Fix e_flags for 32-bit MIPS targets in generated object file
In #95604 the compiler started generating a temporary symbols.o which is added to the linker invocation. This object file has an `e_flags` which is invalid for 32-bit MIPS targets. Even though symbols.o doesn't contain code, linking these targets with [lld fails](https://github.com/llvm/llvm-project/blob/main/lld/ELF/Arch/MipsArchTree.cpp#L76-L79) with
```
rust-lld: error: foo-cgu.0.rcgu.o: ABI 'o32' is incompatible with target ABI 'n64'
```
because it omits the ABI bits (`EF_MIPS_ABI_O32`) so lld assumes it's using the N64 ABI. This breaks linking on nightly for the out-of-tree [mipsel-sony-psx target](https://github.com/ayrtonm/psx-sdk-rs/issues/9), the builtin mipsel-sony-psp target (cc `@overdrivenpotato)` and probably any other 32-bit MIPS target using lld.
This PR sets the ABI in `e_flags` to O32 since that's the only ABI for 32-bit MIPS that LLVM supports. It also sets other `e_flags` bits based on the target to avoid similar issues with the object file arch and PIC. I had to bump the object crate version since some of these constants were [added recently](https://github.com/gimli-rs/object/pull/433). I'm not sure if this PR needs a test, but I can confirm that it fixes the linking issue on both targets I mentioned.
Gracefully handle normalization failures in the prospective inliner cycle detector
Preliminary work for adding the regression test in #96950 to our test suite (it was flaky on glacier).
If this PR solves the flakiness on glacier, we can then merge #96950
don't encode only locally used attrs
Part of https://github.com/rust-lang/compiler-team/issues/505.
We now filter builtin attributes before encoding them in the crate metadata in case they should only be used in the local crate. To prevent accidental misuse `get_attrs` now requires the caller to state which attribute they are interested in. For places where that isn't trivially possible, I've added a method `fn get_attrs_unchecked` which I intend to remove in a followup PR.
After this pull request landed, we can then slowly move all attributes to only be used in the local crate while being certain that we don't accidentally try to access them from extern crates.
cc https://github.com/rust-lang/rust/pull/94963#issuecomment-1082924289
diagnostics: port more diagnostics to derive + support for `()` fields
- Extend diagnostic derive so that spanless subdiagnostics (e.g. some uses of `help`/`note`) can be applied via attributes to fields of type `()` (currently spanless subdiagnostics are applied via attributes on the diagnostic struct itself). A consequence of this is that `Option<()>` fields can be used to represent optional spanless subdiagnostics, which are sometimes useful (e.g. for a `help` that should only show on nightly builds).
- Simplify the "explicit generic args with impl trait" diagnostic struct (from #96760) using support for `Option<()>` spanless subdiagnostics.
- Change `DiagnosticBuilder::set_arg`, used to provide context for Fluent messages, so that it takes anything that implements `IntoDiagnosticArg`, rather than `DiagnosticArgValue` - this improves the ergonomics of manual implementations of `SessionDiagnostic` which are translatable.
- Port "the type parameter `T` must be explicitly specified", "manual implementations of `X` are experimental", "could not resolve substs on overridden impl" diagnostics to diagnostic structs.
- When testing macros from `rustc_macros` in `ui-fulldeps` tests, sometimes paths from the compiler source tree can be shown in error messages - these need to be normalized in `compiletest`.
r? `@oli-obk`
cc `@pvdrz`
