Watch extended configs if present

src/compiler/watchPublic.ts

@@ -246,6 +246,7 @@ namespace ts {
 
         let builderProgram: T;
         let reloadLevel: ConfigFileProgramReloadLevel;                      // level to indicate if the program needs to be reloaded from config file/just filenames etc
+        let extendedConfigFilesMap: ESMap<Path, FileWatcher>;               // Map of file watchers for the extended config files
         let missingFilesMap: ESMap<Path, FileWatcher>;                        // Map of file watchers for the missing files
         let watchedWildcardDirectories: ESMap<string, WildcardDirectoryWatcher>; // map of watchers for the wild card directories in the config file
         let timerToUpdateProgram: any;                                      // timer callback to recompile the program
@@ -354,6 +355,10 @@ namespace ts {
                 configFileWatcher.close();
                 configFileWatcher = undefined;
             }
+            if (extendedConfigFilesMap) {
+                clearMap(extendedConfigFilesMap, closeFileWatcher);
+                extendedConfigFilesMap = undefined!;
+            }
             if (watchedWildcardDirectories) {
                 clearMap(watchedWildcardDirectories, closeFileWatcherOf);
                 watchedWildcardDirectories = undefined!;
@@ -419,6 +424,7 @@ namespace ts {
             resolutionCache.finishCachingPerDirectoryResolution();
 
             // Update watches
+            updateExtendedConfigFilePathsWatch(builderProgram.getProgram(), extendedConfigFilesMap || (extendedConfigFilesMap = new Map()), watchExtendedConfigFile);
             updateMissingFilePathsWatch(builderProgram.getProgram(), missingFilesMap || (missingFilesMap = new Map()), watchMissingFilePath);
             if (needsUpdateInTypeRootWatch) {
                 resolutionCache.updateTypeRootsWatch();
@@ -706,6 +712,10 @@ namespace ts {
             }
         }
 
+        function watchExtendedConfigFile(extendedConfigFile: string) {
+            return watchFile(host, extendedConfigFile, scheduleProgramReload, PollingInterval.High, watchOptions, WatchType.ConfigFile);
+        }
+
         function watchMissingFilePath(missingFilePath: Path) {
             return watchFilePath(missingFilePath, missingFilePath, onMissingFileChange, PollingInterval.Medium, watchOptions, WatchType.MissingFile);
         }

src/compiler/watchUtilities.ts

@@ -257,6 +257,30 @@ namespace ts {
         Full
     }
 
+    /**
+     * Updates the extended config file watches with the new set of extended config files after new program is created
+     */
+    export function updateExtendedConfigFilePathsWatch(
+        program: Program,
+        extendedConfigFilesMap: ESMap<string, FileWatcher>,
+        createExtendedConfigFileWatch: (extendedConfigPath: string) => FileWatcher,
+    ) {
+        const extendedSourceFiles = program.getCompilerOptions().configFile?.extendedSourceFiles || [];
+        // TODO(rbuckton): Should be a `Set` but that requires changing the below code that uses `mutateMap`
+        const newExtendedConfigFilesMap = arrayToMap(extendedSourceFiles, identity, returnTrue);
+        // Update the extended config files watcher
+        mutateMap(
+            extendedConfigFilesMap,
+            newExtendedConfigFilesMap,
+            {
+                // Watch the extended config files
+                createNewValue: createExtendedConfigFileWatch,
+                // Config files that are no longer extended should no longer be watched.
+                onDeleteValue: closeFileWatcher
+            }
+        );
+    }
+
     /**
      * Updates the existing missing file watches with the new set of missing files after new program is created
      */

