fix #6164: Reduce format failure for non default `imports_granularity` #6165

kenoss · 2024-05-19T18:55:39Z

This patch reduces format failure for non default imports_granularity and correct the behavior around some edge cases.

Supports too long line of use ... that contains {}.
Fixes the width calculation of too long lines of use ....

kenoss · 2024-05-19T19:01:13Z

tests/target/issue_3033.rs

-use dom::bindings::codegen::Bindings::BluetoothRemoteGATTServerBinding::BluetoothRemoteGATTServerBinding::
-    BluetoothRemoteGATTServerMethods;
+use dom::bindings::codegen::Bindings::BluetoothRemoteGATTServerBinding::
+    BluetoothRemoteGATTServerBinding::BluetoothRemoteGATTServerMethods;


Exceeds 100 chars. It was preserved because the format failed.

Given that this changes existing behavior these changes need to be version gated

Ah, sorry. I missed the comment. Fixed.

ytmimi

I appreciate you jumping in to work on this, though I'm hoping we can find a way to refactor and simplify the implementation.

I also want to be mindful of your time and say up front that it might be a while before I'm able to get around to a follow up review on this.

ytmimi · 2024-05-21T00:39:14Z

src/imports.rs

+            // Try stacking the next segment, e.g. `use prev::next_segment::...` and
+            // `use prev::{next, segment}`.
+            let can_stack_with_constraint = (|| {
+                // If the segment follows `use ` or `{`, force to consume the segment with overflow.
+                if is_first {
+                    let mut chunk = segment.rewrite(context, shape.infinite_width())?;
+                    let next_shape = if iter.peek().is_some() {
+                        chunk.push_str("::");
+                        shape.offset_left_maybe_overflow(chunk.len())
+                    } else {
+                        shape.clone()
+                    };
+                    Some((chunk, next_shape))
+                } else {
+                    // If the segment follows `use ` or newline, allow overflow by "{".
+                    let s = if prev_is_allow_overflow
+                        && matches!(segment.kind, UseSegmentKind::List(_))
+                    {
+                        shape.add_width(1)
+                    } else {
+                        shape.clone()
+                    };
+                    let mut chunk = segment.rewrite(context, s)?;
+                    let next_shape = match iter.peek().map(|s| &s.kind) {
+                        Some(UseSegmentKind::List(_)) => {
+                            chunk.push_str("::");
+                            let ret = shape.offset_left(chunk.len())?;
+                            // Ensure that there is a room for the next "{".
+                            ret.offset_left(1)?;
+                            ret
+                        }
+                        Some(_) => {
+                            chunk.push_str("::");
+                            shape.offset_left(chunk.len())?
+                        }
+                        None => shape.clone(),
+                    };
+                    Some((chunk, next_shape))
+                }
+            })();
+            match can_stack_with_constraint {
+                Some((chunk, next_shape)) => {
+                    result.push_str(&chunk);
+                    shape = next_shape;
+                    prev_is_allow_overflow = is_first;
+                    is_first = false;
+                }
+                // If the next segment exceeds the given width, continue with newline.
+                None => {
+                    let segment_str = segment.rewrite(context, shape)?;
+                    let mut chunk = format!(
+                        "{}{}",
+                        " ".repeat(shape.indent.block_indent + 4),
+                        segment_str
+                    );
+                    if iter.peek().is_some() {
+                        chunk.push_str("::");
+                    }
+                    result.push_str("\n");
+                    result.push_str(&chunk);
+                    shape = shape_top_level.offset_left_maybe_overflow(segment_str.len());
+                    prev_is_allow_overflow = true;
+                }


I haven't looked at this in too much detail, but my initial thought is that there is a lot of nested logic here that makes this hard to wrap my head around. I think I have a high level understanding of what the code is trying to do, but I'd love to see if you can refactor and simplify the implementation.

Let me think...

Refactored. Looking ahead next + retry.

ytmimi · 2024-05-21T00:39:49Z

src/shape.rs

+    pub(crate) fn add_width(&self, width: usize) -> Shape {
+        Shape {
+            width: self.width + width,
+            ..*self
+        }
+    }


Can you explain a little more why we needed to implement an add_width method on the Shape?

