* In noop_fold_expr, call new_span in these cases:
- ExprMethodCall's identifier
- ExprField's identifier
- ExprTupField's integer
Calling new_span for ExprMethodCall's identifier is necessary to print
an acceptable diagnostic for write!(&2, ""). We see this error:
<std macros>:2:20: 2:66 error: type `&mut _` does not implement any method in scope named `write_fmt`
<std macros>:2 ( & mut * $ dst ) . write_fmt ( format_args ! ( $ ( $ arg ) * ) ) )
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
With this change, we also see a macro expansion backtrace leading to
the write!(&2, "") call site.
* After fully expanding a macro, we replace the expansion expression's
span with the original span. Call fld.new_span to add a backtrace to
this span. (Note that I'm call new_span after bt.pop(), so the macro
just expanded isn't on the backtrace.)
The motivating example for this change is println!("{}"). The format
string literal is concat!($fmt, "arg") and is inside the libstd macro.
We need to see the backtrace to find the println! call site.
* Add a backtrace to the format_args! format expression span.
Addresses #23459
This fixes the bug described in issue #23150. This affected formatting any floating point number into a string in a formatting pattern that: a) required rounding up, and b) required an extra digit on the front.
So `format!("{:.0}", 9.9)` would fail, but `format!("{:.0}", 8.9)` would succeed. This was due to a negative integer being cast to a `usize` resulting in an 'arithmetic operation overflowed' panic.
The fix was to change the order of operations so that the number is zero before casting.
From [here](http://doc.rust-lang.org/nightly/std/primitive.i8.html):
> `fn rotate_right(self, n: u32) -> i8`
> Shifts the bits to the right by a specified __amount amount__, n, wrapping the truncated bits to the beginning of the resulting integer.
...to be less confusing. Since 0 is the smallest number possible for usize, it doesn't make sense to mention it if it's already included, and it should be more clear that the length of the vector is a valid index with the new wording.
r? @steveklabnik
Don't use skolemized parameters but rather fresh variables in coherence. Skolemized parameters wind up preventing unification. Surprised we had no test for this! Fixes#24241.
r? @pnkfelix
Example showing sample inputs, old message, new message:
https://gist.github.com/nikomatsakis/11126784ac678b7eb6ba
Also adds infrastructure for reporting suggestions \"in situ\" and does some (minor) cleanups to `CodeMap`.
r? @brson
Now that the new TOC has landed, I've started doing an editing pass to get the old content into the right shape. I felt this introduction was significant enough to send as its own PR, though, as it's the introduction.
It's possible that we may just want to replace 'the intro' with this directly, but this PR doesn't do that.
This fixes the bug described in issue #23150. This affected formatting any floating point number into a string in a formatting pattern that: a) required rounding up, and b) required an extra digit on the front.
So `format!(\"{:.0}\", 9.9)` would fail, but `format!(\"{:.0}\", 8.9)` would succeed. This was due to a negative integer being cast to a `usize` resulting in an 'arithmetic operation overflowed' panic.
The fix was to change the order of operations so that the number is zero before casting.
Statement macros are now treated somewhat like item macros, in that a statement macro can now expand into a series of statements, rather than just a single statement.
This allows statement macros to be nested inside other kinds of macros and expand properly, where previously the expansion would only work when no nesting was present.
See:
- `src/test/run-pass/macro-stmt_macro_in_expr_macro.rs`
- `src/test/run-pass/macro-nested_stmt_macro.rs`
This changes the interface of the MacResult trait. make_stmt has become make_stmts and now returns a vector, rather than a single item. Plugin writers who were implementing MacResult will have breakage, as well as anyone using MacEager::stmt.
See:
- `src/libsyntax/ext/base.rs`
This also causes a minor difference in behavior to the diagnostics produced by certain malformed macros.
See:
- `src/test/compile-fail/macro-incomplete-parse.rs`
Implements pop() on SmallVector, and uses it to expand the final semicolon
in a statement macro expansion more efficiently.
Corrects the placement of the call to fld.cx.bt_pop(). It must run
unconditionally to reverse the corresponding push.
Use `discriminant_value` intrinsic for `derive(PartialOrd)`
[breaking-change]
This is a [breaking-change] because it can change the result of comparison operators when enum discriminants have been explicitly assigned. Notably in a case like:
```rust
#[derive(PartialOrd)]
enum E { A = 2, B = 1}
```
Under the old deriving, `A < B` held, because `A` came before `B` in the order of declaration. But now we use the ordering according to the provided values, and thus `A > B`. (However, this change is very unlikely to break much, if any, code, since the orderings themselves should all remain well-defined, total, etc.)
Fix#15523
The meaning of each variant of this enum was somewhat ambiguous and it's uncler
that we wouldn't even want to add more enumeration values in the future. As a
result this error has been altered to instead become an opaque structure.
Learning about the "first invalid byte index" is still an unstable feature, but
the type itself is now stable.
