fix(compile): prevent setting unstable feature twice (#24381)

Prevent panic when enabling a feature that is already enabled by
removing duplicate features.

Closes #22015

---------

Co-authored-by: Bartek Iwańczuk <biwanczuk@gmail.com>

7 files changed, 39 insertions, 3 deletions

diff --git a/cli/args/mod.rs b/cli/args/mod.rs
index e1e6f9510..bf52c460f 100644
--- a/cli/args/mod.rs
+++ b/cli/args/mod.rs
@@ -1773,14 +1773,28 @@ impl CliOptions {
       .map(|c| c.json.unstable.clone())
       .unwrap_or_default();
 
-    from_config_file.extend_from_slice(&self.flags.unstable_config.features);
+    self
+      .flags
+      .unstable_config
+      .features
+      .iter()
+      .for_each(|feature| {
+        if !from_config_file.contains(feature) {
+          from_config_file.push(feature.to_string());
+        }
+      });
 
     if *DENO_FUTURE {
-      from_config_file.extend_from_slice(&[
+      let future_features = [
         deno_runtime::deno_ffi::UNSTABLE_FEATURE_NAME.to_string(),
         deno_runtime::deno_fs::UNSTABLE_FEATURE_NAME.to_string(),
         deno_runtime::deno_webgpu::UNSTABLE_FEATURE_NAME.to_string(),
-      ]);
+      ];
+      future_features.iter().for_each(|future_feature| {
+        if !from_config_file.contains(future_feature) {
+          from_config_file.push(future_feature.to_string());
+        }
+      });
     }
 
     from_config_file
diff --git a/tests/specs/compile/repetitive_unstable_flag/.gitignore b/tests/specs/compile/repetitive_unstable_flag/.gitignore
new file mode 100644
index 000000000..ed6b0677d
--- /dev/null
+++ b/tests/specs/compile/repetitive_unstable_flag/.gitignore
@@ -0,0 +1,2 @@
+out.exe
+out
diff --git a/tests/specs/compile/repetitive_unstable_flag/__test__.jsonc b/tests/specs/compile/repetitive_unstable_flag/__test__.jsonc
new file mode 100644
index 000000000..00d38bee6
--- /dev/null
+++ b/tests/specs/compile/repetitive_unstable_flag/__test__.jsonc
@@ -0,0 +1,13 @@
+{
+  "steps": [
+    {
+      "args": "compile --unstable-kv -A --output out main.ts",
+      "output": "compile.out"
+    },
+    {
+      "commandName": "./out",
+      "args": [],
+      "output": "main.out"
+    }
+  ]
+}
diff --git a/tests/specs/compile/repetitive_unstable_flag/compile.out b/tests/specs/compile/repetitive_unstable_flag/compile.out
new file mode 100644
index 000000000..022f2c580
--- /dev/null
+++ b/tests/specs/compile/repetitive_unstable_flag/compile.out
@@ -0,0 +1,2 @@
+Check [WILDCARD]main.ts
+Compile [WILDCARD]main.ts to out[WILDCARD]
diff --git a/tests/specs/compile/repetitive_unstable_flag/deno.json b/tests/specs/compile/repetitive_unstable_flag/deno.json
new file mode 100644
index 000000000..c0401f75f
--- /dev/null
+++ b/tests/specs/compile/repetitive_unstable_flag/deno.json
@@ -0,0 +1,3 @@
+{
+  "unstable": ["kv"]
+}
diff --git a/tests/specs/compile/repetitive_unstable_flag/main.out b/tests/specs/compile/repetitive_unstable_flag/main.out
new file mode 100644
index 000000000..2170a5a7d
--- /dev/null
+++ b/tests/specs/compile/repetitive_unstable_flag/main.out
@@ -0,0 +1 @@
+Duplicate unstable feature issue is resolved as you can see
diff --git a/tests/specs/compile/repetitive_unstable_flag/main.ts b/tests/specs/compile/repetitive_unstable_flag/main.ts
new file mode 100644
index 000000000..c45100cfd
--- /dev/null
+++ b/tests/specs/compile/repetitive_unstable_flag/main.ts
@@ -0,0 +1 @@
+console.log("Duplicate unstable feature issue is resolved as you can see");