gdb: Remove compile-related attributes from struct language

The following patch will add a configure option to disable the compile
subsystem at compilation time. To do that, nearly all code that
interfaces with compile should be confined to the compile sub-folder.

This commit is the first step, removing the compile-related method from
the language struct and adding 2 new functions to compile.c that do the
same job in a slightly different way. Adding things to the language
struct is a more extendable way to add support for languages, but
considering compile is quite bit-rotted and questionably supported, I
don't think it will be extended any time soon, and using ifdefs to
handle disabling compile with configure felt like a messier solution.

There should be no visible changes after this commit.

Approved-By: Tom Tromey <tom@tromey.com>

2 files changed, 78 insertions, 3 deletions

diff --git a/gdb/compile/compile-internal.h b/gdb/compile/compile-internal.h
index f4cc9ee..789782d 100644
--- a/gdb/compile/compile-internal.h
+++ b/gdb/compile/compile-internal.h
@@ -80,4 +80,43 @@ private:
   std::string m_object_file;
 };
 
+struct compile_instance;
+
+/* Create a new instance of the C compiler and return it.  This
+   function never returns NULL, but rather throws an exception on
+   failure.  This is suitable for use as the
+   language_defn::get_compile_instance method.  */
+
+extern std::unique_ptr<compile_instance> c_get_compile_context ();
+
+/* Create a new instance of the C++ compiler and return it.  This
+   function never returns NULL, but rather throws an exception on
+   failure.  This is suitable for use as the
+   language_defn::get_compile_instance method.  */
+
+extern std::unique_ptr<compile_instance> cplus_get_compile_context ();
+
+/* This takes the user-supplied text and returns a new bit of code to
+   compile.
+
+   This is used as the compute_program language method; see that
+   for a description of the arguments.  */
+
+extern std::string c_compute_program (compile_instance *inst,
+				      const char *input,
+				      struct gdbarch *gdbarch,
+				      const struct block *expr_block,
+				      CORE_ADDR expr_pc);
+
+/* This takes the user-supplied text and returns a new bit of code to compile.
+
+   This is used as the compute_program language method; see that
+   for a description of the arguments.  */
+
+extern std::string cplus_compute_program (compile_instance *inst,
+					  const char *input,
+					  struct gdbarch *gdbarch,
+					  const struct block *expr_block,
+					  CORE_ADDR expr_pc);
+
 #endif /* GDB_COMPILE_COMPILE_INTERNAL_H */
diff --git a/gdb/compile/compile.c b/gdb/compile/compile.c
index d6bcc1f..43987f9 100644
--- a/gdb/compile/compile.c
+++ b/gdb/compile/compile.c
@@ -527,6 +527,41 @@ print_callback (void *ignore, const char *message)
   gdb_puts (message, gdb_stderr);
 }
 
+/* Helper for compile_to_object, to find the compile context
+   based on the current language.  */
+static std::unique_ptr<compile_instance>
+get_language_compile_context ()
+{
+  switch (current_language->la_language)
+    {
+    case language_c:
+      return c_get_compile_context ();
+    case language_cplus:
+      return cplus_get_compile_context ();
+    default:
+      return {};
+    }
+}
+
+/* Helper for compile_to_object, to call the correct
+   compute_program based on the current language.  */
+static std::string
+compute_program_language (compile_instance *inst, const char *input,
+			  struct gdbarch *gdbarch,
+			  const struct block *block,
+			  CORE_ADDR pc)
+{
+  switch (current_language->la_language)
+    {
+    case language_c:
+      return c_compute_program (inst, input, gdbarch, block, pc);
+    case language_cplus:
+      return cplus_compute_program (inst, input, gdbarch, block, pc);
+    default:
+      gdb_assert_not_reached ("Unsupported language");
+    }
+}
+
 /* Process the compilation request.  On success it returns the object
    and source file names.  On an error condition, error () is
    called.  */
@@ -550,7 +585,8 @@ compile_to_object (struct command_line *cmd, const char *cmd_string,
 
   /* Set up instance and context for the compiler.  */
   std::unique_ptr<compile_instance> compiler
-    = current_language->get_compile_instance ();
+    = get_language_compile_context ();
+
   if (compiler == nullptr)
     error (_("No compiler support for language %s."),
 	   current_language->name ());
@@ -582,8 +618,8 @@ compile_to_object (struct command_line *cmd, const char *cmd_string,
     error (_("Neither a simple expression, or a multi-line specified."));
 
   std::string code
-    = current_language->compute_program (compiler.get (), input, gdbarch,
-					 expr_block, expr_pc);
+    = compute_program_language (compiler.get (), input, gdbarch,
+				expr_block, expr_pc);
   if (compile_debug)
     gdb_printf (gdb_stdlog, "debug output:\n\n%s", code.c_str ());