Give rustfmt a hint about stdin input #5266

ytmimi · 2022-03-14T13:17:54Z

When formatting text via stdin rustfmt didn't have a way to ignore stdin input.

Now, when passing input to rustfmt via stdin one can also provide the --stdin-file-hint option to inform rustfmt that the input is actually from the hinted at file. rustfmt now uses this hint to determine if it can ignore formatting stdin and immediately echo the input back to the user.

Note: This option can only be passed when formatting files via stdin, and is intended for text editor plugins that call rustfmt by passing input via stdin (e.g. rust-analyzer).

ytmimi · 2022-03-15T01:19:42Z

Looks like the "stable" tests are failing because the ignore list can't be set. I'll add the #[nightly_only_test] to the relevant tests.

~~Also looks like some issues with windows paths.~~
Edit: The issue does not seem to be related to windows paths see comment below

ytmimi · 2022-03-17T23:35:36Z

Looking at (i686-pc-windows-gnu, nightly) logs (but all windows logs should be similar) I added some println! macros to help me debug what's going on. I'm scratching my head because the strings should be the same but the comparison is failing on windows, but succeeding on linux/mac.

Heres' an example of one of the logs

---- rustfmt_stdin_formatting::changes_are_output_to_stdout stdout ----
expect: fn main() {
    println!("hello world!");
}

stdout: fn main() {
    println!("hello world!");
}

stderr: 
thread 'rustfmt_stdin_formatting::changes_are_output_to_stdout' panicked at 'assertion failed: stdout == expected_output', tests\rustfmt\main.rs:212:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Edit:

If you compare the expect value with the stdout value in a python REPL it shows that they're the same, so now I'm really confused 🙃

>>> expect = """
... fn main() {
...     println!("hello world!");
... }
... """
>>> stdout = """
... fn main() {
...     println!("hello world!");
... }
... """
>>> expect == stdout
True

calebcartwright · 2022-03-18T00:19:13Z

I'm scratching my head because the strings should be the same but the comparison is failing on windows, but succeeding on linux/mac.

Haven't looked at this in detail but this type of thing often hints at line endings

ytmimi · 2022-03-18T02:03:53Z

Haven't looked at this in detail but this type of thing often hints at line endings

Ahh I didn't even consider that as a possible issue. I'll investigate that!

ytmimi · 2022-03-18T13:10:11Z

@calebcartwright you were right. It turns out it was a line ending issue. For the tests that were giving me trouble I decided to pass them the newline_style=Unix config option to not have to worry about the line endings.

No rush on the review!

afq984 · 2023-06-27T08:37:37Z

src/bin/main.rs

+
+        // return early if there are issues with the file hint specified
+        if let Some(file_hint) = &options.stdin_file_hint {
+            if !file_hint.exists() {


Is there a reason that the file must exist on the file system?
For our use case #5792 (files in git history) there could be egde cases where the file is not present on disk.

To be honest, it's been a very long time since I've looked at this PR, and I don't remember why. I definitely didn't have your use case in mind when I initially wrote this PR.

It's hard to say when I'll revisit this, but when I do, I'll double check if there are any issues with providing non-existent files as the file hint.

Another use case would be editing usaved files.

When formatting files via stdin rustfmt didn't have a way to ignore stdin input. Now, when passing input to rustfmt via stdin one can also provide the `--stdin-file-hint` option to inform rustfmt that the input is actually from the hinted at file. rustfmt now uses this hint to determine if it can ignore formatting stdin. Note: This option is intended for text editor plugins that call rustfmt by passing input via stdin (e.g. rust-analyzer).

lnicola · 2024-06-27T05:52:17Z

src/bin/main.rs

@@ -90,6 +90,22 @@ pub enum OperationError {
    /// supported with standard input.
    #[error("Emit mode {0} not supported with standard output.")]
    StdinBadEmit(EmitMode),
+    /// Using `--std-file-hint` incorrectly


Suggested change

/// Using `--std-file-hint` incorrectly

/// Using `--stdin-file-hint` incorrectly

lnicola · 2024-06-27T05:53:08Z

src/bin/main.rs

@@ -494,6 +523,13 @@ fn determine_operation(matches: &Matches) -> Result<Operation, OperationError> {
        return Ok(Operation::Stdin { input: buffer });
    }

+    // User's can only pass `--stdin-file-hint` when formating files via stdin.


Suggested change

// User's can only pass `--stdin-file-hint` when formating files via stdin.

// Users can only pass `--stdin-file-hint` when formating files via stdin.

lnicola · 2024-06-27T05:55:39Z

src/bin/main.rs

+            }
+
+            if let Some(ext) = file_hint.extension() {
+                if ext != "rs" {


Does rustfmt reject files with other extensions when passed a path? We should probably match that behavior, someone could use a different extension for various reasons.

ytmimi mentioned this pull request Mar 14, 2022

Allow cargo-fmt to handle formatting individual files. #5071

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ytmimi force-pushed the ignore-stdin branch 2 times, most recently from bb4519e to 2a3ed2c Compare March 15, 2022 01:08

ytmimi mentioned this pull request Mar 15, 2022

Allow to query whether a path is ignored/When using rustfmt via stdin allow passing a path #5137

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ytmimi added 2 commits June 27, 2024 01:42

Add tests that call rustfmt by passing input via stdin

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epage mentioned this pull request Sep 4, 2024

No way to use filetype rules when piping with stdin crate-ci/typos#914

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Give rustfmt a hint about stdin input #5266

Give rustfmt a hint about stdin input #5266

ytmimi commented Mar 14, 2022

ytmimi commented Mar 15, 2022 •

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ytmimi commented Mar 17, 2022 •

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calebcartwright commented Mar 18, 2022

ytmimi commented Mar 18, 2022

ytmimi commented Mar 18, 2022

afq984 Jun 27, 2023

ytmimi Jun 27, 2023

lnicola Jun 27, 2024

lnicola Jun 27, 2024

lnicola Jun 27, 2024

lnicola Jun 27, 2024

	/// Using `--std-file-hint` incorrectly
	/// Using `--stdin-file-hint` incorrectly

	// User's can only pass `--stdin-file-hint` when formating files via stdin.
	// Users can only pass `--stdin-file-hint` when formating files via stdin.

Give rustfmt a hint about stdin input #5266

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Give rustfmt a hint about stdin input #5266

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ytmimi commented Mar 14, 2022

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ytmimi commented Mar 15, 2022 •

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