Fix incremental emit issue where dependency relations implied by synthesized imports would not be detected

src/compiler/program.ts

@@ -2207,6 +2207,10 @@ namespace ts {
             addEmitFlags(importDecl, EmitFlags.NeverApplyImportHelper);
             setParent(externalHelpersModuleReference, importDecl);
             setParent(importDecl, file);
+            // explicitly unset the synthesized flag on these declarations so the checker API will answer questions about them
+            // (which is required to build the dependency graph for incremental emit)
+            (externalHelpersModuleReference as Mutable<Node>).flags &= ~NodeFlags.Synthesized;
+            (importDecl as Mutable<Node>).flags &= ~NodeFlags.Synthesized;
             return externalHelpersModuleReference;
         }
 

src/testRunner/unittests/tscWatch/incremental.ts

@@ -304,5 +304,51 @@ export const Fragment: unique symbol;
             ],
             modifyFs: host => host.writeFile(configFile.path, JSON.stringify({ compilerOptions: { ...jsxImportSourceOptions, jsxImportSource: "preact" } }))
         });
+
+        verifyIncrementalWatchEmit({
+            subScenario: "jsxImportSource backing types added",
+            files: () => [
+                { path: libFile.path, content: libContent },
+                { path: `${project}/index.tsx`, content: `export const App = () => <div propA={true}></div>;` },
+                { path: configFile.path, content: JSON.stringify({ compilerOptions: jsxImportSourceOptions }) }
+            ],
+            modifyFs: host => {
+                host.createDirectory(`${project}/node_modules`);
+                host.createDirectory(`${project}/node_modules/react`);
+                host.createDirectory(`${project}/node_modules/react/jsx-runtime`);
+                host.writeFile(`${project}/node_modules/react/jsx-runtime/index.d.ts`, jsxLibraryContent);
+                host.writeFile(`${project}/node_modules/react/package.json`, JSON.stringify({ name: "react", version: "0.0.1" }));
+            }
+        });
+
+        verifyIncrementalWatchEmit({
+            subScenario: "jsxImportSource backing types removed",
+            files: () => [
+                { path: libFile.path, content: libContent },
+                { path: `${project}/node_modules/react/jsx-runtime/index.d.ts`, content: jsxLibraryContent },
+                { path: `${project}/node_modules/react/package.json`, content: JSON.stringify({ name: "react", version: "0.0.1" }) },
+                { path: `${project}/index.tsx`, content: `export const App = () => <div propA={true}></div>;` },
+                { path: configFile.path, content: JSON.stringify({ compilerOptions: jsxImportSourceOptions }) }
+            ],
+            modifyFs: host => {
+                host.deleteFile(`${project}/node_modules/react/jsx-runtime/index.d.ts`);
+                host.deleteFile(`${project}/node_modules/react/package.json`);
+            }
+        });
+
+        verifyIncrementalWatchEmit({
+            subScenario: "importHelpers backing types removed",
+            files: () => [
+                { path: libFile.path, content: libContent },
+                { path: `${project}/node_modules/tslib/index.d.ts`, content: "export function __assign(...args: any[]): any;" },
+                { path: `${project}/node_modules/tslib/package.json`, content: JSON.stringify({ name: "tslib", version: "0.0.1" }) },
+                { path: `${project}/index.tsx`, content: `export const x = {...{}};` },
+                { path: configFile.path, content: JSON.stringify({ compilerOptions: { importHelpers: true } }) }
+            ],
+            modifyFs: host => {
+                host.deleteFile(`${project}/node_modules/tslib/index.d.ts`);
+                host.deleteFile(`${project}/node_modules/tslib/package.json`);
+            }
+        });
     });
 }

