Turbopack: refactor segment config parsing (#83297)

Closes PACK-5382

Previously, Turbopack validated every single module for route segment config, leading to false positives (on non-page files) and worse build performance. There were also three separate implementations of this logic.

Now, all of these cases are fatal errors, not just warnings.



Examples for errors

```
./bench/basic-app/app/export/inherit/page.tsx:1:28
Next.js can't recognize the exported `preferredRegion` field in route. It needs to be a static string or array of static strings.
> 1 | export { default, runtime, preferredRegion } from '../basic/foo'
    |                            ^^^^^^^^^^^^^^^
The exported configuration object in a source file needs to have a very specific format from which some properties can be statically parsed at compiled-time.

https://nextjs.org/docs/app/api-reference/file-conventions/route-segment-config
```

This error message is slightly different now:

```
    browser log: ./test/integration/app-dir-export/app/another/[slug]/page.js:6:8
    Next.js can't recognize the exported `generateStaticParams` field in route. App pages cannot use both "use client" and export function "generateStaticParams()".
       4 |
       5 |
    >  6 | export function generateStaticParams() {
         |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    >  7 |   return [{ slug: 'first' }, { slug: 'second' }]
         | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    >  8 | }
         | ^^
       9 |
      10 | export default async function Page(props) {
      11 |   const params = await props.params

    The exported configuration object in a source file needs to have a very specific format from which some properties can be statically parsed at compiled-time.

    Import traces:
      Client Component Browser:
        ./test/integration/app-dir-export/app/another/[slug]/page.js [Client Component Browser]
        ./test/integration/app-dir-export/app/another/[slug]/page.js [Server Component]

      Client Component SSR:
        ./test/integration/app-dir-export/app/another/[slug]/page.js [Client Component SSR]
        ./test/integration/app-dir-export/app/another/[slug]/page.js [Server Component]

    https://nextjs.org/docs/app/api-reference/file-conventions/route-segment-config
```

Author: mischnic

crates/next-api/src/app.rs

@@ -1,7 +1,6 @@
 use anyhow::{Context, Result, bail};
 use next_core::{
     all_assets_from_entries,
-    app_segment_config::NextSegmentConfig,
     app_structure::{
         AppPageLoaderTree, CollectedRootParams, Entrypoint as AppEntrypoint,
         Entrypoints as AppEntrypoints, FileSystemPathVec, MetadataItem, collect_root_params,
@@ -34,6 +33,7 @@ use next_core::{
     },
     next_server_utility::{NEXT_SERVER_UTILITY_MERGE_TAG, NextServerUtilityTransition},
     parse_segment_config_from_source,
+    segment_config::{NextSegmentConfig, ParseSegmentMode},
     util::{NextRuntime, app_function_name, module_styles_rule_condition, styles_rule_condition},
 };
 use serde::{Deserialize, Serialize};
@@ -1106,7 +1106,7 @@ impl AppEndpoint {
 
             for layout in root_layouts.iter().rev() {
                 let source = Vc::upcast(FileSource::new(layout.clone()));
-                let layout_config = parse_segment_config_from_source(source);
+                let layout_config = parse_segment_config_from_source(source, ParseSegmentMode::App);
                 config.apply_parent_config(&*layout_config.await?);
             }
 

crates/next-api/src/middleware.rs

@@ -7,7 +7,9 @@ use next_core::{
     next_edge::entry::wrap_edge_entry,
     next_manifests::{EdgeFunctionDefinition, MiddlewareMatcher, MiddlewaresManifestV2, Regions},
     next_server::{ServerContextType, get_server_runtime_entries},
-    util::{MiddlewareMatcherKind, NextRuntime, parse_config_from_source},
+    parse_segment_config_from_source,
+    segment_config::ParseSegmentMode,
+    util::{MiddlewareMatcherKind, NextRuntime},
 };
 use tracing::Instrument;
 use turbo_rcstr::{RcStr, rcstr};
@@ -86,10 +88,12 @@ impl MiddlewareEndpoint {
             userland_module,
         );
 
-        let config =
-            parse_config_from_source(*self.source, userland_module, NextRuntime::Edge).await?;
+        let runtime = parse_segment_config_from_source(*self.source, ParseSegmentMode::Base)
+            .await?
+            .runtime
+            .unwrap_or(NextRuntime::Edge);
 
-        if matches!(config.runtime, NextRuntime::NodeJs) {
+        if matches!(runtime, NextRuntime::NodeJs) {
             return Ok(module);
         }
         Ok(wrap_edge_entry(
@@ -175,11 +179,9 @@ impl MiddlewareEndpoint {
     async fn output_assets(self: Vc<Self>) -> Result<Vc<OutputAssets>> {
         let this = self.await?;
 
-        let userland_module = self.userland_module();
-
         let config =
-            parse_config_from_source(*self.await?.source, userland_module, NextRuntime::Edge)
-                .await?;
+            parse_segment_config_from_source(*self.await?.source, ParseSegmentMode::Base).await?;
+        let runtime = config.runtime.unwrap_or(NextRuntime::Edge);
 
         let next_config = this.project.next_config().await?;
         let has_i18n = next_config.i18n.is_some();
@@ -190,7 +192,7 @@ impl MiddlewareEndpoint {
             .unwrap_or(false);
         let base_path = next_config.base_path.as_ref();
 
