This issue has also been discussed on the comp.lang.ada newsgroup, see [1] for details.
Signal-handling using a protected type as handler is not possible any more if an application includes the Ada.Real_Time.Timing_Events package. It's not necessary to actually use types from the package, including it is enough to break signal handling. I wrote a small reproducer to illustrate the problem, the files are attached. The protected object Signal_Handler defined in the package Handlers is used as a signal handler, which can be attached to a specific interrupt/signal. The Signal_Handler type is used in the small test application implemented as procedure Interrupt_Problem in the interrupt_problem.adb file. As expected, when sending SIGTERM (or other signals) to the running 'Interrupt_Problem' process "Interrupt received ..." is displayed. When the Ada.Real_Time.Timing_Events package is included, this mechanism breaks. The signal handler is not invoked any more when signals are sent to a running 'Interrupt_Problem' process, the Handler.Wait entry is not triggered. The problem seems to have various characteristics on different architectures, see the newsgroup thread [1]. gnatgcc -v output: Using built-in specs. Target: i486-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Debian 4.3.2-1.1' --with-bugurl=file:///usr/share/doc/gcc-4.3/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --enable-nls --with-gxx-include-dir=/usr/include/c++/4.3 --program-suffix=-4.3 --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --enable-mpfr --enable-targets=all --enable-cld --enable-checking=release --build=i486-linux-gnu --host=i486-linux-gnu --target=i486-linux-gnu Thread model: posix gcc version 4.3.2 (Debian 4.3.2-1.1) -- [1] - http://groups.google.com/group/comp.lang.ada/browse_thread/thread/e69505d5161d7d41 -- Summary: Including Ada.Real_Time.Timing_Events breaks signal handling Product: gcc Version: 4.3.2 Status: UNCONFIRMED Severity: normal Priority: P3 Component: ada AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: reet at codelabs dot ch GCC build triplet: i486-linux-gnu GCC host triplet: i486-linux-gnu GCC target triplet: i486-linux-gnu http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40285
