Always treat .d.*.ts files as commonjs-format modules for the purposes of import interop

src/compiler/program.ts

@@ -1396,7 +1396,7 @@ export function getImpliedNodeFormatForFileWorker(
     const shouldLookupFromPackageJson = ModuleResolutionKind.Node16 <= moduleResolution && moduleResolution <= ModuleResolutionKind.NodeNext
         || pathContainsNodeModules(fileName);
     return fileExtensionIsOneOf(fileName, [Extension.Dmts, Extension.Mts, Extension.Mjs]) ? ModuleKind.ESNext :
-        fileExtensionIsOneOf(fileName, [Extension.Dcts, Extension.Cts, Extension.Cjs]) ? ModuleKind.CommonJS :
+        fileExtensionIsOneOf(fileName, [Extension.Dcts, Extension.Cts, Extension.Cjs]) || (isDeclarationFileName(fileName) && !fileExtensionIs(fileName, Extension.Dts)) ? ModuleKind.CommonJS :
         shouldLookupFromPackageJson && fileExtensionIsOneOf(fileName, [Extension.Dts, Extension.Ts, Extension.Tsx, Extension.Js, Extension.Jsx]) ? lookupFromPackageJson() :
         undefined; // other extensions, like `json` or `tsbuildinfo`, are set as `undefined` here but they should never be fed through the transformer pipeline
 

tests/baselines/reference/resolveJsonModuleAllowArbitraryExtensionsNodeNext.errors.txt

@@ -0,0 +1,66 @@
+cjs/index.mts(2,6): error TS2339: Property 'default' does not exist on type '["foo", "bar", "baz"]'.
+cjs/index.mts(4,7): error TS2339: Property 'default' does not exist on type '["foo", "bar", "baz"]'.
+cjs/secondary.cts(2,6): error TS2339: Property 'default' does not exist on type '["foo", "bar", "baz"]'.
+cjs/secondary.cts(4,7): error TS2339: Property 'default' does not exist on type '["foo", "bar", "baz"]'.
+esm/index.mts(2,6): error TS2339: Property 'default' does not exist on type '["foo", "bar", "baz"]'.
+esm/index.mts(4,7): error TS2339: Property 'default' does not exist on type '["foo", "bar", "baz"]'.
+esm/secondary.cts(2,6): error TS2339: Property 'default' does not exist on type '["foo", "bar", "baz"]'.
+esm/secondary.cts(4,7): error TS2339: Property 'default' does not exist on type '["foo", "bar", "baz"]'.
+
+
+==== cjs/package.json (0 errors) ====
+    { "type": "commonjs" }
+==== cjs/foo.json (0 errors) ====
+    ["foo", "bar", "baz"]
+==== cjs/foo.d.json.ts (0 errors) ====
+    declare const data: ["foo", "bar", "baz"];
+    export = data;
+==== cjs/index.mts (2 errors) ====
+    import data from "./foo.json" with { type: "json" };
+    data.default; // foo.d.json.ts is cjs format - error (`default` is whole file, file has no `default` member)
+         ~~~~~~~
+!!! error TS2339: Property 'default' does not exist on type '["foo", "bar", "baz"]'.
+    import data2 = require("./foo.json");
+    data2.default; // `data2` is the whole json object, no `default`
+          ~~~~~~~
+!!! error TS2339: Property 'default' does not exist on type '["foo", "bar", "baz"]'.
+==== cjs/secondary.cts (2 errors) ====
+    import data from "./foo.json";
+    data.default; // error (cjs format `.d.json.ts`, export= object is require result)
+         ~~~~~~~
+!!! error TS2339: Property 'default' does not exist on type '["foo", "bar", "baz"]'.
+    import data2 = require("./foo.json");
+    data2.default; // `data2` is the whole json object, no `default`
+          ~~~~~~~
+!!! error TS2339: Property 'default' does not exist on type '["foo", "bar", "baz"]'.
+==== esm/package.json (0 errors) ====
+    { "type": "module" }
+==== esm/foo.json (0 errors) ====
+    ["foo", "bar", "baz"]
+==== esm/foo.d.json.ts (0 errors) ====
+    declare const data: ["foo", "bar", "baz"];
+    export = data;
+==== esm/index.mts (2 errors) ====
+    import data from "./foo.json" with { type: "json" };
+    data.default; // foo.d.json.ts is cjs format despite package - error! (default import is already the whole json object)
+         ~~~~~~~
+!!! error TS2339: Property 'default' does not exist on type '["foo", "bar", "baz"]'.
+    import data2 = require("./foo.json");
+    data2.default; // `data2` is the whole json object, no `default`
+          ~~~~~~~
+!!! error TS2339: Property 'default' does not exist on type '["foo", "bar", "baz"]'.
+==== esm/secondary.cts (2 errors) ====
+    import data from "./foo.json";
+    data.default; // `export=` object is the whole `require` result, hoisted to `default` by interop helper, no 2nd default
+         ~~~~~~~
+!!! error TS2339: Property 'default' does not exist on type '["foo", "bar", "baz"]'.
+    import data2 = require("./foo.json");
+    data2.default; // `data2` is the whole json object, no `default`
+          ~~~~~~~
+!!! error TS2339: Property 'default' does not exist on type '["foo", "bar", "baz"]'.
+==== root.mts (0 errors) ====
+    import "./cjs/index.mjs";
+    import "./cjs/secondary.mjs";
+    import "./mjs/index.mjs";
+    import "./mjs/secondary.mjs";
+