tests/baselines/reference/tscWatch/incremental/importHelpers-backing-types-removed-incremental.js

@@ -0,0 +1,181 @@
+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; }
+interface ReadonlyArray<T> {}
+declare const console: { log(msg: any): void; };
+
+//// [/users/username/projects/project/node_modules/tslib/index.d.ts]
+export function __assign(...args: any[]): any;
+
+//// [/users/username/projects/project/node_modules/tslib/package.json]
+{"name":"tslib","version":"0.0.1"}
+
+//// [/users/username/projects/project/index.tsx]
+export const x = {...{}};
+
+//// [/users/username/projects/project/tsconfig.json]
+{"compilerOptions":{"importHelpers":true}}
+
+
+/a/lib/tsc.js -i
+Output::
+
+
+Program root files: ["/users/username/projects/project/index.tsx"]
+Program options: {"importHelpers":true,"incremental":true,"configFilePath":"/users/username/projects/project/tsconfig.json"}
+Program structureReused: Not
+Program files::
+/a/lib/lib.d.ts
+/users/username/projects/project/node_modules/tslib/index.d.ts
+/users/username/projects/project/index.tsx
+
+Semantic diagnostics in builder refreshed for::
+/a/lib/lib.d.ts
+/users/username/projects/project/node_modules/tslib/index.d.ts
+/users/username/projects/project/index.tsx
+
+WatchedFiles::
+
+FsWatches::
+
+FsWatchesRecursive::
+
+exitCode:: ExitStatus.Success
+
+//// [/users/username/projects/project/index.js]
+"use strict";
+exports.__esModule = true;
+exports.x = void 0;
+var tslib_1 = require("tslib");
+exports.x = tslib_1.__assign({});
+
+
+//// [/users/username/projects/project/tsconfig.tsbuildinfo]
+{
+  "program": {
+    "fileInfos": {
+      "../../../../a/lib/lib.d.ts": {
+        "version": "3858781397-/// <reference no-default-lib=\"true\"/>\ninterface Boolean {}\ninterface Function {}\ninterface CallableFunction {}\ninterface NewableFunction {}\ninterface IArguments {}\ninterface Number { toExponential: any; }\ninterface Object {}\ninterface RegExp {}\ninterface String { charAt: any; }\ninterface Array<T> { length: number; [n: number]: T; }\ninterface ReadonlyArray<T> {}\ndeclare const console: { log(msg: any): void; };",
+        "signature": "3858781397-/// <reference no-default-lib=\"true\"/>\ninterface Boolean {}\ninterface Function {}\ninterface CallableFunction {}\ninterface NewableFunction {}\ninterface IArguments {}\ninterface Number { toExponential: any; }\ninterface Object {}\ninterface RegExp {}\ninterface String { charAt: any; }\ninterface Array<T> { length: number; [n: number]: T; }\ninterface ReadonlyArray<T> {}\ndeclare const console: { log(msg: any): void; };",
+        "affectsGlobalScope": true
+      },
+      "./node_modules/tslib/index.d.ts": {
+        "version": "1620578607-export function __assign(...args: any[]): any;",
+        "signature": "1620578607-export function __assign(...args: any[]): any;",
+        "affectsGlobalScope": false
+      },
+      "./index.tsx": {
+        "version": "-14168389096-export const x = {...{}};",
+        "signature": "-6508651827-export declare const x: {};\n",
+        "affectsGlobalScope": false
+      }
+    },
+    "options": {
+      "importHelpers": true,
+      "incremental": true,
+      "configFilePath": "./tsconfig.json"
+    },
+    "referencedMap": {
+      "./index.tsx": [
+        "./node_modules/tslib/index.d.ts"
+      ]
+    },
+    "exportedModulesMap": {},
+    "semanticDiagnosticsPerFile": [
+      "../../../../a/lib/lib.d.ts",
+      "./index.tsx",
+      "./node_modules/tslib/index.d.ts"
+    ]
+  },
+  "version": "FakeTSVersion"
+}
+
+
+Change::
+
+Input::
+//// [/users/username/projects/project/node_modules/tslib/index.d.ts] deleted
+//// [/users/username/projects/project/node_modules/tslib/package.json] deleted
+
+Output::
+index.tsx:1:19 - error TS2354: This syntax requires an imported helper but module 'tslib' cannot be found.
+
+1 export const x = {...{}};
+                    ~~~~~
+
+
+Found 1 error.
