Turbopack: Fail when next/font is used in _document

packages/next-swc/crates/next-core/src/next_font/google/mod.rs

@@ -45,7 +45,8 @@ use self::{
 use super::{
     font_fallback::FontFallback,
     util::{
-        get_request_hash, get_request_id, get_scoped_font_family, FontCssProperties, FontFamilyType,
+        can_use_next_font, get_request_hash, get_request_id, get_scoped_font_family,
+        FontCssProperties, FontFamilyType,
     },
 };
 use crate::{
@@ -163,7 +164,12 @@ impl ImportMappingReplacement for NextFontGoogleReplacer {
             return Ok(ImportMapResult::NoEntry.into());
         };
 
-        Ok(self.import_map_result(query.await?.to_string()))
+        let this = &*self.await?;
+        if can_use_next_font(this.project_path, *query).await? {
+            Ok(self.import_map_result(query.await?.to_string()))
+        } else {
+            Ok(ImportMapResult::NoEntry.into())
+        }
     }
 }
 

packages/next-swc/crates/next-core/src/next_font/local/mod.rs

@@ -24,7 +24,10 @@ use self::{
     stylesheet::build_stylesheet,
     util::build_font_family_string,
 };
-use super::{font_fallback::FontFallbacks, util::FontCssProperties};
+use super::{
+    font_fallback::FontFallbacks,
+    util::{can_use_next_font, FontCssProperties},
+};
 use crate::{
     next_app::metadata::split_extension,
     next_font::{
@@ -134,7 +137,12 @@ impl ImportMappingReplacement for NextFontLocalReplacer {
             return Ok(ImportMapResult::NoEntry.into());
         };
 
-        Ok(self.import_map_result(context, query_vc.await?.to_string()))
+        let this = &*self.await?;
+        if can_use_next_font(this.project_path, *query_vc).await? {
+            Ok(self.import_map_result(context, query_vc.await?.to_string()))
+        } else {
+            Ok(ImportMapResult::NoEntry.into())
+        }
     }
 }
 

packages/next-swc/crates/next-core/src/next_font/util.rs

@@ -1,6 +1,13 @@
-use anyhow::Result;
+use anyhow::{Context, Result};
+use serde::Deserialize;
 use turbo_tasks::Vc;
-use turbopack_binding::turbo::tasks_hash::hash_xxh3_hash64;
+use turbo_tasks_fs::{json::parse_json_with_source_context, FileSystemPath};
+use turbopack_binding::{
+    turbo::tasks_hash::hash_xxh3_hash64,
+    turbopack::core::issue::{IssueExt, IssueSeverity, StyledString},
+};
+
+use super::issue::NextFontIssue;
 
 /// CSS properties and values for a given font variation. These are rendered as
 /// values in both the returned JavaScript object and in the referenced css
@@ -72,3 +79,45 @@ pub async fn get_request_id(font_family: Vc<String>, request_hash: u32) -> Resul
         request_hash
     )))
 }
+
+#[derive(Debug, Deserialize)]
+struct HasPath {
+    path: String,
+}
+
+pub(crate) async fn can_use_next_font(
+    project_path: Vc<FileSystemPath>,
+    query: Vc<String>,
+) -> Result<bool> {
+    let query_map = qstring::QString::from(&**query.await?);
+    let request: HasPath = parse_json_with_source_context(
+        query_map
+            .to_pairs()
+            .first()
+            .context("expected one entry")?
+            .0,
+    )?;
+
+    let document_re = lazy_regex::regex!("^(src/)?_document\\.[^/]+$");
+    let path = project_path.join(request.path.clone());
+    let can_use = !document_re.is_match(&request.path);
+    if !can_use {
+        NextFontIssue {
+            path,
+            title: StyledString::Line(vec![
+                StyledString::Code("next/font:".to_string()),
+                StyledString::Text(" error:".to_string()),
+            ])
+            .cell(),
+            description: StyledString::Line(vec![
+                StyledString::Text("Cannot be used within ".to_string()),
+                StyledString::Code(request.path),
+            ])
+            .cell(),
+            severity: IssueSeverity::Error.into(),
+        }
+        .cell()
+        .emit();
+    }
+    Ok(can_use)
+}

test/development/next-font/font-loader-in-document-error.test.ts

@@ -19,10 +19,19 @@ describe('font-loader-in-document-error', () => {
   test('next/font inside _document', async () => {
     const browser = await webdriver(next.url, '/')
     expect(await hasRedbox(browser)).toBeTrue()
-    expect(await getRedboxSource(browser)).toMatchInlineSnapshot(`
-      "pages/_document.js
-      \`next/font\` error:
-      Cannot be used within pages/_document.js."
-    `)
+    if (process.env.TURBOPACK) {
+      // TODO: Turbopack doesn't include pages/
+      expect(await getRedboxSource(browser)).toMatchInlineSnapshot(`
+        "./_document.js
+        next/font: error:
+        Cannot be used within _document.js"
+      `)
+    } else {
+      expect(await getRedboxSource(browser)).toMatchInlineSnapshot(`
+              "pages/_document.js
+              \`next/font\` error:
+              Cannot be used within pages/_document.js."
+          `)
+    }
   })
 })