fix: strip dead imports for client:only components

.changeset/long-swans-smoke.md

@@ -0,0 +1,5 @@
+---
+"@astrojs/compiler": patch
+---
+
+fix: strip dead imports for client:only components

internal/printer/__printer_js__/client_only_component__default_.snap

@@ -39,7 +39,6 @@ import {
   renderScript as $$renderScript,
   createMetadata as $$createMetadata
 } from "http://localhost:3000/";
-import Component from '../components';
 
 export const $$metadata = $$createMetadata(import.meta.url, { modules: [], hydratedComponents: [], clientOnlyComponents: ['../components'], hydrationDirectives: new Set(['only']), hoisted: [] });
 

internal/printer/__printer_js__/client_only_component__multiple_.snap

@@ -41,7 +41,6 @@ import {
   renderScript as $$renderScript,
   createMetadata as $$createMetadata
 } from "http://localhost:3000/";
-import Component from '../components';
 
 export const $$metadata = $$createMetadata(import.meta.url, { modules: [], hydratedComponents: [], clientOnlyComponents: ['../components'], hydrationDirectives: new Set(['only']), hoisted: [] });
 

internal/printer/__printer_js__/client_only_component__named_.snap

@@ -39,7 +39,6 @@ import {
   renderScript as $$renderScript,
   createMetadata as $$createMetadata
 } from "http://localhost:3000/";
-import { Component } from '../components';
 
 export const $$metadata = $$createMetadata(import.meta.url, { modules: [], hydratedComponents: [], clientOnlyComponents: ['../components'], hydrationDirectives: new Set(['only']), hoisted: [] });
 

internal/printer/__printer_js__/client_only_component__namespace_.snap

@@ -39,7 +39,6 @@ import {
   renderScript as $$renderScript,
   createMetadata as $$createMetadata
 } from "http://localhost:3000/";
-import * as components from '../components';
 
 export const $$metadata = $$createMetadata(import.meta.url, { modules: [], hydratedComponents: [], clientOnlyComponents: ['../components'], hydrationDirectives: new Set(['only']), hoisted: [] });
 

internal/printer/__printer_js__/client_only_component__namespaced_default_.snap

@@ -39,7 +39,6 @@ import {
   renderScript as $$renderScript,
   createMetadata as $$createMetadata
 } from "http://localhost:3000/";
-import defaultImport from '../components/ui-1';
 
 export const $$metadata = $$createMetadata(import.meta.url, { modules: [], hydratedComponents: [], clientOnlyComponents: ['../components/ui-1'], hydrationDirectives: new Set(['only']), hoisted: [] });
 

internal/printer/__printer_js__/client_only_component__namespaced_named_.snap

@@ -39,7 +39,6 @@ import {
   renderScript as $$renderScript,
   createMetadata as $$createMetadata
 } from "http://localhost:3000/";
-import { namedImport } from '../components/ui-2';
 
 export const $$metadata = $$createMetadata(import.meta.url, { modules: [], hydratedComponents: [], clientOnlyComponents: ['../components/ui-2'], hydrationDirectives: new Set(['only']), hoisted: [] });
 

internal/printer/__printer_js__/client_only_preserves_import_when_binding_used_in_frontmatter.snap

@@ -0,0 +1,48 @@
+
+[TestPrinter/client:only_preserves_import_when_binding_used_in_frontmatter - 1]
+## Input
+
+```
+/-/-/-/
+import Component from '../components';
+console.log(Component.name);
+/-/-/-/
+<Component client:only />
+```
+
+## Output
+
+```js
+import {
+  Fragment,
+  render as $$render,
+  createAstro as $$createAstro,
+  createComponent as $$createComponent,
+  renderComponent as $$renderComponent,
+  renderHead as $$renderHead,
+  maybeRenderHead as $$maybeRenderHead,
+  unescapeHTML as $$unescapeHTML,
+  renderSlot as $$renderSlot,
+  mergeSlots as $$mergeSlots,
+  addAttribute as $$addAttribute,
+  spreadAttributes as $$spreadAttributes,
+  defineStyleVars as $$defineStyleVars,
+  defineScriptVars as $$defineScriptVars,
+  renderTransition as $$renderTransition,
+  createTransitionScope as $$createTransitionScope,
+  renderScript as $$renderScript,
+  createMetadata as $$createMetadata
+} from "http://localhost:3000/";
+import Component from '../components';
+
+export const $$metadata = $$createMetadata(import.meta.url, { modules: [], hydratedComponents: [], clientOnlyComponents: ['../components'], hydrationDirectives: new Set(['only']), hoisted: [] });
+
+const $$Component = $$createComponent(($$result, $$props, $$slots) => {
+
+console.log(Component.name);
+
+return $$render`${$$renderComponent($$result,'Component',null,{"client:only":true,"client:component-hydration":"only","client:component-path":($$metadata.resolvePath("../components")),"client:component-export":"default"})}`;
+}, undefined, undefined);
+export default $$Component;
+```
+---

internal/printer/__printer_js__/client_only_preserves_mixed_binding_import.snap

@@ -0,0 +1,50 @@
+
+[TestPrinter/client:only_preserves_mixed_binding_import - 1]
+## Input
+
+```
+/-/-/-/
+import Component, { helper } from '../components';
+const data = helper();
+/-/-/-/
+<Component client:only />
+<div>{data}</div>
+```
+
+## Output
+
+```js
+import {
+  Fragment,
+  render as $$render,
+  createAstro as $$createAstro,
+  createComponent as $$createComponent,
+  renderComponent as $$renderComponent,
+  renderHead as $$renderHead,
+  maybeRenderHead as $$maybeRenderHead,
+  unescapeHTML as $$unescapeHTML,
+  renderSlot as $$renderSlot,
+  mergeSlots as $$mergeSlots,
+  addAttribute as $$addAttribute,
+  spreadAttributes as $$spreadAttributes,
+  defineStyleVars as $$defineStyleVars,
+  defineScriptVars as $$defineScriptVars,
+  renderTransition as $$renderTransition,
+  createTransitionScope as $$createTransitionScope,
+  renderScript as $$renderScript,
+  createMetadata as $$createMetadata
+} from "http://localhost:3000/";
+import Component, { helper } from '../components';
+
+export const $$metadata = $$createMetadata(import.meta.url, { modules: [], hydratedComponents: [], clientOnlyComponents: ['../components'], hydrationDirectives: new Set(['only']), hoisted: [] });
+
+const $$Component = $$createComponent(($$result, $$props, $$slots) => {
+
+const data = helper();
+
+return $$render`${$$renderComponent($$result,'Component',null,{"client:only":true,"client:component-hydration":"only","client:component-path":($$metadata.resolvePath("../components")),"client:component-export":"default"})}
+${$$maybeRenderHead($$result)}<div>${data}</div>`;
+}, undefined, undefined);
+export default $$Component;
+```
+---

internal/printer/__printer_js__/client_only_preserves_mixed_import_from_same_specifier.snap

@@ -0,0 +1,53 @@
+
+[TestPrinter/client:only_preserves_mixed_import_from_same_specifier - 1]
+## Input
+
+```
+/-/-/-/
+import Component from '../components';
+import { helper } from '../components';
+const data = helper();
+/-/-/-/
+<Component client:only />
+<div>{data}</div>
+```
+
+## Output
+
+```js
+import {
+  Fragment,
+  render as $$render,
+  createAstro as $$createAstro,
+  createComponent as $$createComponent,
+  renderComponent as $$renderComponent,
+  renderHead as $$renderHead,
+  maybeRenderHead as $$maybeRenderHead,
+  unescapeHTML as $$unescapeHTML,
+  renderSlot as $$renderSlot,
+  mergeSlots as $$mergeSlots,
+  addAttribute as $$addAttribute,
+  spreadAttributes as $$spreadAttributes,
+  defineStyleVars as $$defineStyleVars,
+  defineScriptVars as $$defineScriptVars,
+  renderTransition as $$renderTransition,
+  createTransitionScope as $$createTransitionScope,
+  renderScript as $$renderScript,
+  createMetadata as $$createMetadata
+} from "http://localhost:3000/";
+import { helper } from '../components';
+
+import * as $$module1 from '../components';
+
+export const $$metadata = $$createMetadata(import.meta.url, { modules: [{ module: $$module1, specifier: '../components', assert: {} }], hydratedComponents: [], clientOnlyComponents: ['../components'], hydrationDirectives: new Set(['only']), hoisted: [] });
+
+const $$Component = $$createComponent(($$result, $$props, $$slots) => {
+
+const data = helper();
+
+return $$render`${$$renderComponent($$result,'Component',null,{"client:only":true,"client:component-hydration":"only","client:component-path":($$metadata.resolvePath("../components")),"client:component-export":"default"})}
+${$$maybeRenderHead($$result)}<div>${data}</div>`;
+}, undefined, undefined);
+export default $$Component;
+```
+---

internal/printer/print-to-js.go

@@ -7,6 +7,7 @@ package printer
 import (
 	"bytes"
 	"fmt"
+	"regexp"
 	"sort"
 	"strings"
 	"unicode"
@@ -168,10 +169,72 @@ func render1(p *printer, n *Node, opts RenderOptions) {
 				}
 				render := js_scanner.HoistImports([]byte(c.Data))
 				if len(render.Hoisted) > 0 {
+					// Build set of local binding names used exclusively by
+					// client:only components. The compiler passes null to
+					// $$renderComponent for these, so the import is dead code
+					// and can be stripped to keep Rollup from traversing the
+					// component's dependency tree during prerender.
+					clientOnlyBindings := make(map[string]bool)
+					for _, node := range n.Parent.ClientOnlyComponentNodes {
+						name := node.Data
+						if idx := strings.Index(name, "."); idx != -1 {
+							name = name[:idx]
+						}
+						clientOnlyBindings[name] = true
+					}
+					for _, node := range n.Parent.HydratedComponentNodes {
+						name := node.Data
+						if idx := strings.Index(name, "."); idx != -1 {
+							name = name[:idx]
+						}
+						delete(clientOnlyBindings, name)
+					}
+					// Also exclude server-rendered components (no client: directive)
+					for _, comp := range n.Parent.ServerComponents {
+						name := comp.LocalName
+						if name == "" {
+							name = comp.Specifier
+						}
+						if idx := strings.Index(name, "."); idx != -1 {
+							name = name[:idx]
+						}
+						delete(clientOnlyBindings, name)
+					}
+
+					// Collect frontmatter body text to check for binding usage
+					var bodyText []byte
+					if len(clientOnlyBindings) > 0 {
+						for _, b := range render.Body {
+							bodyText = append(bodyText, b...)
+						}
+					}
+
 					for i, hoisted := range render.Hoisted {
 						if len(bytes.TrimSpace(hoisted)) == 0 {
 							continue
 						}
+						// Strip an import only when every binding it introduces
+						// is a client-only-exclusive component identifier that
+						// does not appear in the frontmatter body.
+						if len(clientOnlyBindings) > 0 {
+							_, stmt := js_scanner.NextImportStatement(hoisted, 0)
+							if len(stmt.Imports) > 0 && !stmt.IsType {
+								allDead := true
+								for _, imp := range stmt.Imports {
+									if !clientOnlyBindings[imp.LocalName] {
+										allDead = false
+										break
+									}
+									if regexp.MustCompile(`\b` + regexp.QuoteMeta(imp.LocalName) + `\b`).Match(bodyText) {
+										allDead = false
+										break
+									}
+								}
+								if allDead {
+									continue
+								}
+							}
+						}
 						hoistedLoc := render.HoistedLocs[i]
 						p.printTextWithSourcemap(string(hoisted)+"\n", loc.Loc{Start: start + hoistedLoc.Start})
 					}

internal/printer/printer_test.go

@@ -507,6 +507,33 @@ import Component from '../components';
 	<Component test="c" client:only />
   </body>
 </html>`,
+		},
+		{
+			name: "client:only preserves mixed import from same specifier",
+			source: `---
+import Component from '../components';
+import { helper } from '../components';
+const data = helper();
+---
+<Component client:only />
+<div>{data}</div>`,
+		},
+		{
+			name: "client:only preserves import when binding used in frontmatter",
+			source: `---
+import Component from '../components';
+console.log(Component.name);
+---
+<Component client:only />`,
+		},
+		{
+			name: "client:only preserves mixed binding import",
+			source: `---
+import Component, { helper } from '../components';
+const data = helper();
+---
+<Component client:only />
+<div>{data}</div>`,
 		},
 		{
 			name:   "iframe",