Falsely flagged "expression must have a constant value" for std::numbers

Environment

• OS and Version: Windows_NT x64 10.0.22631
• VS Code Version: 1.93.1
• C/C++ Extension Version: 1.21.6
• If using SSH remote, specify OS of remote machine: Ubuntu 22.04.4 LTS in WSL2

Bug Summary and Steps to Reproduce

Bug Summary:

The intellisense complains that expression must have a constant value when a constant expression from std::numbers is used in another constant expression.

Steps to reproduce:

#include <numbers>

int main() {
  constexpr double pi_2 = std::numbers::pi / 2.;
  return 0;
}

Expected behavior:

No error.

Configuration and Logs

Configuragions:

{
    "configurations": [
        {
            "name": "Linux",
            "includePath": [
                "${workspaceFolder}/**"
            ],
            "defines": [],
            "compilerPath": "/usr/bin/g++-11",
            "cStandard": "c17",
            "cppStandard": "c++20",
            "intelliSenseMode": "linux-gcc-x64"
        }
    ],
    "version": 4
}

Diagnostics:

-------- Diagnostics - 10/7/2024, 12:07:20 AM
Version: 1.21.6
Current Configuration:
{
    "name": "Linux",
    "includePath": [
        "/home/one/experiments/vscode-intellisense-issue/**"
    ],
    "defines": [],
    "compilerPath": "/usr/bin/g++-11",
    "cStandard": "c17",
    "cppStandard": "c++20",
    "intelliSenseMode": "linux-gcc-x64",
    "compilerPathIsExplicit": true,
    "cStandardIsExplicit": true,
    "cppStandardIsExplicit": true,
    "intelliSenseModeIsExplicit": true,
    "compilerPathInCppPropertiesJson": "/usr/bin/g++-11",
    "mergeConfigurations": false,
    "browse": {
        "path": [
            "/home/one/experiments/vscode-intellisense-issue/**",
            "${workspaceFolder}"
        ],
        "limitSymbolsToIncludedHeaders": true
    }
}
cpptools version (native): 1.21.6.0
Translation Unit Mappings:
[ /home/one/experiments/vscode-intellisense-issue/main.cpp - source TU]:
Translation Unit Configurations:
[ /home/one/experiments/vscode-intellisense-issue/main.cpp ]:
    Process ID: 50136
    Memory Usage: 25 MB
    Compiler Path: /usr/bin/g++-11
    Includes:
    System Includes:
        /usr/include/c++/11
        /usr/include/x86_64-linux-gnu/c++/11
        /usr/include/c++/11/backward
        /usr/lib/gcc/x86_64-linux-gnu/11/include
        /usr/local/include
        /usr/include/x86_64-linux-gnu
        /usr/include
    Standard Version: c++20
    IntelliSense Mode: linux-gcc-x64
    Other Flags:
        --g++
        --gnu_version=110400
Total Memory Usage: 25 MB

------- Workspace parsing diagnostics -------
Number of files discovered (not excluded): 7073

Other Extensions

None

Additional context

If the constant is defined without potential narrowing, the intellisense works fine. For example,

template <typename T>
inline constexpr T pi_v = 3.141592653589793238462643383279502884;
inline constexpr double pi = pi_v<double>;

int main() {
  constexpr double pi_2 = pi / 2.;
  return 0;
}

Note that the definition in std::numbers is something like

template <typename T>
inline constexpr T pi_v = T(3.141592653589793238462643383279502884L);
inline constexpr double pi = pi_v<double>;

The narrowing conversion for the literal is definitely legal.

Reproduce the diagnostic in main.cpp using the provided C++20 configuration with g++-11, and compare IntelliSense's result with the compiler for the std::numbers expression. Trace the constant-expression handling for the std::numbers definition and narrowing conversion. Done means the shown constexpr expression no longer reports an error.