Question

我在Ubuntu 16.04中安装了GNUStep和gobjc。我可以像这样编译Objective-C代码：

gcc codefile.m `gnustep-config --objc-flags` -lobjc -lgnustep-base -o codefile

但我想在GCC中编译Objective-C ++代码。我该怎么办？

Answer 1

Documentation of objc/objc++ dialects in GCC您的version of gcc / gobjc不列出特定选项以选择方言变体。

只需使用标准文件扩展名＆＃34; .mm＆＃34;或＆＃34; .M＆＃34; （另外，您可以将gcc替换为g++以自动将C ++库添加到链接阶段;两个变体都未经测试）：

gcc codefile.mm `gnustep-config --objc-flags` -lobjc -lgnustep-base -o codefile
g++ codefile.mm `gnustep-config --objc-flags` -lobjc -lgnustep-base -o codefile

ObjC ++是"simply source code that mixes Objective-C classes and C++ classes"

Gcc将根据文件扩展名选择模式，有.m的Objective-C和.mm / .M的Objective-C ++，有大量的文件扩展名和相应的语言模式： https://github.com/gcc-mirror/gcc/blob/gcc-4_7_4-release/gcc/gcc.c#L913

static const struct compiler default_compilers[] =
{
  /* Add lists of suffixes of known languages here.  If those languages
     were not present when we built the driver, we will hit these copies
     and be given a more meaningful error than "file not used since
     linking is not done".  */
  {".m",  "#Objective-C", 0, 0, 0}, {".mi",  "#Objective-C", 0, 0, 0},
  {".mm", "#Objective-C++", 0, 0, 0}, {".M", "#Objective-C++", 0, 0, 0},
  {".mii", "#Objective-C++", 0, 0, 0},
 . . .
  /* Next come the entries for C.  */
  {".c", "@c", 0, 0, 1},

-x还有g++选项，允许参数为＃34; objective-c ++＆＃34;手动选择语言方言（gcc -x objective-c++ ...或g++ -x objective-c++）： https://github.com/gcc-mirror/gcc/blob/1cb6c2eb3b8361d850be8e8270c597270a1a7967/gcc/cp/g%2B%2Bspec.c#L167

case OPT_x:
 . . . 
      && (strcmp (arg, "c++") == 0
      || strcmp (arg, "c++-cpp-output") == 0
      || strcmp (arg, "objective-c++") == 0

记录于https://gcc.gnu.org/onlinedocs/gcc/Overall-Options.html

 -x language
明确指定以下输入文件的语言（而不是让编译器根据文件名后缀选择默认值）。此选项适用于所有后续输入文件，直到下一个-x选项。语言的可能值为：
      c  . . .  c++ . . .
      objective-c  objective-c-header  objective-c-cpp-output
      objective-c++ objective-c++-header objective-c++-cpp-output

如何在GCC中编译Objective C ++？

1 个答案: