[m-rev.] for review: Add --error-files-in-subdir option.

[Peter Wang]

Add --error-files-in-subdir option.

Add an option, --error-files-in-subdir, which tells mmc --make
to create .err files under the Mercury subdirectory.

compiler/options.m:
    Add the option.

compiler/file_names.m:
    Replace the existing ext_cur_user_err constructor
    with a constructor, ext_cur_ngs_gs_err_err, in a new category.

    Implement the rules for .err files:

    - When neither of --use-subdirs is enabled, .err files are placed in
      the current directory (as before).

    - When --use-subdirs is enabled, .err files are placed in the
      non-grade-specific Mercury/errs subdirectory.

    - When --use-grade-subdirs is enabled, .err files are placed in a
      grade-specific err subdirectory.

compiler/make.build.m:
compiler/make.file_names.m:
compiler/make.get_module_dep_info.m:
    Conform to above changes.

doc/user_guide.texi:
    Document the option.

NEWS.md:
    Announce change.

diff --git a/NEWS.md b/NEWS.md
index dd483d6fa..13672146c 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -64,6 +64,9 @@ Changes that may break compatibility
   additional options to be passed to the C compiler in order for it to find
   those header files.
 
+* We have added the option `--error-files-in-subdir` to place `.err` files
+  under the `Mercury` subdirectory when using `mmc --make`.
+
 * We have changed the meaning of `mmc --make name.cs`.
 
   The `mmc --make` target `name.cs` now means "build the .cs file
diff --git a/compiler/file_names.m b/compiler/file_names.m
index d28b93b9c..c0ed677c2 100644
--- a/compiler/file_names.m
+++ b/compiler/file_names.m
@@ -198,6 +198,11 @@
             % directory, or into a non-grade-specific subdirectory, or into
             % a grade-specific subdirectory, with search being irrelevant.
 
+    ;       ext_cur_ngs_gs_err(ext_cur_ngs_gs_err)
+            % .err files can be placed into the current directory, or into a
+            % non-grade-specific subdirectory, or into a grade-specific
+            % subdirectory, depending on options.
+
     ;       ext_cur_ngs_gs_java(ext_cur_ngs_gs_java)
             % All extensions using a java-specific set of rules.
             % With respect to directory structure, they use the same sort
@@ -263,7 +268,6 @@
     ;       ext_cur_user_defn_lc                % ".defn_line_counts"
     ;       ext_cur_user_defns                  % ".defns"
     ;       ext_cur_user_depgraph               % ".dependency_graph"
-    ;       ext_cur_user_err                    % ".err"
     ;       ext_cur_user_hlds_dump              % ".hlds_dump"
     ;       ext_cur_user_imports_graph          % ".imports_graph"
     ;       ext_cur_user_lct                    % ".local_call_tree"
@@ -402,6 +406,9 @@
     ;       ext_cur_ngs_gs_misc_used            % ".used"
     ;       ext_cur_ngs_gs_misc_track_flags.    % ".track_flags"
 
+:- type ext_cur_ngs_gs_err
+    --->    ext_cur_ngs_gs_err_err.             % ".err"
+
 :- type ext_cur_ngs_gs_java
             % Java source files generated by the Mercury compiler.
             % The names of these files, and of the directories
@@ -702,6 +709,10 @@ extension_to_string(Globals, Ext) = ExtStr :-
         Ext = ext_cur_ngs_gs(ExtCurNgsGs),
         ext_cur_ngs_gs_extension_dir(Globals, ExtCurNgsGs,
             ExtStr, _SubDirName)
+    ;
+        Ext = ext_cur_ngs_gs_err(ExtCurNgsGsErr),
+        ext_cur_ngs_gs_err_extension_dir(ExtCurNgsGsErr,
+            ExtStr, _SubDirName)
     ;
         Ext = ext_cur_ngs_gs_java(ExtCurNgsGsJava),
         ext_cur_ngs_gs_java_extension_dir(ExtCurNgsGsJava,
@@ -747,7 +758,6 @@ ext_cur_extension(Ext, Str) :-
     ; Ext = ext_cur_user_defn_lc,             Str = ".defn_line_counts"
     ; Ext = ext_cur_user_defns,               Str = ".defns"
     ; Ext = ext_cur_user_depgraph,            Str = ".dependency_graph"
-    ; Ext = ext_cur_user_err,                 Str = ".err"
     ; Ext = ext_cur_user_hlds_dump,           Str = ".hlds_dump"
     ; Ext = ext_cur_user_imports_graph,       Str = ".imports_graph"
     ; Ext = ext_cur_user_lct,                 Str = ".local_call_tree"
@@ -873,6 +883,12 @@ ext_cur_ngs_gs_extension_dir(Globals, Ext, Str, Dir) :-
         Str = ".track_flags", Dir = "track_flags"
     ).
 
