feat: inline const for leaf modules

Cargo.toml

@@ -73,6 +73,7 @@ rustc-hash         = { version = "2.1.0" }
 scopeguard         = "1.2.0"
 serde              = { version = "1.0.217" }
 serde_json         = { version = "1.0.134" }
+sftrace-setup      = { version = "0.1.0" }
 sha2               = { version = "0.10.8" }
 simd-json          = { version = "0.14.3" }
 smol_str           = { version = "0.3.0" }
@@ -87,7 +88,6 @@ url                = { version = "2.5.4" }
 urlencoding        = { version = "2.1.3" }
 ustr               = { package = "ustr-fxhash", version = "1.0.1" }
 xxhash-rust        = { version = "0.8.14" }
-sftrace-setup      = { version = "0.1.0" }
 
 # Pinned
 napi        = { version = "3.0.0-beta.8" }

crates/node_binding/Cargo.toml

@@ -110,9 +110,9 @@ tokio                                  = { workspace = true, features = ["rt", "
 ustr                                   = { workspace = true }
 
 [target.'cfg(not(target_family = "wasm"))'.dependencies]
-tokio = { workspace = true, features = ["parking_lot"] }
 rspack_tracing = { workspace = true }
-sftrace-setup = { workspace = true, optional = true }
+sftrace-setup  = { workspace = true, optional = true }
+tokio          = { workspace = true, features = ["parking_lot"] }
 
 [build-dependencies]
 napi-build = { workspace = true }

crates/node_binding/binding.d.ts

@@ -1059,7 +1059,7 @@ export interface JsRsdoctorModule {
   belongModules: Array<number>
   chunks: Array<number>
   issuerPath: Array<number>
-  bailoutReason?: string
+  bailoutReason: Array<string>
 }
 
 export interface JsRsdoctorModuleGraph {
@@ -1885,6 +1885,7 @@ parallelCodeSplitting: boolean
 rspackFuture?: RawRspackFuture
 cache: boolean | { type: "persistent" } & RawExperimentCacheOptionsPersistent | { type: "memory" }
 useInputFileSystem?: false | Array<RegExp>
+inlineConst: boolean
 }
 
 export interface RawExperimentSnapshotOptions {
@@ -2094,6 +2095,11 @@ export interface RawJavascriptParserOptions {
    * @experimental
    */
   importDynamic?: boolean
+  /**
+   * This option is experimental in Rspack only and subject to change or be removed anytime.
+   * @experimental
+   */
+  inlineConst?: boolean
 }
 
 export interface RawJsonGeneratorOptions {

crates/node_binding/src/raw_options/raw_experiments/mod.rs

@@ -26,6 +26,7 @@ pub struct RawExperiments {
   pub cache: RawExperimentCacheOptions,
   #[napi(ts_type = "false | Array<RegExp>")]
   pub use_input_file_system: Option<WithFalse<Vec<RspackRegex>>>,
+  pub inline_const: bool,
 }
 
 impl From<RawExperiments> for Experiments {
@@ -43,6 +44,7 @@ impl From<RawExperiments> for Experiments {
       top_level_await: value.top_level_await,
       rspack_future: value.rspack_future.unwrap_or_default().into(),
       cache: normalize_raw_experiment_cache_options(value.cache),
+      inline_const: value.inline_const,
     }
   }
 }

crates/node_binding/src/raw_options/raw_module/mod.rs

@@ -289,6 +289,9 @@ pub struct RawJavascriptParserOptions {
   /// This option is experimental in Rspack only and subject to change or be removed anytime.
   /// @experimental
   pub import_dynamic: Option<bool>,
+  /// This option is experimental in Rspack only and subject to change or be removed anytime.
+  /// @experimental
+  pub inline_const: Option<bool>,
 }
 
