Chuanqi Xu 1c9a8004ed Recommit [C++20] [Modules] Serialize the evaluated constant values for VarDecl
Close https://github.com/llvm/llvm-project/issues/62796.

Previously, we didn't serialize the evaluated result for VarDecl. This
caused the compilation of template metaprogramming become slower than
expect. This patch fixes the issue.

This is a recommit tested with asan built clang.
2023-05-24 15:45:16 +08:00

52 lines
1.1 KiB
C++

// RUN: rm -rf %t
// RUN: mkdir -p %t
// RUN: split-file %s %t
//
// RUN: %clang_cc1 -std=c++20 -emit-module-interface %t/Cache.cppm -o %t/Cache.pcm
// RUN: %clang_cc1 -std=c++20 %t/Use.cpp -fmodule-file=Fibonacci.Cache=%t/Cache.pcm \
// RUN: -fsyntax-only -verify
//--- Cache.cppm
export module Fibonacci.Cache;
export namespace Fibonacci
{
constexpr unsigned long Recursive(unsigned long n)
{
if (n == 0)
return 0;
if (n == 1)
return 1;
return Recursive(n - 2) + Recursive(n - 1);
}
template<unsigned long N>
struct Number{};
struct DefaultStrategy
{
constexpr unsigned long operator()(unsigned long n, auto... other) const
{
return (n + ... + other);
}
};
constexpr unsigned long Compute(Number<10ul>, auto strategy)
{
return strategy(Recursive(10ul));
}
template<unsigned long N, typename Strategy = DefaultStrategy>
constexpr unsigned long Cache = Compute(Number<N>{}, Strategy{});
template constexpr unsigned long Cache<10ul>;
}
//--- Use.cpp
// expected-no-diagnostics
import Fibonacci.Cache;
constexpr bool value = Fibonacci::Cache<10ul> == 55;
static_assert(value == true, "");