tests/baselines/reference/resolveJsonModuleAllowArbitraryExtensionsNodeNext.js

@@ -0,0 +1,97 @@
+//// [tests/cases/compiler/resolveJsonModuleAllowArbitraryExtensionsNodeNext.ts] ////
+
+//// [package.json]
+{ "type": "commonjs" }
+//// [foo.json]
+["foo", "bar", "baz"]
+//// [foo.d.json.ts]
+declare const data: ["foo", "bar", "baz"];
+export = data;
+//// [index.mts]
+import data from "./foo.json" with { type: "json" };
+data.default; // foo.d.json.ts is cjs format - error (`default` is whole file, file has no `default` member)
+import data2 = require("./foo.json");
+data2.default; // `data2` is the whole json object, no `default`
+//// [secondary.cts]
+import data from "./foo.json";
+data.default; // error (cjs format `.d.json.ts`, export= object is require result)
+import data2 = require("./foo.json");
+data2.default; // `data2` is the whole json object, no `default`
+//// [package.json]
+{ "type": "module" }
+//// [foo.json]
+["foo", "bar", "baz"]
+//// [foo.d.json.ts]
+declare const data: ["foo", "bar", "baz"];
+export = data;
+//// [index.mts]
+import data from "./foo.json" with { type: "json" };
+data.default; // foo.d.json.ts is cjs format despite package - error! (default import is already the whole json object)
+import data2 = require("./foo.json");
+data2.default; // `data2` is the whole json object, no `default`
+//// [secondary.cts]
+import data from "./foo.json";
+data.default; // `export=` object is the whole `require` result, hoisted to `default` by interop helper, no 2nd default
+import data2 = require("./foo.json");
+data2.default; // `data2` is the whole json object, no `default`
+//// [root.mts]
+import "./cjs/index.mjs";
+import "./cjs/secondary.mjs";
+import "./mjs/index.mjs";
+import "./mjs/secondary.mjs";
+
+
+//// [index.mjs]
+import { createRequire as _createRequire } from "module";
+const __require = _createRequire(import.meta.url);
+import data from "./foo.json" with { type: "json" };
+data.default; // foo.d.json.ts is cjs format - error (`default` is whole file, file has no `default` member)
+const data2 = __require("./foo.json");
+data2.default; // `data2` is the whole json object, no `default`
+//// [secondary.cjs]
+"use strict";
+var __importDefault = (this && this.__importDefault) || function (mod) {
+    return (mod && mod.__esModule) ? mod : { "default": mod };
+};
+Object.defineProperty(exports, "__esModule", { value: true });
+const foo_json_1 = __importDefault(require("./foo.json"));
+foo_json_1.default.default; // error (cjs format `.d.json.ts`, export= object is require result)
+const data2 = require("./foo.json");
+data2.default; // `data2` is the whole json object, no `default`
+//// [index.mjs]
+import { createRequire as _createRequire } from "module";
+const __require = _createRequire(import.meta.url);
+import data from "./foo.json" with { type: "json" };
+data.default; // foo.d.json.ts is cjs format despite package - error! (default import is already the whole json object)
+const data2 = __require("./foo.json");
+data2.default; // `data2` is the whole json object, no `default`
+//// [secondary.cjs]
+"use strict";
+var __importDefault = (this && this.__importDefault) || function (mod) {
+    return (mod && mod.__esModule) ? mod : { "default": mod };
+};
+Object.defineProperty(exports, "__esModule", { value: true });
+const foo_json_1 = __importDefault(require("./foo.json"));
+foo_json_1.default.default; // `export=` object is the whole `require` result, hoisted to `default` by interop helper, no 2nd default
+const data2 = require("./foo.json");
+data2.default; // `data2` is the whole json object, no `default`
+//// [root.mjs]
+import "./cjs/index.mjs";
+import "./cjs/secondary.mjs";
+import "./mjs/index.mjs";
+import "./mjs/secondary.mjs";
+
+
+//// [index.d.mts]
+export {};
+//// [secondary.d.cts]
+export {};
+//// [index.d.mts]
+export {};
+//// [secondary.d.cts]
+export {};
+//// [root.d.mts]
+import "./cjs/index.mjs";
+import "./cjs/secondary.mjs";
+import "./mjs/index.mjs";
+import "./mjs/secondary.mjs";

