Sema: compute InitKindRequest::evaluate in a more performant way.

Use `getSelfNominalTypeDecl` rather than `getDeclaredInterfaceType` in
`InitKindRequest::evaluate`, since it's cheaper to perform.

Author: hborla

include/swift/AST/DiagnosticsSema.def

@@ -2813,13 +2813,13 @@ NOTE(convenience_init_here,none,
 ERROR(designated_init_in_extension,none,
       "designated initializer cannot be declared in an extension of %0; "
       "did you mean this to be a convenience initializer?",
-      (Type))
+      (DeclName))
 ERROR(enumstruct_convenience_init,none,
       "delegating initializers in %0 are not marked with 'convenience'",
       (StringRef))
 ERROR(nonclass_convenience_init,none,
       "convenience initializer not allowed in non-class type %0",
-      (Type))
+      (DeclName))
 ERROR(cfclass_convenience_init,none,
       "convenience initializers are not supported in extensions of CF types",
       ())

lib/Sema/TypeCheckDecl.cpp

@@ -1234,28 +1234,29 @@ InitKindRequest::evaluate(Evaluator &evaluator, ConstructorDecl *decl) const {
 
   // Convenience inits are only allowed on classes and in extensions thereof.
   if (decl->getAttrs().hasAttribute<ConvenienceAttr>()) {
-    if (auto extType = decl->getDeclContext()->getDeclaredInterfaceType()) {
-      auto extClass = extType->getClassOrBoundGenericClass();
+    if (auto nominal = decl->getDeclContext()->getSelfNominalTypeDecl()) {
+      auto classDecl = dyn_cast<ClassDecl>(nominal);
 
       // Forbid convenience inits on Foreign CF types, as Swift does not yet
       // support user-defined factory inits.
-      if (extClass &&
-          extClass->getForeignClassKind() == ClassDecl::ForeignKind::CFType) {
+      if (classDecl &&
+          classDecl->getForeignClassKind() == ClassDecl::ForeignKind::CFType) {
         diags.diagnose(decl->getLoc(), diag::cfclass_convenience_init);
       }
 
-      if (!extClass && !extType->hasError()) {
+      if (!classDecl) {
         auto ConvenienceLoc =
           decl->getAttrs().getAttribute<ConvenienceAttr>()->getLocation();
 
         // Produce a tailored diagnostic for structs and enums.
-        bool isStruct = extType->getStructOrBoundGenericStruct() != nullptr;
-        if (isStruct || extType->getEnumOrBoundGenericEnum()) {
+        bool isStruct = dyn_cast<StructDecl>(nominal) != nullptr;
+        if (isStruct || dyn_cast<EnumDecl>(nominal)) {
           diags.diagnose(decl->getLoc(), diag::enumstruct_convenience_init,
                          isStruct ? "structs" : "enums")
             .fixItRemove(ConvenienceLoc);
         } else {
-          diags.diagnose(decl->getLoc(), diag::nonclass_convenience_init, extType)
+          diags.diagnose(decl->getLoc(), diag::nonclass_convenience_init,
+                         nominal->getName())
             .fixItRemove(ConvenienceLoc);
         }
         return CtorInitializerKind::Designated;
@@ -1264,7 +1265,7 @@ InitKindRequest::evaluate(Evaluator &evaluator, ConstructorDecl *decl) const {
 
     return CtorInitializerKind::Convenience;
 
-  } else if (auto extType = decl->getDeclContext()->getDeclaredInterfaceType()) {
+  } else if (auto nominal = decl->getDeclContext()->getSelfNominalTypeDecl()) {
     // A designated init for a class must be written within the class itself.
     //
     // This is because designated initializers of classes get a vtable entry,
@@ -1273,10 +1274,11 @@ InitKindRequest::evaluate(Evaluator &evaluator, ConstructorDecl *decl) const {
     // If we implement the ability for extensions defined in the same module
     // (or the same file) to add vtable entries, we can re-evaluate this
     // restriction.
-    if (extType->getClassOrBoundGenericClass() &&
+    if (dyn_cast<ClassDecl>(nominal) &&
         !decl->isSynthesized() && isa<ExtensionDecl>(decl->getDeclContext()) &&
         !(decl->getAttrs().hasAttribute<DynamicReplacementAttr>())) {
-      diags.diagnose(decl->getLoc(), diag::designated_init_in_extension, extType)
+      diags.diagnose(decl->getLoc(), diag::designated_init_in_extension,
+                     nominal->getName())
         .fixItInsert(decl->getLoc(), "convenience ");
       return CtorInitializerKind::Convenience;
     }