feat: make eval support --v8-flags=... (#3797)

Closes #3796

cli/flags.rs

@@ -353,6 +353,7 @@ fn repl_parse(flags: &mut DenoFlags, matches: &clap::ArgMatches) {
 }
 
 fn eval_parse(flags: &mut DenoFlags, matches: &clap::ArgMatches) {
+  v8_flags_arg_parse(flags, matches);
   flags.subcommand = DenoSubcommand::Eval;
   flags.allow_net = true;
   flags.allow_env = true;
@@ -797,6 +798,7 @@ This command has implicit access to all permissions (--allow-all)
   deno eval \"console.log('hello world')\"",
     )
     .arg(Arg::with_name("code").takes_value(true).required(true))
+    .arg(v8_flags_arg())
 }
 
 fn info_subcommand<'a, 'b>() -> App<'a, 'b> {
@@ -1549,6 +1551,28 @@ mod tests {
     );
   }
 
+  #[test]
+  fn eval_with_v8_flags() {
+    let r =
+      flags_from_vec_safe(svec!["deno", "eval", "--v8-flags=--help", "42"]);
+    assert_eq!(
+      r.unwrap(),
+      DenoFlags {
+        subcommand: DenoSubcommand::Eval,
+        argv: svec!["deno", "42"],
+        v8_flags: Some(svec!["--help"]),
+        allow_net: true,
+        allow_env: true,
+        allow_run: true,
+        allow_read: true,
+        allow_write: true,
+        allow_plugin: true,
+        allow_hrtime: true,
+        ..DenoFlags::default()
+      }
+    );
+  }
+
   #[test]
   fn repl() {
     let r = flags_from_vec_safe(svec!["deno"]);

cli/tests/integration_tests.rs

@@ -631,12 +631,19 @@ itest!(unbuffered_stdout {
   output: "unbuffered_stdout.ts.out",
 });
 
-itest!(v8_flags {
+// Cannot write the expression to evaluate as "console.log(typeof gc)"
+// because itest! splits args on whitespace.
+itest!(eval_v8_flags {
+  args: "eval --v8-flags=--expose-gc console.log(typeof(gc))",
+  output: "v8_flags.js.out",
+});
+
+itest!(run_v8_flags {
   args: "run --v8-flags=--expose-gc v8_flags.js",
   output: "v8_flags.js.out",
 });
 
-itest!(v8_help {
+itest!(run_v8_help {
   args: "run --v8-flags=--help",
   output: "v8_help.out",
 });