docs: Small clarification on the usage of read_to_string and read_to_end trait methods

[kiseitai3]

Small clarification on the usage of read_to_string and read_to_end trait methods. The goal is to make it clear that these trait methods will become locked up if attempting to read to the end of stdin (which is a bit non-sensical unless the other end closes the pipe).

Fixes: #141714

[rustbot]

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[rustbot]

⚠️ Warning ⚠️

• Some commits in this PR modify submodules.

[kiseitai3]

This is follow up work on #141935. If possible, reassign to @tgross35. A mistake was made in the previous PR. I attempted a rebase and one thing led to another and the branch became a mess, so I killed the branch. That autoclosed the old PR, so I opened a new one with changes more in line with what Trevor asked.

Sorry, but I hope this PR is more like what is expected in this project.

[rust-log-analyzer]

The job mingw-check-2 failed! Check out the build log: (web) (plain)

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

 Documenting std v0.0.0 (/checkout/library/std)
error: unresolved link to `read`
   --> library/std/src/io/mod.rs:929:58
    |
929 |     /// Using `.lines()` with a [`BufReader`] or using [`read`] can provide a better solution
    |                                                          ^^^^ no item named `read` in scope
    |
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
    = note: `-D rustdoc::broken-intra-doc-links` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(rustdoc::broken_intra_doc_links)]`

error: unresolved link to `read`
   --> library/std/src/io/mod.rs:983:58
    |
983 |     /// Using `.lines()` with a [`BufReader`] or using [`read`] can provide a better solution
    |                                                          ^^^^ no item named `read` in scope
    |
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`

error: unresolved link to `read`
    --> library/std/src/io/mod.rs:1297:54
     |
1297 | /// Using `.lines()` with a [`BufReader`] or using [`read`] can provide a better solution
     |                                                      ^^^^ no item named `read` in scope
     |
     = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`

error: could not document `std`
warning: build failed, waiting for other jobs to finish...
[RUSTC-TIMING] std test:false 7.739
Command has failed. Rerun with -v to see more details.
Build completed unsuccessfully in 0:01:00
  local time: Fri Jun  6 01:56:08 UTC 2025
  network time: Fri, 06 Jun 2025 01:56:08 GMT
##[error]Process completed with exit code 1.
Post job cleanup.

[tgross35]

Two tiny requests:

• cat <file> | <my_rust_program -> cat file | my-rust-program, since those are totally valid binary names they don't need the <>. (kebab case is slightly more common for binaries)
• yes | my-rust-program same as above, and I don't think Data or pv are relevant to the output here are they?

[tgross35]

You'll need to add [`read`]: Read::read after this section for the link to go through. Also, looks like there's an extra newline at the end here

[tgross35]

If possible, reassign to @tgross35

I'll let you do this yourself for the experience :) you can request reviews by posting a comment, see rustbot's guidelines:

Use r? to explicitly pick a reviewer

[tgross35]

Also it looks like you accidentally picked up a submodule change here. There's about 1000 different ways to fix this but if you need a suggestion, I would do something like this:

# Reset to the point where your branch forked from `master`. The reset will get rid
# of your commit and mark all of the files as staged
git reset "$(git merge-base HEAD master)"

# Add the thing you care about
git add library/std

# Get ride of the unintentional changes
git restore src/doc

# Re-commit the files (now only what you care about) using 🪄 magic 🪄 to
# reuse the commit message you have now
git commit -C HEAD@{1}

# Update this PR
git push --force-with-lease

Also, you can always check exactly what your PR will look like before pushing with git diff "$(git merge-base HEAD master)", to avoid things like whatever bad luck you ran into with #141935 (comment).

(happy to help with git stuff if you have further questions)