Signed-off-by: David Wood <david@davidtw.co>

Compiletest code sometimes refers to a test's revision as its `cfg`. This
results in two different names for the same thing, one of which is ambiguous
with other kinds of configuration (such as compiletest's own config).

This patch replaces those occurrences of `cfg` with `revision`.

As bonus this makes the errors when failing to load a proc macro more
informative to match the backend loading errors. In addition it makes it
slightly easier to patch rustc to work on platforms that don't support
dynamic linking like wasm.

Fixes rust-lang#121381

Its one use isn't necessary, because it's not possible for errors to
have been emitted at that point.

Currently `has_errors` excludes lint errors. This commit changes it to
include lint errors.

The motivation for this is that for most places it doesn't matter
whether lint errors are included or not. But there are multiple places
where they must be includes, and only one place where they must not be
included. So it makes sense for `has_errors` to do the thing that fits
the most situations, and the new `has_errors_excluding_lint_errors`
method in the one exceptional place.

The same change is made for `err_count`. Annoyingly, this requires the
introduction of `err_count_excluding_lint_errs` for one place, to
preserve existing error printing behaviour. But I still think the change
is worthwhile overall.

Currently `emit_stashed_diagnostic` is called from four(!) different
places: `print_error_count`, `DiagCtxtInner::drop`, `abort_if_errors`,
and `compile_status`.

And `flush_delayed` is called from two different places:
`DiagCtxtInner::drop` and `Queries`.

This is pretty gross! Each one should really be called from a single
place, but there's a bunch of entanglements. This commit cleans up this
mess.

Specifically, it:
- Removes all the existing calls to `emit_stashed_diagnostic`, and adds
  a single new call in `finish_diagnostics`.
- Removes the early `flush_delayed` call in `codegen_and_build_linker`,
  replacing it with a simple early return if delayed bugs are present.
- Changes `DiagCtxtInner::drop` and `DiagCtxtInner::flush_delayed` so
  they both assert that the stashed diagnostics are empty (i.e.
  processed beforehand).
- Changes `interface::run_compiler` so that any errors emitted during
  `finish_diagnostics` (i.e. late-emitted stashed diagnostics) are
  counted and cannot be overlooked. This requires adding
  `ErrorGuaranteed` return values to several functions.
- Removes the `stashed_err_count` call in `analysis`. This is possible
  now that we don't have to worry about calling `flush_delayed` early
  from `codegen_and_build_linker` when stashed diagnostics are pending.
- Changes the `span_bug` case in `handle_tuple_field_pattern_match` to a
  `delayed_span_bug`, because it now can be reached due to the removal
  of the `stashed_err_count` call in `analysis`.
- Slightly changes the expected output of three tests. If no errors are
  emitted but there are delayed bugs, the error count is no longer
  printed. This is because delayed bugs are now always printed after the
  error count is printed (or not printed, if the error count is zero).

There is a lot going on in this commit. It's hard to break into smaller
pieces because the existing code is very tangled. It took me a long time
and a lot of effort to understand how the different pieces interact, and
I think the new code is a lot simpler and easier to understand.

Because it's now simple enough that it doesn't provide much benefit.

It currently is infallible and uses `abort_if_errors` and
`FatalError.raise()` to signal errors. It's easy to instead return a
`Result<_, ErrorGuaranteed>`, which is the more usual way of doing
things.

Replace `abort_if_errors` calls that are certain to abort -- because
we emit an error immediately beforehand -- with `FatalErro.raise()`.

It's clumsy and doesn't improve readability.

…ng, r=oli-obk

Top level error handling

The interactions between the following things are surprisingly complicated:
- `emit_stashed_diagnostics`,
- `flush_delayed`,
- normal return vs `abort_if_errors`/`FatalError.raise()` unwinding in the call to the closure in `interface::run_compiler`.

This PR disentangles it all.

r? `@oli-obk`

coverage: Remove `pending_dups` from the span refiner

When extracting coverage spans from a function's MIR, we need to decide how to handle spans that are associated with more than one node (BCB) in the coverage control flow graph.

The existing code for managing those duplicate spans is very subtle and difficult to modify. But by eagerly deduplicating those extracted spans in a much simpler way, we can remove a massive chunk of complexity from the span refiner.

There is a tradeoff here, in that we no longer try to retain *all* nondominating BCBs that have the same span, only the last one in the (semi-arbitrary) dominance ordering. But in practice, this produces very little difference in our coverage tests, and the simplification is so significant that I think it's worthwhile.

``@rustbot`` label +A-code-coverage

… r=wesleywiser

triagebot: add queue notifications

This seems like it could be useful.

r? ``@wesleywiser``

Consistently refer to a test's `revision` instead of `cfg`

Compiletest allows a test file to specify multiple “revisions” (`//@ revisions: foo bar`), with each revision running as a separate test, and having the ability to define revision-specific headers (`//`@[foo]` ignore-blah`) and revision-specific code (`#[cfg(foo)]`).

The code that implements this feature sometimes uses the term “cfg” instead of “revision”. This results in two confusingly-different names for the same concept, one of which is ambiguous with other kinds of configuration (such as compiletest's own config).

This PR replaces those occurrences of `cfg` with `revision`, so that one name is used consistently.

…-errors

never patterns: Fix liveness analysis in the presence of never patterns

There's a bunch of code that only looks at the first alternative of an or-pattern, under the assumption that all alternatives have the same set of bindings. This is true except for never pattern alternatives  (e.g. `Ok(x) | Err(!)`), so we skip these. I expect there's other code with this problem, I'll have to check that later.

I don't have tests for this yet because mir lowering causes other issues; I'll have some in the next PR.

r? ``@compiler-errors``

…ochenkov

Unify dylib loading between proc macros and codegen backends

As bonus this makes the errors when failing to load a proc macro more informative to match the backend loading errors. In addition it makes it slightly easier to patch rustc to work on platforms that don't support dynamic linking like wasm.

…trochenkov

Solaris linker does not support --strip-debug

Fixes rust-lang#121381

Add a couple tests

Fixes rust-lang#119857
Fixes rust-lang#115497