desktop-packages team mailing list archive

[Anders Kaseorg <andersk@xxxxxxx>]

Public bug reported:

$ cat foo.cc
#include <string>
std::string hello = "Hello, world!\n";
$ cat bar.cc
#include <string>
#include <iostream>
extern std::string hello;
int main() {
    std::cout << hello;
    return 0;
}
$ g++ -c foo.cc && g++ foo.o bar.cc && ./a.out
Hello, world!
$ clang++ -c foo.cc && clang++ foo.o bar.cc && ./a.out
Hello, world!
$ g++ -c foo.cc && clang++ foo.o bar.cc && ./a.out
/tmp/bar-34fb23.o: In function `main':
bar.cc:(.text+0x14): undefined reference to `hello'
clang: error: linker command failed with exit code 1 (use -v to see invocation)
$ clang++ -c foo.cc && g++ foo.o bar.cc && ./a.out
/tmp/ccqU38Mh.o: In function `main':
bar.cc:(.text+0x5): undefined reference to `hello[abi:cxx11]'
collect2: error: ld returned 1 exit status

In practice, this means that many programs using C++ libraries other
than libstdc++ fail to compile with clang++. For example, mosh fails
with undefined references to google::protobuf::internal::empty_string_,
google::protobuf::MessageLite::InitializationErrorString() const, and
google::protobuf::MessageLite::SerializeAsString() const.

** Affects: llvm
     Importance: Unknown
         Status: Unknown

** Affects: llvm-toolchain-3.6 (Ubuntu)
     Importance: Undecided
         Status: New

** Bug watch added: llvm.org/bugs/ #23529
   http://llvm.org/bugs/show_bug.cgi?id=23529

** Also affects: llvm via
   http://llvm.org/bugs/show_bug.cgi?id=23529
   Importance: Unknown
       Status: Unknown

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https://bugs.launchpad.net/bugs/1488254

Title:
  clang++ no longer ABI-compatible with g++

Status in LLVM:
  Unknown
Status in llvm-toolchain-3.6 package in Ubuntu:
  New

Bug description:
  $ cat foo.cc
  #include <string>
  std::string hello = "Hello, world!\n";
  $ cat bar.cc
  #include <string>
  #include <iostream>
  extern std::string hello;
  int main() {
      std::cout << hello;
      return 0;
  }
  $ g++ -c foo.cc && g++ foo.o bar.cc && ./a.out
  Hello, world!
  $ clang++ -c foo.cc && clang++ foo.o bar.cc && ./a.out
  Hello, world!
  $ g++ -c foo.cc && clang++ foo.o bar.cc && ./a.out
  /tmp/bar-34fb23.o: In function `main':
  bar.cc:(.text+0x14): undefined reference to `hello'
  clang: error: linker command failed with exit code 1 (use -v to see invocation)
  $ clang++ -c foo.cc && g++ foo.o bar.cc && ./a.out
  /tmp/ccqU38Mh.o: In function `main':
  bar.cc:(.text+0x5): undefined reference to `hello[abi:cxx11]'
  collect2: error: ld returned 1 exit status

  In practice, this means that many programs using C++ libraries other
  than libstdc++ fail to compile with clang++. For example, mosh fails
  with undefined references to
  google::protobuf::internal::empty_string_,
  google::protobuf::MessageLite::InitializationErrorString() const, and
  google::protobuf::MessageLite::SerializeAsString() const.

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