Implement the error handling proposals from February 2022 on the
mercury-users list, and August 2022 on the mercury-reviews list.
We add io.system_error to the public interface of io.m
and document what its foreign representation is for each backend.
We allow io.error to optionally contain an io.system_error value,
and provide predicates to retrieve the io.system_error from an io.error.
The user may then inspect the system error via foreign code.
We also provide a predicate that takes an io.error and returns a name
for the system error it contains (if any). This makes it relatively easy
for Mercury programs to check for specific error conditions.
By returning platform-specific (actually, implementation-dependent)
error names, we are pushing the responsibility of mapping strings to
error conditions onto the application programmer. On the other hand, it
is not practical for us to map all possible system-specific error codes
to some common set of values. We could do it for a small set of common
error codes/exceptions, perhaps.
The standard library will construct io.error values containing
io.system_errors. However, we do not yet provide a facility for user
code to do the same.
library/io.m:
Move io.system_error to the public interface.
Change the internal representation of io.error to support containing
a io.system_error. An io.system_error may originate from an errno
value or a Windows system error code; the constructor distinguishes
those cases.
Add predicates to retrieve a system_error from io.error.
Add predicate to return the name of the system error in an io.error.
Replace make_err_msg with make_io_error_from_system_error.
Replace make_maybe_win32_err_msg with
make_io_error_from_maybe_win32_error.
Delete ML_make_err_msg and ML_make_win32_err_msg macros.
browser/listing.m:
library/bitmap.m:
library/dir.m:
library/io.call_system.m:
library/io.environment.m:
library/io.file.m:
library/io.text_read.m:
mdbcomp/program_representation.m:
Conform to changes.
Leave comments for followup work.
tools/generate_errno_name:
tools/generate_windows_error_name:
Add scripts to generate mercury_errno_name.c and
mercury_windows_error_name.c.
runtime/Mmakefile:
runtime/mercury_errno_name.c:
runtime/mercury_errno_name.h:
runtime/mercury_windows_error_name.c:
runtime/mercury_windows_error_name.h:
Add MR_errno_name() and MR_win32_error_name() functions,
used by io.m to convert error codes to string names.
tests/hard_coded/null_char.exp:
Update expected output.
library/io.environment.m:
library/io.file.m:
Fully qualify entities in foreign_procs that may be inlined
across module boundaries.
library/io.m:
Move the definition of the private class StreamPipe from here ...
library/io.call_system.m:
... to here where it is actually used.
library/io.environment.m:
Fully qualify a call to a foreign_exported Mercury predicate in order to
avoid an error if its containing foreign_proc is inlined across module
boundaries.
library/io.file.m:
Fully qualify some foreign_exported enum constants for the same reason.
Add missing using directives.
Add a missing definition needed by Mono.
library/io.m:
Delete trailing whitespace.
Delete code moved to io.file.m.
library/io.call_system.m:
library/io.m:
As above.
browser/listing.m:
compiler/process_util.m:
Conform to the change above.
library/io.environment.m:
Delete stray ZZZ.
library/io.call_system.m:
Move the code in the "system access predicates" section of io.m
to this new module.
library/io.environment.m:
Move the predicates dealing with environment variables in io.m
to this new module.
library/io.m:
Delete the code moved to the new modules.
Leave behind in io.m "forwarding predicates", predicates that do nothing
except call the moved predicates in the new modules, to provide backward
compatibility. But do mark the forwarding predicates as obsolete,
to tell people to update their (at their leisure, since the obsoleteness
warning can be turned off).
Also leave behind in io.m the definitions of the types used
by some parameters of some of the moved predicates.
library/MODULES_DOC:
List the new modules among the documented modules.
library/library.m:
List the new modules, including io.file.m (added in a previous change)
among the documented standard library modules.
NEWS:
Announce the changes.
browser/browse.m:
browser/interactive_query.m:
compiler/fact_table.m:
compiler/handle_options.m:
compiler/make.module_target.m:
compiler/mercury_compile_main.m:
compiler/module_cmds.m:
compiler/optimize.m:
compiler/options_file.m:
deep_profiler/conf.m:
deep_profiler/mdprof_cgi.m:
deep_profiler/mdprof_test.m:
library/io.file.m:
mdbcomp/trace_counts.m:
ssdb/ssdb.m:
tests/general/environment.m:
tests/hard_coded/closeable_channel_test.m:
tests/hard_coded/setenv.m:
tests/hard_coded/system_sort.m:
Call the moved predicates directly in their new modules,
not indirectly through io.m.
