• via Digitalmars-d-bugs (25/25) Jun 30 2016 https://issues.dlang.org/show_bug.cgi?id=16223

via Digitalmars-d-bugs <digitalmars-d-bugs puremagic.com> writes:

https://issues.dlang.org/show_bug.cgi?id=16223

          Issue ID: 16223
           Summary: BigUint: undefined shift for small instantiation type
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: phobos
          Assignee: nobody puremagic.com
          Reporter: jbc.engelen gmail.com

Module std.internal.math.biguintcore contains the code:
```
    static BigUint mulInt(T = ulong)(BigUint x, T y) pure nothrow
    {
        if (y==0 || x == 0) return BigUint(ZERO);
        uint hi = cast(uint)(y >>> 32);
```
The ">>> 32" is undefined for sizeof(T)*8 <= 32 (so for T = int, uint, char,
...). There should at least be a check that the function is not instantiated
for types equal or smaller than 32 bits.

No bug yet, because the only usage of mulInt is with T=ulong (bigint.d).

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