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Add initial support for non-type template parameters (#6740)

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This adds basic support for using templates with integer parameters.

https://github.com/carbon-language/carbon-lang/issues/6717
This commit is contained in:
Nicholas Bishop
2026-02-17 21:34:06 +00:00
committed by GitHub
parent 8a8dd01302
commit 6df9d5ba32
2 changed files with 112 additions and 21 deletions
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toolchain/check/cpp/call.cpp
+45 -4
View File
@@ -114,10 +114,51 @@ static auto ConvertArgToTemplateArg(Context& context,
return MakePlaceholderTemplateArg(context, arg_id);
}
if (isa<clang::NonTypeTemplateParmDecl>(param_decl)) {
// TODO: Check the argument has a concrete constant value, and convert it to
// a Clang constant value.
context.TODO(arg_id, "argument for non-type template parameter");
if (const auto* non_type =
dyn_cast<clang::NonTypeTemplateParmDecl>(param_decl)) {
auto param_type = non_type->getType();
// Handle integer parameters.
if (param_type->isIntegerType()) {
// Get the Carbon type corresponding to the parameter's Clang type.
const auto type_expr =
ImportCppType(context, SemIR::LocId(arg_id), param_type);
// Try to convert the argument to the parameter type.
const auto converted_inst_id =
Convert(context, SemIR::LocId(arg_id), arg_id,
{
.kind = ConversionTarget::Value,
.type_id = type_expr.type_id,
});
if (converted_inst_id == SemIR::ErrorInst::InstId) {
return std::nullopt;
}
auto const_inst_id =
context.constant_values().GetConstantInstId(converted_inst_id);
if (const_inst_id.has_value()) {
if (auto int_value =
context.insts().TryGetAs<SemIR::IntValue>(const_inst_id)) {
const auto& ap_int = context.ints().Get(int_value->int_id);
const bool is_unsigned =
!param_type->isSignedIntegerOrEnumerationType();
auto aps_int =
llvm::APSInt(ap_int, is_unsigned)
.extOrTrunc(context.ast_context().getIntWidth(param_type));
auto template_arg = clang::TemplateArgument(context.ast_context(),
aps_int, param_type);
// TODO: provide a better location.
auto loc = clang::TemplateArgumentLocInfo();
return clang::TemplateArgumentLoc(template_arg, loc);
}
}
}
// TODO: Support other types.
context.TODO(arg_id,
"unsupported argument type for non-type template parameter");
return std::nullopt;
}
toolchain/check/testdata/interop/cpp/template/non_type_param.carbon
Vendored
+67 -17
View File
@@ -2,7 +2,7 @@
// Exceptions. See /LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
// INCLUDE-FILE: toolchain/testing/testdata/min_prelude/int.carbon
// INCLUDE-FILE: toolchain/testing/testdata/min_prelude/full.carbon
//
// AUTOUPDATE
// TIP: To test this file alone, run:
@@ -14,20 +14,62 @@
struct A {};
template<int N> struct Simple {};
Simple<123> MakeSimple123() { return Simple<123>(); }
template<int M, int N> struct TwoNonType {};
template<typename T, T N> struct DependentNonType {};
// --- fail_todo_valid.carbon
// --- valid_int_param.carbon
library "[[@TEST_NAME]]";
import Cpp library "templates.h";
var s: Cpp.Simple(123) = Cpp.MakeSimple123();
// --- fail_int_param_mismatch.carbon
library "[[@TEST_NAME]]";
import Cpp library "templates.h";
// CHECK:STDERR: fail_int_param_mismatch.carbon:[[@LINE+7]]:1: error: cannot implicitly convert expression of type `Cpp.Simple` to `Cpp.Simple` [ConversionFailure]
// CHECK:STDERR: var s: Cpp.Simple(456) = Cpp.MakeSimple123();
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR: fail_int_param_mismatch.carbon:[[@LINE+4]]:1: note: type `Cpp.Simple` does not implement interface `Core.ImplicitAs(Cpp.Simple)` [MissingImplInMemberAccessNote]
// CHECK:STDERR: var s: Cpp.Simple(456) = Cpp.MakeSimple123();
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR:
var s: Cpp.Simple(456) = Cpp.MakeSimple123();
// --- nonliteral.carbon
library "[[@TEST_NAME]]";
import Cpp library "templates.h";
var s: Cpp.Simple(100 + 20 + 3) = Cpp.MakeSimple123();
// --- conversion.carbon
library "[[@TEST_NAME]]";
import Cpp library "templates.h";
class C { adapt {}; }
