Add a C++ wrapper for GCC C plug-in

This patch introduces a new class which wraps the GCC C compile plug-in.
It is a little unfortunate that this all happened in between the time that
GCC moved to C++ and GDB moved to C++, leaving us with an ABI promise to
support a C-like interface.  The hope is to isolate GDB from some of this
should it change in the future.

Broadly, what this does is replace calls like:

  C_CTX (context)->c_ops->operation (C_CTX (context), ...);

with calls that now look like:

  context->c_plugin->operation (...);

This API will be further refined in following patches when struct
compile_instance/compile_c_instance are changed into classes.

gdb/ChangeLog:
        * Makefile.in (HFILES_NO_SRCDIR): Add compile/gcc-c-plugin.h.
        * compile/compile-c-types.c: Define GCC_METHODN macros and include
        gcc-c-fe.def to define C plugin.
        (delete_instance): Delete `c_plugin'.
        (new_compile_instance): Initialize `c_plugin'.
        * compile/compile-c.h: Include gcc_c_plugin.h.
        (struct compile_c_instance) <c_plugin>: New member.
        * gcc-c-plugin.h: New file.
        Update all callers with API change.

1 files changed, 64 insertions, 0 deletions

diff --git a/gdb/compile/gcc-c-plugin.h b/gdb/compile/gcc-c-plugin.h
new file mode 100644
index 0000000..12d422f
--- /dev/null
+++ b/gdb/compile/gcc-c-plugin.h
@@ -0,0 +1,64 @@
+/* GCC C plug-in wrapper for GDB.
+
+   Copyright (C) 2018 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* A class representing the C plug-in.  */
+
+class gcc_c_plugin
+{
+public:
+
+  explicit gcc_c_plugin (struct gcc_c_context *gcc_c)
+    : m_context (gcc_c)
+  {
+  }
+
+  /* Set the oracle callbacks to be used by the compiler plug-in.  */
+  void set_callbacks (gcc_c_oracle_function *binding_oracle,
+		      gcc_c_symbol_address_function *address_oracle,
+		      void *datum)
+  {
+    m_context->c_ops->set_callbacks (m_context, binding_oracle,
+				     address_oracle, datum);
+  }
+
+  /* Returns the interface version of the compiler plug-in.  */
+  int version () const { return m_context->c_ops->c_version; }
+
+#define GCC_METHOD0(R, N) R N () const;
+#define GCC_METHOD1(R, N, A) R N (A) const;
+#define GCC_METHOD2(R, N, A, B) R N (A, B) const;
+#define GCC_METHOD3(R, N, A, B, C) R N (A, B, C) const;
+#define GCC_METHOD4(R, N, A, B, C, D) R N (A, B, C, D) const;
+#define GCC_METHOD5(R, N, A, B, C, D, E) R N (A, B, C, D, E) const;
+#define GCC_METHOD7(R, N, A, B, C, D, E, F, G) R N (A, B, C, D, E, F, G) const;
+
+#include "gcc-c-fe.def"
+
+#undef GCC_METHOD0
+#undef GCC_METHOD1
+#undef GCC_METHOD2
+#undef GCC_METHOD3
+#undef GCC_METHOD4
+#undef GCC_METHOD5
+#undef GCC_METHOD7
+
+private:
+  /* The GCC C context.  */
+  struct gcc_c_context *m_context;
+};