Issue-5892: Type alias generic ident should be 4 spaces instead of 8

Author: johnhuichen

.gitignore

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

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::Edition2021 => {
+                    // 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-5892.rs

@@ -0,0 +1,35 @@
+// 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-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>;