tests/baselines/reference/resolveJsonModuleAllowArbitraryExtensionsNodeNext.symbols

@@ -0,0 +1,75 @@
+//// [tests/cases/compiler/resolveJsonModuleAllowArbitraryExtensionsNodeNext.ts] ////
+
+=== cjs/foo.d.json.ts ===
+declare const data: ["foo", "bar", "baz"];
+>data : Symbol(data, Decl(foo.d.json.ts, 0, 13))
+
+export = data;
+>data : Symbol(data, Decl(foo.d.json.ts, 0, 13))
+
+=== cjs/index.mts ===
+import data from "./foo.json" with { type: "json" };
+>data : Symbol(data, Decl(index.mts, 0, 6))
+
+data.default; // foo.d.json.ts is cjs format - error (`default` is whole file, file has no `default` member)
+>data : Symbol(data, Decl(index.mts, 0, 6))
+
+import data2 = require("./foo.json");
+>data2 : Symbol(data2, Decl(index.mts, 1, 13))
+
+data2.default; // `data2` is the whole json object, no `default`
+>data2 : Symbol(data2, Decl(index.mts, 1, 13))
+
+=== cjs/secondary.cts ===
+import data from "./foo.json";
+>data : Symbol(data, Decl(secondary.cts, 0, 6))
+
+data.default; // error (cjs format `.d.json.ts`, export= object is require result)
+>data : Symbol(data, Decl(secondary.cts, 0, 6))
+
+import data2 = require("./foo.json");
+>data2 : Symbol(data2, Decl(secondary.cts, 1, 13))
+
+data2.default; // `data2` is the whole json object, no `default`
+>data2 : Symbol(data2, Decl(secondary.cts, 1, 13))
+
+=== esm/foo.d.json.ts ===
+declare const data: ["foo", "bar", "baz"];
+>data : Symbol(data, Decl(foo.d.json.ts, 0, 13))
+
+export = data;
+>data : Symbol(data, Decl(foo.d.json.ts, 0, 13))
+
+=== esm/index.mts ===
+import data from "./foo.json" with { type: "json" };
+>data : Symbol(data, Decl(index.mts, 0, 6))
+
+data.default; // foo.d.json.ts is cjs format despite package - error! (default import is already the whole json object)
+>data : Symbol(data, Decl(index.mts, 0, 6))
+
+import data2 = require("./foo.json");
+>data2 : Symbol(data2, Decl(index.mts, 1, 13))
+
+data2.default; // `data2` is the whole json object, no `default`
+>data2 : Symbol(data2, Decl(index.mts, 1, 13))
+
+=== esm/secondary.cts ===
+import data from "./foo.json";
+>data : Symbol(data, Decl(secondary.cts, 0, 6))
+
+data.default; // `export=` object is the whole `require` result, hoisted to `default` by interop helper, no 2nd default
+>data : Symbol(data, Decl(secondary.cts, 0, 6))
+
+import data2 = require("./foo.json");
+>data2 : Symbol(data2, Decl(secondary.cts, 1, 13))
+
+data2.default; // `data2` is the whole json object, no `default`
+>data2 : Symbol(data2, Decl(secondary.cts, 1, 13))
+
+=== root.mts ===
+
+import "./cjs/index.mjs";
+import "./cjs/secondary.mjs";
+import "./mjs/index.mjs";
+import "./mjs/secondary.mjs";
+

tests/baselines/reference/resolveJsonModuleAllowArbitraryExtensionsNodeNext.types

