Repository: pytorch
Issue: The error compiling problem of Qt and libtorch(my solution to eliminate the bug)
Labels: module: dependency bug,module: cpp,triaged

When I built the code at first,it run well at the  first

```cpp
#include <LogLevel.hpp>
#include <LogManager.hpp>
#include <QtCharts/QChartView>
#include <QtCharts/QLineSeries>
#include <QtWidgets/QApplication>
#include <iostream>
#include <torch/torch.h>
#include <torch/script.h>

// 定义卷积 + ReLU + 批量归一化的模块
struct ConvReluBn : torch::nn::Module {
    ConvReluBn(int in_channels, int out_channels, int kernel_size, int stride = 1) {
        conv = register_module("conv", torch::nn::Conv2d(
                                               torch::nn::Conv2dOptions(in_channels, out_channels, kernel_size).stride(stride).padding(kernel_size / 2)));
        relu = register_module("relu", torch::nn::ReLU());
        bn = register_module("bn", torch::nn::BatchNorm2d(out_channels));
    }

    torch::Tensor forward(torch::Tensor x) {
        return bn->forward(relu->forward(conv->forward(x)));
    }

private:
    torch::nn::Conv2d conv{nullptr};
    torch::nn::ReLU relu{nullptr};
    torch::nn::BatchNorm2d bn{nullptr};
};

// 定义 plainCNN 类
class plainCNN : public torch::nn::Module {
public:
    plainCNN(int in_channels, int out_channels);
    torch::Tensor forward(torch::Tensor x);

private:
    int mid_channels[3] = {32, 64, 128};
    std::shared_ptr<ConvReluBn> conv1;
    std::shared_ptr<ConvReluBn> down1;
    std::shared_ptr<ConvReluBn> conv2;
    std::shared_ptr<ConvReluBn> down2;
    std::shared_ptr<ConvReluBn> conv3;
    std::shared_ptr<ConvReluBn> down3;
    torch::nn::Conv2d out_conv{nullptr};
};

// 构造函数的实现
plainCNN::plainCNN(int in_channels, int out_channels) {
    conv1 = std::make_shared<ConvReluBn>(in_channels, mid_channels[0], 3);
    down1 = std::make_shared<ConvReluBn>(mid_channels[0], mid_channels[0], 3, 2);
    conv2 = std::make_shared<ConvReluBn>(mid_channels[0], mid_channels[1], 3);
    down2 = std::make_shared<ConvReluBn>(mid_channels[1], mid_channels[1], 3, 2);
    conv3 = std::make_shared<ConvReluBn>(mid_channels[1], mid_channels[2], 3);
    down3 = std::make_shared<ConvReluBn>(mid_channels[2], mid_channels[2], 3, 2);
    out_conv = register_module("out_conv", torch::nn::Conv2d(
                                                   torch::nn::Conv2dOptions(mid_channels[2], out_channels, 3).padding(1)));

    register_module("conv1", conv1);
    register_module("down1", down1);
    register_module("conv2", conv2);
    register_module("down2", down2);
    register_module("conv3", conv3);
    register_module("down3", down3);
}

// forward 方法的实现
torch::Tensor plainCNN::forward(torch::Tensor x) {
