fix(scanner): leave line comments out when collapsing multi-line generics

packages/dtsx/test/generic-parameter-comments.test.tsadded+45-0

Changes to packages/dtsx/test/generic-parameter-comments.test.ts

		@@ -0,0 +1,45 @@
	1	+/**
	2	+ * A `//` comment inside a multi-line type parameter list commented out the rest
	3	+ * of the declaration. Multi-line `<...>` is collapsed onto one line, so
	4	+ *
	5	+ * export function defineComponent<
	6	+ * // props
	7	+ * TypeProps,
	8	+ * ...
	9	+ * >(options: ...): ...
	10	+ *
	11	+ * came out as `defineComponent<// props TypeProps, ...` and everything after
	12	+ * the comment, closing `>` included, was gone. Vue's `defineComponent`,
	13	+ * vue-router's `RouteRecordInfo` and Pinia's store types are all written this
	14	+ * way; their `.d.ts` did not parse.
	15	+ */
	16	+import { describe, expect, it } from 'bun:test'
	17	+import { processCode } from './test-utils'
	18	+
	19	+const transpiler = new Bun.Transpiler({ loader: 'ts', target: 'bun' })
	20	+
	21	+describe('comments in a multi-line type parameter list', () => {
	22	+ it.each([
	23	+ ['function', 'export function f<\n // first\n A,\n B = string, // second\n>(a: A, b: B): void {}\n', 'f<A, B = string,>(a: A, b: B): void;'],
	24	+ ['type alias', 'export type T<\n // note\n A = 1,\n> = A\n', 'type T<A = 1,> = A'],
	25	+ ['interface', 'export interface I<\n // note\n A extends string = string,\n> { a: A }\n', 'interface I<A extends string = string,>'],
	26	+ ['class', 'export class C<\n // note\n T,\n> { v!: T }\n', 'class C<T,>'],
	27	+ ])('leaves the comment out: %s', (_label, code, expected) => {
	28	+ const output = processCode(code)
	29	+ expect(() => transpiler.transformSync(output)).not.toThrow()
	30	+ expect(output).toContain(expected)
	31	+ expect(output).not.toContain('//')
	32	+ })
	33	+
	34	+ it('copies strings and block comments as they are', () => {
	35	+ const output = processCode('export type S<\n /* see http://example.com */ A extends \'//\' | \'a b\' = \'//\',\n> = A\n')
	36	+ expect(() => transpiler.transformSync(output)).not.toThrow()
	37	+ expect(output).toContain('/* see http://example.com */ A extends \'//\' | \'a b\' = \'//\'')
	38	+ })
	39	+
	40	+ it('keeps a multi-line template literal type as written', () => {
	41	+ const output = processCode('export type F<\n // note\n T = `a\nb`,\n> = T\n')
	42	+ expect(() => transpiler.transformSync(output)).not.toThrow()
	43	+ expect(output).toContain('T = `a\nb`')
	44	+ })
	45	+})