@@ -0,0 +1,131 @@
+//// [tests/cases/compiler/resolveJsonModuleAllowArbitraryExtensionsNodeNext.ts] ////
+
+=== cjs/foo.d.json.ts ===
+declare const data: ["foo", "bar", "baz"];
+>data : ["foo", "bar", "baz"]
+>     : ^^^^^^^^^^^^^^^^^^^^^
+
+export = data;
+>data : ["foo", "bar", "baz"]
+>     : ^^^^^^^^^^^^^^^^^^^^^
+
+=== cjs/index.mts ===
+import data from "./foo.json" with { type: "json" };
+>data : ["foo", "bar", "baz"]
+>     : ^^^^^^^^^^^^^^^^^^^^^
+>type : any
+>     : ^^^
+
+data.default; // foo.d.json.ts is cjs format - error (`default` is whole file, file has no `default` member)
+>data.default : any
+>             : ^^^
+>data : ["foo", "bar", "baz"]
+>     : ^^^^^^^^^^^^^^^^^^^^^
+>default : any
+>        : ^^^
+
+import data2 = require("./foo.json");
+>data2 : ["foo", "bar", "baz"]
+>      : ^^^^^^^^^^^^^^^^^^^^^
+
+data2.default; // `data2` is the whole json object, no `default`
+>data2.default : any
+>              : ^^^
+>data2 : ["foo", "bar", "baz"]
+>      : ^^^^^^^^^^^^^^^^^^^^^
+>default : any
+>        : ^^^
+
+=== cjs/secondary.cts ===
+import data from "./foo.json";
+>data : ["foo", "bar", "baz"]
+>     : ^^^^^^^^^^^^^^^^^^^^^
+
+data.default; // error (cjs format `.d.json.ts`, export= object is require result)
+>data.default : any
+>             : ^^^
+>data : ["foo", "bar", "baz"]
+>     : ^^^^^^^^^^^^^^^^^^^^^
+>default : any
+>        : ^^^
+
+import data2 = require("./foo.json");
+>data2 : ["foo", "bar", "baz"]
+>      : ^^^^^^^^^^^^^^^^^^^^^
+
+data2.default; // `data2` is the whole json object, no `default`
+>data2.default : any
+>              : ^^^
+>data2 : ["foo", "bar", "baz"]
+>      : ^^^^^^^^^^^^^^^^^^^^^
+>default : any
+>        : ^^^
+
+=== esm/foo.d.json.ts ===
+declare const data: ["foo", "bar", "baz"];
+>data : ["foo", "bar", "baz"]
+>     : ^^^^^^^^^^^^^^^^^^^^^
+
+export = data;
+>data : ["foo", "bar", "baz"]
+>     : ^^^^^^^^^^^^^^^^^^^^^
+
+=== esm/index.mts ===
+import data from "./foo.json" with { type: "json" };
+>data : ["foo", "bar", "baz"]
+>     : ^^^^^^^^^^^^^^^^^^^^^
+>type : any
+>     : ^^^
+
+data.default; // foo.d.json.ts is cjs format despite package - error! (default import is already the whole json object)
+>data.default : any
+>             : ^^^
+>data : ["foo", "bar", "baz"]
+>     : ^^^^^^^^^^^^^^^^^^^^^
+>default : any
+>        : ^^^
+
+import data2 = require("./foo.json");
+>data2 : ["foo", "bar", "baz"]
+>      : ^^^^^^^^^^^^^^^^^^^^^
+
+data2.default; // `data2` is the whole json object, no `default`
+>data2.default : any
+>              : ^^^
+>data2 : ["foo", "bar", "baz"]
+>      : ^^^^^^^^^^^^^^^^^^^^^
+>default : any
+>        : ^^^
+
+=== esm/secondary.cts ===
+import data from "./foo.json";
+>data : ["foo", "bar", "baz"]
+>     : ^^^^^^^^^^^^^^^^^^^^^
+
+data.default; // `export=` object is the whole `require` result, hoisted to `default` by interop helper, no 2nd default
+>data.default : any
+>             : ^^^
+>data : ["foo", "bar", "baz"]
+>     : ^^^^^^^^^^^^^^^^^^^^^
+>default : any
+>        : ^^^
+
+import data2 = require("./foo.json");
+>data2 : ["foo", "bar", "baz"]
+>      : ^^^^^^^^^^^^^^^^^^^^^
+
+data2.default; // `data2` is the whole json object, no `default`
+>data2.default : any
+>              : ^^^
+>data2 : ["foo", "bar", "baz"]
+>      : ^^^^^^^^^^^^^^^^^^^^^
+>default : any
+>        : ^^^
+
+=== root.mts ===
+
+import "./cjs/index.mjs";
+import "./cjs/secondary.mjs";
+import "./mjs/index.mjs";
+import "./mjs/secondary.mjs";
+