    x = conv1->forward(x);
    x = down1->forward(x);
    x = conv2->forward(x);
    x = down2->forward(x);
    x = conv3->forward(x);
    x = down3->forward(x);
    x = out_conv->forward(x);
    return x;
}

int main(int argc, char *argv[]) {
    // 设置文件日志记录器
    cmx::logManager.setFileAppender("log.txt");
    // 设置控制台日志记录器
    cmx::logManager.setConsoleAppender();

    // 检查 GPU 是否可用
    torch::Device device(torch::kCUDA);
    if (!torch::cuda::is_available()) {
        cmx::logManager.log("CUDA is not available! Falling back to CPU.", cmx::Log::LogLevel::Warning);
        device = torch::Device(torch::kCPU);
    } else {
        cmx::logManager.log("CUDA is available! Using GPU for training.", cmx::Log::LogLevel::Info);
    }

    // 创建模型实例并移动到 GPU
    plainCNN model(3, 10);
    model.to(device);
    model.train();

    // 定义优化器
    torch::optim::SGD optimizer(model.parameters(), /*lr=*/0.01);

    // 数据存储
    QLineSeries *series = new QLineSeries();

    // 训练过程
    size_t train_epochs = 1000;
    std::chrono::steady_clock::time_point start = std::chrono::steady_clock::now();
    for (size_t epoch = 0; epoch < train_epochs; epoch++) {
        // 创建示例输入并移动到 GPU
        torch::Tensor input = torch::randn({1, 3, 224, 224}).to(device);
        torch::Tensor target = torch::randn({1, 10, 28, 28}).to(device);

        // 清空梯度
        optimizer.zero_grad();

        // 前向传播
        auto output = model.forward(input);

        // 计算损失
        auto loss = torch::nn::functional::mse_loss(output, target);

        // 反向传播
        loss.backward();

        // 更新参数
        optimizer.step();

        cmx::logManager.log("Epoch [" + std::to_string(epoch + 1) + "/" + std::to_string(epoch + 1) + "], Loss: " + std::to_string(loss.item<float>()), cmx::Log::LogLevel::Info);

        // 添加损失到图表
        series->append(epoch + 1, loss.item<float>());
    }
    std::chrono::steady_clock::time_point end = std::chrono::steady_clock::now();
    std::chrono::duration<double> elapsed_seconds = end - start;
    cmx::logManager.log("Training completed in " + std::to_string(elapsed_seconds.count()) + " seconds.", cmx::Log::LogLevel::Info);
    cmx::logManager.log("Per epoch average time = " + std::to_string(elapsed_seconds.count() / train_epochs) + " seconds.", cmx::Log::LogLevel::Info);

    // Qt Charts 初始化
    QApplication a(argc, argv);
    QChart *chart = new QChart();
    chart->addSeries(series);
    chart->createDefaultAxes();
    chart->setTitle("Training Loss Over Epochs");

    QChartView *chartView = new QChartView(chart);
    chartView->setRenderHint(QPainter::Antialiasing);
    chartView->resize(800, 600);
    chartView->show();

    return a.exec();
}

