Preserve exports if content is preserved

vercel · Sep 6, 2024 · 6b66991 · 6b66991
1 parent a8b9440
commit 6b66991
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Showing 3 changed files with 53 additions and 8 deletions.
diff --git a/turbopack/crates/turbopack-ecmascript/src/tree_shake/asset.rs b/turbopack/crates/turbopack-ecmascript/src/tree_shake/asset.rs
@@ -14,7 +14,7 @@ use turbopack_core::{
 
 use super::{
     chunk_item::EcmascriptModulePartChunkItem, get_part_id, part_of_module, split, split_module,
-    Key, SplitResult,
+    Key, PartId, SplitResult,
 };
 use crate::{
     chunk::{EcmascriptChunkPlaceable, EcmascriptExports},
@@ -219,11 +219,16 @@ impl Module for EcmascriptModulePartAsset {
 
         let mut assets = deps
             .iter()
-            .map(|&part_id| {
+            .map(|part_id| {
                 Ok(Vc::upcast(SingleModuleReference::new(
                     Vc::upcast(EcmascriptModulePartAsset::new(
                         self.full_module,
-                        ModulePart::internal(part_id),
+                        match part_id {
+                            PartId::Internal(part_id) => ModulePart::internal(*part_id),
+                            PartId::Export(name) => ModulePart::export(name.clone()),
+                            PartId::ModuleEvaluation => ModulePart::evaluation(),
+                            PartId::Exports => ModulePart::exports(),
+                        },
                         self.import_externals,
                     )),
                     Vc::cell("ecmascript module part".into()),

diff --git a/turbopack/crates/turbopack-ecmascript/src/tree_shake/graph.rs b/turbopack/crates/turbopack-ecmascript/src/tree_shake/graph.rs
@@ -207,7 +207,7 @@ pub(super) struct SplitModuleResult {
     pub entrypoints: FxHashMap<Key, u32>,
 
     /// Dependency between parts.
-    pub part_deps: FxHashMap<u32, Vec<u32>>,
+    pub part_deps: FxHashMap<u32, Vec<PartId>>,
     pub modules: Vec<Module>,
 
     pub star_reexports: Vec<ExportAll>,
@@ -248,7 +248,7 @@ impl DepGraph {
     ) -> SplitModuleResult {
         let groups = self.finalize(data);
         let mut exports = FxHashMap::default();
-        let mut part_deps = FxHashMap::<_, Vec<_>>::default();
+        let mut part_deps = FxHashMap::<_, Vec<PartId>>::default();
 
         let star_reexports: Vec<_> = data
             .values()
@@ -270,6 +270,7 @@ impl DepGraph {
         }
 
         let mut declarator = FxHashMap::default();
+        let mut exporter = FxHashMap::default();
 
         for (ix, group) in groups.graph_ix.iter().enumerate() {
             for id in group {
@@ -278,6 +279,10 @@ impl DepGraph {
                 for var in item.var_decls.iter() {
                     declarator.entry(var.clone()).or_insert_with(|| ix as u32);
                 }
+
+                if let Some(export) = &item.export {
+                    exporter.insert(export.clone(), ix as u32);
+                }
             }
         }
 
@@ -388,7 +393,7 @@ impl DepGraph {
             }
 
             // Import variables
-            for var in required_vars {
+            for &var in &required_vars {
                 let Some(&dep) = declarator.get(var) else {
                     continue;
                 };
@@ -407,7 +412,10 @@ impl DepGraph {
                     is_type_only: false,
                 })];
 
-                part_deps.entry(ix as u32).or_default().push(dep);
+                part_deps
+                    .entry(ix as u32)
+                    .or_default()
+                    .push(PartId::Internal(dep));
 
                 chunk
                     .body
@@ -423,6 +431,38 @@ impl DepGraph {
                     })));
             }
 
+            // Depend on exports.
+            //
+            // We preserve the export if the content is preserved.
+            // It's for server actions, where we need to preserve the export if the content is used.
+            for &var in &required_vars {
+                let Some(&dep) = exporter.get(&var.0) else {
+                    continue;
+                };
+
+                if dep == ix as u32 {
+                    continue;
+                }
+
+                part_deps
+                    .entry(ix as u32)
+                    .or_default()
+                    .push(PartId::Export(var.0.as_str().into()));
+
+                chunk
+                    .body
+                    .push(ModuleItem::ModuleDecl(ModuleDecl::Import(ImportDecl {
+                        span: DUMMY_SP,
+                        specifiers: vec![],
+                        src: Box::new(TURBOPACK_PART_IMPORT_SOURCE.into()),
+                        type_only: false,
+                        with: Some(Box::new(create_turbopack_part_id_assert(PartId::Export(
+                            var.0.as_str().into(),
+                        )))),
+                        phase: Default::default(),
+                    })));
+            }
+
             for g in group {
                 // Skip directives, as we copy them to each modules.
                 if let ModuleItem::Stmt(Stmt::Expr(ExprStmt {

diff --git a/turbopack/crates/turbopack-ecmascript/src/tree_shake/mod.rs b/turbopack/crates/turbopack-ecmascript/src/tree_shake/mod.rs
@@ -398,7 +398,7 @@ pub(crate) enum SplitResult {
         modules: Vec<Vc<ParseResult>>,
 
         #[turbo_tasks(trace_ignore)]
-        deps: FxHashMap<u32, Vec<u32>>,
+        deps: FxHashMap<u32, Vec<PartId>>,
 
         #[turbo_tasks(debug_ignore, trace_ignore)]
         star_reexports: Vec<ExportAll>,