PluginModule.onConfigurationChanged not called when plugin config in tsconfig.json changes

[ajafff]

TypeScript Version: 3.3.0-dev.20181208

Search Terms:

plugin configuration change
onConfigurationChanged

Expected behavior:

PluginModule.onConfigurationChanged is called when the configuration of the plugin in tsconfig.json changes. The Project already watches the tsconfig.json and therefore knows when the config of a plugin changes.

Actual behavior:

PluginModule.onConfigurationChanged is only called when the client sends a ConfigurePlugin command.

Related Issues:
#15915 is basically the same issue from 1,5 years ago. Back then it was decided this is working as intended and a plugin is responsible for watching the config file.
In the meantime onConfigurationChanged was introduced in #28106. Since ConfigurePlugin command is supposed to override any config in tsconfig.json, a plugin that watches for config file changes would need special handling to account for that fact.

[ajafff]

Related note: since configurePlugin overrides plugin configuration from tsconfig.json, there is no way for a plugin to know if the initial config is actually from tsconfig.json or configurePlugin command.

[sheetalkamat]

The design in #28106 was to override the globally configured plugin options all the time. So if the plugin is configured globally the local changes in the tsconfig file for plugin options have no effect.
@minestarks please let me know if this was not desired outcome. Thanks

[minestarks]

I'm not aware of any way to specify a plugin configuration in tsconfig.json. Could someone point me to an example? I can't find in the source where tsserver might be reading such options. If plugins have the ability to parse out custom options from tsconfig.json, then I don't think tsserver is involved, so I'm not sure how we could be watching for changes.

I agree with Sheetal about the intention of #28106 - the server command configurePlugin overrides all plugin options, and at the time I thought that was pretty much the only way plugin configurations can be set.