wip treeshake nested namespace imports

It doesn't handle several important edgecases. I don't think this code is currently in the right place.

src/bundler/bundle_v2.zig

@@ -9045,8 +9045,11 @@ const LinkerContext = struct {
             .imports = &named_imports,
         };
         named_imports.sort(sorter);
-
-        for (named_imports.keys(), named_imports.values()) |ref, named_import| {
+        const nested_named_imports = c.graph.ast.items(.nested_named_imports);
+        const named_import_len = named_imports.count();
+        for (0..named_import_len) |named_import_i| {
+            const ref = named_imports.keys()[named_import_i];
+            const named_import = named_imports.values()[named_import_i];
             // Re-use memory for the cycle detector
             c.cycle_detector.clearRetainingCapacity();
 
@@ -9078,6 +9081,36 @@ const LinkerContext = struct {
                             },
                         },
                     ) catch unreachable;
+
+                    if (nested_named_imports[source_index].get(import_ref)) |nested| {
+                        for (nested.slice()) |nested_import| {
+                            if (c.graph.meta.items(.resolved_exports)[result.source_index].get(nested_import.alias)) |matching_export| {
+                                var named_import_entry = named_imports.getOrPut(nested_import.ref) catch unreachable;
+                                if (!named_import_entry.found_existing) {
+                                    named_import_entry.value_ptr.* = js_ast.NamedImport{
+                                        .alias = nested_import.alias,
+                                        .import_record_index = named_import.import_record_index,
+                                        .namespace_ref = import_ref,
+                                    };
+
+                                    imports_to_bind.put(
+                                        c.allocator,
+                                        nested_import.ref,
+                                        .{
+                                            .data = matching_export.data,
+                                        },
+                                    ) catch unreachable;
+                                }
+                            } else if (c.graph.symbols.get(nested_import.ref)) |nested_symbol| {
+                                nested_symbol.namespace_alias = js_ast.G.NamespaceAlias{
+                                    .namespace_ref = import_ref,
+                                    .alias = nested_import.alias,
+                                };
+                            }
+
+                            // }
+                        }
+                    }
                 },
                 .namespace => {
                     c.graph.symbols.get(import_ref).?.namespace_alias = js_ast.G.NamespaceAlias{
@@ -9217,6 +9250,7 @@ const LinkerContext = struct {
                             continue :next_export;
                         }
                     }
+
                     const ref = entry.value_ptr.ref;
                     var resolved = resolved_exports.getOrPut(this.allocator, entry.key_ptr.*) catch unreachable;
                     if (!resolved.found_existing) {
@@ -9384,6 +9418,9 @@ const LinkerContext = struct {
             for (this.export_star_records[source_index]) |id| {
                 const records: []const ImportRecord = this.import_records[id].slice();
                 for (records) |record| {
+                    // ignore external export * from
+                    if (record.source_index.isInvalid()) continue;
+
                     // This file has dynamic exports if the exported imports are from a file
                     // that either has dynamic exports directly or transitively by itself
                     // having an export star from a file with dynamic exports.

src/js_ast.zig

@@ -5210,12 +5210,12 @@ pub const S = struct {
         pub fn canBeMovedAround(self: ExportDefault) bool {
             return switch (self.value) {
                 .expr => |e| switch (e.data) {
-                    .e_class => |class| class.extends == null,
+                    .e_class => |class| class.canClassBeMoved(),
                     .e_arrow, .e_function => true,
                     else => e.canBeConstValue(),
                 },
                 .stmt => |s| switch (s.data) {
-                    .s_class => |class| class.class.extends == null,
+                    .s_class => |class| class.class.canClassBeMoved(),
                     .s_function => true,
                     else => false,
                 },
@@ -5719,6 +5719,7 @@ pub const Ast = struct {
     // since we already have to traverse the AST then anyway and the parser pass
     // is conveniently fully parallelized.
     named_imports: NamedImports = NamedImports.init(bun.failing_allocator),
+    nested_named_imports: NestedNamedImports = NestedNamedImports.init(bun.failing_allocator),
     named_exports: NamedExports = NamedExports.init(bun.failing_allocator),
     export_star_import_records: []u32 = &([_]u32{}),
 
