Fix `@derivative` attribute type-checking crash, so far reproducible only via
`-parse-stdlib`.
The crash occurs because it is not sufficient for type-checking to check for
`Differentiable` conformances. We must also check for invalid `TangentVector`
associated types.
Resolves SR-12559.
Disable `SILCombiner::visitPartialApplyInst` from rewriting `partial_apply` with
with `@convention(method)` callee to `thin_to_thick_function`.
This fixes SIL verification errors: `thin_to_thick_function` only supports
`@convention(thin)` operands.
Resolves SR-12548.
Add implicit declarations generated by the differentiation transform to a
`SynthesizedFileUnit` instead of an ad-hoc pre-existing `SourceFile`.
Resolves TF-1232: type reconstruction for AutoDiff-generated declarations.
Previously, type reconstruction failed because retroactively adding declarations
to a `SourceFile` did not update name lookup caches.
Previously, two conditions were necessary to enable differentiable programming:
- Using the `-enable-experimental-differentiable-programming` frontend flag.
- Importing the `_Differentiation` module.
Importing the `_Differentiation` module is the true condition because it
contains the required compiler-known `Differentiable` protocol. The frontend
flag is redundant and cumbersome.
Now, the frontend flag is removed.
Importing `_Differentiation` is the only condition.
Remove meaningless `assert(false)` assertion from
`hasOverridingDifferentiableAttribute` in `TypeCheckDeclOverride.cpp`.
The assertion served no purpose and can safely be removed.
Resolves TF-1167. Add test.
