(I don't understand why this works, and so I don't quite trust this yet. I'm pushing it up to see if anyone else can replicate this performance increase)
Somehow llvm is able to optimize this version of Vec::reserve into dramatically faster than the old version. In micro-benchmarks this was 2-10 times faster. It also reduce my Rust compile time from 41 minutes to 27 minutes.
Closes#19281.
The test harness will make sure that the panic message contains the
specified string. This is useful to help make `#[should_fail]` tests a
bit less brittle by decreasing the chance that the test isn't
"accidentally" passing due to a panic occurring earlier than expected.
The behavior is in some ways similar to JUnit's `expected` feature:
`@Test(expected=NullPointerException.class)`.
Without the message assertion, this test would pass even though it's not
actually reaching the intended part of the code:
```rust
#[test]
#[should_fail(message = "out of bounds")]
fn test_oob_array_access() {
let idx: uint = from_str("13o").unwrap(); // oops, this will panic
[1i32, 2, 3][idx];
}
```
JSON doesn't distinguish between integer and float. They are just
numbers. Also, in the current implementation, a fractional number
without the fractional part is encoded without a decimal point.
Thereforce, when the value is decoded, it is first rendered as Json,
either I64 or U64. This reduces type safety, because while the original
intention was to cast the value to float, it can also be casted to
integer.
As a workaround of this problem, this commit makes the encoder always
emit a decimal point even if it is not necessary. If the fractional part
of a float number is zero, ".0" is padded to the end of the result.
[breaking-change]
When an integral value is expected by the user but a fractional value is
found, the current implementation uses std::num::cast() to coerce to an
integer type, losing the fractional part. This behavior is not desirable
because the number loses precision without notice.
This commit makes it raise ExpectedError when such a situation arises.
[breaking-change]
serialize::json::Encoder currently uses f64 to emit any integral type.
This is possibly due to the behavior of JavaScript, which uses f64 to
represent any numeric value.
This leads to a problem that only the integers in the range of [-2^53+1,
2^53-1] can be encoded. Therefore, i64 and u64 cannot be used reliably
in the current implementation.
RFC 7159 suggests that good interoperability can be achieved if the
range is respected by implementations. However, it also says that
implementations are allowed to set the range of number accepted. And it
seems that the JSON encoders outside of the JavaScript world usually
make use of i64 values.
This commit removes the float preprocessing done in the emit_* methods.
It also increases performance, because transforming f64 into String
costs more than that of an integral type.
Fixes#18319
[breaking-change]
Now that we have an overloaded comparison (`==`) operator, and that `Vec`/`String` deref to `[T]`/`str` on method calls, many `as_slice()`/`as_mut_slice()`/`to_string()` calls have become redundant. This patch removes them. These were the most common patterns:
- `assert_eq(test_output.as_slice(), "ground truth")` -> `assert_eq(test_output, "ground truth")`
- `assert_eq(test_output, "ground truth".to_string())` -> `assert_eq(test_output, "ground truth")`
- `vec.as_mut_slice().sort()` -> `vec.sort()`
- `vec.as_slice().slice(from, to)` -> `vec.slice(from_to)`
---
Note that e.g. `a_string.push_str(b_string.as_slice())` has been left untouched in this PR, since we first need to settle down whether we want to favor the `&*b_string` or the `b_string[]` notation.
This is rebased on top of #19167
cc @alexcrichton @aturon
Closes#18959
Technically, this causes code that once compiled to no longer compile, but
that code probably never ran.
[breaking-change]
------------
Not quite sure the error message is good enough, I feel like it ought to tell you "because it inherits from non-object-safe trait Foo", so I've opened up a follow-up issue #19538
There is already a test for `union` in the test namespace, but this commit adds a doctest that will appear in the rustdocs.
Someone on IRC said, *Write doctests!*, so here I am.
I am not sure this is the best way to demonstrate the behavior of the union function, so I am open to suggestions for improving this. If I am on the right track I'd be glad to include similar doctests for `intersection`, `difference`, etc.
