feat: TC39 decorator proposal support (#22040)

This commit adds support for [TC39 Decorator
Proposal](https://github.com/tc39/proposal-decorators).

These decorators are only available in transpiled sources - ie.
non-JavaScript files (because of lack of support in V8).

This entails that "experimental TypeScript decorators" are not available
by default
and require to be configured, with a configuration like this:
```
{
  "compilerOptions": {
    "experimentalDecorators": true
  }
}
```


Closes https://github.com/denoland/deno/issues/19160

---------

Signed-off-by: Bartek Iwańczuk <biwanczuk@gmail.com>
Co-authored-by: crowlkats <crowlkats@toaxl.com>
Co-authored-by: Divy Srivastava <dj.srivastava23@gmail.com>

10 files changed, 82 insertions, 4 deletions

diff --git a/cli/tests/testdata/run/decorators/experimental/deno.json b/cli/tests/testdata/run/decorators/experimental/deno.json
new file mode 100644
index 000000000..504cd646e
--- /dev/null
+++ b/cli/tests/testdata/run/decorators/experimental/deno.json
@@ -0,0 +1,5 @@
+{
+  "compilerOptions": {
+    "experimentalDecorators": true
+  }
+}
diff --git a/cli/tests/testdata/run/no_check_decorators.ts.out b/cli/tests/testdata/run/decorators/experimental/no_check/main.out
index 015f7076e..015f7076e 100644
--- a/cli/tests/testdata/run/no_check_decorators.ts.out
+++ b/cli/tests/testdata/run/decorators/experimental/no_check/main.out
diff --git a/cli/tests/testdata/run/no_check_decorators.ts b/cli/tests/testdata/run/decorators/experimental/no_check/main.ts
index 9f7ec550d..9f7ec550d 100644
--- a/cli/tests/testdata/run/no_check_decorators.ts
+++ b/cli/tests/testdata/run/decorators/experimental/no_check/main.ts
diff --git a/cli/tests/testdata/run/decorators/experimental/runtime/main.out b/cli/tests/testdata/run/decorators/experimental/runtime/main.out
new file mode 100644
index 000000000..0fc1d4590
--- /dev/null
+++ b/cli/tests/testdata/run/decorators/experimental/runtime/main.out
@@ -0,0 +1,7 @@
+@A evaluated
+@B evaluated
+@B called
+@A called
+fn() called from @A
+fn() called from @B
+C.test() called
diff --git a/cli/tests/testdata/run/decorators/experimental/runtime/main.ts b/cli/tests/testdata/run/decorators/experimental/runtime/main.ts
new file mode 100644
index 000000000..40a26bbd4
--- /dev/null
+++ b/cli/tests/testdata/run/decorators/experimental/runtime/main.ts
@@ -0,0 +1,42 @@
+// deno-lint-ignore-file
+function a() {
+  console.log("@A evaluated");
+  return function (
+    target: any,
+    propertyKey: string,
+    descriptor: PropertyDescriptor,
+  ) {
+    console.log("@A called");
+    const fn = descriptor.value;
+    descriptor.value = function () {
+      console.log("fn() called from @A");
+      fn();
+    };
+  };
+}
+
+function b() {
+  console.log("@B evaluated");
+  return function (
+    target: any,
+    propertyKey: string,
+    descriptor: PropertyDescriptor,
+  ) {
+    console.log("@B called");
+    const fn = descriptor.value;
+    descriptor.value = function () {
+      console.log("fn() called from @B");
+      fn();
+    };
+  };
+}
+
+class C {
+  @a()
+  @b()
+  static test() {
+    console.log("C.test() called");
+  }
+}
+
+C.test();
diff --git a/cli/tests/testdata/run/ts_decorators.ts.out b/cli/tests/testdata/run/decorators/experimental/ts/main.out
index ee77417cf..ee77417cf 100644
--- a/cli/tests/testdata/run/ts_decorators.ts.out
+++ b/cli/tests/testdata/run/decorators/experimental/ts/main.out
diff --git a/cli/tests/testdata/run/ts_decorators.ts b/cli/tests/testdata/run/decorators/experimental/ts/main.ts
index 95fba6cd4..95fba6cd4 100644
--- a/cli/tests/testdata/run/ts_decorators.ts
+++ b/cli/tests/testdata/run/decorators/experimental/ts/main.ts
diff --git a/cli/tests/testdata/run/decorators/tc39_proposal/main.out b/cli/tests/testdata/run/decorators/tc39_proposal/main.out
new file mode 100644
index 000000000..39394952e
--- /dev/null
+++ b/cli/tests/testdata/run/decorators/tc39_proposal/main.out
@@ -0,0 +1,3 @@
+starting m with arguments 1
+C.m 1
+ending m
diff --git a/cli/tests/testdata/run/decorators/tc39_proposal/main.ts b/cli/tests/testdata/run/decorators/tc39_proposal/main.ts
new file mode 100644
index 000000000..00c8a8502
--- /dev/null
+++ b/cli/tests/testdata/run/decorators/tc39_proposal/main.ts
@@ -0,0 +1,21 @@
+// deno-lint-ignore no-explicit-any
+function logged(value: any, { kind, name }: { kind: string; name: string }) {
+  if (kind === "method") {
+    return function (...args: unknown[]) {
+      console.log(`starting ${name} with arguments ${args.join(", ")}`);
+      // @ts-ignore this has implicit any type
+      const ret = value.call(this, ...args);
+      console.log(`ending ${name}`);
+      return ret;
+    };
+  }
+}
+
+class C {
+  @logged
+  m(arg: number) {
+    console.log("C.m", arg);
+  }
+}
+
+new C().m(1);
diff --git a/cli/tests/testdata/run/runtime_decorators.ts b/cli/tests/testdata/run/runtime_decorators.ts
index 5da109110..40a26bbd4 100644
--- a/cli/tests/testdata/run/runtime_decorators.ts
+++ b/cli/tests/testdata/run/runtime_decorators.ts
@@ -1,5 +1,5 @@
 // deno-lint-ignore-file
-function A() {
+function a() {
   console.log("@A evaluated");
   return function (
     target: any,
@@ -15,7 +15,7 @@ function A() {
   };
 }
 
-function B() {
+function b() {
   console.log("@B evaluated");
   return function (
     target: any,
@@ -32,8 +32,8 @@ function B() {
 }
 
 class C {
-  @A()
-  @B()
+  @a()
+  @b()
   static test() {
     console.log("C.test() called");
   }