carbon-language/carbon-lang
1
0
Fork 0
mirror of https://github.com/carbon-language/carbon-lang.git synced 2026-10-05 11:21:05 +01:00
Code Issues Packages Projects Releases 10 Wiki Activity

Support accessing associated functions by member access into facets (#4872)

Browse Source 
For an expression such as `(Type as Interface).AssocFn()`, track the
`Self` type `Type` in the result of the member access so that it's
available when checking the function call.

This introduces a new kind of type, `ImplFunctionType`, that represents
the type of a function that is expected within an impl, modeled as the
type of the function within the interface plus a value to use as `Self`.
Calls to values of this type behave like calls to the underlying
function except that the `Self` parameter is pre-bound to the self type
from the facet.

In order to support this, fix an issue where the imported list of
generic bindings lost their association with their enclosing generic.
This adds a little complexity to `import_ref`, including a new recursive
cycle that I intend to address in a follow-up PR.

---------

Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
This commit is contained in:
Richard Smith
2025-02-04 22:38:38 +00:00
committed by GitHub
co-authored by Jon Ross-Perkins
parent dcfccd3187
commit fcfb1345d5
234 changed files with 4213 additions and 2531 deletions
Download Patch File Download Diff File Expand all files Collapse all files
toolchain/check/member_access.cpp
+58 -43
View File
@@ -14,6 +14,7 @@
#include "toolchain/check/import_ref.h"
#include "toolchain/check/interface.h"
#include "toolchain/diagnostics/diagnostic_emitter.h"
#include "toolchain/sem_ir/function.h"
#include "toolchain/sem_ir/generic.h"
#include "toolchain/sem_ir/ids.h"
#include "toolchain/sem_ir/inst.h"
@@ -354,51 +355,57 @@ static auto LookupMemberNameInScope(Context& context, SemIR::LocId loc_id,
static auto PerformInstanceBinding(Context& context, SemIR::LocId loc_id,
SemIR::InstId base_id,
SemIR::InstId member_id) -> SemIR::InstId {
auto member_type_id = context.insts().Get(member_id).type_id();
CARBON_KIND_SWITCH(context.types().GetAsInst(member_type_id)) {
case CARBON_KIND(SemIR::UnboundElementType unbound_element_type): {
// Convert the base to the type of the element if necessary.
base_id = ConvertToValueOrRefOfType(context, loc_id, base_id,
unbound_element_type.class_type_id);
// Find the specified element, which could be either a field or a base
// class, and build an element access expression.
auto element_id = context.constant_values().GetConstantInstId(member_id);
CARBON_CHECK(element_id.has_value(),
"Non-constant value {0} of unbound element type",
context.insts().Get(member_id));
auto index = GetClassElementIndex(context, element_id);
auto access_id = context.GetOrAddInst<SemIR::ClassElementAccess>(
loc_id, {.type_id = unbound_element_type.element_type_id,
.base_id = base_id,
.index = index});
if (SemIR::GetExprCategory(context.sem_ir(), base_id) ==
SemIR::ExprCategory::Value &&
SemIR::GetExprCategory(context.sem_ir(), access_id) !=
SemIR::ExprCategory::Value) {
// Class element access on a value expression produces an ephemeral
// reference if the class's value representation is a pointer to the
// object representation. Add a value binding in that case so that the
// expression category of the result matches the expression category of
// the base.
access_id = ConvertToValueExpr(context, access_id);
}
return access_id;
}
case CARBON_KIND(SemIR::FunctionType fn_type): {
if (IsInstanceMethod(context.sem_ir(), fn_type.function_id)) {
return context.GetOrAddInst<SemIR::BoundMethod>(
loc_id, {.type_id = context.GetSingletonType(
SemIR::BoundMethodType::SingletonInstId),
.object_id = base_id,
.function_decl_id = member_id});
}
[[fallthrough]];
}
default:
// Not an instance member: no instance binding.
// If the member is a function, check whether it's an instance method.
if (auto callee = SemIR::GetCalleeFunction(context.sem_ir(), member_id);
callee.function_id.has_value()) {
if (!IsInstanceMethod(context.sem_ir(), callee.function_id) ||
callee.self_id.has_value()) {
// Found a static member function or an already-bound method.
return member_id;
}
return context.GetOrAddInst<SemIR::BoundMethod>(
loc_id, {.type_id = context.GetSingletonType(
SemIR::BoundMethodType::SingletonInstId),
.object_id = base_id,
.function_decl_id = member_id});
}
// Otherwise, if it's a field, form a class element access.
if (auto unbound_element_type =
context.types().TryGetAs<SemIR::UnboundElementType>(
context.insts().Get(member_id).type_id())) {
// Convert the base to the type of the element if necessary.
base_id = ConvertToValueOrRefOfType(context, loc_id, base_id,
unbound_element_type->class_type_id);
// Find the specified element, which could be either a field or a base
// class, and build an element access expression.
auto element_id = context.constant_values().GetConstantInstId(member_id);
CARBON_CHECK(element_id.has_value(),
"Non-constant value {0} of unbound element type",
context.insts().Get(member_id));
auto index = GetClassElementIndex(context, element_id);
auto access_id = context.GetOrAddInst<SemIR::ClassElementAccess>(
loc_id, {.type_id = unbound_element_type->element_type_id,
.base_id = base_id,
.index = index});
if (SemIR::GetExprCategory(context.sem_ir(), base_id) ==
SemIR::ExprCategory::Value &&
SemIR::GetExprCategory(context.sem_ir(), access_id) !=
SemIR::ExprCategory::Value) {
// Class element access on a value expression produces an ephemeral
// reference if the class's value representation is a pointer to the
// object representation. Add a value binding in that case so that the
// expression category of the result matches the expression category
// of the base.
access_id = ConvertToValueExpr(context, access_id);
}
return access_id;
}
// Not an instance member: no instance binding.
return member_id;
}
// Validates that the index (required to be an IntValue) is valid within the
@@ -496,6 +503,14 @@ auto PerformMemberAccess(Context& context, SemIR::LocId loc_id,
base_type_const_id, lookup_scopes,
/*lookup_in_type_of_base=*/true);
// For name lookup into a facet, never perform instance binding.
// TODO: According to the design, this should be a "lookup in base" lookup,
// not a "lookup in type of base" lookup, and the facet itself should have
// member names that directly name members of the `impl`.
if (context.IsFacetType(base_type_id)) {
return member_id;
}
// Perform instance binding if we found an instance member.
member_id = PerformInstanceBinding(context, loc_id, base_id, member_id);