@@ -5740,7 +5741,13 @@ pub const Ast = struct {
     };
     pub const CommonJSNamedExports = bun.StringArrayHashMapUnmanaged(CommonJSNamedExport);
 
-    pub const NamedImports = std.ArrayHashMap(Ref, NamedImport, RefHashCtx, true);
+    pub const NestedNamedImport = struct {
+        alias: string,
+        ref: Ref,
+    };
+
+    pub const NamedImports = std.ArrayHashMap(Ref, NamedImport, RefHashCtx, false);
+    pub const NestedNamedImports = std.ArrayHashMap(Ref, BabyList(NestedNamedImport), RefHashCtx, false);
     pub const NamedExports = bun.StringArrayHashMap(NamedExport);
     pub const ConstValuesMap = std.ArrayHashMapUnmanaged(Ref, Expr, RefHashCtx, false);
 
@@ -9288,7 +9295,7 @@ pub const Macro = struct {
                                 this.caller.loc,
                                 this.allocator,
                                 "cannot coerce {s} to Bun's AST. Please return a valid macro using the JSX syntax",
-                                .{@tagName(value.jsType())},
+                                .{@tagName(value.jsTypeLoose())},
                             ) catch unreachable;
                             break :brk error.MacroFailed;
                         },
@@ -9320,7 +9327,7 @@ pub const Macro = struct {
                             var blob_: ?JSC.WebCore.Blob = null;
                             var mime_type: ?HTTP.MimeType = null;
 
-                            if (value.jsType() == .DOMWrapper) {
+                            if (value.jsTypeLoose() == .DOMWrapper) {
                                 if (value.as(JSC.WebCore.Response)) |resp| {
                                     mime_type = HTTP.MimeType.init(resp.mimeType(null));
                                     blob_ = resp.body.use();
@@ -9535,7 +9542,7 @@ pub const Macro = struct {
                         this.caller.loc,
                         this.allocator,
                         "cannot coerce {s} to Bun's AST. Please return a valid macro using the JSX syntax",
-                        .{@tagName(value.jsType())},
+                        .{@tagName(value.jsTypeLoose())},
                     ) catch unreachable;
                     return error.MacroFailed;
                 }

src/js_parser.zig

@@ -2904,6 +2904,7 @@ pub const Parser = struct {
         var before = ListManaged(js_ast.Part).init(p.allocator);
         var after = ListManaged(js_ast.Part).init(p.allocator);
         var parts = ListManaged(js_ast.Part).init(p.allocator);
+
         defer {
             after.deinit();
             before.deinit();
@@ -2919,6 +2920,7 @@ pub const Parser = struct {
         if (!p.options.tree_shaking) {
             try p.appendPart(&parts, stmts);
         } else {
+
             // When tree shaking is enabled, each top-level statement is potentially a separate part.
             for (stmts) |stmt| {
                 switch (stmt.data) {
@@ -4811,6 +4813,7 @@ fn NewParser_(
         import_items_for_namespace: std.AutoHashMapUnmanaged(Ref, ImportItemForNamespaceMap) = .{},
         is_import_item: RefMap = .{},
         named_imports: NamedImportsType,
+        nested_named_imports: js_ast.Ast.NestedNamedImports,
         named_exports: js_ast.Ast.NamedExports,
         import_namespace_cc_map: Map(ImportNamespaceCallOrConstruct, bool) = .{},
 
