[m-rev.] for review: stand-alone interface and non-C grades

[Julien Fischer]

For review by anyone.


Stand-alone interfaces and non-C grades.

Clarify the situation with stand-alone interfaces and non-C grades.  The
documentation currently says that they are not currently supported for the
non-C grades, which is inaccurate.  They are not actually required for the Java
and C# backends.  The may however be needed for Erlang.

doc/user_guide.texi:
 	Stand-alone interface are *not* required if the target language is
 	C# or Java.

compiler/mercury_compiler.m:
 	Fix an XXX: generate a more accurate error message if
 	'--generate-standalone-interface' is used with one of the
 	non-C target languages.

Julien

diff --git a/compiler/mercury_compile.m b/compiler/mercury_compile.m
index acf502e..f6ddfc6 100644
--- a/compiler/mercury_compile.m
+++ b/compiler/mercury_compile.m
@@ -471,11 +471,18 @@ main_after_setup(DetectedGradeFlags, OptionVariables, OptionArgs, Args,
              ( Target = target_il
              ; Target = target_csharp
              ; Target = target_java
-            ; Target = target_erlang
              ),
-            % XXX this message is nonsense.  These targets do
-            % not require standalone interfaces since they natively
-            % provide an equivalent mechanism.
+            NotRequiredMsg = [
+                words("Error:"),
+                quote("--generate-standalone-interface"),
+                words("is not required for target language"),
+                words(compilation_target_string(Target)),
+                suffix(".")
+            ],
+            write_error_pieces_plain(Globals, NotRequiredMsg, !IO),
+            io.set_exit_status(1, !IO)
+        ;
+            Target = target_erlang,
              NYIMsg = [
                  words("Sorry,"),
                  quote("--generate-standalone-interface"),
diff --git a/doc/user_guide.texi b/doc/user_guide.texi
index 20f7f64..3f79b20 100644
--- a/doc/user_guide.texi
+++ b/doc/user_guide.texi
@@ -10959,8 +10959,15 @@ the argument of @samp{--generate-standalone-interface} option.
  @c XXX Mention that stand-alone interfaces work with debugging or
  @c (deep) profiling?

-Stand-alone interfaces are not currently supported for target languages
-other than C.
+Stand-alone interfaces are @emph{not} required if the target language is Java
+or C#.
+For those target languages the Mercury runtime will be automatically
+initialised when the classes or library assemblies containing code generated
+by the Mercury compiler are loaded.
+
+Stand-alone interfaces are not currently supported when the target language is
+Erlang.
+
  For an example of using a stand-alone interface see the
  @samp{samples/c_interface/standalone_c} directory in the Mercury distribution.