Support import with { type: "json" } and others (#16624)

docs/bundler/loaders.md

@@ -4,6 +4,12 @@ The Bun bundler implements a set of default loaders out of the box. As a rule of
 
 Bun uses the file extension to determine which built-in _loader_ should be used to parse the file. Every loader has a name, such as `js`, `tsx`, or `json`. These names are used when building [plugins](https://bun.sh/docs/bundler/plugins) that extend Bun with custom loaders.
 
+You can explicitly specify which loader to use using the 'loader' import attribute.
+
+```ts
+import my_toml from "./my_file" with { loader: "toml" };
+```
+
 ## Built-in loaders
 
 ### `js`

src/bake/DevServer.zig

@@ -5096,6 +5096,7 @@ const DirectoryWatchStore = struct {
             // loaders do not depend on importing other files.
             .file,
             .json,
+            .jsonc,
             .toml,
             .wasm,
             .napi,

src/bun.js/api/JSTranspiler.zig

@@ -490,6 +490,8 @@ fn transformOptionsFromJSC(globalObject: JSC.C.JSContextRef, temp_allocator: std
                 &transpiler.log,
                 source,
                 allocator,
+                .json,
+                false,
             ) catch null) orelse break :macros;
             transpiler.macro_map = PackageJSON.parseMacrosJSON(allocator, json, &transpiler.log, &source);
         }

src/bun.js/bindings/ZigGlobalObject.cpp

@@ -4403,6 +4403,10 @@ JSC::JSInternalPromise* GlobalObject::moduleLoaderFetch(JSGlobalObject* globalOb
 
             if (params.type() == ScriptFetchParameters::Type::HostDefined) {
                 typeAttributeString = params.hostDefinedImportType();
+            } else if (params.type() == ScriptFetchParameters::Type::JSON) {
+                typeAttributeString = "json"_s;
+            } else if (params.type() == ScriptFetchParameters::Type::WebAssembly) {
+                typeAttributeString = "webassembly"_s;
             }
         }
     }

src/bun.js/javascript.zig

@@ -2427,93 +2427,15 @@ pub const VirtualMachine = struct {
 
         const specifier_clone = _specifier.toUTF8(bun.default_allocator);
         defer specifier_clone.deinit();
-        const normalized_file_path_from_specifier, const specifier = ModuleLoader.normalizeSpecifier(jsc_vm, specifier_clone.slice());
         const referrer_clone = referrer.toUTF8(bun.default_allocator);
         defer referrer_clone.deinit();
-        var path = Fs.Path.init(normalized_file_path_from_specifier);
 
-        // For blobs.
-        var blob_source: ?JSC.WebCore.Blob = null;
         var virtual_source_to_use: ?logger.Source = null;
-        defer {
-            if (blob_source) |*blob| {
-                blob.deinit();
-            }
-        }
-
-        const loader, const virtual_source = brk: {
-            if (jsc_vm.module_loader.eval_source) |eval_source| {
-                if (strings.endsWithComptime(specifier, bun.pathLiteral("/[eval]"))) {
-                    break :brk .{ .tsx, eval_source };
-                }
-                if (strings.endsWithComptime(specifier, bun.pathLiteral("/[stdin]"))) {
-                    break :brk .{ .tsx, eval_source };
-                }
-            }
-
-            var ext_for_loader = path.name.ext;
-
-            // Support errors within blob: URLs
-            // Be careful to handle Bun.file(), in addition to regular Blob/File objects
-            // Bun.file() should be treated the same as a file path.
-            if (JSC.WebCore.ObjectURLRegistry.isBlobURL(specifier)) {
-                if (JSC.WebCore.ObjectURLRegistry.singleton().resolveAndDupe(specifier["blob:".len..])) |blob| {
-                    blob_source = blob;
-
-                    if (blob.getFileName()) |filename| {
-                        const current_path = Fs.Path.init(filename);
-                        if (blob.needsToReadFile()) {
-                            path = current_path;
-                        }
-
-                        ext_for_loader = current_path.name.ext;
-                    } else if (blob.getMimeTypeOrContentType()) |mime_type| {
-                        if (strings.hasPrefixComptime(mime_type.value, "application/javascript-jsx")) {
-                            ext_for_loader = ".jsx";
-                        } else if (strings.hasPrefixComptime(mime_type.value, "application/typescript-jsx")) {
-                            ext_for_loader = ".tsx";
-                        } else if (strings.hasPrefixComptime(mime_type.value, "application/javascript")) {
-                            ext_for_loader = ".js";
-                        } else if (strings.hasPrefixComptime(mime_type.value, "application/typescript")) {
-                            ext_for_loader = ".ts";
-                        } else if (strings.hasPrefixComptime(mime_type.value, "application/json")) {
-                            ext_for_loader = ".json";
-                        } else if (strings.hasPrefixComptime(mime_type.value, "application/json5")) {
-                            ext_for_loader = ".jsonc";
-                        } else if (strings.hasPrefixComptime(mime_type.value, "application/jsonc")) {
-                            ext_for_loader = ".jsonc";
-                        } else if (mime_type.category == .text) {
-                            ext_for_loader = ".txt";
-                        } else {
-                            // Be maximally permissive.
-                            ext_for_loader = ".tsx";
-                        }
-                    } else {
-                        // Be maximally permissive.
-                        ext_for_loader = ".tsx";
-                    }
-
-                    if (!blob.needsToReadFile()) {
-                        virtual_source_to_use = logger.Source{
-                            .path = path,
-                            .contents = blob.sharedView(),
-                        };
-                    }
-                } else {
-                    return error.ModuleNotFound;
-                }
-            }
-
-            break :brk .{
-                jsc_vm.transpiler.options.loaders.get(ext_for_loader) orelse brk2: {
-                    if (strings.eqlLong(specifier, jsc_vm.main, true)) {
-                        break :brk2 options.Loader.js;
-                    }
-                    break :brk2 options.Loader.file;
-                },
-                if (virtual_source_to_use) |*src| src else null,
-            };
+        var blob_to_deinit: ?JSC.WebCore.Blob = null;
+        const lr = options.getLoaderAndVirtualSource(specifier_clone.slice(), jsc_vm, &virtual_source_to_use, &blob_to_deinit, null) catch {
+            return error.ModuleNotFound;
         };
+        defer if (blob_to_deinit) |*blob| blob.deinit();
 
         // .print_source, which is used by exceptions avoids duplicating the entire source code
         // but that means we have to be careful of the lifetime of the source code
@@ -2523,13 +2445,13 @@ pub const VirtualMachine = struct {
 
         return try ModuleLoader.transpileSourceCode(
             jsc_vm,
-            specifier,
+            lr.specifier,
             referrer_clone.slice(),
             _specifier,
-            path,
-            loader,
+            lr.path,
+            lr.loader orelse if (lr.is_main) .js else .file,
             log,
-            virtual_source,
+            lr.virtual_source,
             null,
             VirtualMachine.source_code_printer.?,
             globalObject,