modern mode doesn't work with typescript

[troy351]

Version

3.0.0-rc.1

Reproduction link

no need

Steps to reproduce

create vue project with the steps below

1. vue create demo
2. Manually select features
3. Babel && TypeScript
4. N
5. Y
6. In dedicated config files
7. N

After finish, run vue-cli-service build --modern.

What is expected?

bundles should be different

What is actually happening?

check dist/app.hash.js and dist/app-legacy.hash.js, they are identical except the source map comment part.

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In pure js project, the modern bundle using arrow function for render function while the legacy bundle using function declaration.
In ts project, both bundles using function declaration.

[archseer]

@yyx990803 I think it still doesn't work on typescript:

-rw-r--r--   1 speed  staff   394K Sep 19 18:49 app-legacy.49d50903.js
-rw-r--r--   1 speed  staff   394K Sep 19 18:50 app.b75421a2.js

I also can't find the arrow function used anywhere in the modern bundle:

$ rg "=>" app.b75421a2.js
(empty)