Update mod.rs #141935

kiseitai3 · 2025-06-02T23:01:41Z

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

Small clarification on the usage of `read_to_string` and `read_to_end` trait methods.

rustbot · 2025-06-02T23:01:45Z

r? @tgross35

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tgross35

Thanks for the PR, I think this is a worthwhile change but the wording could use some adjustment.

Could you please also update the commit summary and PR description? They currently both say "Update mod.rs" but instead need to say what the actual change is.

library/std/src/io/mod.rs

tgross35 · 2025-06-03T06:46:19Z

library/std/src/io/mod.rs

+    /// # Notes
+    ///
+    /// Be careful using this trait method with streams that are expected to be continuous. For example, using 
+    /// `read_to_string` with streams like `stdin` will simply lock the application into waiting on the 
+    /// transmission of data to conclude. It is recommended you use this method if you know the stream will be closed
+    /// at the other end. The problem is that EOF or End of File is never reached for streams that never close or are finite.
+    ///
    /// (See also the [`std::fs::read_to_string`] convenience function for
    /// reading from a file.)


Nit, could you move the new section under the existing "see also"? Since the "see also" is referring to reading a file in the example above.

Only issue now is that committing to my feature branch generated internal merges and I did not realize that was prohibited. Tried resetting and rebasing my branch without success.

What are you running into? Usually fixing it looks something like this:

# If you haven't yet, add rust-lang/rust as a remote and update it git remote add upstream [email protected]:rust-lang/rust.git git fetch upstream master # Do the rebase (from this branch) git rebase -i upstream/master

Then for every line except the first replace pick with f (or fixup), and git push --force-with-lease to update this PR.

…to_end` trait methods.

…ed usage note section to std::io::read_to_string as well.

…' into 141714_stdin_read_to_string_docs # Conflicts: # library/std/src/io/mod.rs

…' into 141714_stdin_read_to_string_docs

tgross35 · 2025-06-04T02:17:25Z

library/std/src/io/mod.rs

+    /// `read_to_end` attempts to read a source until EOF, but many sources are continuous streams
+    /// that do not send EOF. In these cases, `read_to_end` will block indefinitely. Standard input
+    /// is one such stream which may be finite if piped, but is typically continuous. For example,
+    /// `cat <file> | <my_rust_program>` will correctly terminate with an `EOF` upon closure of cat.
+    /// `yes "Data" | pv | <my_rust_program` or `tail -f <file> | <my_rust_program>` may not close
+    /// the stream or insert an `EOF` termination character.


This looks much better to me. I think the cat example would be good to keep, but maybe translate the other example into words in case someone doesn't know what the -f flag does

/// `read_to_end` attempts to read a source until EOF, but many sources are continuous streams /// that do not send EOF. In these cases, `read_to_end` will block indefinitely. Standard input /// is one such stream which may be finite if piped from a finite source (e.g. `cat foo.txt | /// my-program`), but is typically continuous (reading user input or sources that stay open).

I am making adjustments, but did not have time to complete tonight.

Not a problem, there is no deadline :)

This adds an `iter!` macro that can be used to create movable generators. This also adds a yield_expr feature so the `yield` keyword can be used within iter! macro bodies. This was needed because several unstable features each need `yield` expressions, so this allows us to stabilize them separately from any individual feature. Co-authored-by: Oli Scherer <[email protected]> Co-authored-by: Jieyou Xu <[email protected]> Co-authored-by: Travis Cross <[email protected]>

The panic machinery uses TLS, so panicking if no TLS keys are left can lead to infinite recursion (see rust-lang#140798 (comment)). Rather than having separate logic for the panic count and the thread name, just always abort the process if a TLS key allocation fails. This also has the benefit of aligning the key-based TLS implementation with the documentation, which does not mention that a panic could also occur because of resource exhaustion.

- Add AbiMapping for encoding the nuance of deprecated ABIs

makes entry_abi a lowering of the ABI string, so now it can be ```json "entry_abi": "C", "entry_abi": "win64", "entry_abi": "aapcs", ```

The submodule was causing issues in rust-lang/rust, so eliminiate it here. `build-musl` is also removed from `libm-test`'s default features so the crate doesn't need to be built by default.

This will be used by `josh` tooling.

