fix skipPrefixes bug

stint/io.nim

@@ -213,10 +213,14 @@ func skipPrefixes(current_idx: var int, str: string, radix: range[2..16]) {.inli
     elif str[1] in {'o', 'O'}:
       doAssert radix == 8, "Parsing mismatch, 0o prefix is only valid for an octal number (base 8)"
       current_idx = 2
-    elif str[1] in {'b', 'B'}:
-      # this check will fail if we have radix 16 and input "0bcdef12345" which is a valid hex
-      doAssert radix == 2, "Parsing mismatch, 0b prefix is only valid for a binary number (base 2)"
-      current_idx = 2
+    elif str[1] in {'b', 'B'}:      
+      if radix == 2:
+        current_idx = 2
+      elif radix == 16:
+        # allow something like "0bcdef12345" which is a valid hex
+        current_idx = 0
+      else:
+        doAssert false, "Parsing mismatch, 0b prefix is only valid for a binary number (base 2), or hex number"      
 
 func nextNonBlank(current_idx: var int, s: string) {.inline.} =
   ## Move the current index, skipping white spaces and "_" characters.

tests/all_tests.nim

@@ -1,5 +1,5 @@
 # Stint
-# Copyright 2018 Status Research & Development GmbH
+# Copyright 2018-2023 Status Research & Development GmbH
 # Licensed under either of
 #
 #  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
@@ -31,9 +31,8 @@ import
   test_int_muldiv,
   test_int_exp
 
-
 import
   test_io,
   test_conversion,
-  t_randomized_divmod
-
+  t_randomized_divmod,
+  test_bugfix

tests/test_bugfix.nim

@@ -0,0 +1,20 @@
+# Copyright 2023 Status Research & Development GmbH
+# Licensed under either of
+#
+#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
+#  * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
+#
+# at your option. This file may not be copied, modified, or distributed except according to those terms.
+
+import ../stint, unittest
+
+suite "various bugfix":
+  test "skipPrefixes bug":
+    let x = "0b1010101".parse(UInt128, 2)
+    let z = "0bcdef12345".parse(UInt128, 16)
+    
+    check x == 0b1010101.u128
+    check z == 0x0bcdef12345.u128
+    
+    expect(AssertionDefect):
+      discard "0bcdef12345".parse(UInt128, 10)