 impl From<RawJavascriptParserOptions> for JavascriptParserOptions {
@@ -329,6 +332,7 @@ impl From<RawJavascriptParserOptions> for JavascriptParserOptions {
       require_dynamic: value.require_dynamic,
       require_resolve: value.require_resolve,
       import_dynamic: value.import_dynamic,
+      inline_const: value.inline_const,
     }
   }
 }

crates/rspack/src/builder/mod.rs

@@ -1712,6 +1712,7 @@ impl ModuleOptionsBuilder {
           require_dynamic: Some(true),
           require_resolve: Some(true),
           import_dynamic: Some(true),
+          inline_const: Some(false),
           ..Default::default()
         }),
       );
@@ -3667,6 +3668,8 @@ pub struct ExperimentsBuilder {
   parallel_code_splitting: Option<bool>,
   /// Whether to enable async web assembly.
   async_web_assembly: Option<bool>,
+  /// Whether to enable inline constants.
+  inline_const: Option<bool>,
   // TODO: lazy compilation
 }
 
@@ -3683,6 +3686,7 @@ impl From<Experiments> for ExperimentsBuilder {
       future_defaults: None,
       css: None,
       async_web_assembly: None,
+      inline_const: Some(value.inline_const),
     }
   }
 }
@@ -3700,6 +3704,7 @@ impl From<&mut ExperimentsBuilder> for ExperimentsBuilder {
       css: value.css.take(),
       parallel_code_splitting: value.parallel_code_splitting.take(),
       async_web_assembly: value.async_web_assembly.take(),
+      inline_const: value.inline_const.take(),
     }
   }
 }
@@ -3791,6 +3796,7 @@ impl ExperimentsBuilder {
     w!(self.output_module, false);
 
     let parallel_code_splitting = d!(self.parallel_code_splitting, false);
+    let inline_const = d!(self.inline_const, production);
 
     Ok(Experiments {
       layers,
@@ -3799,6 +3805,7 @@ impl ExperimentsBuilder {
       rspack_future,
       parallel_code_splitting,
       cache,
+      inline_const,
     })
   }
 }

crates/rspack/tests/snapshots/defaults__default_options.snap

@@ -1417,6 +1417,9 @@ CompilerOptions {
                             import_dynamic: Some(
                                 true,
                             ),
+                            inline_const: Some(
+                                false,
+                            ),
                         },
                     ),
                 },
@@ -1453,6 +1456,7 @@ CompilerOptions {
         top_level_await: true,
         rspack_future: RspackFuture,
         cache: Disabled,
+        inline_const: false,
     },
     node: Some(
         NodeOption {

crates/rspack_core/src/concatenated_module.rs

@@ -42,8 +42,8 @@ use crate::{
   define_es_module_flag_statement, filter_runtime, impl_source_map_config, merge_runtime_condition,
   merge_runtime_condition_non_false, module_update_hash, property_access, property_name,
   reserved_names::RESERVED_NAMES, returning_function, runtime_condition_expression,
-  subtract_runtime_condition, to_identifier, AsyncDependenciesBlockIdentifier, BoxDependency,
-  BoxDependencyTemplate, BoxModuleDependency, BuildContext, BuildInfo, BuildMeta,
+  subtract_runtime_condition, to_identifier, to_normal_comment, AsyncDependenciesBlockIdentifier,
+  BoxDependency, BoxDependencyTemplate, BoxModuleDependency, BuildContext, BuildInfo, BuildMeta,
   BuildMetaDefaultObject, BuildMetaExportsType, BuildResult, ChunkGraph, ChunkInitFragments,
   ChunkRenderContext, CodeGenerationDataTopLevelDeclarations, CodeGenerationExportsFinalNames,
   CodeGenerationPublicPathAutoReplace, CodeGenerationResult, Compilation, ConcatenatedModuleIdent,
@@ -53,7 +53,7 @@ use crate::{
   LibIdentOptions, MaybeDynamicTargetExportInfoHashKey, Module, ModuleArgument, ModuleGraph,
   ModuleGraphCacheArtifact, ModuleGraphConnection, ModuleIdentifier, ModuleLayer, ModuleType,
   PrefetchExportsInfoMode, Resolve, RuntimeCondition, RuntimeGlobals, RuntimeSpec, SourceType,
-  SpanExt, Template, UsageState, DEFAULT_EXPORT, NAMESPACE_OBJECT_EXPORT,
+  SpanExt, UsageState, UsedName, UsedNameItem, DEFAULT_EXPORT, NAMESPACE_OBJECT_EXPORT,
 };
 
