Fix #7920 - do not add comma for explicit inexact object with indexer…

… property (#7923)

* 7920 run tests for trailingComma:es5 option as well

* 7920 example of wrong behavior - comma is always added at the end of the inexact object type

* 7920 add test cases for trailingComma: 'all'

* 7920 fix - do not force trailing comma on explicit inexact type if it has indexer or no properties

* 7920 add changelog

changelog_unreleased/flow/pr-7923.md

@@ -0,0 +1,52 @@
+#### Do not add comma for explicit inexact object with indexer property or no properties ([#7923](https://github.com/prettier/prettier/pull/7923) by [@DmitryGonchar](https://github.com/DmitryGonchar))
+
+<!-- prettier-ignore -->
+```jsx
+// Input
+type T = {
+  a: number,
+  ...,
+}
+
+type T = {
+   [string]: number,
+  ...,
+}
+
+type T = {
+  // comment
+  ...,
+}
+
+// Prettier stable
+type T = {
+  a: number,
+  ...
+}
+
+type T = {
+   [string]: number,
+  ...,
+}
+
+type T = {
+  // comment
+  ...,
+}
+
+// Prettier master
+type T = {
+  a: number,
+  ...
+}
+
+type T = {
+   [string]: number,
+  ...
+}
+
+type T = {
+  // comment
+  ...
+}
+```

src/language-js/printer-estree.js

@@ -1416,11 +1416,11 @@ function printPathNoParens(path, options, print, args) {
       const lastElem = getLast(n[propertiesField]);
 
       const canHaveTrailingSeparator = !(
-        lastElem &&
-        (lastElem.type === "RestProperty" ||
-          lastElem.type === "RestElement" ||
-          hasNodeIgnoreComment(lastElem) ||
-          n.inexact)
+        n.inexact ||
+        (lastElem &&
+          (lastElem.type === "RestProperty" ||
+            lastElem.type === "RestElement" ||
+            hasNodeIgnoreComment(lastElem)))
       );
 
       let content;