src/testRunner/unittests/tscWatch/watchEnvironment.ts

@@ -497,5 +497,161 @@ namespace ts.tscWatch {
                 verifyWorker("-extendedDiagnostics");
             });
         });
+
+        describe("handles watch for extended configs", () => {
+            verifyTscWatch({
+                scenario,
+                subScenario: "watchExtends/with several extended configs",
+                commandLineArgs: ["-w", "-p", "/a/b/tsconfig.json"],
+                sys: () => {
+                    const firstExtendedFile: File = {
+                        path: "/a/b/first.tsconfig.json",
+                        content: JSON.stringify({
+                            compilerOptions: {
+                                strict: false,
+                            }
+                        })
+                    };
+                    const secondExtendedFile: File = {
+                        path: "/a/b/second.tsconfig.json",
+                        content: JSON.stringify({
+                            extends: "./first.tsconfig.json",
+                            compilerOptions: {
+                                strictNullChecks: true,
+                            }
+                        })
+                    };
+                    const thirdExtendedFile: File = {
+                        path: "/a/b/third.tsconfig.json",
+                        content: JSON.stringify({
+                            extends: "./second.tsconfig.json",
+                            compilerOptions: {
+                                strictBindCallApply: true,
+                            }
+                        })
+                    };
+                    const fourthExtendedFile: File = {
+                        path: "/a/b/fourth.tsconfig.json",
+                        content: JSON.stringify({
+                            extends: "./third.tsconfig.json",
+                            compilerOptions: {
+                                strictFunctionTypes: true,
+                            }
+                        })
+                    };
+                    const configFile: File = {
+                        path: "/a/b/tsconfig.json",
+                        content: JSON.stringify({
+                            extends: "./fourth.tsconfig.json",
+                            compilerOptions: {
+                                strictPropertyInitialization: true,
+                            }
+                        })
+                    };
+                    const files = [
+                        libFile, commonFile1, commonFile2, firstExtendedFile, secondExtendedFile, thirdExtendedFile,
+                        fourthExtendedFile, configFile
+                    ];
+                    return createWatchedSystem(files);
+                },
+                changes: emptyArray
+            });
+
+            verifyTscWatch({
+                scenario,
+                subScenario: "watchExtends/with watchFile option",
+                commandLineArgs: ["-w", "-p", "/a/b/tsconfig.json"],
+                sys: () => {
+                    const extendedFile: File = {
+                        path: "/a/b/extended.tsconfig.json",
+                        content: JSON.stringify({
+                            watchOptions: {
+                                watchFile: "UseFsEvents"
+                            }
+                        })
+                    };
+                    const configFile: File = {
+                        path: "/a/b/tsconfig.json",
+                        content: JSON.stringify({
+                            extends: "./extended.tsconfig.json"
+                        })
+                    };
+                    const files = [libFile, commonFile1, commonFile2, extendedFile, configFile];
+                    return createWatchedSystem(files);
+                },
+                changes: emptyArray
+            });
+
+            verifyTscWatch({
+                scenario,
+                subScenario: "watchExtends/with watchDirectory option",
+                commandLineArgs: ["-w", "-p", "/a/b/tsconfig.json"],
+                sys: () => {
+                    const extendedFile: File = {
+                        path: "/a/b/extended.tsconfig.json",
+                        content: JSON.stringify({
+                            watchOptions: {
+                                watchDirectory: "UseFsEvents"
+                            }
+                        })
+                    };
+                    const configFile: File = {
+                        path: "/a/b/tsconfig.json",
+                        content: JSON.stringify({
+                            extends: "./extended.tsconfig.json"
+                        })
+                    };
+                    const files = [libFile, commonFile1, commonFile2, extendedFile, configFile];
+                    return createWatchedSystem(files, { runWithoutRecursiveWatches: true });
+                },
+                changes: emptyArray
+            });
+
+            verifyTscWatch({
+                scenario,
+                subScenario: "watchExtends/with fallbackPolling option",
+                commandLineArgs: ["-w", "-p", "/a/b/tsconfig.json"],
+                sys: () => {
+                    const extendedFile: File = {
+                        path: "/a/b/extended.tsconfig.json",
+                        content: JSON.stringify({
+                            watchOptions: {
+                                fallbackPolling: "PriorityInterval"
+                            }
+                        })
+                    };
+                    const configFile: File = {
+                        path: "/a/b/tsconfig.json",
+                        content: JSON.stringify({
+                            extends: "./extended.tsconfig.json"
+                        })
+                    };
+                    const files = [libFile, commonFile1, commonFile2, extendedFile, configFile];
+                    return createWatchedSystem(files, { runWithoutRecursiveWatches: true, runWithFallbackPolling: true });
+                },
+                changes: emptyArray
+            });
+
+            verifyTscWatch({
+                scenario,
+                subScenario: "watchExtends/with watchFile as watch options to extend",
+                commandLineArgs: ["-w", "-p", "/a/b/tsconfig.json", "--watchFile", "UseFsEvents"],
+                sys: () => {
+                    const extendedFile: File = {
+                        path: "/a/b/extended.tsconfig.json",
+                        content: "{}"
+                    };
+                    const configFile: File = {
+                        path: "/a/b/tsconfig.json",
+                        content: JSON.stringify({
+                            extends: "./extended.tsconfig.json"
+                        })
+                    };
+                    const files = [libFile, commonFile1, commonFile2, extendedFile, configFile];
+                    return createWatchedSystem(files);
+                },
+                changes: emptyArray
+            });
+        });
     });
 }

