Improve error messaging around function dot-notation deploys

Environment info

firebase-tools: 8.1.1 Platform: MacOs

Test case

$ firebase deploy --only functions:trig-users-onUserUpdate

Steps to reproduce

1. Have a project setup
2. Create a cloud function
3. Try to deploy just that function, ex:

$ firebase deploy --only functions:trig-users-onUserUpdate

Expected behavior

...
✔  functions[trig-users-onUserUpdate(us-central1)]: Successful update operation.
...

Function deployed.

Actual behavior

i  functions: current functions in project: trig-auth-createAuthUser(us-central1), trig-auth-onDeleteUser(us-central1), trig-users-onUserUpdate(us-central1)
⚠  functions: the following filters were specified but do not match any functions in the project: trig-users-onUserUpdate

Function wasn’t deployed

[mbleigh]

We use dot notation because we allow for exporting groups of functions and deploying them together, for instance:

exports.myGroup = {fn1: functions.https.onRequest(), fn2: functions.https.onRequest()}

Where I can now deploy both functions with:

firebase deploy --only functions:myGroup
# or
firebase deploy --only functions:myGroup.fn1

Function names cannot have periods in them, but the hierarchy makes dot-notation make more sense than dash notation.

I think the action here is probably to have a better error message before deploy if you include dashes (which are not allowed by our trigger parser), so I’ll leave it open and edit the title to reflect.

[MichaelGradek]

The issue is that, for some reason, the deploy --only filter expects you to use dot notation to separate the modules / directories.

If you try this, it will work:

$ firebase deploy --only functions:trig.users.onUserUpdate

i.e. change the - for .

I believe this is very counter intuitive, but it is what it is for now.

¯_(ツ)_/¯