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Renumber inner parameters when checking an impl function against an interface function. (#5113)

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This allows the numbering of the parameters to match when checking for a
valid redeclaration. It also prepares us to produce the proper numbering
when generating a thunk.
This commit is contained in:
Richard Smith
2025-03-12 13:54:49 +00:00
committed by GitHub
parent e6872f9499
commit 6fd139b805
6 changed files with 626 additions and 6 deletions
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toolchain/check/interface.cpp
+29 -3
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@@ -126,8 +126,9 @@ static auto GetGenericArgsWithSelfType(Context& context,
auto GetSelfSpecificForInterfaceMemberWithSelfType(
Context& context, SemIRLoc loc, SemIR::SpecificId interface_specific_id,
SemIR::GenericId generic_id, SemIR::TypeId self_type_id,
SemIR::InstId witness_inst_id) -> SemIR::SpecificId {
SemIR::GenericId generic_id, SemIR::SpecificId enclosing_specific_id,
SemIR::TypeId self_type_id, SemIR::InstId witness_inst_id)
-> SemIR::SpecificId {
const auto& generic = context.generics().Get(generic_id);
auto self_specific_args = context.inst_blocks().Get(
context.specifics().Get(generic.self_specific_id).args_id);
@@ -136,11 +137,36 @@ auto GetSelfSpecificForInterfaceMemberWithSelfType(
context, interface_specific_id, generic_id, self_type_id, witness_inst_id,
self_specific_args.size());
// Determine the number of specific arguments that enclose the point where
// this self specific will be used from. In an impl, this will be the number
// of parameters that the impl has.
int num_enclosing_specific_args =
context.inst_blocks()
.Get(context.specifics().GetArgsOrEmpty(enclosing_specific_id))
.size();
// The index of each remaining generic parameter is adjusted to match the
// numbering at the point where the self specific is used.
int index_delta = num_enclosing_specific_args - arg_ids.size();
// Take any trailing argument values from the self specific.
// TODO: If these refer to outer arguments, for example in their types, we may
// need to perform extra substitutions here.
for (auto arg_id : self_specific_args.drop_front(arg_ids.size())) {
arg_ids.push_back(context.constant_values().GetConstantInstId(arg_id));
auto new_arg_id = context.constant_values().GetConstantInstId(arg_id);
if (index_delta) {
// If this parameter would have a new index in the context described by
// `enclosing_specific_id`, form a new binding with an adjusted index.
auto bind_name = context.insts().GetAs<SemIR::BindSymbolicName>(
context.constant_values().GetConstantInstId(arg_id));
auto entity_name = context.entity_names().Get(bind_name.entity_name_id);
entity_name.bind_index_value += index_delta;
CARBON_CHECK(entity_name.bind_index_value >= 0);
bind_name.entity_name_id =
context.entity_names().AddCanonical(entity_name);
new_arg_id = context.constant_values().GetInstId(
TryEvalInst(context, arg_id, bind_name));
}
arg_ids.push_back(new_arg_id);
}
return MakeSpecific(context, loc, generic_id, arg_ids);