+
+
+
+Program root files: ["/users/username/projects/project/index.tsx"]
+Program options: {"importHelpers":true,"incremental":true,"configFilePath":"/users/username/projects/project/tsconfig.json"}
+Program structureReused: Not
+Program files::
+/a/lib/lib.d.ts
+/users/username/projects/project/index.tsx
+
+Semantic diagnostics in builder refreshed for::
+/users/username/projects/project/index.tsx
+
+WatchedFiles::
+
+FsWatches::
+
+FsWatchesRecursive::
+
+exitCode:: ExitStatus.DiagnosticsPresent_OutputsGenerated
+
+//// [/users/username/projects/project/index.js] file written with same contents
+//// [/users/username/projects/project/tsconfig.tsbuildinfo]
+{
+  "program": {
+    "fileInfos": {
+      "../../../../a/lib/lib.d.ts": {
+        "version": "3858781397-/// <reference no-default-lib=\"true\"/>\ninterface Boolean {}\ninterface Function {}\ninterface CallableFunction {}\ninterface NewableFunction {}\ninterface IArguments {}\ninterface Number { toExponential: any; }\ninterface Object {}\ninterface RegExp {}\ninterface String { charAt: any; }\ninterface Array<T> { length: number; [n: number]: T; }\ninterface ReadonlyArray<T> {}\ndeclare const console: { log(msg: any): void; };",
+        "signature": "3858781397-/// <reference no-default-lib=\"true\"/>\ninterface Boolean {}\ninterface Function {}\ninterface CallableFunction {}\ninterface NewableFunction {}\ninterface IArguments {}\ninterface Number { toExponential: any; }\ninterface Object {}\ninterface RegExp {}\ninterface String { charAt: any; }\ninterface Array<T> { length: number; [n: number]: T; }\ninterface ReadonlyArray<T> {}\ndeclare const console: { log(msg: any): void; };",
+        "affectsGlobalScope": true
+      },
+      "./index.tsx": {
+        "version": "-14168389096-export const x = {...{}};",
+        "signature": "-6508651827-export declare const x: {};\n",
+        "affectsGlobalScope": false
+      }
+    },
+    "options": {
+      "importHelpers": true,
+      "incremental": true,
+      "configFilePath": "./tsconfig.json"
+    },
+    "referencedMap": {},
+    "exportedModulesMap": {},
+    "semanticDiagnosticsPerFile": [
+      "../../../../a/lib/lib.d.ts",
+      [
+        "./index.tsx",
+        [
+          {
+            "file": "./index.tsx",
+            "start": 18,
+            "length": 5,
+            "messageText": "This syntax requires an imported helper but module 'tslib' cannot be found.",
+            "category": 1,
+            "code": 2354
+          }
+        ]
+      ]
+    ]
+  },
+  "version": "FakeTSVersion"
+}
+

tests/baselines/reference/tscWatch/incremental/importHelpers-backing-types-removed-watch.js

@@ -0,0 +1,133 @@
+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; }
+interface ReadonlyArray<T> {}
+declare const console: { log(msg: any): void; };
+
+//// [/users/username/projects/project/node_modules/tslib/index.d.ts]
+export function __assign(...args: any[]): any;
+
+//// [/users/username/projects/project/node_modules/tslib/package.json]
+{"name":"tslib","version":"0.0.1"}
+
+//// [/users/username/projects/project/index.tsx]
+export const x = {...{}};
+
+//// [/users/username/projects/project/tsconfig.json]
+{"compilerOptions":{"importHelpers":true}}
+
+
+/a/lib/tsc.js -w
+Output::
+>> Screen clear
+[12:00:29 AM] Starting compilation in watch mode...
+
+[12:00:32 AM] Found 0 errors. Watching for file changes.