Consider this case:

// With max width 40 // | use long_segment_loooooooooooooooooong::{Foo, Bar}; // should be formated to use long_segment_loooooooooooooooooong::{ Foo, Bar, };

Look at the UseTree::rewrite(), especially

let s = if prev_is_allow_overflow && matches!(segment.kind, UseSegmentKind::List(_)) { shape.add_width(1) } else { shape.clone() };

Let's trace the behavior of the format above.

committed = "use " // 35 = 40 - (4 + 1) shape = {indent: 0, offset: 4, width: 35} // len = 34 segment = "long_segment_loooooooooooooooooong" // 34 + 2 exceeds 35, but the above segment should be stacked to the current line because this is the first segment committed = "use long_segment_loooooooooooooooooong::" // with overflow. shape = {indent: 0, offset: 40, width: 0} prev_is_allow_overflow = true // TIMING1 segment = "{Foo, Bar}" // Here, we must secure the room for "{" since `prev_is_allow_overflow == true`, or `segment.rewrite(context, shape)?` fails. s = {indent: 0, offset: 40, width: 1} committed = "use long_segment_loooooooooooooooooong::{\n Foo,\n Bar,\n}"

Alternative options:

Use segment.rewrite(context, shape.infinite_width())?; at the TIMING1 instead.

We can't do that because it produces

use long_segment_loooooooooooooooooong::{Foo, Bar};

Add a variant of UseSegment::rewirte() that can handle yet another argument should_commit_open_brace_even_if_no_width.

It's not simple compared to adding Shape::add_width()...

So, I added Shape::add_width().

ytmimi · 2024-05-21T00:41:21Z

src/shape.rs

+    pub(crate) fn offset_left_maybe_overflow(&self, width: usize) -> Shape {
+        self.add_offset(width).saturating_sub_width(width)
+    }


Similarly, can you explain what offset_left_maybe_overflow is for?

Similar. There are the cases that we need to allow overflow temporarily. We can proceed Shape with this method without fail.

kenoss · 2024-05-21T14:06:24Z

Thank you for quick look!

I'll rethink and refactor. I'll mention once I've done.

kenoss · 2024-05-23T13:20:02Z

@ytmimi Could you have a look? Thanks!

ytmimi · 2024-05-24T14:52:49Z

@ytmimi Could you have a look? Thanks!

I really appreciate you taking the time to make these changes. As I mentioned in #6165 (review) I likely won't have time to re-review this for a little while, and I'll follow up when I can

kenoss · 2024-05-24T17:34:22Z

np. Take your time.

…anularity` This patch reduces format failure for non default `imports_granularity` and correct the behavior around some edge cases. - Supports too long line of `use ...` that contains `{}`. - Fixes the width calculation of too long lines of `use ...`.

kenoss · 2024-08-20T17:13:30Z

Rebased and conflict resolved. Updated using RewriteResult/RewriteError.

kenoss · 2024-08-20T17:14:08Z

This is a friendly ping.

Three months passed.

@ytmimi Could you have a look? Let me know if I can help.

ytmimi · 2024-08-20T17:29:29Z

@kenoss I know it's been some time, but I unfortunately haven't had the bandwidth. Right now my main focus is getting rustfmt ready for the upcoming edition release, mentoring the GSoC project, triaging issues, and working on smaller bugfixes. I appreciate your patience on this.

kenoss · 2024-08-20T18:19:10Z

I understand your situation. (But... I wonder why don't you add more reviewers? It looks other PRs also are stuck with review.)

OK. Then, I'll pause to make this PR fresh. Let me know when you can review. Then, I'll rebase it.

rustbot added the pr-not-reviewed label May 19, 2024

kenoss commented May 19, 2024

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ytmimi requested changes May 21, 2024

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kenoss force-pushed the fix-6164 branch from a68dffe to 19e453d Compare May 23, 2024 13:01

kenoss requested a review from ytmimi May 24, 2024 14:45

ytmimi added pr-follow-up-review-pending and removed pr-not-reviewed labels May 24, 2024

kenoss force-pushed the fix-6164 branch 2 times, most recently from 03c8503 to 435e3c6 Compare June 1, 2024 18:44

kenoss force-pushed the fix-6164 branch from 435e3c6 to f150768 Compare June 4, 2024 17:21

kenoss force-pushed the fix-6164 branch 2 times, most recently from 24de098 to 8b634f2 Compare June 25, 2024 12:37

kenoss force-pushed the fix-6164 branch from 8b634f2 to 6729294 Compare July 10, 2024 14:41

kenoss force-pushed the fix-6164 branch from 6729294 to 667b3dc Compare July 20, 2024 16:03

kenoss added 2 commits August 21, 2024 01:39

Update using RewriteError

727179e

kenoss force-pushed the fix-6164 branch from 667b3dc to 727179e Compare August 20, 2024 17:11

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fix #6164: Reduce format failure for non default `imports_granularity` #6165

fix #6164: Reduce format failure for non default `imports_granularity` #6165

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fix #6164: Reduce format failure for non default imports_granularity #6165

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fix #6164: Reduce format failure for non default imports_granularity #6165

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fix #6164: Reduce format failure for non default `imports_granularity` #6165

fix #6164: Reduce format failure for non default `imports_granularity` #6165

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