Bug 12835 – std.random.uniform with open lower bound cannot support smaller integral types or character types

Created attachment 1359 Code snippet illustrating the problem std.random.uniform will fail to compile if an open lower bound is specified (i.e. boundaries == "(]" or "()") and either: * the type requested is a character type, or * the type requested is an integral type smaller than int (i.e. ushort, short, ubyte, byte). The attached code sample will allow the problem to be seen: attempting to compile it results in errors: /opt/dmd/import/std/random.d(1336): Error: cannot implicitly convert expression (cast(int)a + 1) of type int to ushort /opt/dmd/import/std/random.d(1197): Error: template instance std.random.uniform!("()", ushort, ushort, MersenneTwisterEngine!(uint, 32LU, 624LU, 397LU, 31LU, 2567483615u, 11LU, 7LU, 2636928640u, 15LU, 4022730752u, 18LU)) error instantiating uniform.d(10): instantiated from here: uniform!("()", ushort, ushort) uniform.d(21): instantiated from here: uniformTest!ushort ... and so on for the other unsupported types. Note that this problem persists whether the uniform() is the recently-updated one provide in PR 1717 or the uniform preceding it, so we can't simply solve the problem by reverting a patch.

If we look at the problematic line in the _old_ std.random (i.e. before PR 1717 was merged), we have the following: ResultType min = cast(ResultType) a + 1; I'm presuming that this is probably simply a typo and that line should read, ResultType min = cast(ResultType) (a + 1); .... ?

Fix submitted: https://github.com/D-Programming-Language/phobos/pull/2221

Commits pushed to master at https://github.com/D-Programming-Language/phobos https://github.com/D-Programming-Language/phobos/commit/88d86ecda0c53568e4c7036ec85aa7a5a27438f9 Fix Issue #12835: open lower bound for integral-type uniform() Added a cast to ensure the setting of lower bound can handle character types and integral types smaller than int. The additional unittests should prevent such issues from arising again. https://github.com/D-Programming-Language/phobos/commit/9e96ee3d38b563fb70c8761a0ccee663d59810cc Merge pull request #2221 from WebDrake/uniform-lowerbound Fix Issue #12835: open lower bound for integral-type uniform()