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Interop support for nullptr and nullptr_t. (#6353)

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Add a `Core.CppCompat.NullptrT` type that C++'s `nullptr_t` maps into.
Map `nullptr` to an uninitialized constant of that type -- `nullptr`
doesn't actually have any defined bits within it, despite having the
same representation as `void*`.
This commit is contained in:
Richard Smith
2025-11-12 23:23:48 +00:00
committed by GitHub
parent 931039dcbc
commit 86b02ee8af
15 changed files with 521 additions and 124 deletions
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toolchain/check/cpp/import.cpp
+26 -11
View File
@@ -46,6 +46,7 @@
#include "toolchain/check/import.h"
#include "toolchain/check/inst.h"
#include "toolchain/check/literal.h"
#include "toolchain/check/member_access.h"
#include "toolchain/check/name_lookup.h"
#include "toolchain/check/operator.h"
#include "toolchain/check/pattern.h"
@@ -1106,6 +1107,12 @@ static auto MapBuiltinIntegerType(Context& context, SemIR::LocId loc_id,
return TypeExpr::None;
}
static auto MapNullptrType(Context& context, SemIR::LocId loc_id) -> TypeExpr {
return ExprAsType(
context, loc_id,
LookupNameInCore(context, loc_id, {"CppCompat", "NullptrT"}));
}
// Maps a C++ builtin type to a Carbon type.
// TODO: Support more builtin types.
static auto MapBuiltinType(Context& context, SemIR::LocId loc_id,
@@ -1134,6 +1141,8 @@ static auto MapBuiltinType(Context& context, SemIR::LocId loc_id,
} else if (type.isVoidType()) {
return ExprAsType(context, Parse::NodeId::None,
SemIR::CppVoidType::TypeInstId);
} else if (type.isNullPtrType()) {
return MapNullptrType(context, loc_id);
}
return TypeExpr::None;
@@ -2097,10 +2106,10 @@ static auto IsTopCppScope(Context& context, SemIR::NameScopeId scope_id)
return name_scope.parent_scope_id() == SemIR::NameScopeId::Package;
}
// For builtin names like `Cpp.long`, return the associated types.
static auto LookupBuiltinTypes(Context& context, SemIR::LocId loc_id,
SemIR::NameScopeId scope_id,
SemIR::NameId name_id) -> SemIR::InstId {
// For a builtin name like `Cpp.long`, returns the associated type.
static auto LookupBuiltinName(Context& context, SemIR::LocId loc_id,
SemIR::NameScopeId scope_id,
SemIR::NameId name_id) -> SemIR::InstId {
if (!IsTopCppScope(context, scope_id)) {
return SemIR::InstId::None;
}
@@ -2132,6 +2141,12 @@ static auto LookupBuiltinTypes(Context& context, SemIR::LocId loc_id,
.Case("void", ast_context.VoidTy)
.Default(clang::QualType());
if (builtin_type.isNull()) {
if (*name == "nullptr") {
// Map `Cpp.nullptr` to an uninitialized value of type `Core.CppNullptrT`.
auto type_id = MapNullptrType(context, loc_id).type_id;
return GetOrAddInst<SemIR::UninitializedValue>(
context, SemIR::LocId::None, {.type_id = type_id});
}
return SemIR::InstId::None;
}
@@ -2227,14 +2242,14 @@ static auto ImportConstructorsIntoScope(Context& context, SemIR::LocId loc_id,
naming_class, std::move(overload_set));
}
// Imports a builtin type from Clang to Carbon and adds the name into the
// scope.
static auto ImportBuiltinTypesIntoScope(Context& context, SemIR::LocId loc_id,
SemIR::NameScopeId scope_id,
SemIR::NameId name_id)
// Attempts to import a builtin name from Clang to Carbon and adds the name into
// the scope.
static auto ImportBuiltinNameIntoScope(Context& context, SemIR::LocId loc_id,
SemIR::NameScopeId scope_id,
SemIR::NameId name_id)
-> SemIR::ScopeLookupResult {
SemIR::InstId builtin_inst_id =
LookupBuiltinTypes(context, loc_id, scope_id, name_id);
LookupBuiltinName(context, loc_id, scope_id, name_id);
if (builtin_inst_id.has_value()) {
AddNameToScope(context, scope_id, name_id, SemIR::AccessKind::Public,
builtin_inst_id);
@@ -2351,7 +2366,7 @@ auto ImportNameFromCpp(Context& context, SemIR::LocId loc_id,
}
auto lookup = ClangLookupName(context, scope_id, name_id);
if (!lookup) {
return ImportBuiltinTypesIntoScope(context, loc_id, scope_id, name_id);
return ImportBuiltinNameIntoScope(context, loc_id, scope_id, name_id);
}
// Access checks are performed separately by the Carbon name lookup logic.
lookup->suppressAccessDiagnostics();