[Interactive inlay hints] Get source file from parameter node

src/server/session.ts

@@ -1875,14 +1875,24 @@ export class Session<TMessage = string> implements EventSender {
             return {
                 ...hint,
                 position: scriptInfo.positionToLineOffset(position),
-                displayParts: displayParts?.map(({ text, span, file }) => ({
-                    text,
-                    span: span && {
-                        start: scriptInfo.positionToLineOffset(span.start),
-                        end: scriptInfo.positionToLineOffset(span.start + span.length),
-                        file: file!,
-                    },
-                })),
+                displayParts: displayParts?.map(({ text, span, file }) => {
+                    if (span) {
+                        Debug.assertIsDefined(file, "Target file should be defined together with its span.");
+                        const scriptInfo = this.projectService.getScriptInfo(file)!;
+
+                        return {
+                            text,
+                            span: {
+                                start: scriptInfo.positionToLineOffset(span.start),
+                                end: scriptInfo.positionToLineOffset(span.start + span.length),
+                                file,
+                            },
+                        };
+                    }
+                    else {
+                        return { text };
+                    }
+                }),
             };
         });
     }

src/services/inlayHints.ts

@@ -62,7 +62,6 @@ import {
     Signature,
     skipParentheses,
     some,
-    SourceFile,
     Symbol,
     SymbolFlags,
     SyntaxKind,
@@ -157,11 +156,11 @@ export function provideInlayHints(context: InlayHintsContext): InlayHint[] {
         return isArrowFunction(node) || isFunctionExpression(node) || isFunctionDeclaration(node) || isMethodDeclaration(node) || isGetAccessorDeclaration(node);
     }
 
-    function addParameterHints(text: string, parameter: Identifier, position: number, isFirstVariadicArgument: boolean, sourceFile: SourceFile | undefined) {
+    function addParameterHints(text: string, parameter: Identifier, position: number, isFirstVariadicArgument: boolean) {
         let hintText = `${isFirstVariadicArgument ? "..." : ""}${text}`;
         let displayParts: InlayHintDisplayPart[] | undefined;
         if (shouldUseInteractiveInlayHints(preferences)) {
-            displayParts = [getNodeDisplayPart(hintText, parameter, sourceFile!), { text: ":" }];
+            displayParts = [getNodeDisplayPart(hintText, parameter), { text: ":" }];
             hintText = "";
         }
         else {
@@ -247,8 +246,6 @@ export function provideInlayHints(context: InlayHintsContext): InlayHint[] {
             return;
         }
 
-        const sourceFile = shouldUseInteractiveInlayHints(preferences) ? expr.getSourceFile() : undefined;
-
         let signatureParamPos = 0;
         for (const originalArg of args) {
             const arg = skipParentheses(originalArg);
@@ -287,7 +284,7 @@ export function provideInlayHints(context: InlayHintsContext): InlayHint[] {
                     continue;
                 }
 
-                addParameterHints(name, parameter, originalArg.getStart(), isFirstVariadicArgument, sourceFile);
+                addParameterHints(name, parameter, originalArg.getStart(), isFirstVariadicArgument);
             }
         }
     }
@@ -437,7 +434,8 @@ export function provideInlayHints(context: InlayHintsContext): InlayHint[] {
         return true;
     }
 
-    function getNodeDisplayPart(text: string, node: Node, sourceFile: SourceFile): InlayHintDisplayPart {
+    function getNodeDisplayPart(text: string, node: Node): InlayHintDisplayPart {
+        const sourceFile = node.getSourceFile();
         return {
             text,
             span: createTextSpanFromNode(node, sourceFile),

tests/baselines/reference/inlayHintsInteractiveMultifileFunctionCalls.baseline

@@ -0,0 +1,21 @@
+helperB("hello, world!");
+        ^
+{
+  "text": "",
+  "position": 45,
+  "kind": "Parameter",
+  "whitespaceAfter": true,
+  "displayParts": [
+    {
+      "text": "bParam",
+      "span": {
+        "start": 61,
+        "length": 6
+      },
+      "file": "/tests/cases/fourslash/bbb.mts"
+    },
+    {
+      "text": ":"
+    }
+  ]
+}

tests/cases/fourslash/inlayHintsInteractiveMultifileFunctionCalls.ts

@@ -0,0 +1,24 @@
+/// <reference path="fourslash.ts" />
+
+// @Target: esnext
+// @module: nodenext
+
+// @Filename: aaa.mts
+////import { helperB } from "./bbb.mjs";
+////helperB("hello, world!");
+
+// @Filename: bbb.mts
+////import { helperC } from "./ccc.mjs";
+
+////export function helperB(bParam: string) {
+////    helperC(bParam);
+////}
+
+// @Filename: ccc.mts
+////export function helperC(cParam: string) {}
+
+goTo.file("./aaa.mts");
+verify.baselineInlayHints(undefined, {
+    includeInlayParameterNameHints: "all",
+    interactiveInlayHints: true
+});