Fix comments around heritage clauses (#19897)

changelog_unreleased/typescript/19897-2.md

@@ -0,0 +1,32 @@
+#### Fix comment before the first heritage clause (#19897 by @fisker)
+
+<!-- prettier-ignore -->
+```tsx
+// Input
+class Foo
+  extends Bar
+  implements
+    // Comment for Ifoo
+    IFoo,
+    IBar {
+  // ...
+}
+
+// Prettier stable
+class Foo
+  extends Bar
+  // Comment for Ifoo
+  implements IFoo, IBar {
+  // ...
+}
+
+// Prettier main
+class Foo
+  extends Bar
+  implements
+    // Comment for Ifoo
+    IFoo,
+    IBar {
+  // ...
+}
+```

changelog_unreleased/typescript/19897.md

@@ -0,0 +1,30 @@
+#### Fix unstable comment before the first heritage clause (#19897 by @fisker)
+
+<!-- prettier-ignore -->
+```tsx
+// Input
+class MyClass extends MySuperClass implements /* foo */ ISomething, /* bar */ IOtherThing, /* baz */ IThirdThing {
+}
+
+// Prettier stable (First format)
+class MyClass
+  extends MySuperClass
+  implements
+    /* foo */ ISomething,
+    /* bar */ IOtherThing,
+    /* baz */ IThirdThing {}
+
+// Prettier stable (Second format)
+class MyClass
+  extends MySuperClass
+  /* foo */
+  implements ISomething, /* bar */ IOtherThing, /* baz */ IThirdThing {}
+
+// Prettier main
+class MyClass
+  extends MySuperClass
+  implements
+    /* foo */ ISomething,
+    /* bar */ IOtherThing,
+    /* baz */ IThirdThing {}
+```

src/language-js/comments/handle-comments.js

@@ -316,6 +316,7 @@ function handleClassComments({
   precedingNode,
   enclosingNode,
   followingNode,
+  options,
 }) {
   if (isClassLikeNode(enclosingNode)) {
     // @ts-expect-error -- Safe
@@ -332,13 +333,12 @@ function handleClassComments({
 
     // Don't add leading comments to `implements`, `extends`, `mixins` to
     // avoid printing the comment after the keyword.
-    if (followingNode) {
+    if (followingNode && precedingNode) {
       // @ts-expect-error -- Safe
       const { superClass } = enclosingNode;
       if (
         superClass &&
         followingNode === superClass &&
-        precedingNode &&
         (precedingNode === enclosingNode.id ||
           precedingNode === enclosingNode.typeParameters)
       ) {
@@ -346,20 +346,27 @@ function handleClassComments({
         return true;
       }
 
-      for (const prop of ["implements", "extends", "mixins"]) {
-        if (enclosingNode[prop] && followingNode === enclosingNode[prop][0]) {
+      for (const property of ["implements", "extends", "mixins"]) {
+        const firstHeritageClause = enclosingNode[property]?.[0];
+        if (followingNode === firstHeritageClause) {
           if (
-            precedingNode &&
-            (precedingNode === enclosingNode.id ||
+            precedingNode === enclosingNode.id ||
             precedingNode === enclosingNode.typeParameters ||
-              precedingNode === superClass)
+            precedingNode === superClass
+          ) {
+            if (
+              stripComments(options)
+                .slice(locEnd(comment), locStart(firstHeritageClause))
+                .trim() === property
             ) {
               addTrailingComment(precedingNode, comment);
-          } else {
-            addDanglingComment(enclosingNode, comment, prop);
-          }
               return true;
             }
+          } else {
+            addDanglingComment(enclosingNode, comment, property);
+            return true;
+          }
+        }
       }
     }
   }

tests/format/typescript/class-comment/__snapshots__/format.test.js.snap

@@ -94,8 +94,10 @@ class a2 extends b implements z {
 
 class a3
   extends b
+  implements
     // comment
-  implements z, y
+    z,
+    y
 {
   constructor() {}
 }
@@ -121,8 +123,8 @@ class a5
 
 class a6
   extends b
-  // comment-z1
   implements
+    // comment-z1
     z, // comment-z2
     // comment-y1
     y
@@ -133,8 +135,8 @@ class a6
 
 class a7
   extends b
-  // comment-z1
   implements
+    // comment-z1
     z, // comment-z2
     // comment-y1
     y
@@ -147,8 +149,8 @@ class a7
 
 class a8
   extends b // comment-b
-  // comment-z1
   implements
+    // comment-z1
     z, // comment-z2
     // comment-y1
     y
@@ -161,8 +163,8 @@ class a9
   // comment-b1
   extends b // comment-b2
   // comment-b3
-  // comment-z1
   implements
+    // comment-z1
     z, // comment-z2
     // comment-y1
     y
@@ -263,6 +265,40 @@ class G4<
 ================================================================================
 `;
 
+exports[`issue-16228.ts format 1`] = `
+====================================options=====================================
+parsers: ["typescript", "flow"]
+                                                      printWidth: 80 (default) |
+=====================================input======================================
+class C11 extends S implements /* foo */ Foo, /* bar */ Bar {
+}
+class C12 extends S implements /* foo */ Foo, /* bar */ Bar, /* baz */ Baz__________________________________ {
+}
+
+interface I11 extends /* foo */ Foo, /* bar */ Bar {
+}
+interface I12 extends /* foo */ Foo, /* bar */ Bar, /* baz */ Baz__________________________________ {
+}
+
+=====================================output=====================================
+class C11 extends S implements /* foo */ Foo, /* bar */ Bar {}
+class C12
+  extends S
+  implements
+    /* foo */ Foo,
+    /* bar */ Bar,
+    /* baz */ Baz__________________________________ {}
+
+interface I11 extends /* foo */ Foo, /* bar */ Bar {}
+interface I12
+  extends
+    /* foo */ Foo,
+    /* bar */ Bar,
+    /* baz */ Baz__________________________________ {}
+
+================================================================================
+`;
+
 exports[`misc.ts format 1`] = `
 ====================================options=====================================
 parsers: ["typescript", "flow"]

tests/format/typescript/class-comment/issue-16228.ts

@@ -0,0 +1,9 @@
+class C11 extends S implements /* foo */ Foo, /* bar */ Bar {
+}
+class C12 extends S implements /* foo */ Foo, /* bar */ Bar, /* baz */ Baz__________________________________ {
+}
+
+interface I11 extends /* foo */ Foo, /* bar */ Bar {
+}
+interface I12 extends /* foo */ Foo, /* bar */ Bar, /* baz */ Baz__________________________________ {
+}