Function resolve

packages/webpack5/src/configuration/base.ts:522–548

(id, baseDir, importOptions)

						// custom resolver to resolve platform extensions in @import statements
						// ie. @import "foo.css" would import "foo.ios.css" if the platform is ios and it exists
						resolve(id, baseDir, importOptions) {
							const extensions =
								platform === 'visionos' ? [platform, 'ios'] : [platform];
							for (const platformTarget of extensions) {
								const ext = extname(id);
								const platformExt = ext ? `.${platformTarget}${ext}` : '';

								if (!id.includes(platformExt)) {
									const platformRequest = id.replace(ext, platformExt);
									const extPath = resolve(baseDir, platformRequest);

									try {
										return require.resolve(platformRequest, {
											paths: [baseDir],
										});
									} catch {}

									if (existsSync(extPath)) {
										console.log(`resolving "${id}" to "${platformRequest}"`);
										return extPath;
									}
								}
							}

							// fallback to postcss-import default resolution
							return id;
						},
					},
				],
			],