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.
