Issue-5892: Type alias generic rewrite follows the same rule as trait

rewrite

Issue-189: rhs should use indent of last line of lhs

Author: johnhuichen

.gitignore

@@ -23,3 +23,6 @@ tests/cargo-fmt/**/target
 .idea/
 .vscode/
 *~
+
+# nvim local dap settings
+.nvim-dap.lua

rust-toolchain

@@ -1,3 +1,3 @@
 [toolchain]
-channel = "nightly-2024-08-17"
+channel = "nightly-2024-08-08"
 components = ["llvm-tools", "rustc-dev"]

src/expr.rs

@@ -2057,12 +2057,38 @@ fn rewrite_assignment(
     let lhs_shape = shape.sub_width(operator_str.len() + 1)?;
     let lhs_str = format!("{} {}", lhs.rewrite(context, lhs_shape)?, operator_str);
 
+    let lhs_lines: Vec<&str> = lhs_str.split("\n").collect();
+
+    let mut rhs_shape = shape.clone();
+
+    for line in lhs_lines.into_iter().rev() {
+        let mut indent_width = 0;
+        let mut first_char = ' ';
+        for char in line.chars() {
+            if char != ' ' {
+                first_char = char;
+                break;
+            } else {
+                indent_width += 1;
+            }
+        }
+
+        if first_char != '/' {
+            let indent = Indent::from_width(&context.config, indent_width);
+            rhs_shape = Shape::indented(indent, &context.config);
+            break;
+        }
+    }
+
+    println!("config={:?}", context.config.max_width());
+    println!("old shape={shape:?}");
+    println!("new shape={rhs_shape:?}");
     rewrite_assign_rhs(
         context,
         lhs_str,
         rhs,
         &RhsAssignKind::Expr(&rhs.kind, rhs.span),
-        shape,
+        rhs_shape,
     )
 }
 

src/items.rs

@@ -1768,10 +1768,27 @@ fn rewrite_ty<R: Rewrite>(
 
     if let Some(bounds) = generic_bounds_opt {
         if !bounds.is_empty() {
-            // 2 = `: `
-            let shape = Shape::indented(indent, context.config).offset_left(result.len() + 2)?;
-            let type_bounds = bounds.rewrite(context, shape).map(|s| format!(": {}", s))?;
-            result.push_str(&type_bounds);
+            match context.config.style_edition() {
+                style_edition if style_edition < StyleEdition::Edition2024 => {
+                    // 2 = `: `
+                    let shape =
+                        Shape::indented(indent, context.config).offset_left(result.len() + 2)?;
+                    let type_bounds = bounds.rewrite(context, shape).map(|s| format!(": {}", s))?;
+                    result.push_str(&type_bounds);
+                }
+                _ => {
+                    let shape =
+                        Shape::indented(indent, context.config).offset_left(result.len())?;
+                    result = rewrite_assign_rhs_with(
+                        context,
+                        result.clone() + ":",
+                        bounds,
+                        shape,
+                        &RhsAssignKind::Bounds,
+                        RhsTactics::ForceNextLineWithoutIndent,
+                    )?;
+                }
+            }
         }
     }
 

src/types.rs

@@ -1211,7 +1211,7 @@ fn join_bounds_inner(
     //       or the single item is of type `Trait`,
     //          and any of the internal arrays contains more than one item;
     let retry_with_force_newline = match context.config.style_edition() {
-        style_edition @ _ if style_edition <= StyleEdition::Edition2021 => {
+        style_edition if style_edition <= StyleEdition::Edition2021 => {
             !force_newline
                 && items.len() > 1
                 && (result.0.contains('\n') || result.0.len() > shape.width)

tests/source/issue-189.rs

@@ -0,0 +1,14 @@
+// rustfmt-style_edition: 2024
+
+impl SomeType {
+    fn method(&mut self) {
+        self.array[array_index as usize]
+            .as_mut()
+            .expect("thing must exist")
+            .extra_info = Some(ExtraInfo {
+                parent,
+                count: count as u16,
+                children: children.into_boxed_slice(),
+            });
+    }
+}

