,3 +842,31 @@ fn test_invalid_format() {
         .no_stdout()
         .stderr_contains("format '%g%g' has too many % directives");
 }
+
+#[test]
+fn test_parse_scientific_zero() {
+    new_ucmd!()
+        .args(&["0e15", "1"])
+        .succeeds()
+        .stdout_only("0\n1\n");
+    new_ucmd!()
+        .args(&["0.0e15", "1"])
+        .succeeds()
+        .stdout_only("0\n1\n");
+    new_ucmd!()
+        .args(&["0", "1"])
+        .succeeds()
+        .stdout_only("0\n1\n");
+    new_ucmd!()
+        .args(&["-w", "0e15", "1"])
+        .succeeds()
+        .stdout_only("0000000000000000\n0000000000000001\n");
+    new_ucmd!()
+        .args(&["-w", "0.0e15", "1"])
+        .succeeds()
+        .stdout_only("0000000000000000\n0000000000000001\n");
+    new_ucmd!()
+        .args(&["-w", "0", "1"])
+        .succeeds()
+        .stdout_only("0\n1\n");
+}