Create a crate that handles pulling from and pushing to rust-lang/rust. This can be invoked with the following: $ cargo run -p josh-sync -- rustc-pull $ RUSTC_GIT=/path/to/rust/checkout cargo run -p josh-sync -- rustc-push <username>

To prepare for merging from rust-lang/rust, set the version file to: df8102f Auto merge of rust-lang#142002 - onur-ozkan:follow-ups2, r=jieyouxu

This was introduced before `#[panic_handler]` was stable, but should no longer be needed. Additionally, we only need it for `builtins-test-intrinsics`, not as a dependency of `compiler-builtins`.

…to_end` trait methods.

rustbot · 2025-06-06T00:13:09Z

This PR changes how LLVM is built. Consider updating src/bootstrap/download-ci-llvm-stamp.

Some changes occurred in compiler/rustc_codegen_gcc

cc @antoyo, @GuillaumeGomez

compiler-builtins is developed in its own repository. If possible, consider making this change to rust-lang/compiler-builtins instead.

cc @tgross35

Some changes occurred to constck

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cc @WaffleLapkin

Some changes occurred to the CTFE machinery

cc @RalfJung, @oli-obk, @lcnr

rustdoc-json-types is a public (although nightly-only) API. If possible, consider changing src/librustdoc/json/conversions.rs; otherwise, make sure you bump the FORMAT_VERSION constant.

cc @CraftSpider, @aDotInTheVoid, @Enselic, @obi1kenobi

Some changes occurred to the CTFE / Miri interpreter

cc @rust-lang/miri

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

Some changes occurred in compiler/rustc_codegen_cranelift

cc @bjorn3

These commits modify compiler targets.
(See the Target Tier Policy.)

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

This PR modifies src/bootstrap/src/core/config.

If appropriate, please update CONFIG_CHANGE_HISTORY in src/bootstrap/src/utils/change_tracker.rs.

The rustc-dev-guide subtree was changed. If this PR only touches the dev guide consider submitting a PR directly to rust-lang/rustc-dev-guide otherwise thank you for updating the dev guide with your changes.

cc @BoxyUwU, @jieyouxu, @Kobzol

These commits modify the Cargo.lock file. Unintentional changes to Cargo.lock can be introduced when switching branches and rebasing PRs.

If this was unintentional then you should revert the changes before this PR is merged.
Otherwise, you can ignore this comment.

Some changes occurred in compiler/rustc_attr_parsing

cc @jdonszelmann

Some changes occurred to the intrinsics. Make sure the CTFE / Miri interpreter
gets adapted for the changes, if necessary.

cc @rust-lang/miri, @RalfJung, @oli-obk, @lcnr

Some changes occurred in compiler/rustc_sanitizers

cc @rcvalle

Some changes occurred in src/doc/rustc/src/platform-support

cc @Noratrieb

rustbot · 2025-06-06T00:13:13Z

⚠️ Warning ⚠️

There are issue links (such as #123) in the commit messages of the following commits.
Please move them to the PR description, to avoid spamming the issues with references to the commit, and so this bot can automatically canonicalize them to avoid issues with subtree.
- 4993831
The following commits have merge commits (commits with multiple parents) in your changes. We have a no merge policy so these commits will need to be removed for this pull request to be merged.
You can start a rebase with the following commands:
```
$ # rebase
$ git pull --rebase https://github.com/rust-lang/rust.git master
$ git push --force-with-lease
```

rustbot · 2025-06-06T01:06:00Z

⚠️ Warning ⚠️

There are issue links (such as #123) in the commit messages of the following commits.
Please move them to the PR description, to avoid spamming the issues with references to the commit, and so this bot can automatically canonicalize them to avoid issues with subtree.
- 4993831
The following commits have merge commits (commits with multiple parents) in your changes. We have a no merge policy so these commits will need to be removed for this pull request to be merged.
You can start a rebase with the following commands:
```
$ # rebase
$ git pull --rebase https://github.com/rust-lang/rust.git master
$ git push --force-with-lease
```

kiseitai3 · 2025-06-06T01:12:29Z

Well, the rebase made a mess. I decided to kill the messy branch and cherry pick my commit into a fresh version of the branch. I will open a new PR.

rust-log-analyzer · 2025-06-06T01:48:06Z

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 7.970
Command has failed. Rerun with -v to see more details.
Build completed unsuccessfully in 0:01:03
  local time: Fri Jun  6 01:47:57 UTC 2025
  network time: Fri, 06 Jun 2025 01:47:57 GMT
##[error]Process completed with exit code 1.
Post job cleanup.

