Paul Berry
83bea5cfbb
The order of operations for type inference of a generic invocation is now: 1. Create some constraints on type parameters by trying to match the return type of the invocation target as a subtype of the incoming type context. (For a constructor invocation, the return type of the invocation target is considered the raw uninstantiated type of the class enclosing the constructor declaration.) 2. Downwards inference: partially solve the set of type constraints accumulated in step 1, to produce a preliminary mapping of type parameters to type schemas. 3. Recursively infer all arguments to the invocation, except that if experimental feature `inference-update-1` is enabled, skip any arguments that are function literals (a.k.a. "closures"). Obtain the type contexts for the recursive inference by substituting the preliminary mapping (from step 2) into the corresponding parameter types of the invocation target. For each argument that is recursively inferred, create additional constraints on type parameters using the resulting static type. 4. If no arguments were skipped during step 3, go to step 7 (this always happens if `inference-update-1` is disabled). 5. Horizontal inference: partially solve the set of type constraints accumulated so far, to produce an updated preliminary mapping of type parameters to type schemas. 6. Recursively infer all of the invocation arguments that were previously skipped. As in step 3, obtain the type contexts for the recursive inference by substituting the preliminary mapping (this time from step 5) into the corresponding parameter types of the invocation target. Again, for each argument that is recursively inferred, create additional constraints on type parameters using the resulting static type. 7. Upwards inference: solve the set of type constraints accumulated so far, to produce a final mapping of type parameters to types. Check that each type is a subtype of the bound of its corresponding type parameter. 8. Check that the static type of each argument is assignable to the type obtained by substituting the final mapping (from step 7) into the corresponding parameter type of the invocation target. 9. Finally, obtain the static type of the invocation by substituting the final mapping (from step 7) into the return type of the invocation target. This addresses simpler cases of https://github.com/dart-lang/language/issues/731. Note that if experimental flag `inference-update-1` is disabled, the behavior is unchanged. Note that steps 2 and 5 use the same algorithm as each other (they only differ in how many type constraints have been accumulated so far), so I've renamed the function that performs it from `downwardsInfer` to `partialInfer`. Change-Id: I10d3288d4f4ba9e2b6bc18409186ddc67ca2ee9d Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/238881 Reviewed-by: Samuel Rawlins <srawlins@google.com> Commit-Queue: Paul Berry <paulberry@google.com>
Package validation
The packages in pkg/ are automatically validated on the LUCI CI bots. The
validation is largely done by the tools/package_deps package; it can be tested
locally via:
dart tools/package_deps/bin/package_deps.dart
Packages which are published
There are several packages developed in pkg/ which are published to pub.
Validation of these packages is particularly important because the pub tools are
not used for these packages during development; we get our dependency versions
from the DEPS file. Its very easy for the dependencies specified in a package's
pubspec file to get out of date wrt the packages and versions actually used.
In order to better ensure we're publishing correct packages, we validate some properties of the pubspec files on our CI system. These validations include:
- that the dependencies listed in the pubspec are used in the package
- that all the packages used by the source are listed in the pubspec
- that we don't use relative path deps to pkg/ or third_party/ packages
Packages which are not published
For packages in pkg/ which we do not intend to be published, we put the following comment in the pubspec.yaml file:
# This package is not intended for consumption on pub.dev. DO NOT publish.
publish_to: none
These pubspecs are still validated by the package validation tool. The contents are more informational as the pubspecs for these packages are not consumed by the pub tool or ecosystem.
We validate:
- that the dependencies listed in the pubspec are used in the package
- that all the packages used by the source are listed in the pubspec
- that a reference to a pkg/ package is done via a relative path dependency