MissingFilePaths are on demand and dont need to be stored

Author: sheetalkamat

src/compiler/builder.ts

@@ -87,7 +87,6 @@ namespace ts {
         sourceFileToPackageName: ESMap<Path, string>;
         projectReferences: readonly ProjectReference[] | undefined;
         resolvedProjectReferences: readonly (ResolvedProjectReferenceOfProgramFromBuildInfo | undefined)[] | undefined;
-        missingPaths: readonly Path[];
         resolvedTypeReferenceDirectives: ESMap<string, ResolvedTypeReferenceDirectiveWithFailedLookupLocations>;
         fileProcessingDiagnostics: FilePreprocessingDiagnostic[] | undefined;
     }
@@ -351,7 +350,6 @@ namespace ts {
             sourceFileToPackageName: state.program.sourceFileToPackageName,
             projectReferences: state.program.getProjectReferences(),
             resolvedProjectReferences: state.program.getResolvedProjectReferences()?.map(mapResolvedProjectReference),
-            missingPaths: state.program.getMissingFilePaths(),
             resolvedTypeReferenceDirectives: state.program.getResolvedTypeReferenceDirectives(),
             fileProcessingDiagnostics: state.program.getFileProcessingDiagnostics(),
         };
@@ -897,7 +895,6 @@ namespace ts {
         filesByName: readonly [fileId: ProgramBuildInfoFileId, file: ProgramBuildInfoFileId | typeof missingSourceOfProjectReferenceRedirect | typeof missingFile][] | undefined;
         projectReferences: readonly PersistedProgramProjectReference[] | undefined;
         resolvedProjectReferences: readonly (PersistedProgramResolvedProjectReference | undefined)[] | undefined;
-        missingPaths: readonly ProgramBuildInfoFileId[] | undefined;
         resolvedTypeReferenceDirectives: readonly PersistedProgramResolutionEntry[] | undefined;
         fileProcessingDiagnostics: readonly PersistedProgramFilePreprocessingDiagnostic[] | undefined;
         resolutions: readonly PersistedProgramResolution[] | undefined;
@@ -998,7 +995,6 @@ namespace ts {
                 filesByName,
                 projectReferences: program.getProjectReferences()?.map(toPersistedProgramProjectReference),
                 resolvedProjectReferences: program.getResolvedProjectReferences()?.map(toPersistedProgramResolvedProjectReference),
-                missingPaths: mapToReadonlyArrayOrUndefined(program.getMissingFilePaths(), toFileId),
                 resolvedTypeReferenceDirectives: toPersistedProgramResolutionMap(program.getResolvedTypeReferenceDirectives()),
                 fileProcessingDiagnostics: mapToReadonlyArrayOrUndefined(program.getFileProcessingDiagnostics(), toPersistedProgramFilePreprocessingDiagnostic),
                 resolutions: mapToReadonlyArrayOrUndefined(resolutions, toPersistedProgramResolution),
@@ -1639,7 +1635,6 @@ namespace ts {
                 sourceFileToPackageName,
                 projectReferences: program.peristedProgram.projectReferences?.map(toProjectReference),
                 resolvedProjectReferences: program.peristedProgram.resolvedProjectReferences?.map(toResolvedProjectReference),
-                missingPaths: mapToReadonlyArray(program.peristedProgram.missingPaths, toFilePath),
                 resolvedTypeReferenceDirectives: toResolutionMap(program.peristedProgram.resolvedTypeReferenceDirectives) || new Map(),
                 fileProcessingDiagnostics: map(program.peristedProgram.fileProcessingDiagnostics, toFileProcessingDiagnostic),
             };
@@ -1771,6 +1766,7 @@ namespace ts {
     }
 
     function createProgramFromBuildInfo(persistedProgramInfo: PersistedProgramState, compilerOptions: CompilerOptions): ProgramFromBuildInfo {
+        let missingFilePaths: readonly Path[] | undefined;
         return {
             programFromBuildInfo: true,
             getCompilerOptions: () => compilerOptions,
@@ -1782,7 +1778,7 @@ namespace ts {
             },
             getProjectReferences: () => persistedProgramInfo.projectReferences,
             getResolvedProjectReferences: () => persistedProgramInfo.resolvedProjectReferences,
-            getMissingFilePaths: () => persistedProgramInfo.missingPaths,
+            getMissingFilePaths: () => missingFilePaths ||= getMissingFilePaths(persistedProgramInfo.filesByName),
             getFileIncludeReasons: () => persistedProgramInfo.fileIncludeReasons,
             getResolvedTypeReferenceDirectives: () => persistedProgramInfo.resolvedTypeReferenceDirectives,
             getFilesByNameMap: () => persistedProgramInfo.filesByName,

