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Fix the start-less-than-end assertion in std.rand.Random.range (#1325)

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The function returns a value in [start, end), but was asserting
start <= end instead of start < end.  With this fix, range(1, 1)
will now assertion error instead of dividing by zero.
This commit is contained in:
Matthew D. Steele 2018-08-03 11:44:39 -04:00 committed by Andrew Kelley
parent 298abbcff8
commit c2a08d7c51
1 changed files with 5 additions and 4 deletions
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9
std/rand/index.zig
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@ -30,7 +30,7 @@ pub const DefaultCsprng = Isaac64;
pub const Random = struct {
fillFn: fn (r: *Random, buf: []u8) void,
/// Read random bytes into the specified buffer until fill.
/// Read random bytes into the specified buffer until full.
pub fn bytes(r: *Random, buf: []u8) void {
r.fillFn(r, buf);
}
@ -48,10 +48,10 @@ pub const Random = struct {
}
}
/// Get a random unsigned integer with even distribution between `start`
/// inclusive and `end` exclusive.
/// Return a random integer with even distribution between `start`
/// inclusive and `end` exclusive. `start` must be less than `end`.
pub fn range(r: *Random, comptime T: type, start: T, end: T) T {
assert(start <= end);
assert(start < end);
if (T.is_signed) {
const uint = @IntType(false, T.bit_count);
if (start >= 0 and end >= 0) {
@ -664,6 +664,7 @@ test "Random range" {
testRange(&prng.random, -4, 3);
testRange(&prng.random, -4, -1);
testRange(&prng.random, 10, 14);
// TODO: test that prng.random.range(1, 1) causes an assertion error
}
fn testRange(r: *Random, start: i32, end: i32) void {