ptr_aligment_type: add more APIs

[GrigorenkoPV]

As per #102070 (comment)

Tracking issue: #102070

Mostly duplicating methods that previously worked with usize-represented alignments.

Naming follows a convention of align: usize, alignment: Alignment.

Based on top of #148769

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[GrigorenkoPV]

Conflicts with #148769, let's wait for that first

[joboet]

I really prefer the current spelling of Alignment::of as opposed to alignment_of and therefore would like to suggest adding of_val and of_val_raw as associated methods instead of free-standing functions in mem.

[scottmcm]

This rename is so big that github hides it by default.

Please make this PR just the api addition. If you also want to rename this field, that's fine, but please do it separately because of how much it touches.

[scottmcm]

fix: you don't need the return, the true, or the false here.

[GrigorenkoPV]

Looks like the failure is due to the rename of master branch and is unrelated to this PR

[bors]

☔ The latest upstream changes (presumably #149109) made this pull request unmergeable. Please resolve the merge conflicts.

[rust-log-analyzer]

The job aarch64-gnu-llvm-20-2 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

 Documenting core v0.0.0 (/checkout/library/core)
error: public documentation for `from_size_alignment_unchecked` links to private item `Layout::from_size_alignment`
   --> library/core/src/alloc/layout.rs:148:11
    |
148 |     /// [`Layout::from_size_alignment`].
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^ this item is private
    |
    = note: this link will resolve properly if you pass `--document-private-items`
    = note: `-D rustdoc::private-intra-doc-links` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(rustdoc::private_intra_doc_links)]`

error: public documentation for `adjust_alignment_to` links to private item `Layout::from_size_alignment`
   --> library/core/src/alloc/layout.rs:309:57
    |
309 |     /// `alignment` violates the conditions listed in [`Layout::from_size_alignment`].
    |                                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^ this item is private
    |
    = note: this link will resolve properly if you pass `--document-private-items`

error: could not document `core`
warning: build failed, waiting for other jobs to finish...
[RUSTC-TIMING] core test:false 25.385
Bootstrap failed while executing `--stage 2 test --skip tests --skip coverage-map --skip coverage-run --skip library --skip tidyselftest`
Command `/checkout/obj/build/aarch64-unknown-linux-gnu/stage0/bin/cargo doc --target aarch64-unknown-linux-gnu -Zbinary-dep-depinfo -j 4 -Zroot-dir=/checkout --locked --color=always --release -p alloc -p compiler_builtins -p core -p panic_abort -p panic_unwind -p proc_macro -p rustc-std-workspace-core -p std -p std_detect -p sysroot -p test -p unwind --features 'backtrace panic-unwind compiler-builtins-c' --manifest-path /checkout/library/sysroot/Cargo.toml --no-deps --target-dir /checkout/obj/build/aarch64-unknown-linux-gnu/stage1-std/aarch64-unknown-linux-gnu/doc -Zskip-rustdoc-fingerprint -Zrustdoc-map [workdir=/checkout]` failed with exit code 101
Created at: src/bootstrap/src/core/build_steps/doc.rs:795:21
Executed at: src/bootstrap/src/core/build_steps/doc.rs:828:22

Command has failed. Rerun with -v to see more details.
Build completed unsuccessfully in 0:30:41
  local time: Fri Dec 19 22:33:53 UTC 2025
  network time: Fri, 19 Dec 2025 22:33:54 GMT
##[error]Process completed with exit code 1.
##[group]Run echo "disk usage:"