[NFC] Simplify Differentiable Signature Checking

Author: CodaFi

lib/Sema/TypeCheckAttr.cpp

@@ -4007,9 +4007,7 @@ static AbstractFunctionDecl *findAutoDiffOriginalFunctionDecl(
 /// `checkGenericSignature` is used to check generic signatures, if specified.
 /// Otherwise, generic signatures are checked for equality.
 static bool checkFunctionSignature(
-    CanAnyFunctionType required, CanType candidate,
-    Optional<std::function<bool(GenericSignature, GenericSignature)>>
-        checkGenericSignature = None) {
+    CanAnyFunctionType required, CanType candidate) {
   // Check that candidate is actually a function.
   auto candidateFnTy = dyn_cast<AnyFunctionType>(candidate);
   if (!candidateFnTy)
@@ -4022,12 +4020,7 @@ static bool checkFunctionSignature(
   // Check that generic signatures match.
   auto requiredGenSig = required.getOptGenericSignature();
   auto candidateGenSig = candidateFnTy.getOptGenericSignature();
-  // Call generic signature check function, if specified.
-  // Otherwise, check that generic signatures are equal.
-  if (!checkGenericSignature) {
-    if (candidateGenSig != requiredGenSig)
-      return false;
-  } else if (!(*checkGenericSignature)(requiredGenSig, candidateGenSig)) {
+  if (!candidateGenSig.requirementsNotSatisfiedBy(requiredGenSig).empty()) {
     return false;
   }
 
@@ -4684,14 +4677,6 @@ static bool typeCheckDerivativeAttr(ASTContext &Ctx, Decl *D,
   auto *originalFnType =
       getDerivativeOriginalFunctionType(derivativeInterfaceType);
 
-  // Returns true if the generic parameters in `source` satisfy the generic
-  // requirements in `target`.
-  std::function<bool(GenericSignature, GenericSignature)>
-      checkGenericSignatureSatisfied =
-          [&](GenericSignature source, GenericSignature target) {
-            return target.requirementsNotSatisfiedBy(source).empty();
-          };
-
   // Returns true if the derivative function and original function candidate are
   // defined in compatible type contexts. If the derivative function and the
   // original function candidate have different parents, return false.
@@ -4724,8 +4709,7 @@ static bool typeCheckDerivativeAttr(ASTContext &Ctx, Decl *D,
     // Error if the original candidate does not have the expected type.
     if (!checkFunctionSignature(
             cast<AnyFunctionType>(originalFnType->getCanonicalType()),
-            originalCandidate->getInterfaceType()->getCanonicalType(),
-            checkGenericSignatureSatisfied))
+            originalCandidate->getInterfaceType()->getCanonicalType()))
       return AbstractFunctionDeclLookupErrorKind::CandidateTypeMismatch;
     return None;
   };
@@ -5315,21 +5299,12 @@ void AttributeChecker::visitTransposeAttr(TransposeAttr *attr) {
     return;
   }
 
-  // Returns true if the generic parameters in `source` satisfy the generic
-  // requirements in `target`.
-  std::function<bool(GenericSignature, GenericSignature)>
-      checkGenericSignatureSatisfied =
-          [&](GenericSignature source, GenericSignature target) {
-            return target.requirementsNotSatisfiedBy(source).empty();
-          };
-
   auto isValidOriginalCandidate = [&](AbstractFunctionDecl *originalCandidate)
       -> Optional<AbstractFunctionDeclLookupErrorKind> {
     // Error if the original candidate does not have the expected type.
     if (!checkFunctionSignature(
             cast<AnyFunctionType>(expectedOriginalFnType->getCanonicalType()),
-            originalCandidate->getInterfaceType()->getCanonicalType(),
-            checkGenericSignatureSatisfied))
+            originalCandidate->getInterfaceType()->getCanonicalType()))
       return AbstractFunctionDeclLookupErrorKind::CandidateTypeMismatch;
     return None;
   };