generic-comment

Author: danakj

toolchain/check/handle_interface.cpp

@@ -146,7 +146,7 @@ auto HandleParseNode(Context& context,
   // type is the interface.
   SemIR::TypeId self_type_id =
       GetInterfaceType(context, interface_id, self_specific_id);
-  interface_info.self_param_id = GetSelfParameter(
+  interface_info.self_param_id = GetImplicitSelfGenericParameter(
       context, self_type_id, interface_info.scope_id, /*is_template=*/false);
 
   // Enter the interface scope.

toolchain/check/handle_named_constraint.cpp

@@ -145,7 +145,7 @@ auto HandleParseNode(Context& context,
   // type is the named constraint.
   SemIR::TypeId self_type_id =
       GetNamedConstraintType(context, named_constraint_id, self_specific_id);
-  constraint_info.self_param_id = GetSelfParameter(
+  constraint_info.self_param_id = GetImplicitSelfGenericParameter(
       context, self_type_id, constraint_info.scope_id, is_template);
 
   // Enter the constraint scope.

toolchain/check/interface.cpp

@@ -222,9 +222,9 @@ auto GetTypeForSpecificAssociatedEntity(Context& context, SemIR::LocId loc_id,
   CARBON_FATAL("Unexpected kind for associated constant {0}", decl);
 }
 
-auto GetSelfParameter(Context& context, SemIR::TypeId type_id,
-                      SemIR::NameScopeId scope_id, bool is_template)
-    -> SemIR::InstId {
+auto GetImplicitSelfGenericParameter(Context& context, SemIR::TypeId type_id,
+                                     SemIR::NameScopeId scope_id,
+                                     bool is_template) -> SemIR::InstId {
   auto entity_name_id = context.entity_names().AddSymbolicBindingName(
       SemIR::NameId::SelfType, scope_id,
       context.scope_stack().AddCompileTimeBinding(), is_template);
@@ -292,9 +292,11 @@ auto TryGetExistingDecl(
 
   if (is_definition && existing_decl_entity->has_definition_started()) {
     // DiagnoseIfInvalidRedecl would diagnose an error in this case, since we'd
-    // have two definitions. Normally we'd still use the pre-existing definition
-    // as a forward declaration anyway, for error recovery, but we can't for
-    // generics.
+    // have two definitions. Given the declaration parts of the definitions
+    // match, we would be able to use the prior declaration for error recovery,
+    // except that having two definitions causes larger problems for generics.
+    // All interfaces (and named constraints) are generic with an implicit Self
+    // compile time binding.
     return std::nullopt;
   }
 

toolchain/check/interface.h

@@ -43,12 +43,12 @@ auto GetTypeForSpecificAssociatedEntity(Context& context, SemIR::LocId loc_id,
     -> SemIR::TypeId;
 
 // Creates a symbolic binding for `Self` of type `type_id` in the scope of
-// `scope_id`, and add the name `Self` for the binding.
+// `scope_id`, and add the name `Self` for the compile time binding.
 //
 // Returns the symbolic binding instruction.
-auto GetSelfParameter(Context& context, SemIR::TypeId type_id,
-                      SemIR::NameScopeId scope_id, bool is_template)
-    -> SemIR::InstId;
+auto GetImplicitSelfGenericParameter(Context& context, SemIR::TypeId type_id,
+                                     SemIR::NameScopeId scope_id,
+                                     bool is_template) -> SemIR::InstId;
 
 // Given a search result `lookup_result` for `name_context`, returns the
 // previous valid declaration of `name_context` if there is one. Otherwise,