Fix an inconsistency which prevented `mmc --make' from being able to

Estimated hours taken: 0.2
Branches: main, release

compiler/make.module_target.m:
	Fix an inconsistency which prevented `mmc --make' from being able to
	make `.opt' or `.analysis' files on platforms/grades where `mmc
	--make' is unable to fork().

compiler/make.module_target.m

@@ -309,7 +309,8 @@ build_target(CompilationTask, TargetFile, Imports, TouchedTargetFiles,
     TargetFile = ModuleName - _FileType,
     CompilationTask = Task - TaskOptions,
     (
-        CompilationTask = process_module(compile_to_target_code) - _,
+        CompilationTask = process_module(ModuleTask) - _,
+        forkable_module_compilation_task_type(ModuleTask),
         \+ can_fork
     ->
         % We need a temporary file to pass the arguments to
@@ -378,9 +379,7 @@ build_target_2(ModuleName, process_module(ModuleTask), ArgFileName,
     % it can be difficult to kill the compiler otherwise.
     io.set_output_stream(ErrorStream, OldOutputStream, !IO),
     ( 
-        (ModuleTask = compile_to_target_code
-        ; ModuleTask = make_optimization_interface
-        ; ModuleTask = make_analysis_registry)
+        forkable_module_compilation_task_type(ModuleTask)
     ->
         call_in_forked_process(call_mercury_compile_main([ModuleArg]),
             invoke_mmc(ErrorStream, ArgFileName, AllOptionArgs ++ [ModuleArg]),
@@ -483,6 +482,13 @@ compile_foreign_code_file(ErrorStream, _, Imports,
     compile_target_code.compile_csharp_file(ErrorStream, Imports,
         CSharpFile, DLLFile, Succeeded, !IO).
 
+:- pred forkable_module_compilation_task_type(module_compilation_task_type::in)
+    is semidet.
+
+forkable_module_compilation_task_type(compile_to_target_code).
+forkable_module_compilation_task_type(make_optimization_interface).
+forkable_module_compilation_task_type(make_analysis_registry).
+
 %-----------------------------------------------------------------------------%
 
 :- pred foreign_code_file(module_name::in, pic::in, foreign_language::in,