fix rust-lang#6164: Reduce format failure for non default imports_granularity

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 ...`.

Author: kenoss

src/imports.rs

@@ -19,7 +19,7 @@ use crate::config::{Edition, IndentStyle, StyleEdition};
 use crate::lists::{
     ListFormatting, ListItem, Separator, definitive_tactic, itemize_list, write_list,
 };
-use crate::rewrite::{Rewrite, RewriteContext, RewriteErrorExt, RewriteResult};
+use crate::rewrite::{Rewrite, RewriteContext, RewriteError, RewriteErrorExt, RewriteResult};
 use crate::shape::Shape;
 use crate::sort::version_sort;
 use crate::source_map::SpanUtils;
@@ -1110,9 +1110,9 @@ impl Rewrite for UseSegment {
                     use_tree_list,
                     // 1 = "{" and "}"
                     shape
-                        .offset_left_opt(1)
-                        .and_then(|s| s.sub_width_opt(1))
-                        .unknown_error()?,
+                        .offset_left(1)
+                        .unknown_error()?
+                        .saturating_sub_width(1),
                 )?
             }
         })
@@ -1126,18 +1126,107 @@ impl Rewrite for UseTree {
 
     // This does NOT format attributes and visibility or add a trailing `;`.
     fn rewrite_result(&self, context: &RewriteContext<'_>, mut shape: Shape) -> RewriteResult {
-        let mut result = String::with_capacity(256);
-        let mut iter = self.path.iter().peekable();
-        while let Some(segment) = iter.next() {
-            let segment_str = segment.rewrite_result(context, shape)?;
-            result.push_str(&segment_str);
-            if iter.peek().is_some() {
-                result.push_str("::");
-                // 2 = "::"
-                shape = shape.offset_left(2 + segment_str.len(), self.span())?;
+        if context.config.style_edition() >= StyleEdition::Edition2024 {
+            fn proceed(
+                context: &RewriteContext<'_>,
+                span: &Span,
+                shape: &Shape,
+                curr_segment: &UseSegment,
+                curr_segment_is_allow_overflow: bool,
+                next_segment: Option<&&UseSegment>,
+            ) -> Result<(String, Shape), RewriteError> {
+                let mut rewritten_segment = curr_segment.rewrite_result(context, shape.clone())?;
+                if next_segment.is_some() {
+                    rewritten_segment.push_str("::");
+                }
+                let reserved_room_for_brace = match next_segment.map(|s| &s.kind) {
+                    Some(UseSegmentKind::List(_)) => "{".len(),
+                    _ => 0,
+                };
+                let next_shape = if matches!(&curr_segment.kind, UseSegmentKind::List(_)) {
+                    // This is the last segment and we won't use `next_shape`. Return `shape`
+                    // unchanged.
+                    shape.clone()
+                } else if curr_segment_is_allow_overflow {
+                    // If the segment follows `use ` or newline, force to consume the segment with
+                    // overflow.
+
+                    let s = shape.offset_left_maybe_overflow(rewritten_segment.len());
+                    if s.width == 0 {
+                        // We have to to commit current segment in this line. Make a room for next
+                        // round.
+                        s.add_width(reserved_room_for_brace)
+                    } else {
+                        s.clone()
+                    }
+                } else {
+                    let Some(ret) = shape.offset_left(rewritten_segment.len()) else {
+                        return Err(RewriteError::ExceedsMaxWidth {
+                            configured_width: shape.width,
+                            span: span.clone(),
+                        });
+                    };
+                    // Check that there is a room for the next "{". If not, return an error for
+                    // retry with newline.
+                    if ret.offset_left(reserved_room_for_brace).is_none() {
+                        return Err(RewriteError::ExceedsMaxWidth {
+                            configured_width: shape.width,
+                            span: span.clone(),
+                        });
+                    }
+                    ret
+                };
+                Ok((rewritten_segment, next_shape))
+            }
+
+            let shape_top_level = shape.clone();
+            let mut result = String::with_capacity(256);
+            let mut is_first = true;
+            let mut iter = self.path.iter().peekable();
+            let span = self.span();
+            while let Some(segment) = iter.next() {
+                let allow_overflow = is_first;
+                is_first = false;
+                match proceed(context, &span, &shape, segment, allow_overflow, iter.peek()) {
+                    Ok((rewritten_segment, next_shape)) => {
+                        result.push_str(&rewritten_segment);
+                        shape = next_shape;
+                        continue;
+                    }
+                    Err(RewriteError::ExceedsMaxWidth { .. }) => {
+                        // If the first `proceed()` failed with no room, retry with newline.
+                    }
+                    Err(e) => {
+                        // Abort otherwise.
+                        return Err(e);
+                    }
+                }
+                result.push_str("\n");
+                result.push_str(&" ".repeat(shape.indent.block_indent + 4));
+                shape = shape_top_level.clone();
+                let allow_overflow = true;
+                let (rewritten_segment, next_shape) =
+                    proceed(context, &span, &shape, segment, allow_overflow, iter.peek())?;
+                result.push_str(&rewritten_segment);
+                shape = next_shape;
+            }
+            Ok(result)
+        } else {
+            let mut result = String::with_capacity(256);
+            let mut iter = self.path.iter().peekable();
+            while let Some(segment) = iter.next() {
+                let segment_str = segment.rewrite_result(context, shape)?;
+                result.push_str(&segment_str);
+                if iter.peek().is_some() {
+                    result.push_str("::");
+                    // 2 = "::"
+                    shape = shape
+                        .offset_left(2 + segment_str.len())
+                        .max_width_error(shape.width, self.span())?;
+                }
             }
+            Ok(result)
         }
-        Ok(result)
     }
 }
 