RalfJung · 2025-06-06T06:23:47Z

Next time please also pick a meaningful PR description. :) there are hundreds of mod.rs files so the current one says nothing. It also fails to say what is being updated in that file.

Update mod.rs

4d56e88

Small clarification on the usage of `read_to_string` and `read_to_end` trait methods.

rustbot assigned tgross35 Jun 2, 2025

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Jun 2, 2025

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tgross35 requested changes Jun 3, 2025

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rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jun 3, 2025

kiseitai3 and others added 4 commits June 3, 2025 20:32

docs: Small clarification on the usage of read_to_string and `read_…

95ff1e4

…to_end` trait methods.

docs: Amended usage notes sections in read_to_end/read_to_string. Add…

ffabd27

…ed usage note section to std::io::read_to_string as well.

Merge remote-tracking branch 'origin/141714_stdin_read_to_string_docs…

28d3682

…' into 141714_stdin_read_to_string_docs # Conflicts: # library/std/src/io/mod.rs

Merge branch 'rust-lang:master' into 141714_stdin_read_to_string_docs

f9499d9

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rustbot added the has-merge-commits PR has merge commits, merge with caution. label Jun 4, 2025

Merge remote-tracking branch 'origin/141714_stdin_read_to_string_docs…

ac993c4

…' into 141714_stdin_read_to_string_docs

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tgross35 reviewed Jun 4, 2025

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oli-obk and others added 11 commits June 5, 2025 20:06

compiler: add CanonAbi

10a81ef

compiler: add AbiMap

20e554b

- Add AbiMapping for encoding the nuance of deprecated ABIs

compiler: use CanonAbi for entry_abi

80767ea

makes entry_abi a lowering of the ABI string, so now it can be ```json "entry_abi": "C", "entry_abi": "win64", "entry_abi": "aapcs", ```

compiler: change Conv to CanonAbi

d76aaea

cg_llvm: convert to CanonAbi

608fe82

cg_clif: convert to CanonAbi

bf29712

cg_gcc: convert to CanonAbi

3b9480d

miri: sed to CanonAbi

0f617e3

bless test for CanonAbi::X86(SysV64) change

bc91070

tgross35 and others added 9 commits June 5, 2025 20:06

Replace the musl submodule with a download script

fb54651

The submodule was causing issues in rust-lang/rust, so eliminiate it here. `build-musl` is also removed from `libm-test`'s default features so the crate doesn't need to be built by default.

Add an empty rust-version file

d84e222

This will be used by `josh` tooling.

Add tooling for josh syncs

f3ef1b0

Create a crate that handles pulling from and pushing to rust-lang/rust. This can be invoked with the following: $ cargo run -p josh-sync -- rustc-pull $ RUSTC_GIT=/path/to/rust/checkout cargo run -p josh-sync -- rustc-push <username>

Update the upstream Rust version

4993831

To prepare for merging from rust-lang/rust, set the version file to: df8102f Auto merge of rust-lang#142002 - onur-ozkan:follow-ups2, r=jieyouxu

panic-handler: Remove the no_core feature

fb80bfd

This was introduced before `#[panic_handler]` was stable, but should no longer be needed. Additionally, we only need it for `builtins-test-intrinsics`, not as a dependency of `compiler-builtins`.

Rename LifetimeSyntax variants to lang-team-approved names

3432db9

Introduce the mismatched_lifetime_syntaxes lint

8563905

Replace elided_named_lifetimes with mismatched_lifetime_syntaxes

8587e1a

docs: Small clarification on the usage of read_to_string and `read_…

7298055

…to_end` trait methods.

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kiseitai3 force-pushed the 141714_stdin_read_to_string_docs branch from 61ca3f6 to 7298055 Compare June 6, 2025 01:05

kiseitai3 closed this Jun 6, 2025

kiseitai3 deleted the 141714_stdin_read_to_string_docs branch June 6, 2025 01:08

kiseitai3 mentioned this pull request Jun 6, 2025

docs: Small clarification on the usage of read_to_string and read_to_end trait methods #142102

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Update mod.rs #141935

Update mod.rs #141935

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edited by tgross35

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