fix(cli/emit): Check JS roots with // @ts-check (#14090)

cli/emit.rs

@@ -279,12 +279,21 @@ fn get_tsc_roots(
       .entries()
       .into_iter()
       .filter_map(|(specifier, module_entry)| match module_entry {
-        ModuleEntry::Module { media_type, .. } => match &media_type {
+        ModuleEntry::Module {
+          media_type,
+          ts_check,
+          ..
+        } => match &media_type {
           MediaType::TypeScript
           | MediaType::Tsx
           | MediaType::Mts
           | MediaType::Cts
           | MediaType::Jsx => Some((specifier.clone(), *media_type)),
+          MediaType::JavaScript | MediaType::Mjs | MediaType::Cjs
+            if check_js || *ts_check =>
+          {
+            Some((specifier.clone(), *media_type))
+          }
           _ => None,
         },
         _ => None,
@@ -461,20 +470,25 @@ pub fn check_and_maybe_emit(
         // resolve it via the graph.
         let graph_data = graph_data.read();
         let specifier = graph_data.follow_redirect(&specifiers[0]);
-        let (source_bytes, media_type) = match graph_data.get(&specifier) {
-          Some(ModuleEntry::Module {
-            code, media_type, ..
-          }) => (code.as_bytes(), *media_type),
-          _ => {
-            log::debug!("skipping emit for {}", specifier);
-            continue;
-          }
-        };
+        let (source_bytes, media_type, ts_check) =
+          match graph_data.get(&specifier) {
+            Some(ModuleEntry::Module {
+              code,
+              media_type,
+              ts_check,
+              ..
+            }) => (code.as_bytes(), *media_type, *ts_check),
+            _ => {
+              log::debug!("skipping emit for {}", specifier);
+              continue;
+            }
+          };
         // Sometimes if `tsc` sees a CommonJS file or a JSON module, it will
         // _helpfully_ output it, which we don't really want to do unless
         // someone has enabled check_js.
         if matches!(media_type, MediaType::Json)
           || (!check_js
+            && !ts_check
             && matches!(
               media_type,
               MediaType::JavaScript | MediaType::Cjs | MediaType::Mjs
@@ -862,10 +876,13 @@ fn valid_emit(
   reload_exclusions: &HashSet<ModuleSpecifier>,
 ) -> bool {
   let config_bytes = ts_config.as_bytes();
-  let emit_js = ts_config.get_check_js();
+  let check_js = ts_config.get_check_js();
   for (specifier, module_entry) in graph_data.entries() {
     if let ModuleEntry::Module {
-      code, media_type, ..
+      code,
+      media_type,
+      ts_check,
+      ..
     } = module_entry
     {
       match media_type {
@@ -875,7 +892,7 @@ fn valid_emit(
         | MediaType::Tsx
         | MediaType::Jsx => {}
         MediaType::JavaScript | MediaType::Mjs | MediaType::Cjs => {
-          if !emit_js {
+          if !check_js && !ts_check {
             continue;
           }
         }

cli/graph_util.rs

@@ -13,12 +13,18 @@ use deno_graph::ModuleGraphError;
 use deno_graph::ModuleKind;
 use deno_graph::Range;
 use deno_graph::Resolved;
+use once_cell::sync::Lazy;
+use regex::Regex;
 use std::collections::BTreeMap;
 use std::collections::HashMap;
 use std::collections::HashSet;
 use std::collections::VecDeque;
 use std::sync::Arc;
 
+/// Matches the `@ts-check` pragma.
+static TS_CHECK_RE: Lazy<Regex> =
+  Lazy::new(|| Regex::new(r#"(?i)^\s*@ts-check(?:\s+|$)"#).unwrap());
+
 pub fn contains_specifier(
   v: &[(ModuleSpecifier, ModuleKind)],
   specifier: &ModuleSpecifier,
@@ -33,6 +39,8 @@ pub enum ModuleEntry {
     code: Arc<String>,
     dependencies: BTreeMap<String, Dependency>,
     media_type: MediaType,
+    /// Whether or not this is a JS/JSX module with a `@ts-check` directive.
+    ts_check: bool,
     /// A set of type libs that the module has passed a type check with this
     /// session. This would consist of window, worker or both.
     checked_libs: HashSet<TypeLib>,
@@ -122,9 +130,23 @@ impl GraphData {
               }
             }
           }
+          let ts_check = match &media_type {
+            MediaType::JavaScript
+            | MediaType::Mjs
+            | MediaType::Cjs
+            | MediaType::Jsx => {
+              let parsed_source = module.maybe_parsed_source.as_ref().unwrap();
+              parsed_source
+                .get_leading_comments()
+                .iter()
+                .any(|c| TS_CHECK_RE.is_match(&c.text))
+            }
+            _ => false,
+          };
           let module_entry = ModuleEntry::Module {
             code,
             dependencies: module.dependencies.clone(),
+            ts_check,
             media_type,
             checked_libs: Default::default(),
             maybe_types,

cli/tests/integration/run_tests.rs

@@ -2726,3 +2726,10 @@ itest!(complex_error {
   output: "complex_error.ts.out",
   exit_code: 1,
 });
+
+// Regression test for https://github.com/denoland/deno/issues/12143.
+itest!(js_root_with_ts_check {
+  args: "run --quiet js_root_with_ts_check.js",
+  output: "js_root_with_ts_check.js.out",
+  exit_code: 1,
+});

cli/tests/testdata/js_root_with_ts_check.js

@@ -0,0 +1,5 @@
+// @ts-check
+
+/** @type {number} */
+const a = "";
+console.log(a);

cli/tests/testdata/js_root_with_ts_check.js.out

@@ -0,0 +1,4 @@
+error: TS2322 [ERROR]: Type 'string' is not assignable to type 'number'.
+const a = "";
+      ^
+    at [WILDCARD]