src/shape.rs

@@ -286,10 +286,29 @@ impl Shape {
             .ok_or_else(|| self.exceeds_max_width_error(span))
     }
 
+    pub(crate) fn add_width(&self, width: usize) -> Shape {
+        Shape {
+            width: self.width + width,
+            ..*self
+        }
+    }
+
+    pub(crate) fn shrink_left(&self, width: usize) -> Option<Shape> {
+        Some(Shape {
+            width: self.width.checked_sub(width)?,
+            indent: self.indent + width,
+            offset: self.offset + width,
+        })
+    }
+
     pub(crate) fn offset_left_opt(&self, delta: usize) -> Option<Shape> {
         self.add_offset(delta).sub_width_opt(delta)
     }
 
+    pub(crate) fn offset_left_maybe_overflow(&self, width: usize) -> Shape {
+        self.add_offset(width).saturating_sub_width(width)
+    }
+
     pub(crate) fn used_width(&self) -> usize {
         self.indent.block_indent + self.offset
     }

tests/source/5131_crate.rs

@@ -12,3 +12,153 @@ use foo::d::e;
 use qux::h;
 use qux::h as h2;
 use qux::i;
+
+mod indent4 {
+    use column_____________________________________________________________________________________102::{
+        Foo,
+        bar::Bar,
+        bar::baz::Baz,
+        Foo2,
+        bar::Bar2,
+    };
+
+    use column_______________________________________________________________________________096::{
+        Foo,
+        bar::Bar,
+        bar::baz::Baz,
+        Foo2,
+        bar::Bar2,
+    };
+
+    use column_________________________________________________________________________090::{
+        Foo,
+        bar::Bar,
+        bar::baz::Baz,
+        Foo2,
+        bar::Bar2,
+    };
+
+    use c012::c018::c024::c030::c036::c042::c048::c054::c060::c066::c072::c078::c084::c090::c096::c102::{
+        Foo,
+        bar::Bar,
+        bar::baz::Baz,
+        Foo2,
+        bar::Bar2,
+    };
+
+    use c012::c018::c024::c030::c036::c042::c048::c054::c060::c066::c072::c078::c084::c090::c096::{
+        Foo,
+        bar::Bar,
+        bar::baz::Baz,
+        Foo2,
+        bar::Bar2,
+    };
+
+    use c012::c018::c024::c030::c036::c042::c048::c054::c060::c066::c072::c078::c084::c090::{
+        Foo,
+        bar::Bar,
+        bar::baz::Baz,
+        Foo2,
+        bar::Bar2,
+    };
+
+    use c012::c018::c024::c030::c036::c042::c048::c054::c060::c066::c072::c078::c084::{
+        Foo,
+        bar::Bar,
+        bar::baz::Baz,
+        Foo2,
+        bar::Bar2,
+    };
+}
+
+use smithay::{
+    backend::renderer::element::{
+        default_primary_scanout_output_compare, utils::select_dmabuf_feedback, RenderElementStates,
+    },
+    delegate_compositor, delegate_data_control, delegate_data_device, delegate_fractional_scale,
+    delegate_input_method_manager, delegate_keyboard_shortcuts_inhibit, delegate_layer_shell,
+    delegate_output, delegate_pointer_constraints, delegate_pointer_gestures,
+    delegate_presentation, delegate_primary_selection, delegate_relative_pointer, delegate_seat,
+    delegate_security_context, delegate_shm, delegate_tablet_manager, delegate_text_input_manager,
+    delegate_viewporter, delegate_virtual_keyboard_manager, delegate_xdg_activation,
+    delegate_xdg_decoration, delegate_xdg_shell,
+    desktop::{
