Fix merge issues and @differentiable attribute type-checking.

- Fix `resolveDifferentiableAttrDerivativeGenericSignature`.
  - Generic signature should be returned directly instead of retrieved from
    generic environment.
- Delete `DifferentiableAttributeParameterIndicesRequest`.
  - That request was upstreamed and renamed to
    `DifferentiableAttributeTypeCheckRequest`.

Stdlib compilation (`TensorFlow` module) fixed.

Author: dan-zheng

include/swift/AST/Attr.h

@@ -1702,10 +1702,6 @@ class DifferentiableAttr final
   friend TrailingObjects;
   friend class DifferentiableAttributeTypeCheckRequest;
 
-  // SWIFT_ENABLE_TENSORFLOW
-  friend class DifferentiableAttributeParameterIndicesRequest;
-  // SWIFT_ENABLE_TENSORFLOW END
-
   /// The declaration on which the `@differentiable` attribute is declared.
   /// May not be a valid declaration for `@differentiable` attributes.
   /// Resolved during parsing and deserialization.

include/swift/AST/TypeCheckRequests.h

@@ -1660,30 +1660,6 @@ class CompareDeclSpecializationRequest
   bool isCached() const { return true; }
 };
 
-// SWIFT_ENABLE_TENSORFLOW
-class DifferentiableAttributeParameterIndicesRequest :
-    public SimpleRequest<DifferentiableAttributeParameterIndicesRequest,
-                         IndexSubset *(DifferentiableAttr *, Decl *),
-                         CacheKind::SeparatelyCached> {
-public:
-  using SimpleRequest::SimpleRequest;
-
-private:
-  friend SimpleRequest;
-
-  // Evaluation.
-  llvm::Expected<IndexSubset *>
-  evaluate(Evaluator &evaluator, DifferentiableAttr *attr, Decl *decl) const;
-
-public:
-  // Separate caching.
-  bool isCached() const { return true; }
-  Optional<IndexSubset *> getCachedResult() const;
-  void cacheResult(IndexSubset *value) const;
-};
-// SWIFT_ENABLE_TENSORFLOW END
-
-
 /// Checks whether this declaration inherits its superclass' designated and
 /// convenience initializers.
 class InheritsSuperclassInitializersRequest

include/swift/AST/TypeCheckerTypeIDZone.def

@@ -40,11 +40,6 @@ SWIFT_REQUEST(TypeChecker, DefaultArgumentInitContextRequest,
               Initializer *(ParamDecl *), SeparatelyCached, NoLocationInfo)
 SWIFT_REQUEST(TypeChecker, DefaultDefinitionTypeRequest,
               Type(AssociatedTypeDecl *), Cached, NoLocationInfo)
-// SWIFT_ENABLE_TENSORFLOW
-SWIFT_REQUEST(TypeChecker, DifferentiableAttributeParameterIndicesRequest,
-              IndexSubset *(DifferentiableAttr *, Decl *),
-              SeparatelyCached, NoLocationInfo)
-// SWIFT_ENABLE_TENSORFLOW END
 SWIFT_REQUEST(TypeChecker, DefaultTypeRequest,
               Type(KnownProtocolKind, const DeclContext *), SeparatelyCached,
               NoLocationInfo)

lib/AST/TypeCheckRequests.cpp

@@ -1055,24 +1055,6 @@ void swift::simple_display(llvm::raw_ostream &out,
   desc.nameLoc.print(out, desc.dc->getASTContext().SourceMgr);
 }
 
-//----------------------------------------------------------------------------//
-// DifferentiableAttributeParameterIndicesRequest computation.
-//----------------------------------------------------------------------------//
-
-Optional<IndexSubset *>
-DifferentiableAttributeParameterIndicesRequest::getCachedResult() const {
-  auto *attr = std::get<0>(getStorage());
-  if (attr->hasBeenTypeChecked())
-    return attr->ParameterIndicesAndBit.getPointer();
-  return None;
-}
-
-void DifferentiableAttributeParameterIndicesRequest::cacheResult(
-    IndexSubset *parameterIndices) const {
-  auto *attr = std::get<0>(getStorage());
-  attr->ParameterIndicesAndBit.setPointerAndInt(parameterIndices, true);
-}
-
 //----------------------------------------------------------------------------//
 // InheritsSuperclassInitializersRequest computation.
 //----------------------------------------------------------------------------//