mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-09-24 22:02:23 +01:00
Ivana Ivanovska
3b0dad9dd5
Adds support for object-like macros with a single replacement
numeric-literal kind token. Only macros that evaluate to an integer
constant are supported for now. When detected at name lookup, they are
imported as a constant integer value in Carbon.
Demo:
```c++
// --- macros.h
#define CONFIG_VALUE 2
```
``` c++
// main.carbon
library "Main";
import Cpp library "macros.h";
import Core library "io";
fn Run() {
let a: i32 = Cpp.CONFIG_VALUE;
Core.Print(a);
}
```
```c++
$ bazel-bin/toolchain/carbon compile main.carbon
$ bazel-bin/toolchain/carbon link main.o \--output=demo_carbon
$ ./demo_carbon
2
```
Part of #6303
47 lines
1.7 KiB
C++
47 lines
1.7 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#include "toolchain/check/cpp/macros.h"
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#include "clang/AST/ASTContext.h"
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#include "clang/Sema/Sema.h"
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namespace Carbon::Check {
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auto TryEvaluateMacroToConstant(Context& context, SemIR::LocId loc_id,
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SemIR::NameId name_id,
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clang::MacroInfo* macro_info) -> clang::Expr* {
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auto name_str_opt = context.names().GetAsStringIfIdentifier(name_id);
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CARBON_CHECK(macro_info, "macro info missing");
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if (macro_info->getNumTokens() != 1) {
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context.TODO(loc_id,
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llvm::formatv("Unsupported: macro with {0} replacement tokens",
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macro_info->getNumTokens()));
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return nullptr;
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}
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const clang::Token& tok = macro_info->getReplacementToken(0);
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if (!tok.is(clang::tok::numeric_constant)) {
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context.TODO(loc_id,
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"Unsupported: macro replacement token kind: " +
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std::string(clang::tok::getTokenName(tok.getKind())));
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return nullptr;
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}
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clang::Sema& sema = context.clang_sema();
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clang::ExprResult result = sema.ActOnNumericConstant(tok);
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clang::Expr* result_expr = result.get();
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if (!result_expr || result.isInvalid()) {
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CARBON_DIAGNOSTIC(
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InCppMacroEvaluation, Error,
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"failed to evaluate macro Cpp.{0} to a valid constant expression",
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std::string);
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context.emitter().Emit(loc_id, InCppMacroEvaluation, (*name_str_opt).str());
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return nullptr;
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}
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return result_expr;
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}
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} // namespace Carbon::Check
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