error out when repr(align) exceeds COFF limit

[nthery]

The PE-COFF binary format limits section alignment to 8192 bytes. Emit error when alignment exceeds this limit to avoid crash in llvm.

Closes #142386.

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[rustbot]

Some changes occurred in diagnostic error codes

cc @GuillaumeGomez

Some changes occurred in compiler/rustc_passes/src/check_attr.rs

cc @jdonszelmann

[rust-log-analyzer]

The job mingw-check-tidy failed! Check out the build log: (web) (plain)

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fmt check
fmt: checked 6070 files
tidy check
Running eslint on rustdoc JS files
tidy error: /checkout/compiler/rustc_passes/messages.ftl: message `passes_repr_align_greater_than_target_max` appears before `passes_repr_align_greater_than_coff_max`, but is alphabetically later than it
run `./x.py test tidy --bless` to sort the file correctly
tidy: Skipping binary file check, read-only filesystem
##[error]tidy error: /checkout/compiler/rustc_error_codes/src/error_codes/E0805.md:7: line longer than 80 chars
removing old virtual environment
creating virtual environment at '/checkout/obj/build/venv' using 'python3.10' and 'venv'
creating virtual environment at '/checkout/obj/build/venv' using 'python3.10' and 'virtualenv'
Requirement already satisfied: pip in ./build/venv/lib/python3.10/site-packages (25.1.1)
linting python files
All checks passed!
checking python file formatting
28 files already formatted
checking C++ file formatting
some tidy checks failed
Command has failed. Rerun with -v to see more details.
Build completed unsuccessfully in 0:01:21
  local time: Tue Jun 17 19:01:15 UTC 2025
  network time: Tue, 17 Jun 2025 19:01:15 GMT
##[error]Process completed with exit code 1.
Post job cleanup.

[workingjubilee]

It only needs to error if we generate a static based on this.

[folkertdev]

Could you include testing alignment on functions here in this PR (if relevant, but I suspect it is). I think you can just add it to the test files you already modify.

#![feature(fn_align)]

// ...

// and then you can annotate a function with `#[repr(align(N))]`
#[repr(align(16))]
fn foo() {}

[workingjubilee]

@nthery This simple version that rejects repr(align(0x4000)) will need to be cratered. Nonetheless please finish writing up the PR so we can do so.

[workingjubilee]

...wait, we can't crater for Windows.

[workingjubilee]

fbbth.

[bors]

☔ The latest upstream changes (presumably #138165) made this pull request unmergeable. Please resolve the merge conflicts.

[nthery]

Could you include testing alignment on functions here in this PR (if relevant, but I suspect it is). I think you can just add it to the test files you already modify.

#![feature(fn_align)]

// ...

// and then you can annotate a function with `#[repr(align(N))]`
#[repr(align(16))]
fn foo() {}

It is relevant indeed. I reproduced the original bug with a function alignment exceeding 0x2000 bytes. Thanks for spotting this. I will add some test points.