从Qt / C ++调用OCaml：未定义参考

Question

机器/系统/编译器：Surface Pro 3 / VMWare / GCC 5.4.0上的Ubuntu 16.04 64位

我需要从我的Qt应用程序中调用OCaml代码。 我按照install.doc中的说明从源代码构建了OCaml 4.05，但没有编译本机代码编译器。

现在，在Qt中，我有以下代码：

.pro

QT       += core gui

TARGET = Editor
TEMPLATE = app

unix:!macx: LIBS += -L$$PWD/../../../../../../../../../usr/local/lib/ocaml/ -lcamlrun
INCLUDEPATH += $$PWD/../../../../../../../../../usr/local/lib/ocaml
DEPENDPATH += $$PWD/../../../../../../../../../usr/local/lib/ocaml
unix:!macx: PRE_TARGETDEPS += $$PWD/../../../../../../../../../usr/local/lib/ocaml/libcamlrun.a

LIBS += -L$$PWD/../../../../../../../../../usr/lib/x86_64-linux-gnu/ -ldl

SOURCES += \
    main.cpp \
    mainwindow.cpp \

HEADERS += \
    mainwindow.h \

FORMS += \
    mainwindow.ui

RESOURCES += \
    resources.qrc

主窗口

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
extern "C" {
    #include "caml/mlvalues.h"
    #include "caml/callback.h"
}

namespace Ui {
    class MainWindow;
}

class MainWindow : public QMainWindow
{
    ...
};
#endif // MAINWINDOW_H

主窗口

#include "mainwindow.h"

char* callCaml(int arg)
{
    static value* closure = nullptr;
    if (!closure)
        closure = caml_named_value("fct");
    return String_val( caml_callback(*closure, Val_int(arg)) );
}

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent)
    ,ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    caml_main((char**)(&("a.o")));
    msgBox.setText(callCaml(7));
    msgBox.show();
}

OCaml代码

let fct = string_of_int;;

let () = Callback.register "fct" fct;;

编译命令

ocamlc -output-obj -o a.o caml.ml

它给了我一个警告：

a.c: In function ‘caml_startup_exn’:
a.c:2738:10: warning: implicit declaration of function 
‘caml_startup_code_exn’ [-Wimplicit-function-declaration]
return caml_startup_code_exn(caml_code, sizeof(caml_code),
       ^

现在，当我用Qt编译项目时，出现一些错误

/.../usr/local/lib/ocaml//libcamlrun.a(startup.o): In function `caml_main':
startup.c:(.text+0x6ab): undefined reference to `caml_names_of_builtin_cprim'
startup.c:(.text+0x6cf): undefined reference to `caml_names_of_builtin_cprim'
/.../usr/local/lib/ocaml//libcamlrun.a(dynlink.o): In function `caml_build_primitive_table':
dynlink.c:(.text+0x223): undefined reference to `caml_names_of_builtin_cprim'
dynlink.c:(.text+0x242): undefined reference to `caml_names_of_builtin_cprim'
dynlink.c:(.text+0x262): undefined reference to `caml_builtin_cprim'
/.../usr/local/lib/ocaml//libcamlrun.a(dynlink.o): In function `caml_build_primitive_table_builtin':
dynlink.c:(.text+0x3b3): undefined reference to `caml_builtin_cprim'
dynlink.c:(.text+0x3d4): undefined reference to `caml_builtin_cprim'
collect2: error: ld returned 1 exit status

我澄清说我是Linux和Qt的新手。 谢谢您的帮助 ！

Answer 1

我不确定您做错了什么。 虽然不太可能，也许是因为您没有构建本机编译器，所以缺少了一些东西。 无论如何，使用ubuntu提供的ocaml我无法重现您的问题。

因此，我建议运行“ apt-get install ocaml”并使用它来编译源代码。