Sema: Use getNextDepth()/getMaxDepth()

Author: slavapestov

lib/Sema/CSSimplify.cpp

@@ -1572,8 +1572,7 @@ shouldOpenExistentialCallArgument(ValueDecl *callee, unsigned paramIdx,
 
   auto genericSig = callee->getInnermostDeclContext()
       ->getGenericSignatureOfContext().getCanonicalSignature();
-  if (genericParam->getDepth() <
-          genericSig.getGenericParams().back()->getDepth())
+  if (genericParam->getDepth() < genericSig->getMaxDepth())
     return std::nullopt;
 
   // If the existential argument conforms to all of protocol requirements on

lib/Sema/CodeSynthesis.cpp

@@ -541,9 +541,7 @@ createDesignatedInitOverrideGenericParams(ASTContext &ctx,
   if (genericParams == nullptr)
     return nullptr;
 
-  unsigned depth = 0;
-  if (auto classSig = classDecl->getGenericSignature())
-    depth = classSig.getGenericParams().back()->getDepth() + 1;
+  unsigned depth = classDecl->getGenericSignature().getNextDepth();
 
   SmallVector<GenericTypeParamDecl *, 4> newParams;
   for (auto *param : genericParams->getParams()) {

lib/Sema/PreCheckExpr.cpp

@@ -713,8 +713,8 @@ Expr *TypeChecker::resolveDeclRefExpr(UnresolvedDeclRefExpr *UDRE,
         if (!xGeneric)
           return false;
 
-        unsigned xDepth = xGeneric->getGenericParams().back()->getDepth();
-        unsigned yDepth = yGeneric->getGenericParams().back()->getDepth();
+        unsigned xDepth = xGeneric->getGenericSignature()->getMaxDepth();
+        unsigned yDepth = yGeneric->getGenericSignature()->getMaxDepth();
         return xDepth < yDepth;
       });
     }

lib/Sema/TypeCheckGeneric.cpp

@@ -96,10 +96,7 @@ OpaqueResultTypeRequest::evaluate(Evaluator &evaluator,
   // types and their interface constraints.
   auto originatingDC = originatingDecl->getInnermostDeclContext();
   auto outerGenericSignature = originatingDC->getGenericSignatureOfContext();
-  unsigned opaqueSignatureDepth =
-      outerGenericSignature
-          ? outerGenericSignature.getGenericParams().back()->getDepth() + 1
-          : 0;
+  unsigned opaqueSignatureDepth = outerGenericSignature.getNextDepth();
 
   // Determine the context of the opaque type declaration we'll be creating.
   auto parentDC = originatingDecl->getDeclContext();