@@ -17396,6 +17399,71 @@ fn NewParser_(
                         }
                     }
                 },
+                .e_import_identifier => |id| {
+
+                    // Rewrite property accesses on explicit namespace imports as an identifier.
+                    // This lets us replace them easily in the printer to rebind them to
+                    // something else without paying the cost of a whole-tree traversal during
+                    // module linking just to rewrite these EDot expressions.
+                    if (p.options.bundle and js_lexer.isLatin1Identifier([]const u8, name)) {
+                        var import_items_for_namespace_entry = p.import_items_for_namespace.getOrPut(p.allocator, id.ref) catch unreachable;
+                        if (!import_items_for_namespace_entry.found_existing) {
+                            import_items_for_namespace_entry.value_ptr.* = ImportItemForNamespaceMap.init(p.allocator);
+                        }
+                        var import_items = import_items_for_namespace_entry.value_ptr;
+                        const ref = (import_items.get(name) orelse brk: {
+                            const generated_name = std.fmt.allocPrint(p.allocator, "{s}_{s}", .{ p.loadNameFromRef(id.ref), name }) catch unreachable;
+                            // Generate a new import item symbol in the module scope
+                            const new_item = LocRef{
+                                .loc = name_loc,
+                                .ref = p.newSymbol(.import, generated_name) catch unreachable,
+                            };
+                            p.module_scope.generated.push(p.allocator, new_item.ref.?) catch unreachable;
+
+                            import_items.put(name, new_item) catch unreachable;
+                            p.is_import_item.put(p.allocator, new_item.ref.?, {}) catch unreachable;
+
+                            var symbol = &p.symbols.items[new_item.ref.?.innerIndex()];
+
+                            // Mark this as generated in case it's missing. We don't want to
+                            // generate errors for missing import items that are automatically
+                            // generated.
+                            symbol.import_item_status = .generated;
+
+                            var nested_entry = p.nested_named_imports.getOrPutValue(
+                                id.ref,
+                                .{},
+                            ) catch unreachable;
+                            nested_entry.value_ptr.push(p.allocator, .{
+                                .ref = new_item.ref.?,
+                                .alias = name,
+                            }) catch unreachable;
+
+                            break :brk new_item;
+                        }).ref.?;
+
+                        // Undo the usage count for the namespace itself. This is used later
+                        // to detect whether the namespace symbol has ever been "captured"
+                        // or whether it has just been used to read properties off of.
+                        //
+                        // The benefit of doing this is that if both this module and the
+                        // imported module end up in the same module group and the namespace
+                        // symbol has never been captured, then we don't need to generate
+                        // any code for the namespace at all.
+                        p.ignoreUsage(id.ref);
+
+                        // Track how many times we've referenced this symbol
+                        p.recordUsage(ref);
+
+                        return p.handleIdentifier(
+                            name_loc,
+                            E.Identifier{ .ref = ref },
+                            name,
+                            identifier_opts,
+                        );
+                    }
+                },
+
                 .e_string => |str| {
                     if (p.options.features.minify_syntax) {
                         // minify "long-string".length to 11
@@ -21182,6 +21250,7 @@ fn NewParser_(
                 .approximate_newline_count = p.lexer.approximate_newline_count,
                 .exports_kind = exports_kind,
                 .named_imports = p.named_imports,
+                .nested_named_imports = p.nested_named_imports,
                 .named_exports = p.named_exports,
                 .import_keyword = p.esm_import_keyword,
                 .export_keyword = p.esm_export_keyword,
@@ -21254,6 +21323,7 @@ fn NewParser_(
                 .define = define,
                 .import_records = undefined,
                 .named_imports = undefined,
+                .nested_named_imports = undefined,
                 .named_exports = js_ast.Ast.NamedExports.init(allocator),
                 .log = log,
                 .allocator = allocator,
@@ -21286,6 +21356,7 @@ fn NewParser_(
             if (comptime !only_scan_imports_and_do_not_visit) {
                 this.import_records = @TypeOf(this.import_records).init(allocator);
                 this.named_imports = NamedImportsType.init(allocator);
+                this.nested_named_imports = js_ast.Ast.NestedNamedImports.init(allocator);
             }
 
             this.to_expr_wrapper_namespace = Binding2ExprWrapper.Namespace.init(this);