feat: ensure render tag is passed a snippet function

Author: dummdidumm

packages/svelte2tsx/src/htmlxtojsx_v2/nodes/RenderTag.ts

@@ -6,18 +6,20 @@ import { BaseNode } from '../../interfaces';
  * `{@render foo(x)}` --> `;foo(x);`
  */
 export function handleRenderTag(str: MagicString, renderTag: BaseNode): void {
-    str.overwrite(renderTag.start, renderTag.expression.start, ';', { contentOnly: true });
+    str.overwrite(renderTag.start, renderTag.expression.start, ';__sveltets_2_ensureSnippet(', {
+        contentOnly: true
+    });
     if (renderTag.argument) {
         str.overwrite(
             withTrailingPropertyAccess(str.original, renderTag.argument.end),
             renderTag.end,
-            ');'
+            '));'
         );
     } else {
         str.overwrite(
             withTrailingPropertyAccess(str.original, renderTag.expression.end),
             renderTag.end,
-            '();'
+            '());'
         );
     }
 }

packages/svelte2tsx/svelte-shims-v4.d.ts

@@ -145,6 +145,9 @@ declare function __sveltets_2_nonNullable<T>(type: T): NonNullable<T>;
 
 declare function __sveltets_2_cssProp(prop: Record<string, any>): {};
 
+// @ts-ignore Svelte v3/v4 don't have this
+declare function __sveltets_2_ensureSnippet(val: ReturnType<import('svelte').Snippet>): any;
+
 /** @internal PRIVATE API, DO NOT USE */
 type __sveltets_2_SvelteAnimationReturnType = {
     delay?: number,

packages/svelte2tsx/svelte-shims.d.ts

@@ -224,6 +224,9 @@ declare function __sveltets_2_nonNullable<T>(type: T): NonNullable<T>;
 
 declare function __sveltets_2_cssProp(prop: Record<string, any>): {};
 
+// @ts-ignore Svelte v3/v4 don't have this
+declare function __sveltets_2_ensureSnippet(val: ReturnType<import('svelte').Snippet>): any;
+
 /** @internal PRIVATE API, DO NOT USE */
 type __sveltets_2_SvelteAnimationReturnType = {
     delay?: number,

packages/svelte2tsx/test/htmlx2jsx/samples/snippet.skip/expectedv2.js

@@ -2,8 +2,8 @@
 	 { svelteHTML.createElement("div", {}); x; }
 return __sveltets_2_any(0)}
 
-;foo(1);
-;foo();
+;__sveltets_2_ensureSnippet(foo(1));
+;__sveltets_2_ensureSnippet(foo());
 
  { const $$_tnenopmoC0C = __sveltets_2_ensureComponent(Component); new $$_tnenopmoC0C({ target: __sveltets_2_any(), props: {bar:(x) => {
 		 { svelteHTML.createElement("div", {}); x; }

packages/svelte2tsx/test/htmlx2jsx/samples/ts-in-template.skip/expectedv2.js

@@ -18,7 +18,7 @@ item as string;
 
  var foo/*Ωignore_startΩ*/: import('svelte').Snippet<string>/*Ωignore_endΩ*/ = (bar: string) => { return __sveltets_2_any(0)}
 
-;foo(bar as string);
+;__sveltets_2_ensureSnippet(foo(bar as string));
 
  { svelteHTML.createElement("button", { "onclick":(e: Event) => {e as any},});  }
  { const $$_tnenopmoC0C = __sveltets_2_ensureComponent(Component); new $$_tnenopmoC0C({ target: __sveltets_2_any(), props: {  "attr":attr as boolean,}});}