+        space::SpaceElement,
+        utils::{
+            surface_presentation_feedback_flags_from_states, surface_primary_scanout_output,
+            update_surface_primary_scanout_output, OutputPresentationFeedback,
+        },
+        PopupKind, PopupManager, Space,
+    },
+    input::{
+        keyboard::{Keysym, LedState, XkbConfig},
+        pointer::{CursorImageStatus, PointerHandle},
+        Seat, SeatHandler, SeatState,
+    },
+    output::Output,
+    reexports::{
+        calloop::{generic::Generic, Interest, LoopHandle, Mode, PostAction},
+        wayland_protocols::xdg::decoration::{
+            self as xdg_decoration,
+            zv1::server::zxdg_toplevel_decoration_v1::Mode as DecorationMode,
+        },
+        wayland_server::{
+            backend::{ClientData, ClientId, DisconnectReason},
+            protocol::{wl_data_source::WlDataSource, wl_surface::WlSurface},
+            Display, DisplayHandle, Resource,
+        },
+    },
+    utils::{Clock, Monotonic, Rectangle},
+    wayland::{
+        compositor::{get_parent, with_states, CompositorClientState, CompositorState},
+        dmabuf::DmabufFeedback,
+        fractional_scale::{
+            with_fractional_scale, FractionalScaleHandler, FractionalScaleManagerState,
+        },
+        input_method::{InputMethodHandler, InputMethodManagerState, PopupSurface},
+        keyboard_shortcuts_inhibit::{
+            KeyboardShortcutsInhibitHandler, KeyboardShortcutsInhibitState,
+            KeyboardShortcutsInhibitor,
+        },
+        output::{OutputHandler, OutputManagerState},
+        pointer_constraints::{
+            with_pointer_constraint, PointerConstraintsHandler, PointerConstraintsState,
+        },
+        pointer_gestures::PointerGesturesState,
+        presentation::PresentationState,
+        relative_pointer::RelativePointerManagerState,
+        seat::WaylandFocus,
+        security_context::{
+            SecurityContext, SecurityContextHandler, SecurityContextListenerSource,
+            SecurityContextState,
+        },
+        selection::data_device::{
+            set_data_device_focus, ClientDndGrabHandler, DataDeviceHandler, DataDeviceState,
+            ServerDndGrabHandler,
+        },
+        selection::{
+            primary_selection::{
+                set_primary_focus, PrimarySelectionHandler, PrimarySelectionState,
+            },
+            wlr_data_control::{DataControlHandler, DataControlState},
+            SelectionHandler,
+        },
+        shell::{
+            wlr_layer::WlrLayerShellState,
+            xdg::{
+                decoration::{XdgDecorationHandler, XdgDecorationState},
+                ToplevelSurface, XdgShellState, XdgToplevelSurfaceData,
+            },
+        },
+        shm::{ShmHandler, ShmState},
+        socket::ListeningSocketSource,
+        tablet_manager::{TabletManagerState, TabletSeatTrait},
+        text_input::TextInputManagerState,
+        viewporter::ViewporterState,
+        virtual_keyboard::VirtualKeyboardManagerState,
+        xdg_activation::{
+            XdgActivationHandler, XdgActivationState, XdgActivationToken, XdgActivationTokenData,
+        },
+        xdg_foreign::{XdgForeignHandler, XdgForeignState},
+    },
+};