Previously, Template.templateAttrs was introduced to capture attribute
bindings which originated from microsyntax (e.g. bindings in *ngFor="...").
This means that a Template node can have two different structures, depending
on whether it originated from microsyntax or from a literal <ng-template>.
In the literal case, the node behaves much like an Element node, it has
attributes, inputs, and outputs which determine which directives apply.
In the microsyntax case, though, only the templateAttrs should be used
to determine which directives apply.
Previously, both the t2_binder and the TemplateDefinitionBuilder were using
the wrong set of attributes to match directives - combining the attributes,
inputs, outputs, and templateAttrs of the Template node regardless of its
origin. In the TDB's case this wasn't a problem, since the TDB collects a
global Set of directives used in the template, so it didn't matter whether
the directive was also recognized on the <ng-template>. t2_binder's API
distinguishes between directives on specific nodes, though, so it's more
sensitive to mismatching.
In particular, this showed up as an assertion failure in template type-
checking in certain cases, when a directive was accidentally matched on
a microsyntax template element and also had a binding which referenced a
variable declared in the microsyntax. This resulted in the type-checker
attempting to generate a reference to a variable that didn't exist in that
scope.
The fix is to distinguish between the two cases and select the appropriate
set of attributes to match on accordingly.
Testing strategy: tested in the t2_binder tests.
PR Close#29698
This commit introduces the "t2" API, which processes parsed template ASTs
and performs a number of functions such as binding (the process of
semantically interpreting cross-references within the template) and
directive matching. The API is modeled on TypeScript's TypeChecker API,
with oracle methods that give access to collected metadata.
This work is a prerequisite for the upcoming template type-checking
functionality, and will also become the basis for a refactored
TemplateDefinitionBuilder.
PR Close#26203
Alex Rickabaugh
Andrew Kushnir