fix(check): do not suggest running with `--unstable` (#23092)

Closes #23079

6 files changed, 38 insertions, 2 deletions

diff --git a/cli/tsc/99_main_compiler.js b/cli/tsc/99_main_compiler.js
index e6123d25e..e47300491 100644
--- a/cli/tsc/99_main_compiler.js
+++ b/cli/tsc/99_main_compiler.js
@@ -354,7 +354,7 @@ delete Object.prototype.__proto__;
       case 2339: {
         const property = getProperty();
         if (property && unstableDenoProps.has(property)) {
-          return `${msg} 'Deno.${property}' is an unstable API. Did you forget to run with the '--unstable' flag? ${unstableMsgSuggestion}`;
+          return `${msg} 'Deno.${property}' is an unstable API. ${unstableMsgSuggestion}`;
         }
         return msg;
       }
@@ -363,7 +363,7 @@ delete Object.prototype.__proto__;
         if (property && unstableDenoProps.has(property)) {
           const suggestion = getMsgSuggestion();
           if (suggestion) {
-            return `${msg} 'Deno.${property}' is an unstable API. Did you forget to run with the '--unstable' flag, or did you mean '${suggestion}'? ${unstableMsgSuggestion}`;
+            return `${msg} 'Deno.${property}' is an unstable API. Did you mean '${suggestion}'? ${unstableMsgSuggestion}`;
           }
         }
         return msg;
diff --git a/tests/specs/check/unstable_suggestion/__test__.jsonc b/tests/specs/check/unstable_suggestion/__test__.jsonc
new file mode 100644
index 000000000..28fe022be
--- /dev/null
+++ b/tests/specs/check/unstable_suggestion/__test__.jsonc
@@ -0,0 +1,11 @@
+{
+  "steps": [{
+    "args": "check main.ts",
+    "output": "main.out",
+    "exitCode": 1
+  }, {
+    "args": "check no_default_lib.ts",
+    "output": "no_default_lib.out",
+    "exitCode": 1
+  }]
+}
diff --git a/tests/specs/check/unstable_suggestion/main.out b/tests/specs/check/unstable_suggestion/main.out
new file mode 100644
index 000000000..ba8b2800c
--- /dev/null
+++ b/tests/specs/check/unstable_suggestion/main.out
@@ -0,0 +1,10 @@
+Check file:///[WILDLINE]main.ts
+error: TS2551 [ERROR]: Property 'dlopen' does not exist on type 'typeof Deno'. Did you mean 'open'? 'Deno.dlopen' is an unstable API. Did you mean 'open'? If not, try changing the 'lib' compiler option to include 'deno.unstable' or add a triple-slash directive to the top of your entrypoint (main file): /// <reference lib="deno.unstable" />
+Deno.dlopen("path/to/lib", {});
+     ~~~~~~
+    at file:///[WILDLINE]/main.ts:5:6
+
+    'open' is declared here.
+      export function open(
+                      ~~~~
+        at asset:///lib.deno.ns.d.ts:[WILDLINE]
diff --git a/tests/specs/check/unstable_suggestion/main.ts b/tests/specs/check/unstable_suggestion/main.ts
new file mode 100644
index 000000000..02a5cfbdf
--- /dev/null
+++ b/tests/specs/check/unstable_suggestion/main.ts
@@ -0,0 +1,5 @@
+/// <reference no-default-lib="true" />
+/// <reference lib="deno.ns" />
+
+// unstable apis removed here, so should error
+Deno.dlopen("path/to/lib", {});
diff --git a/tests/specs/check/unstable_suggestion/no_default_lib.out b/tests/specs/check/unstable_suggestion/no_default_lib.out
new file mode 100644
index 000000000..1ec2ae3e5
--- /dev/null
+++ b/tests/specs/check/unstable_suggestion/no_default_lib.out
@@ -0,0 +1,5 @@
+Check file:///[WILDLINE]/no_default_lib.ts
+error: TS2304 [ERROR]: Cannot find name 'Deno'. Do you need to change your target library? Try changing the 'lib' compiler option to include 'deno.ns' or add a triple-slash directive to the top of your entrypoint (main file): /// <reference lib="deno.ns" />
+console.log(Deno);
+            ~~~~
+    at file:///[WILDLINE]/no_default_lib.ts:5:13
diff --git a/tests/specs/check/unstable_suggestion/no_default_lib.ts b/tests/specs/check/unstable_suggestion/no_default_lib.ts
new file mode 100644
index 000000000..2b3aa6dfc
--- /dev/null
+++ b/tests/specs/check/unstable_suggestion/no_default_lib.ts
@@ -0,0 +1,5 @@
+/// <reference no-default-lib="true" />
+/// <reference lib="es5" />
+/// <reference lib="dom" />
+
+console.log(Deno);