 type ExportsDefinitionArgs = Vec<(String, String)>;
@@ -991,6 +991,7 @@ impl Module for ConcatenatedModule {
 
     let mut exports_map: HashMap<Atom, String> = HashMap::default();
     let mut unused_exports: HashSet<Atom> = HashSet::default();
+    let mut inlined_exports: HashSet<Atom> = HashSet::default();
 
     let root_info = module_to_info_map
       .get(&self.root_module_ctxt.id)
@@ -1021,6 +1022,10 @@ impl Module for ConcatenatedModule {
         unused_exports.insert(name);
         continue;
       };
+      let UsedNameItem::Str(used_name) = used_name else {
+        inlined_exports.insert(name);
+        continue;
+      };
       exports_map.insert(used_name.clone(), {
         let final_name = Self::get_final_name(
           &compilation.get_module_graph(),
@@ -1164,6 +1169,13 @@ impl Module for ConcatenatedModule {
         join_atom(unused_exports.iter(), ", ")
       )));
     }
+    // List inlined exports
+    if !inlined_exports.is_empty() {
+      result.add(RawStringSource::from(format!(
+        "\n// INLINED EXPORTS: {}\n",
+        join_atom(inlined_exports.iter(), ", ")
+      )));
+    }
 
     let mut namespace_object_sources: IdentifierMap<String> = IdentifierMap::default();
 
@@ -1210,7 +1222,7 @@ impl Module for ConcatenatedModule {
             continue;
           }
 
-          if let Some(used_name) =
+          if let Some(UsedNameItem::Str(used_name)) =
             ExportInfoGetter::get_used_name(export_info.as_data(&module_graph), None, runtime)
           {
             let final_name = Self::get_final_name(
@@ -2256,16 +2268,36 @@ impl ConcatenatedModule {
           if let Some(used_name) =
             ExportsInfoGetter::get_used_name(&exports_info, runtime, &export_name)
           {
-            // https://github.com/webpack/webpack/blob/1f99ad6367f2b8a6ef17cce0e058f7a67fb7db18/lib/optimize/ConcatenatedModule.js#L402-L404
-            let used_name = used_name.to_used_name_vec();
-
-            return Binding::Symbol(SymbolBinding {
-              info_id: info.module,
-              name: direct_export.as_str().into(),
-              ids: used_name[1..].to_vec(),
-              export_name,
-              comment: None,
-            });
+            match used_name {
+              UsedName::Normal(used_name) => {
+                // https://github.com/webpack/webpack/blob/1f99ad6367f2b8a6ef17cce0e058f7a67fb7db18/lib/optimize/ConcatenatedModule.js#L402-L404
+                return Binding::Symbol(SymbolBinding {
+                  info_id: info.module,
+                  name: direct_export.as_str().into(),
+                  ids: used_name[1..].to_vec(),
+                  export_name,
+                  comment: None,
+                });
+              }
+              UsedName::Inlined(inlined) => {
+                return Binding::Raw(RawBinding {
+                  raw_name: format!(
+                    "{} {}",
+                    to_normal_comment(&format!(
+                      "inlined export {}",
+                      property_access(&export_name, 0)
+                    )),
+                    inlined.render()
+                  )
+                  .into(),
+                  // Inlined export is definitely a terminal binding
+                  ids: vec![],
+                  export_name,
+                  info_id: info.module,
+                  comment: None,
+                });
+              }
+            }
           } else {
             return Binding::Raw(RawBinding {
               raw_name: "/* unused export */ undefined".into(),
@@ -2335,20 +2367,29 @@ impl ConcatenatedModule {
           // That's how webpack write https://github.com/webpack/webpack/blob/1f99ad6367f2b8a6ef17cce0e058f7a67fb7db18/lib/optimize/ConcatenatedModule.js#L463-L471
           let used_name = ExportsInfoGetter::get_used_name(&exports_info, runtime, &export_name)
             .expect("should have export name");
-
-          let used_name = used_name.to_used_name_vec();
-          return Binding::Raw(RawBinding {
-            info_id: info.module,
-            raw_name: info
-              .namespace_object_name
-              .as_ref()
-              .expect("should have raw name")
-              .as_str()
-              .into(),
-            ids: used_name,
-            export_name,
-            comment: None,
-          });
+          return match used_name {
+            UsedName::Normal(used_name) => Binding::Raw(RawBinding {
+              info_id: info.module,
+              raw_name: info
+                .namespace_object_name
+                .as_ref()
+                .expect("should have raw name")
+                .as_str()
+                .into(),
+              ids: used_name,
+              export_name,
+              comment: None,
+            }),
+            // Inlined namespace export symbol is not possible for now but we compat it here
+            UsedName::Inlined(inlined) => Binding::Raw(RawBinding {
+              info_id: info.module,
+              raw_name: inlined.render().into(),
+              // Inlined export is definitely a terminal binding
+              ids: vec![],
+              export_name,
+              comment: None,
+            }),
+          };
         }
 
