In JIT compiled apps, component definitions are compiled upon first
access. For a component class `A` that extends component class `B`, the
`B` component is also compiled when the `InheritDefinitionFeature` runs
during the compilation of `A` before it has finalized. A problem arises
when the compilation of `B` would flush the NgModule scoping queue,
where the NgModule declaring `A` is still pending. The scope information
would be applied to the definition of `A`, but its compilation is still
in progress so requesting the component definition would compile `A`
again from scratch. This "inner compilation" is correctly assigned the
NgModule scope, but once the "outer compilation" of `A` finishes it
would overwrite the inner compilation's definition, losing the NgModule
scope information.
In summary, flushing the NgModule scope queue could trigger a reentrant
compilation, where JIT compilation is non-reentrant. To avoid the
reentrant compilation, a compilation depth counter is introduced to
avoid flushing the NgModule scope during nested compilations.
Fixes#37105
PR Close#37795
2e9fdbde9e