+:- pred ext_cur_ngs_gs_err_extension_dir(ext_cur_ngs_gs_err::in,
+    string::out, string::out) is det.
+
+ext_cur_ngs_gs_err_extension_dir(Ext, Str, Dir) :-
+    Ext = ext_cur_ngs_gs_err_err, Str = ".err",  Dir = "errs".
+
 :- pred ext_cur_ngs_gs_java_extension_dir(ext_cur_ngs_gs_java::in,
     string::out, string::out) is det.
 
@@ -919,6 +935,7 @@ module_name_to_base_file_name_no_ext(Ext, ModuleName) = BaseNameNoExt :-
         ; Ext = ext_cur_ngs(_)
         ; Ext = ext_cur_gs(_)
         ; Ext = ext_cur_ngs_gs(_)
+        ; Ext = ext_cur_ngs_gs_err(_)
         ; Ext = ext_cur_ngs_max_cur(_)
         ; Ext = ext_cur_ngs_gs_max_cur(_)
         ; Ext = ext_cur_ngs_gs_max_ngs(_)
@@ -1160,6 +1177,31 @@ ext_to_dir_path(Globals, Search, Ext, DirNames) :-
                 _ExtStr, SubDirName),
             DirNames = make_gs_dir_names(Globals, SubDirName)
         )
+    ;
+        Ext = ext_cur_ngs_gs_err(ExtCurNgsGsErr),
+        globals.lookup_bool_option(Globals, error_files_in_subdir,
+            ErrorFilesInSubdir),
+        (
+            ErrorFilesInSubdir = no,
+            DirNames = []
+        ;
+            ErrorFilesInSubdir = yes,
+            globals.get_subdir_setting(Globals, SubdirSetting),
+            (
+                SubdirSetting = use_cur_dir,
+                DirNames = []
+            ;
+                SubdirSetting = use_cur_ngs_subdir,
+                ext_cur_ngs_gs_err_extension_dir(ExtCurNgsGsErr,
+                    _ExtStr, SubDirName),
+                DirNames = make_ngs_dir_names(SubDirName)
+            ;
+                SubdirSetting = use_cur_ngs_gs_subdir,
+                ext_cur_ngs_gs_err_extension_dir(ExtCurNgsGsErr,
+                    _ExtStr, SubDirName),
+                DirNames = make_gs_dir_names(Globals, SubDirName)
+            )
+        )
     ;
         Ext = ext_cur_ngs_gs_java(ExtCurNgsGsJava),
         % The Java code generator starts every .java file it creates with
diff --git a/compiler/make.build.m b/compiler/make.build.m
index a570d92b3..06b11bfce 100644
--- a/compiler/make.build.m
+++ b/compiler/make.build.m
@@ -275,7 +275,8 @@ setup_for_build_with_module_options(ProgressStream, DefaultOptionTable,
 open_module_error_stream(ProgressStream, Globals, ModuleName, MaybeErrorStream,
         !Info, !IO) :-
     module_name_to_file_name_create_dirs(Globals, $pred,
-        ext_cur(ext_cur_user_err), ModuleName, ErrorFileName, !IO),
+        ext_cur_ngs_gs_err(ext_cur_ngs_gs_err_err), ModuleName, ErrorFileName,
+        !IO),
     ErrorFileModules0 = make_info_get_error_file_modules(!.Info),
     ( if set.contains(ErrorFileModules0, ModuleName) then
         % Write the output to a temporary file first, to allow us to print
diff --git a/compiler/make.file_names.m b/compiler/make.file_names.m
index c93c67a43..32b94c636 100644
--- a/compiler/make.file_names.m
+++ b/compiler/make.file_names.m
@@ -197,7 +197,7 @@ target_type_to_target_extension(Target, TargetExt) :-
         TargetExt = source
     ;
         Target = module_target_errors,
-        TargetExt = extension(ext_cur(ext_cur_user_err))
+        TargetExt = extension(ext_cur_ngs_gs_err(ext_cur_ngs_gs_err_err))
     ;
         Target = module_target_int0,
         TargetExt = extension(ext_cur_ngs(ext_cur_ngs_int_int0))
@@ -263,7 +263,7 @@ date_file_extension(ModuleTargetType, Ext) :-
         % We need a timestamp file for `.err' files because errors are written
         % to the `.err' file even when writing interfaces. The timestamp
         % is only updated when compiling to target code.
-        Ext = ext_cur_ngs_gs(ext_cur_ngs_gs_misc_err_date)
+        Ext = ext_cur_ngs_gs_err(ext_cur_ngs_gs_err_err)
     ;
         ModuleTargetType = module_target_int0,
         Ext = ext_cur_ngs(ext_cur_ngs_int_date_int0)
diff --git a/compiler/make.get_module_dep_info.m b/compiler/make.get_module_dep_info.m
index 23db18fb1..eb61e71f5 100644
--- a/compiler/make.get_module_dep_info.m
+++ b/compiler/make.get_module_dep_info.m
@@ -584,8 +584,8 @@ cannot_write_module_dep_files(Globals, ProgressStream, MESI, ErrorStream,
         Globals, UnredirectGlobals),
     close_module_error_stream_handle_errors(ProgressStream, UnredirectGlobals,
         ModuleName, MESI, ErrorStream, !Info, !IO),
-    module_name_to_file_name(Globals, $pred, ext_cur(ext_cur_user_err),
-        ModuleName, ErrFileName),
+    module_name_to_file_name(Globals, $pred,
+        ext_cur_ngs_gs_err(ext_cur_ngs_gs_err_err), ModuleName, ErrFileName),
     io.file.remove_file(ErrFileName, _, !IO),
 