-        let matchers = if let Some(matchers) = config.matcher.as_ref() {
+        let matchers = if let Some(matchers) = config.middleware_matcher.as_ref() {
             matchers
                 .iter()
                 .map(|matcher| {
@@ -247,7 +249,7 @@ impl MiddlewareEndpoint {
             }]
         };
 
-        if matches!(config.runtime, NextRuntime::NodeJs) {
+        if matches!(runtime, NextRuntime::NodeJs) {
             let chunk = self.node_chunk().to_resolved().await?;
             let mut output_assets = vec![chunk];
             if this.project.next_mode().await?.is_production() {
@@ -296,7 +298,7 @@ impl MiddlewareEndpoint {
             let all_assets =
                 get_asset_paths_from_root(&node_root_value, &all_output_assets).await?;
 
-            let regions = if let Some(regions) = config.regions.as_ref() {
+            let regions = if let Some(regions) = config.preferred_region.as_ref() {
                 if regions.len() == 1 {
                     regions
                         .first()

crates/next-api/src/pages.rs

@@ -23,9 +23,9 @@ use next_core::{
     pages_structure::{
         PagesDirectoryStructure, PagesStructure, PagesStructureItem, find_pages_structure,
     },
-    util::{
-        NextRuntime, get_asset_prefix_from_pathname, pages_function_name, parse_config_from_source,
-    },
+    parse_segment_config_from_source,
+    segment_config::ParseSegmentMode,
+    util::{NextRuntime, get_asset_prefix_from_pathname, pages_function_name},
 };
 use serde::{Deserialize, Serialize};
 use tracing::Instrument;
@@ -930,7 +930,9 @@ impl PageEndpoint {
             .module();
 
         let config =
-            parse_config_from_source(self.source(), ssr_module, NextRuntime::default()).await?;
+            parse_segment_config_from_source(self.source(), ParseSegmentMode::Base).await?;
+
+        let runtime = config.runtime.unwrap_or(NextRuntime::NodeJs);
 
         Ok(
             // `/_app` and `/_document` never get rendered directly so they don't need to be
@@ -944,9 +946,9 @@ impl PageEndpoint {
                     // /_app and /_document are always rendered for Node.js for this case. For edge
                     // they're included in the page bundle.
                     runtime: NextRuntime::NodeJs,
-                    regions: config.regions.clone(),
+                    regions: config.preferred_region.clone(),
                 }
-            } else if config.runtime == NextRuntime::Edge {
+            } else if runtime == NextRuntime::Edge {
                 let modules = create_page_ssr_entry_module(
                     this.pathname.clone(),
                     reference_type,
@@ -955,7 +957,7 @@ impl PageEndpoint {
                     self.source(),
                     this.original_name.clone(),
                     *this.pages_structure,
-                    config.runtime,
+                    runtime,
                     this.pages_project.project().next_config(),
                 )
                 .await?;
@@ -964,8 +966,8 @@ impl PageEndpoint {
                     ssr_module: modules.ssr_module,
                     app_module: modules.app_module,
                     document_module: modules.document_module,
-                    runtime: config.runtime,
-                    regions: config.regions.clone(),
+                    runtime,
+                    regions: config.preferred_region.clone(),
                 }
             } else {
                 let modules = create_page_ssr_entry_module(
@@ -976,16 +978,16 @@ impl PageEndpoint {
                     self.source(),
                     this.original_name.clone(),
                     *this.pages_structure,
-                    config.runtime,
+                    runtime,
                     this.pages_project.project().next_config(),
                 )
                 .await?;
                 InternalSsrChunkModule {
                     ssr_module: modules.ssr_module,
                     app_module: modules.app_module,
                     document_module: modules.document_module,
-                    runtime: config.runtime,
-                    regions: config.regions.clone(),
+                    runtime,
+                    regions: config.preferred_region.clone(),
                 }
             }
             .cell(),

crates/next-api/src/project.rs

@@ -21,7 +21,9 @@ use next_core::{
         get_server_module_options_context, get_server_resolve_options_context,
     },
     next_telemetry::NextFeatureTelemetry,
-    util::{NextRuntime, OptionEnvMap, parse_config_from_source},
+    parse_segment_config_from_source,
+    segment_config::ParseSegmentMode,
+    util::{NextRuntime, OptionEnvMap},
 };
 use serde::{Deserialize, Serialize};
 use tracing::Instrument;
@@ -66,7 +68,6 @@ use turbopack_core::{
         export_usage::{OptionExportUsageInfo, compute_export_usage_info},
     },
     output::{OutputAsset, OutputAssets},
-    reference_type::{EntryReferenceSubType, ReferenceType},
     resolve::{FindContextFileResult, find_context_file},
     source_map::OptionStringifiedSourceMap,
     version::{
@@ -1412,16 +1413,12 @@ impl Project {
         };
         let source = Vc::upcast(FileSource::new(fs_path.clone()));
 
-        let module = edge_module_context
-            .process(
-                source,
-                ReferenceType::Entry(EntryReferenceSubType::Middleware),
-            )
-            .module();
-
-        let config = parse_config_from_source(source, module, NextRuntime::Edge).await?;
+        let runtime = parse_segment_config_from_source(source, ParseSegmentMode::Base)
+            .await?
+            .runtime
+            .unwrap_or(NextRuntime::Edge);
 
-        if matches!(config.runtime, NextRuntime::NodeJs) {
+        if matches!(runtime, NextRuntime::NodeJs) {
             Ok(self.node_middleware_context())
         } else {
             Ok(edge_module_context)