Ensure equal FileIncludeReasons are not duplicitively added

src/compiler/program.ts

@@ -83,6 +83,7 @@ import {
     fileExtensionIsOneOf,
     FileIncludeKind,
     FileIncludeReason,
+    fileIncludeReasonIsEqual,
     fileIncludeReasonToDiagnostics,
     FilePreprocessingDiagnostics,
     FilePreprocessingDiagnosticsKind,
@@ -3797,7 +3798,11 @@ export function createProgram(rootNamesOrOptions: readonly string[] | CreateProg
     }
 
     function addFileIncludeReason(file: SourceFile | undefined, reason: FileIncludeReason) {
-        if (file) fileReasons.add(file.path, reason);
+        if (file) {
+            const existing = fileReasons.get(file.path);
+            if (some(existing, r => fileIncludeReasonIsEqual(r, reason))) return;
+            fileReasons.add(file.path, reason);
+        }
     }
 
     function addFileToFilesByName(file: SourceFile | undefined, path: Path, fileName: string, redirectedPath: Path | undefined) {

src/compiler/types.ts

@@ -4598,6 +4598,8 @@ export interface AutomaticTypeDirectiveFile {
     packageId: PackageId | undefined;
 }
 
+// Note: if updating FileIncludeReason, ensure fileIncludeReasonIsEqual is also updated.
+
 /** @internal */
 export type FileIncludeReason =
     | RootFile

src/compiler/utilities.ts

@@ -24,6 +24,7 @@ import {
     AssignmentDeclarationKind,
     AssignmentExpression,
     AssignmentOperatorToken,
+    AutomaticTypeDirectiveFile,
     BarBarEqualsToken,
     BinaryExpression,
     binarySearch,
@@ -136,6 +137,8 @@ import {
     FileExtensionInfo,
     fileExtensionIs,
     fileExtensionIsOneOf,
+    FileIncludeKind,
+    FileIncludeReason,
     FileWatcher,
     filter,
     find,
@@ -399,6 +402,7 @@ import {
     lastOrUndefined,
     LateVisibilityPaintedStatement,
     length,
+    LibFile,
     LiteralImportTypeNode,
     LiteralLikeElementAccessExpression,
     LiteralLikeNode,
@@ -466,6 +470,7 @@ import {
     PrintHandlers,
     PrivateIdentifier,
     ProjectReference,
+    ProjectReferenceFile,
     PrologueDirective,
     PropertyAccessEntityNameExpression,
     PropertyAccessExpression,
@@ -481,6 +486,7 @@ import {
     QuestionQuestionEqualsToken,
     ReadonlyCollection,
     ReadonlyTextRange,
+    ReferencedFile,
     removeTrailingDirectorySeparator,
     RequireOrImportCall,
     RequireVariableStatement,
@@ -492,6 +498,7 @@ import {
     returnFalse,
     ReturnStatement,
     returnUndefined,
+    RootFile,
     SatisfiesExpression,
     ScriptKind,
     ScriptTarget,
@@ -852,6 +859,36 @@ export function typeDirectiveIsEqualTo(oldResolution: ResolvedTypeReferenceDirec
             oldResolution.resolvedTypeReferenceDirective.originalPath === newResolution.resolvedTypeReferenceDirective.originalPath;
 }
 
+/** @internal */
+export function fileIncludeReasonIsEqual(a: FileIncludeReason, b: FileIncludeReason): boolean {
+    if (a === b) return true;
+    if (a.kind !== b.kind) return false;
+
+    switch (a.kind) {
+        case FileIncludeKind.RootFile:
+            Debug.type<RootFile>(b);
+            return a.index === b.index;
+        case FileIncludeKind.LibFile:
+            Debug.type<LibFile>(b);
+            return a.index === b.index;
+        case FileIncludeKind.SourceFromProjectReference:
+        case FileIncludeKind.OutputFromProjectReference:
+            Debug.type<ProjectReferenceFile>(b);
+            return a.index === b.index;
+        case FileIncludeKind.Import:
+        case FileIncludeKind.ReferenceFile:
+        case FileIncludeKind.TypeReferenceDirective:
+        case FileIncludeKind.LibReferenceDirective:
+            Debug.type<ReferencedFile>(b);
+            return a.file === b.file && a.index === b.index;
+        case FileIncludeKind.AutomaticTypeDirectiveFile:
+            Debug.type<AutomaticTypeDirectiveFile>(b);
+            return a.typeReference === b.typeReference && packageIdIsEqual(a.packageId, b.packageId);
+        default:
+            return Debug.assertNever(a);
+    }
+}
+
 /** @internal */
 export function hasChangesInResolutions<K, V>(
     names: readonly K[],

tests/baselines/reference/tsserver/watchEnvironment/external-project-watch-options-errors.js

@@ -79,7 +79,6 @@ Info seq  [hh:mm:ss:mss] 	Files (4)
 	../../../../a/lib/lib.d.ts
 	  Default library for target 'es5'
 	node_modules/bar/foo.d.ts
-	  Imported via "./foo" from file 'node_modules/bar/index.d.ts'
 	  Imported via "./foo" from file 'node_modules/bar/index.d.ts'
 	  Root file specified for compilation
 	node_modules/bar/index.d.ts

tests/baselines/reference/tsserver/watchEnvironment/external-project-watch-options-in-host-configuration.js

@@ -106,7 +106,6 @@ Info seq  [hh:mm:ss:mss] 	Files (4)
 	../../../../a/lib/lib.d.ts
 	  Default library for target 'es5'
 	node_modules/bar/foo.d.ts
-	  Imported via "./foo" from file 'node_modules/bar/index.d.ts'
 	  Imported via "./foo" from file 'node_modules/bar/index.d.ts'
 	  Root file specified for compilation
 	node_modules/bar/index.d.ts

tests/baselines/reference/tsserver/watchEnvironment/external-project-watch-options.js

@@ -77,7 +77,6 @@ Info seq  [hh:mm:ss:mss] 	Files (4)
 	../../../../a/lib/lib.d.ts
 	  Default library for target 'es5'
 	node_modules/bar/foo.d.ts
-	  Imported via "./foo" from file 'node_modules/bar/index.d.ts'
 	  Imported via "./foo" from file 'node_modules/bar/index.d.ts'
 	  Root file specified for compilation
 	node_modules/bar/index.d.ts