Autotools 交叉编译和生成源 [英] Autotools cross compilation and generated sources

问题描述

我正在尝试使用自动工具(autoconf、automake、libtool)作为构建系统来创建库.库必须是可交叉编译的，但构建它的步骤之一是在整个过程中通过从源代码构建的可执行文件生成源代码.

I'm trying to create a library using autotools (autoconf, automake, libtool) as a build system. The library has to be cross-compileable, but one of the steps of building it is to generate sources by executable built from sources during the whole process.

问题是我无法使用 automake 的系统来构建中间二进制文件，因为当它进行交叉编译时，它不会在--build"上运行以生成源.

The problem is I cannot use automake's system to build the intermediate binary because when it's cross compile it wouldn't run on '--build' to generate sources.

解决这个问题的一种方法是创建单独的 autools 项目来构建中间二进制文件，但我想避免它，因为中间可执行文件和最终库有许多常见的头文件和其他数据"文件，所以我想将它保留在一个地方，除了那些中间二进制文件应该是noinst".

One way to work this around it to create separate autools project to build intermediate binaries but I want to avoid it because there are many headers and other "data" files common for intermediate executable and final library so I want to keep it in one place, besides those intermediate binaries should be "noinst".

有没有其他方法可以使其正常工作并保持可移植性?我试图使用 ax_prog_cxx_for_build 但我找不到 --build交叉编译时EXEEXT.

Is there any other way to make it work properly and retain portability? I was trying to use ax_prog_cxx_for_build but I couldn't find --build's EXEEXT when cross compiling.

这是一个问题的例子，只是为了说明我的问题:

Here's an example of the issue just to illustrate my problem:

#                                               -*- Autoconf -*-
# Process this file with autoconf to produce a configure script.

AC_PREREQ([2.68])
AC_INIT([libfoobar], [0.1.0], [<NOBUGS>])
AM_INIT_AUTOMAKE([foreign])
LT_INIT

AC_CONFIG_SRCDIR([src/bar.cpp])
AC_CONFIG_HEADERS([config.h])
AC_CONFIG_MACRO_DIR([m4])
AC_CONFIG_FILES([Makefile
                 src/Makefile])

# Checks for programs.
AC_PROG_CXX

# Checks for libraries.

# Checks for header files.

# Checks for typedefs, structures, and compiler characteristics.

# Checks for library functions.

AC_OUTPUT

Makefile.am

ACLOCAL_AMFLAGS = -I m4

SUBDIRS = src

src/Makefile.am

bin_PROGRAMS = bar
lib_LTLIBRARIES = libfoo.la

noinst_bar_SOURCES = bar.cpp

libfoo_la_SOURCES = foo.cpp
nodist_libfoo_la_SOURCES = foobar.h

BUILT_SOURCES: foobar.h

foobar.h: bar$(EXEEXT) Makefile
    ./$< >$@
CLEANFILES = foobar.h

src/foo.cpp

#include "foobar.h"

extern "C" int foo() {
    return foobar_value;
}

src/bar.cpp

#include <iostream>

int main() {
    std::cout << "#ifndef FOOBAR_H" << std::endl;
    std::cout << "#define FOOBAR_H" << std::endl;
    std::cout << std::endl;
    std::cout << "static const int foobar_value = 0xdeadbeef;" << std::endl;
    std::cout << std::endl;
    std::cout << "#endif" << std::endl;
}

推荐答案

如果您使用 AX_PROG_CXX_FOR_BUILD，那么你应该使用的EXEEXT 是BUILD_EXEEXT，它定义在宏AX_PROG_CC_FOR_BUILD(AX_PROG_CXX_FOR_BUILD 需要).将 EXEEXT 用于由 CXX_FOR_BUILD 构建的东西将是一个错误，因为这是宿主工具链的扩展.因此，在这种情况下，您将需要更多类似的东西:

If you're using AX_PROG_CXX_FOR_BUILD, then the EXEEXT you should be using is BUILD_EXEEXT which is defined in the macro AX_PROG_CC_FOR_BUILD (which AX_PROG_CXX_FOR_BUILD requires). Using EXEEXT for something built by CXX_FOR_BUILD would be an error, since that's the extension for the host toolchain. So in this case you'll need something more like:

configure.ac

#                                               -*- Autoconf -*-
# Process this file with autoconf to produce a configure script.

AC_PREREQ([2.68])
AC_INIT([libfoobar], [0.1.0], [<NOBUGS>])
AM_INIT_AUTOMAKE([foreign])
LT_INIT
AC_CANONICAL_BUILD
AC_CANONICAL_HOST

AC_CONFIG_SRCDIR([src/bar.cpp])
AC_CONFIG_HEADERS([config.h])
AC_CONFIG_MACRO_DIR([m4])
AC_CONFIG_FILES([Makefile
                 src/Makefile])

# Checks for programs.
AC_PROG_CXX
AX_PROG_CXX_FOR_BUILD

# Checks for libraries.

# Checks for header files.

# Checks for typedefs, structures, and compiler characteristics.

# Checks for library functions.

AC_OUTPUT

src/Makefile.am

noinst_PROGRAMS = bar
lib_LTLIBRARIES = libfoo.la

bar_SOURCES = bar.cpp

LINK_FOR_BUILD.cpp = $(CXX_FOR_BUILD) $(CXXFLAGS_FOR_BUILD) $(CPPFLAGS_FOR_BUILD) $(LDFLAGS_FOR_BUILD) $(TARGET_ARCH_FOR_BUILD)

bar$(BUILD_EXEEXT) : $(bar_OBJECTS)
            $(LINK_FOR_BUILD.cpp) $^ $(LOADLIBES_FOR_BUILD) $(LDLIBS_FOR_BUILD) -o $@

$(bar_OBJECTS) : CC=$(CC_FOR_BUILD)
$(bar_OBJECTS) : CXXFLAGS=$(CXXFLAGS_FOR_BUILD)
$(bar_OBJECTS) : CPPFLAGS=$(CPPFLAGS_FOR_BUILD)

libfoo_la_SOURCES = foo.cpp
nodist_libfoo_la_SOURCES = foobar.h

BUILT_SOURCES: foobar.h

foobar.h: bar$(BUILD_EXEEXT) Makefile
    ./$< >$@
CLEANFILES = foobar.h

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