tests/baselines/reference/tscWatch/watchEnvironment/watchExtends/with-fallbackPolling-option.js

@@ -0,0 +1,79 @@
+Input::
+//// [/a/lib/lib.d.ts]
+/// <reference no-default-lib="true"/>
+interface Boolean {}
+interface Function {}
+interface CallableFunction {}
+interface NewableFunction {}
+interface IArguments {}
+interface Number { toExponential: any; }
+interface Object {}
+interface RegExp {}
+interface String { charAt: any; }
+interface Array<T> { length: number; [n: number]: T; }
+
+//// [/a/b/commonFile1.ts]
+let x = 1
+
+//// [/a/b/commonFile2.ts]
+let y = 1
+
+//// [/a/b/extended.tsconfig.json]
+{"watchOptions":{"fallbackPolling":"PriorityInterval"}}
+
+//// [/a/b/tsconfig.json]
+{"extends":"./extended.tsconfig.json"}
+
+
+/a/lib/tsc.js -w -p /a/b/tsconfig.json
+Output::
+>> Screen clear
+[12:00:19 AM] Starting compilation in watch mode...
+
+[12:00:24 AM] Found 0 errors. Watching for file changes.
+
+
+
+Program root files: ["/a/b/commonFile1.ts","/a/b/commonFile2.ts"]
+Program options: {"watch":true,"project":"/a/b/tsconfig.json","configFilePath":"/a/b/tsconfig.json"}
+Program structureReused: Not
+Program files::
+/a/lib/lib.d.ts
+/a/b/commonFile1.ts
+/a/b/commonFile2.ts
+
+Semantic diagnostics in builder refreshed for::
+/a/lib/lib.d.ts
+/a/b/commonFile1.ts
+/a/b/commonFile2.ts
+
+WatchedFiles::
+/a/b/tsconfig.json:
+  {"fileName":"/a/b/tsconfig.json","pollingInterval":250}
+/a/b/commonfile1.ts:
+  {"fileName":"/a/b/commonFile1.ts","pollingInterval":250}
+/a/b/commonfile2.ts:
+  {"fileName":"/a/b/commonFile2.ts","pollingInterval":250}
+/a/lib/lib.d.ts:
+  {"fileName":"/a/lib/lib.d.ts","pollingInterval":250}
+/a/b/extended.tsconfig.json:
+  {"fileName":"/a/b/extended.tsconfig.json","pollingInterval":250}
+/a/b/node_modules/@types:
+  {"fileName":"/a/b/node_modules/@types","pollingInterval":500}
+/a/b:
+  {"fileName":"/a/b","pollingInterval":500}
+
+FsWatches::
+
+FsWatchesRecursive::
+
+exitCode:: ExitStatus.undefined
+
+//// [/a/b/commonFile1.js]
+var x = 1;
+
+
+//// [/a/b/commonFile2.js]
+var y = 1;
+
+