tests/source/issue-5892.rs

@@ -0,0 +1,33 @@
+// rustfmt-style_edition: 2024
+
+type AAAAAAAAAAAAA:
+    BBBBBBBBBBBBBBB<
+        CCCCCCCCCCCCCCCCC,
+        DDDDDDDDDDDDDDDDD,
+        EEEEEEEEEEEEEEEEE,
+        FFFFFFFFFFFFFFFFF,
+        GGGGGGGGGGGGGGGGG,
+        HHHHHHHHHHHHHHHHH,
+        IIIIIIIIIIIIIIIII,
+    >;
+
+type AAAAAAAAAAAAA:
+    BBBBBBBBBBBBBBB<
+        CCCCCCCCCCCCCCCCC,
+        DDDDDDDDDDDDDDDDD,
+        EEEEEEEEEEEEEEEEE,
+        FFFFFFFFFFFFFFFFF,
+        GGGGGGGGGGGGGGGGG,
+        HHHHHHHHHHHHHHHHH,
+        IIIIIIIIIIIIIIIII,
+    > + Eq
+    + PartialEq;
+
+// previous error: maximum length exceeded
+type SomeType:
+    BBBBBBBBBBBBBBB<CCCCCCCCCCCCCCCCC, DDDDDDDDDDDDDDDDD, EEEEEEEEEEEEEEEEE, FFFFFFFFFFFFFFFFF>
+    + AAAAAAAAAAAAA;
+
+// previous error: maximum length exceeded
+type SomeType:
+    BBBBBBBBBBBBBBB<CCCCCCCCCCCCCCCCC, DDDDDDDDDDDDDDDDD, EEEEEEEEEEEEEEEEE, FFFFFFFFFFFFFFFFF>;

tests/target/issue-189.rs

@@ -0,0 +1,24 @@
+// rustfmt-style_edition: 2024
+
+impl SomeType {
+    fn method(&mut self) {
+        self.array[array_index as usize]
+            .as_mut()
+            .expect("thing must exist")
+            .extra_info = Some(ExtraInfo {
+            parent,
+            count: count as u16,
+            children: children.into_boxed_slice(),
+        });
+    }
+}
+
+impl SomeType {
+    fn method(&mut self) {
+        self.array[array_index as usize]
+            .as_mut()
+            .expect("thing must exist")
+            .extra_info =
+            long_long_long_long_long_long_long_long_long_long_long_long_long_long_long;
+    }
+}

tests/target/issue-5892.rs

@@ -0,0 +1,33 @@
+// rustfmt-style_edition: 2024
+
+type AAAAAAAAAAAAA:
+    BBBBBBBBBBBBBBB<
+        CCCCCCCCCCCCCCCCC,
+        DDDDDDDDDDDDDDDDD,
+        EEEEEEEEEEEEEEEEE,
+        FFFFFFFFFFFFFFFFF,
+        GGGGGGGGGGGGGGGGG,
+        HHHHHHHHHHHHHHHHH,
+        IIIIIIIIIIIIIIIII,
+    >;
+
+type AAAAAAAAAAAAA:
+    BBBBBBBBBBBBBBB<
+        CCCCCCCCCCCCCCCCC,
+        DDDDDDDDDDDDDDDDD,
+        EEEEEEEEEEEEEEEEE,
+        FFFFFFFFFFFFFFFFF,
+        GGGGGGGGGGGGGGGGG,
+        HHHHHHHHHHHHHHHHH,
+        IIIIIIIIIIIIIIIII,
+    > + Eq
+    + PartialEq;
+
+// previous error: maximum length exceeded
+type SomeType:
+    BBBBBBBBBBBBBBB<CCCCCCCCCCCCCCCCC, DDDDDDDDDDDDDDDDD, EEEEEEEEEEEEEEEEE, FFFFFFFFFFFFFFFFF>
+    + AAAAAAAAAAAAA;
+
+// previous error: maximum length exceeded
+type SomeType:
+    BBBBBBBBBBBBBBB<CCCCCCCCCCCCCCCCC, DDDDDDDDDDDDDDDDD, EEEEEEEEEEEEEEEEE, FFFFFFFFFFFFFFFFF>;