Flow: Print trailing comma in type parameters when --trailing-comma=es5

changelog_unreleased/flow/14085.md

@@ -0,0 +1,40 @@
+#### [BREAKING] Print trailing comma in type parameters and tuple types when `--trailing-comma=es5` (#14086, #14085 by @fisker)
+
+<!-- prettier-ignore -->
+```js
+// Input
+type Foo =  [
+  {
+    from: string,
+    to: string,
+  }, // <- 1
+];
+type Foo = Promise<
+  | { ok: true, bar: string, baz: SomeOtherLongType }
+  | { ok: false, bar: SomeOtherLongType }, // <- 2
+>;
+
+// Prettier stable
+type Foo = [
+  {
+    from: string,
+    to: string,
+  } // <- 1
+];
+type Foo = Promise<
+  | { ok: true, bar: string, baz: SomeOtherLongType }
+  | { ok: false, bar: SomeOtherLongType } // <- 2
+>;
+
+// Prettier main
+type Foo = [
+  {
+    from: string,
+    to: string,
+  }, // <- 1
+];
+type Foo = Promise<
+  | { ok: true, bar: string, baz: SomeOtherLongType }
+  | { ok: false, bar: SomeOtherLongType }, // <- 2
+>;
+```

src/language-js/print/type-parameters.js

@@ -79,7 +79,7 @@ function printTypeParameters(path, options, print, paramsKey) {
         !node[paramsKey][0].constraint &&
         path.parent.type === "ArrowFunctionExpression"
       ? ","
-      : shouldPrintComma(options, "all")
+      : shouldPrintComma(options)
       ? ifBreak(",")
       : "";
 

tests/format/flow/function-parentheses/__snapshots__/jsfmt.spec.js.snap

@@ -69,7 +69,7 @@ const selectorByPath:
 const selectorByPath: (Path) => SomethingSelector<
   SomethingUEditorContextType,
   SomethingUEditorContextType,
-  SomethingBulkValue<string>
+  SomethingBulkValue<string>,
 > = memoizeWithArgs(/* ... */);
 
 ================================================================================

tests/format/flow/generic/__snapshots__/jsfmt.spec.js.snap

@@ -63,7 +63,7 @@ var X = {
     E,
     F,
     G,
-    T: (a: A, b: B, c: C, d: D, e: E, f: F) => G // eslint-disable-line space-before-function-paren
+    T: (a: A, b: B, c: C, d: D, e: E, f: F) => G, // eslint-disable-line space-before-function-paren
   >(method: T, scope: any, a: A, b: B, c: C, d: D, e: E, f: F): G {},
 };
 
@@ -316,7 +316,7 @@ type State = {
 type State = {
   errors: Immutable.Map<
     Ahohohhohohohohohohohohohohooh,
-    Fbt | Immutable.Map<ErrorIndex, Fbt>
+    Fbt | Immutable.Map<ErrorIndex, Fbt>,
   >,
   shouldValidate: boolean,
 };
@@ -398,7 +398,7 @@ type Foo = Promise<
 =====================================output=====================================
 type Foo = Promise<
   | { ok: true, bar: string, baz: SomeOtherLongType }
-  | { ok: false, bar: SomeOtherLongType }
+  | { ok: false, bar: SomeOtherLongType },
 >;
 
 ================================================================================