[MacPorts] #72064: clang-19 @19.1.7+analyzer: undefined symbol error when using std::make_exception_ptr

[MacPorts]

#72064: clang-19 @19.1.7+analyzer: undefined symbol error when using
std::make_exception_ptr
------------------------+----------------------
 Reporter:  diegonehab  |      Owner:  (none)
     Type:  defect      |     Status:  new
 Priority:  Normal      |  Milestone:
Component:  ports       |    Version:  2.10.5
 Keywords:  haspatch    |       Port:  clang-19
------------------------+----------------------
 There is an issue with clang-18 and clang-19 on macOS < 15.0.

 It has been reported here

 https://github.com/llvm/llvm-project/issues/77653

 and a patch is available here

 https://github.com/h-vetinari/llvm-
 project/commit/95421fd66d41d1cad4eb8d427a038786a524e950

 The problem can be tested with a simple program:

 {{{
 $ cat problem.cpp
 #include <exception>
 #include <iostream>
 #include <stdexcept>

 int main() {
     try {
         std::rethrow_exception(std::make_exception_ptr(std::bad_alloc{}));
     } catch (std::exception &e) {
         std::cout << "Caught exception: '" << e.what() << "'\n";
     }
 }
 }}}

 When compiling and running this program with clang-18 or clang-19, before
 the patch, we get an unexpected missing symbol
 {{{
 clang++-mp-19 -o problem problem.cpp && ./problem
 dyld[55759]: Symbol not found:
 __ZNSt13exception_ptr31__from_native_exception_pointerEPv
   Referenced from: <9E6BCC37-F397-30B0-BE47-0BAAFD863D63> problem
   Expected in:     <EC33CD83-7098-3AD6-82C8-BC03AC81E87B>
 /usr/lib/libc++.1.dylib
 Abort trap: 6

 }}}

 Whereas, after the patch, we get the expected behavior

 {{{
 $ clang++-mp-19 -o problem problem.cpp && ./problem
 Caught exception: 'std::bad_alloc'
 }}}

 The patch provided is for clang-19, but the same modification can be made
 to clang-18.
 The only difference is that, for clang-18, instead of modifying file
 `libcxx/include/__configuration/availability.h`, we should modify file
 `libcxx/include/__availability` like so:

 {{{
 --- __availability      2025-02-14 13:48:16
 +++ __availability.new  2025-02-14 13:48:42
 @@ -103,7 +103,7 @@
  // These macros controls the availability of __cxa_init_primary_exception
  // in the built library, which std::make_exception_ptr might use
  // (see libcxx/include/__exception/exception_ptr.h).
 -#  define _LIBCPP_AVAILABILITY_HAS_INIT_PRIMARY_EXCEPTION 1
 +#  define _LIBCPP_AVAILABILITY_HAS_INIT_PRIMARY_EXCEPTION 0
  #  define _LIBCPP_AVAILABILITY_INIT_PRIMARY_EXCEPTION

  // These macros control the availability of all parts of <filesystem>
 that
 }}}

-- 
Ticket URL: <https://trac.macports.org/ticket/72064>
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