fix(npm): improve declaration resolution for filename with different extensions (#19966)

postcss was importing `./index.js` from `./index.d.mts` where there also
existed a `./index.d.ts`.

Closes #19575

cli/tests/integration/npm_tests.rs

@@ -2088,3 +2088,11 @@ itest!(reserved_word_exports {
   envs: env_vars_for_npm_tests(),
   http_server: true,
 });
+
+itest!(check_package_file_dts_dmts_dcts {
+  args: "check npm/file_dts_dmts_dcts/main.ts",
+  output: "npm/file_dts_dmts_dcts/main.out",
+  envs: env_vars_for_npm_tests_no_sync_download(),
+  http_server: true,
+  exit_code: 1,
+});

cli/tests/testdata/npm/file_dts_dmts_dcts/main.out

@@ -0,0 +1,24 @@
+Download http://localhost:4545/npm/registry/@denotest/file-dts-dmts-dcts
+Download http://localhost:4545/npm/registry/@denotest/file-dts-dmts-dcts/1.0.0.tgz
+Check file:///[WILDCARD]/main.ts
+error: TS2322 [ERROR]: Type '5' is not assignable to type '"dts"'.
+const value1: Dts1 = 5;
+      ~~~~~~
+    at file:///[WILDCARD]
+
+TS2322 [ERROR]: Type '5' is not assignable to type '"mts"'.
+const value2: Mts1 = 5;
+      ~~~~~~
+    at file:///[WILDCARD]
+
+TS2322 [ERROR]: Type '5' is not assignable to type '"mts"'.
+const value3: Mts2 = 5;
+      ~~~~~~
+    at file:///[WILDCARD]
+
+TS2322 [ERROR]: Type '5' is not assignable to type '"cts"'.
+const value4: Cts1 = 5;
+      ~~~~~~
+    at file:///[WILDCARD]
+
+Found 4 errors.

cli/tests/testdata/npm/file_dts_dmts_dcts/main.ts

@@ -0,0 +1,9 @@
+import { Value as Dts1 } from "npm:@denotest/file-dts-dmts-dcts/js";
+import { Value as Mts1 } from "npm:@denotest/file-dts-dmts-dcts";
+import { Value as Mts2 } from "npm:@denotest/file-dts-dmts-dcts/mjs";
+import { Value as Cts1 } from "npm:@denotest/file-dts-dmts-dcts/cjs";
+
+const value1: Dts1 = 5;
+const value2: Mts1 = 5;
+const value3: Mts2 = 5;
+const value4: Cts1 = 5;

cli/tests/testdata/npm/registry/@denotest/file-dts-dmts-dcts/1.0.0/main.d.cts

@@ -0,0 +1 @@
+export type Value = "cts";

cli/tests/testdata/npm/registry/@denotest/file-dts-dmts-dcts/1.0.0/main.d.mts

@@ -0,0 +1 @@
+export type Value = "mts";

cli/tests/testdata/npm/registry/@denotest/file-dts-dmts-dcts/1.0.0/main.d.ts

@@ -0,0 +1 @@
+export type Value = "dts";

cli/tests/testdata/npm/registry/@denotest/file-dts-dmts-dcts/1.0.0/package.json

@@ -0,0 +1,13 @@
+{
+  "name": "@denotest/dts-and-dmts-same-file",
+  "version": "1.0.0",
+  "exports": {
+    ".": {
+      "import": "./main.mjs",
+      "require": "./main.js"
+    },
+    "./mjs": "./main.mjs",
+    "./cjs": "./main.cjs",
+    "./js": "./main.js"
+  }
+}

ext/node/resolution.rs

@@ -527,37 +527,67 @@ impl NodeResolver {
     fn probe_extensions(
       fs: &dyn deno_fs::FileSystem,
       path: &Path,
+      lowercase_path: &str,
       referrer_kind: NodeModuleKind,
     ) -> Option<PathBuf> {
-      let specific_dts_path = match referrer_kind {
-        NodeModuleKind::Cjs => with_known_extension(path, "d.cts"),
-        NodeModuleKind::Esm => with_known_extension(path, "d.mts"),
-      };
-      if fs.exists(&specific_dts_path) {
-        return Some(specific_dts_path);
+      let mut searched_for_d_mts = false;
+      let mut searched_for_d_cts = false;
+      if lowercase_path.ends_with(".mjs") {
+        let d_mts_path = with_known_extension(path, "d.mts");
+        if fs.exists(&d_mts_path) {
+          return Some(d_mts_path);
+        }
+        searched_for_d_mts = true;
+      } else if lowercase_path.ends_with(".cjs") {
+        let d_cts_path = with_known_extension(path, "d.cts");
+        if fs.exists(&d_cts_path) {
+          return Some(d_cts_path);
+        }
+        searched_for_d_cts = true;
       }
+
       let dts_path = with_known_extension(path, "d.ts");
       if fs.exists(&dts_path) {
-        Some(dts_path)
-      } else {
-        None
+        return Some(dts_path);
       }
+
+      let specific_dts_path = match referrer_kind {
+        NodeModuleKind::Cjs if !searched_for_d_cts => {
+          Some(with_known_extension(path, "d.cts"))
+        }
+        NodeModuleKind::Esm if !searched_for_d_mts => {
+          Some(with_known_extension(path, "d.mts"))
+        }
+        _ => None, // already searched above
+      };
+      if let Some(specific_dts_path) = specific_dts_path {
+        if fs.exists(&specific_dts_path) {
+          return Some(specific_dts_path);
+        }
+      }
+      None
     }
 
     let lowercase_path = path.to_string_lossy().to_lowercase();
     if lowercase_path.ends_with(".d.ts")
       || lowercase_path.ends_with(".d.cts")
-      || lowercase_path.ends_with(".d.ts")
+      || lowercase_path.ends_with(".d.mts")
     {
       return Some(path);
     }
-    if let Some(path) = probe_extensions(&*self.fs, &path, referrer_kind) {
+    if let Some(path) =
+      probe_extensions(&*self.fs, &path, &lowercase_path, referrer_kind)
+    {
       return Some(path);
     }
     if self.fs.is_dir(&path) {
-      if let Some(path) =
-        probe_extensions(&*self.fs, &path.join("index"), referrer_kind)
-      {
+      let index_path = path.join("index.js");
+      if let Some(path) = probe_extensions(
+        &*self.fs,
+        &index_path,
+        &index_path.to_string_lossy().to_lowercase(),
+        referrer_kind,
+      ) {
         return Some(path);
       }
     }