     ModuleDepMap0 = make_info_get_maybe_module_dep_info_map(!.Info),
diff --git a/compiler/options.m b/compiler/options.m
index 526319d6c..8e13f11ff 100644
--- a/compiler/options.m
+++ b/compiler/options.m
@@ -1143,6 +1143,7 @@
     ;       options_search_directories
     ;       setting_only_use_subdirs
     ;       setting_only_use_grade_subdirs
+    ;       error_files_in_subdir
     ;       std_int_file_not_written_msgs
     ;       search_directories
     ;       intermod_directories
@@ -2132,6 +2133,7 @@ optdef(oc_buildsys, config_file,                        maybe_string(yes(""))).
 optdef(oc_buildsys, options_search_directories,         accumulating(["."])).
 optdef(oc_buildsys, setting_only_use_subdirs,           bool(no)).
 optdef(oc_buildsys, setting_only_use_grade_subdirs,     bool(no)).
+optdef(oc_buildsys, error_files_in_subdir,              bool(no)).
 optdef(oc_buildsys, std_int_file_not_written_msgs,      bool(no)).
 optdef(oc_buildsys, search_directories,                 accumulating(["."])).
 optdef(oc_buildsys, intermod_directories,               accumulating([])).
@@ -3304,6 +3306,7 @@ long_table("config-file",          config_file).
 long_table("options-search-directory", options_search_directories).
 long_table("use-subdirs",          setting_only_use_subdirs).
 long_table("use-grade-subdirs",    setting_only_use_grade_subdirs).
+long_table("error-files-in-subdir", error_files_in_subdir).
 long_table("std-int-file-not-written-msgs",
                     std_int_file_not_written_msgs).
 long_table("search-directory",     search_directories).
@@ -7015,6 +7018,10 @@ options_help_build_system(Stream, !IO) :-
         "\tthe current directory.",
         "\t`--use-grade-subdirs' does not work with Mmake (it does",
         "\twork with `mmc --make').",
+        "--error-files-in-subdir",
+        "\tGenerate .err files under the `Mercury' subdirectory",
+        "\trather than in the current directory.",
+        "\t(This option is only supported by `mmc --make'.)",
 % This is used to eliminate the need for a .int_err_exp file for the
 % -use-subdir case for every test in the tests/invalid_make_int directory.
 %       "--std-int-file-not-written-msgs",
diff --git a/doc/user_guide.texi b/doc/user_guide.texi
index 05e14881f..54151c795 100644
--- a/doc/user_guide.texi
+++ b/doc/user_guide.texi
@@ -10641,6 +10641,18 @@ current directory.
 @samp{--use-grade-subdirs} does not work with Mmake (it does
 work with @samp{mmc --make}).
 
+ at sp 1
+ at item --error-files-in-subdir
+ at findex --error-files-in-subdir
+ at cindex File names
+ at cindex Directories
+ at cindex Subdirectories
+ at cindex @file{Mercury} subdirectory
+Generate @file{.err} files (containing compiler error messages)
+under the @file{Mercury} subdirectory
+rather than in the current directory,
+when using @samp{mmc --make}.
+
 @sp 1
 @item --order-make-by-timestamp
 @findex --order-make-by-timestamp
-- 
2.44.0