14.12.2 Bugs Fixed

• Compiler: pathological case bug.
• SP_raise_exception() and SP_fail() would sometimes not be handled correctly when foreign code called Prolog recursively. Now, exceptions are preserved in callbacks from foreign functions.
• format/[2,3] et al. used to treat all non-reserved exceptions as consistency errors. Now non-error exceptions, i.e. not error/2, are passed on to the caller.

  Reserved exceptions from the goal invoked for the ‘~@’ spec are now passed on to the caller. This ensures that timeout:time_out/3 and other interrupts will be able to terminate such a goal.

• Source-linked debugging could sometimes indicate the wrong line of code.
• see/1 and tell/1 would not accept stream objects.
• Multiple issues when changing one of the standard streams (user_input, user_output, and user_error) with set_prolog_flag/2. These issues affected stream_property/2, current_stream/3 and could lead to access to freed memory during close/[1,2].
• stream_property/2 no longer returns an eol/1 property for binary streams.
• SICStus no longer sets any environment variables. Setting environment variables has undefined behavior in multi-threaded processes, especially on UNIX-like operating systems. Symptoms included segmentation fault in getenv() if several SICStus runtimes were initialized at the same time in different threads of the same process. See below for the new concept “System Properties”, which has replaced most uses of environment variables.
• SP_event() handlers are no longer allowed to run when the SICStus runtime calls Prolog code in contexts where their result, e.g. failure or exception, cannot be propagated to the caller. This could potentially lead to timeouts and other asynchronous events being ignored.
• If open/4 fails to open a file for writing, then it will now generate a permission_error, as prescribed by the ISO Prolog standard. It used to raise a system error.
• The open/4 option if_exists(generate_unique_name) would sometimes access and use freed memory when generating a new file name.
• SP_get_list_n_codes() would report more bytes written than what was actually written.
• Goals run as part of initialization/1 now have access to the load context (prolog_load_context/2), similarly to how other goals appearing in directives are treated. This also means that absolute_file_name/[2,3] will use the location saved in the load context as default directory.

  Please note: The change in default directory for absolute_file_name/[2,3], and thus open/[3,4] et al., is an incompatible change that may affect some programs. Old code that depends on the current directive may need to be updated to explicitly call file_systems:current_directory/1.

  If the old code looked like:

  %% Pre 4.1.0 version
  :- initialization read_some_file('myfile').
  

  then it can be rewritten as follows (which will also work in older versions of SICStus Prolog):

  %% >= 4.1.0 version
  :- use_module(library(file_systems), [current_directory/1]).
  :- initialization  current_directory(CWD),
                     absolute_file_name('myfile', Absfile,
                                        [relative_to(CWD)]),
                     read_some_file(Absfile).
  

• prolog_load_context(stream,S) will now only succeed when compiling or consulting the code. It used to return a closed stream instead of failing.
• library(clpfd):
  • - nvalue/2 would miss solutions.
  • - element/3 did not maintain arc-consistency in its first argument.
  • - Undefined behavior when combining CLPFD with frozen goals, now made consistent.
  • - Strength reduction problem for some propositional constraints.
  • - Missing meta-predicate declaration for fd_global/[3,4].
  • - Some data was not protected from garbage collection.
  • - Output of copy_term/3 was sometimes incomplete or not correct.
• Exported, non-existing predicates: file_systems:file_must_exist/[1,2], lists3:nextto/3, lists3:nth/4.
• The directory listing predicates in library(file_systems), e.g. directory_member_of_directory/2, no longer fail if they encounter a broken symbolic link.
• library(process): Process creation would leak small amounts of memory.
• library(random): maybe/0 would always fail the first time.
• A typo prevented library(detcheck) from working.
• The spdet tool now tries the extension ‘.pro’ in addition to ‘.pl’. Other minor improvements.
• library(xref): slightly more precise.
• sockets:socket_client_open/3 would give system error with SPIO_E_HOST_NOT_FOUND when connecting to localhost on some platforms.
• system:environ/2 would leak memory if called with a variable as first argument.
• The Emacs mode did not work in recent Emacsen.