Move FileReference mode into helper

Author: weswigham

src/compiler/emitter.ts

@@ -3993,8 +3993,10 @@ namespace ts {
             }
             for (const directive of types) {
                 const pos = writer.getTextPos();
-                // Should we elide `resolution-mode` if it matches the mode the currentSourceFile defaults to?
-                writeComment(`/// <reference types="${directive.fileName}" ${directive.resolutionMode && directive.resolutionMode !== currentSourceFile?.impliedNodeFormat ? `resolution-mode="${directive.resolutionMode === ModuleKind.ESNext ? "import" : "require"}"` : ""}/>`);
+                const resolutionMode = directive.resolutionMode && directive.resolutionMode !== currentSourceFile?.impliedNodeFormat
+                    ? `resolution-mode="${directive.resolutionMode === ModuleKind.ESNext ? "import" : "require"}"`
+                    : "";
+                writeComment(`/// <reference types="${directive.fileName}" ${resolutionMode}/>`);
                 if (bundleFileInfo) bundleFileInfo.sections.push({ pos, end: writer.getTextPos(), kind: !directive.resolutionMode ? BundleFileSectionKind.Type : directive.resolutionMode === ModuleKind.ESNext ? BundleFileSectionKind.TypeResolutionModeImport : BundleFileSectionKind.TypeResolutionModeRequire, data: directive.fileName });
                 writeLine();
             }

src/compiler/moduleNameResolver.ts

@@ -347,7 +347,7 @@ namespace ts {
         // are present in a non-modal project; while in theory we'd like to either ignore the mode or provide faithful modern resolution, depending on what we feel is best,
         // in practice, not every cache has the options available to intelligently make the choice to ignore the mode request, and it's unclear how modern "faithful modern
         // resolution" should be (`node12`? `nodenext`?). As such, witnessing a mode-overriding triple-slash reference in a non-modal module resolution
-        // context should _probably_ be an error - and that should likely be handled by the `Program`.
+        // context should _probably_ be an error - and that should likely be handled by the `Program` (which is what we do).
         if (resolutionMode === ModuleKind.ESNext && (getEmitModuleResolutionKind(options) === ModuleResolutionKind.Node12 || getEmitModuleResolutionKind(options) === ModuleResolutionKind.NodeNext)) {
             features |= NodeResolutionFeatures.EsmMode;
         }

src/compiler/program.ts

@@ -518,7 +518,7 @@ namespace ts {
         const cache = new Map<string, T>();
         for (const name of names) {
             let result: T;
-            const mode = (!isString(name) ? name.resolutionMode : undefined) || containingFileMode;
+            const mode = getModeForFileReference(name, containingFileMode);
             // We lower-case all type references because npm automatically lowercases all packages. See GH#9824.
             const strName = isString(name) ? name : name.fileName.toLowerCase();
             const cacheKey = mode !== undefined ? `${mode}|${strName}` : strName;
@@ -540,6 +540,11 @@ namespace ts {
         impliedNodeFormat?: SourceFile["impliedNodeFormat"];
     };
 
+    /* @internal */
+    export function getModeForFileReference(ref: FileReference | string, containingFileMode: SourceFile["impliedNodeFormat"]) {
+        return (isString(ref) ? containingFileMode : ref.resolutionMode) || containingFileMode;
+    }
+
     /* @internal */
     export function getModeForResolutionAtIndex(file: SourceFileImportsList, index: number) {
         if (file.impliedNodeFormat === undefined) return undefined;

src/compiler/resolutionCache.ts

@@ -400,7 +400,7 @@ namespace ts {
                 // import's syntax may override the file's default mode.
                 // Type references instead supply a `containingSourceFileMode` and a non-string entry which contains
                 // a default file mode override if applicable.
-                const mode = !isString(entry) ? entry.resolutionMode || containingSourceFileMode :
+                const mode = !isString(entry) ? getModeForFileReference(entry, containingSourceFileMode) :
                     containingSourceFile ? getModeForResolutionAtIndex(containingSourceFile, i) : undefined;
                 i++;
                 let resolution = resolutionsInFile.get(name, mode);

src/compiler/utilities.ts

@@ -219,7 +219,7 @@ namespace ts {
             const entry = names[i];
             // We lower-case all type references because npm automatically lowercases all packages. See GH#9824.
             const name = !isString(entry) ? entry.fileName.toLowerCase() : entry;
-            const mode = !isString(entry) ? entry.resolutionMode || oldSourceFile?.impliedNodeFormat : oldSourceFile && getModeForResolutionAtIndex(oldSourceFile, i);
+            const mode = !isString(entry) ? getModeForFileReference(entry, oldSourceFile?.impliedNodeFormat) : oldSourceFile && getModeForResolutionAtIndex(oldSourceFile, i);
             const oldResolution = oldResolutions && oldResolutions.get(name, mode);
             const changed =
                 oldResolution