         panic!(
@@ -2361,24 +2402,41 @@ impl ConcatenatedModule {
         if let Some(used_name) =
           ExportsInfoGetter::get_used_name(&exports_info, runtime, &export_name)
         {
-          let used_name = used_name.to_used_name_vec();
-          let comment = if used_name == export_name {
-            String::new()
-          } else {
-            Template::to_normal_comment(&join_atom(export_name.iter(), ","))
-          };
-          Binding::Raw(RawBinding {
-            raw_name: format!(
-              "{}{}",
-              info.name.as_ref().expect("should have name"),
-              comment
-            )
-            .into(),
-            ids: used_name,
-            export_name,
-            info_id: info.module,
-            comment: None,
-          })
+          match used_name {
+            UsedName::Normal(used_name) => {
+              let comment = if used_name == export_name {
+                String::new()
+              } else {
+                to_normal_comment(&property_access(&export_name, 0))
+              };
+              Binding::Raw(RawBinding {
+                raw_name: format!(
+                  "{}{}",
+                  info.name.as_ref().expect("should have name"),
+                  comment
+                )
+                .into(),
+                ids: used_name,
+                export_name,
+                info_id: info.module,
+                comment: None,
+              })
+            }
+            UsedName::Inlined(inlined) => {
+              let comment = to_normal_comment(&format!(
+                "inlined export {}",
+                property_access(&export_name, 0)
+              ));
+              Binding::Raw(RawBinding {
+                raw_name: format!("{}{}", inlined.render(), comment).into(),
+                // Inlined export is definitely a terminal binding
+                ids: vec![],
+                export_name,
+                info_id: info.module,
+                comment: None,
+              })
+            }
+          }
         } else {
           Binding::Raw(RawBinding {
             raw_name: "/* unused export */ undefined".into(),

crates/rspack_core/src/dependency/context_element_dependency.rs

@@ -123,7 +123,11 @@ impl Dependency for ContextElementDependency {
       referenced_exports
         .iter()
         .map(|export| {
-          ExtendedReferencedExport::Export(ReferencedExport::new(vec![export.clone()], false))
+          ExtendedReferencedExport::Export(ReferencedExport::new(
+            vec![export.clone()],
+            false,
+            false,
+          ))
         })
         .collect_vec()
     } else {