TypeScript: Improve argument expansion with `as` type expressions (#6471)

CHANGELOG.unreleased.md

@@ -709,4 +709,4 @@ const fooooooooooooooo: SomeThing<boolean> = looooooooooooooooooooooooooooooongN
 [@g-harel]: https://github.com/g-harel
 [@jounqin]: https://github.com/JounQin
 [@bakkot]: https://gibhub.com/bakkot
-[@thorn0]: https://github.com/thorn0
+[@thorn0]: https://github.com/thorn0

src/language-js/printer-estree.js

@@ -3756,8 +3756,8 @@ function couldGroupArg(arg) {
       (arg.properties.length > 0 || arg.comments)) ||
     (arg.type === "ArrayExpression" &&
       (arg.elements.length > 0 || arg.comments)) ||
-    arg.type === "TSTypeAssertion" ||
-    arg.type === "TSAsExpression" ||
+    (arg.type === "TSTypeAssertion" && couldGroupArg(arg.expression)) ||
+    (arg.type === "TSAsExpression" && couldGroupArg(arg.expression)) ||
     arg.type === "FunctionExpression" ||
     (arg.type === "ArrowFunctionExpression" &&
       // we want to avoid breaking inside composite return types but not simple keywords

tests/typescript_argument_expansion/__snapshots__/jsfmt.spec.js.snap

@@ -0,0 +1,87 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`argument_expansion.js 1`] = `
+====================================options=====================================
+parsers: ["typescript"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+const bar = [1,2,3].reduce((carry, value) => {
+  return [...carry, value];
+}, ([] as unknown) as number[]);
+
+const bar = [1,2,3].reduce((carry, value) => {
+  return [...carry, value];
+}, <Array<number>>[]);
+
+const bar = [1,2,3].reduce((carry, value) => {
+  return [...carry, value];
+}, ([1, 2, 3] as unknown) as number[]);
+
+const bar = [1,2,3].reduce((carry, value) => {
+  return [...carry, value];
+}, <Array<number>>[1, 2, 3]);
+
+const bar = [1,2,3].reduce((carry, value) => {
+  return {...carry, [value]: true};
+}, ({} as unknown) as {[key: number]: boolean});
+
+const bar = [1,2,3].reduce((carry, value) => {
+  return {...carry, [value]: true};
+}, <{[key: number]: boolean}>{});
+
+const bar = [1,2,3].reduce((carry, value) => {
+  return {...carry, [value]: true};
+}, ({1: true} as unknown) as {[key: number]: boolean});
+
+const bar = [1,2,3].reduce((carry, value) => {
+  return {...carry, [value]: true};
+}, <{[key: number]: boolean}>{1: true});
+
+=====================================output=====================================
+const bar = [1, 2, 3].reduce((carry, value) => {
+  return [...carry, value];
+}, ([] as unknown) as number[]);
+
+const bar = [1, 2, 3].reduce((carry, value) => {
+  return [...carry, value];
+}, <Array<number>>[]);
+
+const bar = [1, 2, 3].reduce(
+  (carry, value) => {
+    return [...carry, value];
+  },
+  ([1, 2, 3] as unknown) as number[]
+);
+
+const bar = [1, 2, 3].reduce(
+  (carry, value) => {
+    return [...carry, value];
+  },
+  <Array<number>>[1, 2, 3]
+);
+
+const bar = [1, 2, 3].reduce((carry, value) => {
+  return { ...carry, [value]: true };
+}, ({} as unknown) as { [key: number]: boolean });
+
+const bar = [1, 2, 3].reduce((carry, value) => {
+  return { ...carry, [value]: true };
+}, <{ [key: number]: boolean }>{});
+
+const bar = [1, 2, 3].reduce(
+  (carry, value) => {
+    return { ...carry, [value]: true };
+  },
+  ({ 1: true } as unknown) as { [key: number]: boolean }
+);
+
+const bar = [1, 2, 3].reduce(
+  (carry, value) => {
+    return { ...carry, [value]: true };
+  },
+  <{ [key: number]: boolean }>{ 1: true }
+);
+
+================================================================================
+`;

tests/typescript_argument_expansion/argument_expansion.js

@@ -0,0 +1,31 @@
+const bar = [1,2,3].reduce((carry, value) => {
+  return [...carry, value];
+}, ([] as unknown) as number[]);
+
+const bar = [1,2,3].reduce((carry, value) => {
+  return [...carry, value];
+}, <Array<number>>[]);
+
+const bar = [1,2,3].reduce((carry, value) => {
+  return [...carry, value];
+}, ([1, 2, 3] as unknown) as number[]);
+
+const bar = [1,2,3].reduce((carry, value) => {
+  return [...carry, value];
+}, <Array<number>>[1, 2, 3]);
+
+const bar = [1,2,3].reduce((carry, value) => {
+  return {...carry, [value]: true};
+}, ({} as unknown) as {[key: number]: boolean});
+
+const bar = [1,2,3].reduce((carry, value) => {
+  return {...carry, [value]: true};
+}, <{[key: number]: boolean}>{});
+
+const bar = [1,2,3].reduce((carry, value) => {
+  return {...carry, [value]: true};
+}, ({1: true} as unknown) as {[key: number]: boolean});
+
+const bar = [1,2,3].reduce((carry, value) => {
+  return {...carry, [value]: true};
+}, <{[key: number]: boolean}>{1: true});

tests/typescript_argument_expansion/jsfmt.spec.js

@@ -0,0 +1 @@
+run_spec(__dirname, ["typescript"]);