```

But when I include more Qt header files to my project ,an error occured
```
D:\MyLibs\libtorch-win-shared-with-deps-2.5.0+cu124\libtorch\include\ATen\core\ivalue_inl.h(1567,35): error C2059: 语法错误:“<parameter-list>” [D:\study\libTorchProject\cmake-build-release-visual-studio\main.vcxproj]
D:\MyLibs\libtorch-win-shared-with-deps-2.5.0+cu124\libtorch\include\ATen\core\ivalue_inl.h(1567,44): error C2334: “{”的前面有意外标记；跳过明显的函数体 [D:\study\libTorchProject\cmake-build-release-visual-studio\main.vcxproj]
D:\MyLibs\libtorch-win-shared-with-deps-2.5.0+cu124\libtorch\include\ATen\core\ivalue_inl.h(1783,3): error C2760: 语法错误: 此处出现意外的“(”；应为“ID 表达式” [D:\study\libTorchProject\cmake-build-release-visual-studio\main.vcxproj]
D:\MyLibs\libtorch-win-shared-with-deps-2.5.0+cu124\libtorch\include\ATen\core\ivalue_inl.h(1783,3): error C2760: 语法错误: 此处出现意外的“.”；应为“statement” [D:\study\libTorchProject\cmake-build-release-visual-studio\main.vcxproj]
D:\MyLibs\libtorch-win-shared-with-deps-2.5.0+cu124\libtorch\include\ATen\core\ivalue_inl.h(1783,3): message : 已跳过错误恢复:“.” [D:\study\libTorchProject\cmake-build-release-visual-studio\main.vcxproj]
D:\MyLibs\libtorch-win-shared-with-deps-2.5.0+cu124\libtorch\include\ATen\core\ivalue_inl.h(1783,3): error C2760: 语法错误: 此处出现意外的“)”；应为“;” [D:\study\libTorchProject\cmake-build-release-visual-studio\main.vcxproj]
D:\MyLibs\libtorch-win-shared-with-deps-2.5.0+cu124\libtorch\include\ATen\core\ivalue_inl.h(1783,3): error C3878: 语法错误:“expression_statement”后出现意外标记“)” [D:\study\libTorchProject\cmake-build-release-visual-studio\main.vcxproj]
D:\MyLibs\libtorch-win-shared-with-deps-2.5.0+cu124\libtorch\include\ATen\core\ivalue_inl.h(1783,3): error C3878: 语法错误:“statement”后出现意外标记“)” [D:\study\libTorchProject\cmake-build-release-visual-studio\main.vcxproj]
D:\MyLibs\libtorch-win-shared-with-deps-2.5.0+cu124\libtorch\include\ATen\core\ivalue_inl.h(1783,3): error C3878: 语法错误:“selection_statement”后出现意外标记“)” [D:\study\libTorchProject\cmake-build-release-visual-studio\main.vcxproj]
D:\MyLibs\libtorch-win-shared-with-deps-2.5.0+cu124\libtorch\include\ATen\core\ivalue_inl.h(1783,3): message : 已跳过错误恢复:“) ) )” [D:\study\libTorchProject\cmake-build-release-visual-studio\main.vcxproj]
D:\MyLibs\libtorch-win-shared-with-deps-2.5.0+cu124\libtorch\include\ATen\core\ivalue_inl.h(1801,3): error C2760: 语法错误: 此处出现意外的“(”；应为“ID 表达式” [D:\study\libTorchProject\cmake-build-release-visual-studio\main.vcxproj]
D:\MyLibs\libtorch-win-shared-with-deps-2.5.0+cu124\libtorch\include\ATen\core\ivalue_inl.h(1801,3): error C2760: 语法错误: 此处出现意外的“.”；应为“statement” [D:\study\libTorchProject\cmake-build-release-visual-studio\main.vcxproj]
D:\MyLibs\libtorch-win-shared-with-deps-2.5.0+cu124\libtorch\include\ATen\core\ivalue_inl.h(1801,3): message : 已跳过错误恢复:“.” [D:\study\libTorchProject\cmake-build-release-visual-studio\main.vcxproj]
D:\MyLibs\libtorch-win-shared-with-deps-2.5.0+cu124\libtorch\include\ATen\core\ivalue_inl.h(1801,3): error C2760: 语法错误: 此处出现意外的“)”；应为“;” [D:\study\libTorchProject\cmake-build-release-visual-studio\main.vcxproj]
D:\MyLibs\libtorch-win-shared-with-deps-2.5.0+cu124\libtorch\include\ATen\core\ivalue_inl.h(1801,3): error C3878: 语法错误:“expression_statement”后出现意外标记“)” [D:\study\libTorchProject\cmake-build-release-visual-studio\main.vcxproj]
D:\MyLibs\libtorch-win-shared-with-deps-2.5.0+cu124\libtorch\include\ATen\core\ivalue_inl.h(1801,3): error C3878: 语法错误:“statement”后出现意外标记“)” [D:\study\libTorchProject\cmake-build-release-visual-studio\main.vcxproj]
D:\MyLibs\libtorch-win-shared-with-deps-2.5.0+cu124\libtorch\include\ATen\core\ivalue_inl.h(1801,3): error C3878: 语法错误:“selection_statement”后出现意外标记“)” [D:\study\libTorchProject\cmake-build-release-visual-studio\main.vcxproj]
D:\MyLibs\libtorch-win-shared-with-deps-2.5.0+cu124\libtorch\include\ATen\core\ivalue_inl.h(1801,3): message : 已跳过错误恢复:“) ) )” [D:\study\libTorchProject\cmake-build-release-visual-studio\main.vcxproj]

```

After a long time of debug,I have discovered that the errors are caused by qt slots conflicting with libtorch structures with the same name.According to a similar answer from the stackoverflow.

It's a nice way to deal with such problem by this

~~~cpp
#include <LogLevel.hpp>
#include <LogManager.hpp>
#include <QtCharts/QChartView>
#include <QtCharts/QLineSeries>
#include <QtWidgets/QApplication>
#include <iostream>
#undef slots
#include <torch/torch.h>
#include <torch/script.h>
#define slots Q_SLOTS
~~~

In that way,you can build your project successfully.

cc @jbschlosser