This refactoring tries to make numeric fallback easier to reason about.
Instead of applying all fallbacks at an arbitrary point in the middle
of inference, we apply the fallback only when necessary and only for
the variable that requires it, which for numeric fallback turns out to
be just casts.
The only visible consequence seems to be some error messages where
instead of getting `i32` we get `{integer}` because we are less eager
about fallback.
The bigger goal is to make it easier to integrate user fallbacks into
inference, if we ever figure that out.
Libtest json output
A revisit to my [last PR](https://github.com/rust-lang/rust/pull/45923).
Events are now more atomic, printed in a flat hierarchy.
For the normal test output:
```
running 1 test
test f ... FAILED
failures:
---- f stdout ----
thread 'f' panicked at 'assertion failed: `(left == right)`
left: `3`,
right: `4`', f.rs:3:1
note: Run with `RUST_BACKTRACE=1` for a backtrace.
failures:
f
test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out
```
The JSON equivalent is:
```
{ "type": "suite", "event": "started", "test_count": "1" }
{ "type": "test", "event": "started", "name": "f" }
{ "type": "test", "event": "failed", "name": "f" }
{ "type": "suite", "event": "failed", "passed": 0, "failed": 1, "allowed_fail": 0, "ignored": 0, "measured": 0, "filtered_out": "0" }
{ "type": "test_output", "name": "f", "output": "thread 'f' panicked at 'assertion failed: `(left == right)`
left: `3`,
right: `4`', f.rs:3:1
note: Run with `RUST_BACKTRACE=1` for a backtrace.
" }
```
For E0277 on `for` loops, point at the "head" expression
When E0277's span points at a `for` loop, the actual issue is in the
element being iterated. Instead of pointing at the entire loop, point
only at the first line (when possible) so that the span ends in the
element for which E0277 was triggered.
MIR's `Const::get_field()` attempts to retrieve the value for a given
field in a constant. In the case of a union constant it was falling
through to a generic `const_get_elt` based on the field index. As union
fields don't have an index this caused an ICE in `llvm_field_index`.
Fix by simply returning the current value when accessing any field in a
union. This works because all union fields start at byte offset 0.
The added test uses `const_fn` it ensure the field is extracted using
MIR's const evaluation. The crash is reproducible without it, however.
Fixes#47788
libtest: Split HumanFormatter into {Pretty,Terse}
libtest: Fixed padding of benchmarks when not benchmarking
libtest: Fixed benchmarks' names not showing in terse-mode
libtest: Formatting
If an error message is emitted that spans several files, only the
primary file currently has line and column data attached. This is
useful information, even in files other than the one in which the error
occurs. We can often work out which line and column the error
corresponds to in other files — in this case it is helpful to add them
(in the case of ambiguity, the first relevant line/column is picked,
which is still helpful than none).
Fix ICE when use trees have multiple empty nested groups
The issue was caused by an oversight of mine in the original use_nested_groups PR, where different paths were resolved with the same `NodeId` in some cases (such as in `use {{}, {}};`).
Fixes#47673
r? @petrochenkov