+
+
+
+Program root files: ["/users/username/projects/project/index.tsx"]
+Program options: {"importHelpers":true,"watch":true,"configFilePath":"/users/username/projects/project/tsconfig.json"}
+Program structureReused: Not
+Program files::
+/a/lib/lib.d.ts
+/users/username/projects/project/node_modules/tslib/index.d.ts
+/users/username/projects/project/index.tsx
+
+Semantic diagnostics in builder refreshed for::
+/a/lib/lib.d.ts
+/users/username/projects/project/node_modules/tslib/index.d.ts
+/users/username/projects/project/index.tsx
+
+WatchedFiles::
+/users/username/projects/project/tsconfig.json:
+  {"fileName":"/users/username/projects/project/tsconfig.json","pollingInterval":250}
+/users/username/projects/project/index.tsx:
+  {"fileName":"/users/username/projects/project/index.tsx","pollingInterval":250}
+/users/username/projects/project/node_modules/tslib/index.d.ts:
+  {"fileName":"/users/username/projects/project/node_modules/tslib/index.d.ts","pollingInterval":250}
+/a/lib/lib.d.ts:
+  {"fileName":"/a/lib/lib.d.ts","pollingInterval":250}
+
+FsWatches::
+
+FsWatchesRecursive::
+/users/username/projects/project/node_modules:
+  {"directoryName":"/users/username/projects/project/node_modules","fallbackPollingInterval":500,"fallbackOptions":{"watchFile":"PriorityPollingInterval"}}
+/users/username/projects/project/node_modules/@types:
+  {"directoryName":"/users/username/projects/project/node_modules/@types","fallbackPollingInterval":500,"fallbackOptions":{"watchFile":"PriorityPollingInterval"}}
+/users/username/projects/project:
+  {"directoryName":"/users/username/projects/project","fallbackPollingInterval":500,"fallbackOptions":{"watchFile":"PriorityPollingInterval"}}
+
+exitCode:: ExitStatus.undefined
+
+//// [/users/username/projects/project/index.js]
+"use strict";
+exports.__esModule = true;
+exports.x = void 0;
+var tslib_1 = require("tslib");
+exports.x = tslib_1.__assign({});
+
+
+
+Change::
+
+Input::
+//// [/users/username/projects/project/node_modules/tslib/index.d.ts] deleted
+//// [/users/username/projects/project/node_modules/tslib/package.json] deleted
+
+Output::
+>> Screen clear
+[12:00:35 AM] Starting compilation in watch mode...
+
+index.tsx:1:19 - error TS2354: This syntax requires an imported helper but module 'tslib' cannot be found.
+
+1 export const x = {...{}};
+                    ~~~~~
+
+[12:00:39 AM] Found 1 error. Watching for file changes.
+
+
+
+Program root files: ["/users/username/projects/project/index.tsx"]
+Program options: {"importHelpers":true,"watch":true,"configFilePath":"/users/username/projects/project/tsconfig.json"}
+Program structureReused: Not
+Program files::
+/a/lib/lib.d.ts
+/users/username/projects/project/index.tsx
+
+Semantic diagnostics in builder refreshed for::
+/a/lib/lib.d.ts
+/users/username/projects/project/index.tsx
+
+WatchedFiles::
+/users/username/projects/project/tsconfig.json:
+  {"fileName":"/users/username/projects/project/tsconfig.json","pollingInterval":250}
+/users/username/projects/project/index.tsx:
+  {"fileName":"/users/username/projects/project/index.tsx","pollingInterval":250}
+/a/lib/lib.d.ts:
+  {"fileName":"/a/lib/lib.d.ts","pollingInterval":250}
+
+FsWatches::
+
+FsWatchesRecursive::
+/users/username/projects/project/node_modules:
+  {"directoryName":"/users/username/projects/project/node_modules","fallbackPollingInterval":500,"fallbackOptions":{"watchFile":"PriorityPollingInterval"}}
+/users/username/projects/project/node_modules/@types:
+  {"directoryName":"/users/username/projects/project/node_modules/@types","fallbackPollingInterval":500,"fallbackOptions":{"watchFile":"PriorityPollingInterval"}}
+/users/username/projects/project:
+  {"directoryName":"/users/username/projects/project","fallbackPollingInterval":500,"fallbackOptions":{"watchFile":"PriorityPollingInterval"}}
+
+exitCode:: ExitStatus.undefined
+
+//// [/users/username/projects/project/index.js] file written with same contents