src/compiler/program.ts

@@ -759,6 +759,17 @@ namespace ts {
         }
     }
 
+    /*@internal*/
+    export function getMissingFilePaths(filesByName: ESMap<Path, SourceFile | SourceFileOfProgramFromBuildInfo | Path | typeof missingSourceOfProjectReferenceRedirect | typeof missingFile>): readonly Path[] {
+        let missingFilePaths: Path[] | undefined;
+        filesByName.forEach((file, path) => {
+            if (file === missingFile) {
+                (missingFilePaths ||= []).push(path);
+            }
+        });
+        return missingFilePaths || emptyArray;
+    }
+
     export function getConfigFileParsingDiagnostics(configFileParseResult: ParsedCommandLine): readonly Diagnostic[] {
         return configFileParseResult.options.configFile ?
             [...configFileParseResult.options.configFile.parseDiagnostics, ...configFileParseResult.errors] :
@@ -1033,16 +1044,13 @@ namespace ts {
                 }
             }
 
-            missingFilePaths = arrayFrom(mapDefinedIterator(filesByName.entries(), ([path, file]) => file === missingFile ? path : undefined));
             files = stableSort(processingDefaultLibFiles, compareDefaultLibFiles).concat(processingOtherFiles);
             processingDefaultLibFiles = undefined;
             processingOtherFiles = undefined;
             packageIdToSourceFile = undefined!;
             filesByNameIgnoreCase = undefined!;
         }
 
-        Debug.assert(!!missingFilePaths);
-
         // Release any files we have acquired in the old program but are
         // not part of the new program.
         if (oldProgram && !isProgramFromBuildInfo(oldProgram) && host.onReleaseOldSourceFile) {
@@ -1070,7 +1078,7 @@ namespace ts {
             getSourceFile,
             getSourceFileByPath,
             getSourceFiles: () => files,
-            getMissingFilePaths: () => missingFilePaths!, // TODO: GH#18217
+            getMissingFilePaths,
             getFilesByNameMap: () => filesByName,
             getCompilerOptions: () => options,
             getSyntacticDiagnostics,
@@ -1146,6 +1154,10 @@ namespace ts {
 
         return program;
 
+        function getMissingFilePaths() {
+            return missingFilePaths ||= ts.getMissingFilePaths(filesByName);
+        }
+
         function resolveModuleNamesWorker(moduleNames: string[], containingFile: SourceFile, reusedNames: string[] | undefined): readonly ResolvedModuleWithFailedLookupLocations[] {
             if (!moduleNames.length) return emptyArray;
             const containingFileName = getNormalizedAbsolutePath(containingFile.originalFileName, currentDirectory);
@@ -1658,8 +1670,6 @@ namespace ts {
                 return StructureIsReused.SafeModules;
             }
 
-            missingFilePaths = oldProgram.getMissingFilePaths();
-
             // update fileName -> file mapping
             for (let index = 0; index < newSourceFiles.length; index++) {
                 const newSourceFile = newSourceFiles[index];
@@ -1734,7 +1744,7 @@ namespace ts {
                     // Use local caches
                     const path = toPath(f);
                     if (getSourceFileByPath(path)) return true;
-                    if (contains(missingFilePaths, path)) return false;
+                    if (contains(getMissingFilePaths(), path)) return false;
                     // Before falling back to the host
                     return host.fileExists(f);
                 },

src/testRunner/unittests/tsbuild/helpers.ts

@@ -318,7 +318,6 @@ interface Symbol {
             filesByName: MapLike<string | typeof missingSourceOfProjectReferenceRedirect | typeof missingFile> | undefined;
             projectReferences: readonly ProjectReference[] | undefined;
             resolvedProjectReferences: readonly (ReadablePersistedProgramResolvedProjectReference | undefined)[] | undefined;
-            missingPaths: readonly string[] | undefined;
             resolvedTypeReferenceDirectives: readonly ReadablePersistedProgramResolutionEntry[] | undefined;
             fileProcessingDiagnostics: readonly ReadablePersistedProgramFilePreprocessingDiagnostic[] | undefined;
             resolutions: readonly ReadablePersistedProgramResolution[] | undefined;
@@ -366,7 +365,6 @@ interface Symbol {
                 filesByName,
                 projectReferences: buildInfo.program.peristedProgram.projectReferences?.map(toProjectReference),
                 resolvedProjectReferences: buildInfo.program.peristedProgram.resolvedProjectReferences?.map(toReadableResolvedProjectReference),
-                missingPaths: buildInfo.program.peristedProgram.missingPaths?.map(toFileName),
                 resolvedTypeReferenceDirectives: buildInfo.program.peristedProgram.resolvedTypeReferenceDirectives?.map(toReadablePersistedProgramResolutionEntry),
                 fileProcessingDiagnostics: buildInfo.program.peristedProgram.fileProcessingDiagnostics?.map(toReadablePersistedProgramFilePreprocessingDiagnostic),
                 resolutions