impl C as Core.ImplicitAs(i32) {
eval fn Convert[self: Self]() -> i32 { return 123; }
}
var s: Cpp.Simple({} as C) = Cpp.MakeSimple123();
// --- valid.carbon
library "[[@TEST_NAME]]";
import Cpp library "templates.h";
//@dump-sem-ir-begin
// CHECK:STDERR: fail_todo_valid.carbon:[[@LINE+4]]:23: error: semantics TODO: `argument for non-type template parameter` [SemanticsTodo]
// CHECK:STDERR: var x: Cpp.TwoNonType(1, 2);
// CHECK:STDERR: ^
// CHECK:STDERR:
var x: Cpp.TwoNonType(1, 2);
//@dump-sem-ir-end
@@ -40,13 +82,13 @@ import Cpp library "templates.h";
var n: i32;
//@dump-sem-ir-begin
// CHECK:STDERR: fail_todo_dependent.carbon:[[@LINE+4]]:34: error: semantics TODO: `argument for non-type template parameter` [SemanticsTodo]
// CHECK:STDERR: fail_todo_dependent.carbon:[[@LINE+4]]:34: error: semantics TODO: `unsupported argument type for non-type template parameter` [SemanticsTodo]
// CHECK:STDERR: var x: Cpp.DependentNonType(i32, 1);
// CHECK:STDERR: ^
// CHECK:STDERR:
var x: Cpp.DependentNonType(i32, 1);
// CHECK:STDERR: fail_todo_dependent.carbon:[[@LINE+4]]:35: error: semantics TODO: `argument for non-type template parameter` [SemanticsTodo]
// CHECK:STDERR: fail_todo_dependent.carbon:[[@LINE+4]]:35: error: semantics TODO: `unsupported argument type for non-type template parameter` [SemanticsTodo]
// CHECK:STDERR: var y: Cpp.DependentNonType(i32*, &n);
// CHECK:STDERR: ^~
// CHECK:STDERR:
@@ -59,9 +101,12 @@ library "[[@TEST_NAME]]";
import Cpp library "templates.h";
// CHECK:STDERR: fail_type_argument.carbon:[[@LINE+4]]:23: error: semantics TODO: `argument for non-type template parameter` [SemanticsTodo]
// CHECK:STDERR: fail_type_argument.carbon:[[@LINE+7]]:26: error: cannot implicitly convert expression of type `type` to `i32` [ConversionFailure]
// CHECK:STDERR: var x: Cpp.TwoNonType(1, Cpp.A);
// CHECK:STDERR: ^
// CHECK:STDERR: ^~~~~
// CHECK:STDERR: fail_type_argument.carbon:[[@LINE+4]]:26: note: type `type` does not implement interface `Core.ImplicitAs(i32)` [MissingImplInMemberAccessNote]
// CHECK:STDERR: var x: Cpp.TwoNonType(1, Cpp.A);
// CHECK:STDERR: ^~~~~
// CHECK:STDERR:
var x: Cpp.TwoNonType(1, Cpp.A);
@@ -73,15 +118,20 @@ import Cpp library "templates.h";
var n: i32;
// CHECK:STDERR: fail_no_conversion.carbon:[[@LINE+4]]:23: error: semantics TODO: `argument for non-type template parameter` [SemanticsTodo]
// CHECK:STDERR: fail_no_conversion.carbon:[[@LINE+7]]:26: error: cannot implicitly convert expression of type `i32*` to `i32` [ConversionFailure]
// CHECK:STDERR: var x: Cpp.TwoNonType(1, &n);
// CHECK:STDERR: ^
// CHECK:STDERR: ^~
// CHECK:STDERR: fail_no_conversion.carbon:[[@LINE+4]]:26: note: type `i32*` does not implement interface `Core.ImplicitAs(i32)` [MissingImplInMemberAccessNote]
// CHECK:STDERR: var x: Cpp.TwoNonType(1, &n);
// CHECK:STDERR: ^~
// CHECK:STDERR:
var x: Cpp.TwoNonType(1, &n);
// CHECK:STDOUT: --- fail_todo_valid.carbon
// CHECK:STDOUT: --- valid.carbon
// CHECK:STDOUT:
// CHECK:STDOUT: constants {
// CHECK:STDOUT: %TwoNonType: type = class_type @TwoNonType [concrete]
// CHECK:STDOUT: %pattern_type.8a6: type = pattern_type %TwoNonType [concrete]
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: imports {
@@ -89,11 +139,11 @@ var x: Cpp.TwoNonType(1, &n);
// CHECK:STDOUT:
// CHECK:STDOUT: file {
// CHECK:STDOUT: name_binding_decl {
// CHECK:STDOUT: %x.patt: <error> = ref_binding_pattern x [concrete]
// CHECK:STDOUT: %x.var_patt: <error> = var_pattern %x.patt [concrete]
// CHECK:STDOUT: %x.patt: %pattern_type.8a6 = ref_binding_pattern x [concrete]
// CHECK:STDOUT: %x.var_patt: %pattern_type.8a6 = var_pattern %x.patt [concrete]
// CHECK:STDOUT: }
// CHECK:STDOUT: %x.var: ref <error> = var %x.var_patt [concrete = <error>]
// CHECK:STDOUT: %x: ref <error> = ref_binding x, <error> [concrete = <error>]
// CHECK:STDOUT: %x.var: ref %TwoNonType = var %x.var_patt [concrete]
// CHECK:STDOUT: %x: ref %TwoNonType = ref_binding x, %x.var [concrete = %x.var]
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: --- fail_todo_dependent.carbon