fix some corner cases

Author: Yu-zh

strconv/decimal.mbt

@@ -688,3 +688,9 @@ test "parse_decimal with large numbers and truncation" {
     content="10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
   )
 }
+
+test "corner cases" {
+  inspect!(parse_decimal?(".123"), content="Ok(0.123)")
+  inspect!(parse_decimal?("."), content="Err(invalid syntax)")
+  inspect!(parse_decimal?("-"), content="Err(invalid syntax)")
+}

strconv/double_test.mbt

@@ -36,3 +36,9 @@ test "try_fast_path overflow when mantissa is too large" {
   // The function successfully falls back to slow path
   inspect!(result, content="9.007199254740991e+38")
 }
+
+test "corner cases" {
+  inspect!(@strconv.parse_double?(".123"), content="Ok(0.123)")
+  inspect!(@strconv.parse_double?("."), content="Err(invalid syntax)")
+  inspect!(@strconv.parse_double?("-"), content="Err(invalid syntax)")
+}

strconv/int.mbt

@@ -70,7 +70,12 @@ pub fn parse_int64(str : String, base~ : Int = 0) -> Int64!StrConvError {
 
   // calculate overflow threshold
   let overflow_threshold = overflow_threshold(num_base, neg)
-
+  let has_digit = match rest {
+    ['0'..='9' | 'a'..='z' | 'A'..='Z', ..]
+    | ['_', '0'..='9' | 'a'..='z' | 'A'..='Z', ..] => true
+    _ => false
+  }
+  guard has_digit else { syntax_err!() }
   // convert
   loop rest, 0L, allow_underscore {
     ['_'], _, _ =>

strconv/int_test.mbt

@@ -115,3 +115,12 @@ test "@moonbitlang/core/strconv.parse_int64/boundary_cases" {
 test "panic @moonbitlang/core/strconv.parse_int64/invalid_base" {
   ignore(@moonbitlang/core/strconv.parse_int64!("12345x"))
 }
+
+test "edge cases" {
+  // Invalid: Missing digits after hex prefix
+  inspect!(@strconv.parse_int64?("0x"), content="Err(invalid syntax)")
+  inspect!(@strconv.parse_int64?("0x_"), content="Err(invalid syntax)")
+
+  // Underscore is allowed between the prefix and the first digit
+  inspect!(@strconv.parse_int64?("0x_DEADBEEF"), content="Ok(3735928559)")
+}

strconv/uint.mbt

@@ -37,6 +37,12 @@ pub fn parse_uint64(str : String, base~ : Int = 0) -> UInt64!StrConvError {
     16 => UINT64_MAX / 16 + 1
     _ => UINT64_MAX / num_base.to_uint64() + 1
   }
+  let has_digit = match rest {
+    ['0'..='9' | 'a'..='z' | 'A'..='Z', ..]
+    | ['_', '0'..='9' | 'a'..='z' | 'A'..='Z', ..] => true
+    _ => false
+  }
+  guard has_digit else { syntax_err!() }
   loop rest, 0UL, allow_underscore {
     ['_'], _, _ =>
       // the last character cannot be underscore

strconv/uint_test.mbt

@@ -84,9 +84,9 @@ test "@strconv.parse_uint64/hex_and_edge_cases" {
 
 test "edge cases" {
   // Invalid: Missing digits after hex prefix
-  // inspect!(@strconv.parse_uint64?("0x"), content="Err(invalid syntax)")
-
-  // Invalid underscore placements in hexadecimal strings
-  // inspect!(@strconv.parse_uint64?("0x_DEADBEEF"), content="Err(invalid syntax)")
+  inspect!(@strconv.parse_uint64?("0x"), content="Err(invalid syntax)")
+  inspect!(@strconv.parse_uint64?("0x_"), content="Err(invalid syntax)")
 
+  // Underscore is allowed between the prefix and the first digit
+  inspect!(@strconv.parse_uint64?("0x_DEADBEEF"), content="Ok(3735928559)")
 }