[PATCH 4/6] Some symbol-related Python safety fixes

[Tom Tromey <tom@tromey.com>]

This makes some symbol-related Python safety fixes, with a goal of
simplifying some code and removing some FIXMEs.

A method can now return a 'symbol *'; this will be handled by a new
to_python overload.

A safe wrapper is now provided for symbol_to_symbol_object.
---
 gdb/python/py-frame.c        |  9 +++----
 gdb/python/py-safety.h       | 10 ++++++++
 gdb/python/py-symbol.c       | 59 ++++++++++++--------------------------------
 gdb/python/python-internal.h |  9 ++++---
 4 files changed, 34 insertions(+), 53 deletions(-)

diff --git a/gdb/python/py-frame.c b/gdb/python/py-frame.c
index 58b08c3d454..e4dd9e9252e 100644
--- a/gdb/python/py-frame.c
+++ b/gdb/python/py-frame.c
@@ -103,7 +103,7 @@ struct frame_object : public PyObject
 
   /* Implementation of gdb.Frame.function (self) -> gdb.Symbol.
      Returns the symbol for the function corresponding to this frame.  */
-  gdbpy_ref<> function ();
+  symbol *function ();
 
   /* Implementation of gdb.Frame.older (self) -> gdb.Frame.
      Returns the frame immediately older (outer) to this frame, or None if
@@ -267,7 +267,7 @@ frame_object::block ()
 }
 
 
-gdbpy_ref<>
+symbol *
 frame_object::function ()
 {
   frame_info_ptr frame = require_frame ();
@@ -277,10 +277,7 @@ frame_object::function ()
   gdb::unique_xmalloc_ptr<char> funname
     = find_frame_funname (frame, &funlang, &sym);
 
-  if (sym != nullptr)
-    return symbol_to_symbol_object (sym);
-
-  return py_none ();
+  return sym;
 }
 
 /* Convert a frame_info struct to a Python Frame object.
diff --git a/gdb/python/py-safety.h b/gdb/python/py-safety.h
index 0653947fe90..0d5a45e72fd 100644
--- a/gdb/python/py-safety.h
+++ b/gdb/python/py-safety.h
@@ -120,6 +120,16 @@ to_python (gdbpy_ref<> &&value)
   return value.release ();
 }
 
+static inline PyObject *
+to_python (symbol *sym)
+{
+  if (sym == nullptr)
+    return py_none ().release ();
+  /* Note that currently this might return NULL on error; but that is
+     fine in this context.  */
+  return symbol_to_symbol_object (sym).release ();
+}
+
 /* An instantiation of this function is used when calling a gdb method
    from Python.  It accepts some number of arguments (normally
    gdbpy_borrowed_ref or gdbpy_opt_borrowed_ref), and then calls the
diff --git a/gdb/python/py-symbol.c b/gdb/python/py-symbol.c
index b5dcca5658d..0d4515643f5 100644
--- a/gdb/python/py-symbol.c
+++ b/gdb/python/py-symbol.c
@@ -289,6 +289,15 @@ symbol_to_symbol_object (struct symbol *sym)
   return gdbpy_ref<> (sym_obj);
 }
 
+gdbpy_ref<>
+safe_symbol_to_symbol_object (symbol *sym)
+{
+  gdbpy_ref<> result = symbol_to_symbol_object (sym);
+  if (result == nullptr)
+    throw gdb_python_exception ();
+  return result;
+}
+
 /* Return the symbol that is wrapped by this symbol object.  */
 struct symbol *
 symbol_object_to_symbol (PyObject *obj)
@@ -363,14 +372,8 @@ gdbpy_lookup_symbol (gdbpy_borrowed_ref<> args, gdbpy_opt_borrowed_ref<> kw)
   gdbpy_ref<> ret_tuple = gdbpy_tuple_new (2);
 
   gdbpy_ref<> sym_obj;
-  if (symbol)
-    {
-      sym_obj = symbol_to_symbol_object (symbol);
-      /* FIXME: Python safety.  symbol_to_symbol_object should throw,
-	 but the other callers aren't ready for this yet.  */
-      if (sym_obj == nullptr)
-	throw gdb_python_exception ();
-    }
+  if (symbol != nullptr)
+    sym_obj = safe_symbol_to_symbol_object (symbol);
   else
     sym_obj = py_none ();
 
@@ -386,7 +389,7 @@ gdbpy_lookup_symbol (gdbpy_borrowed_ref<> args, gdbpy_opt_borrowed_ref<> kw)
 /* Implementation of
    gdb.lookup_global_symbol (name [, domain]) -> symbol or None.  */
 
-gdbpy_ref<>
+symbol *
 gdbpy_lookup_global_symbol (gdbpy_borrowed_ref<> args,
 			    gdbpy_opt_borrowed_ref<> kw)
 {
@@ -398,27 +401,13 @@ gdbpy_lookup_global_symbol (gdbpy_borrowed_ref<> args,
 				      &domain);
 
   domain_search_flags flags = from_scripting_domain (domain);
-  struct symbol *symbol = lookup_global_symbol (name, NULL, flags).symbol;
-
-  gdbpy_ref<> sym_obj;
-  if (symbol != nullptr)
-    {
-      /* FIXME: Python safety.  symbol_to_symbol_object should throw,
-	 but the other callers aren't ready for this yet.  */
-      sym_obj = symbol_to_symbol_object (symbol);
-      if (sym_obj == nullptr)
-	throw gdb_python_exception ();
-    }
-  else
-    sym_obj = py_none ();
-
-  return sym_obj;
+  return lookup_global_symbol (name, NULL, flags).symbol;
 }
 
 /* Implementation of
    gdb.lookup_static_symbol (name [, domain]) -> symbol or None.  */
 
-gdbpy_ref<>
+symbol *
 gdbpy_lookup_static_symbol (gdbpy_borrowed_ref<> args,
 			    gdbpy_opt_borrowed_ref<> kw)
 {
@@ -455,19 +444,7 @@ gdbpy_lookup_static_symbol (gdbpy_borrowed_ref<> args,
   if (symbol == nullptr)
     symbol = lookup_static_symbol (name, flags).symbol;
 
-  gdbpy_ref<> sym_obj;
-  if (symbol != nullptr)
-    {
-      /* FIXME: Python safety.  symbol_to_symbol_object should throw,
-	 but the other callers aren't ready for this yet.  */
-      sym_obj = symbol_to_symbol_object (symbol);
-      if (sym_obj == nullptr)
-	throw gdb_python_exception ();
-    }
-  else
-    sym_obj = py_none ();
-
-  return sym_obj;
+  return symbol;
 }
 
 /* Implementation of
@@ -512,11 +489,7 @@ gdbpy_lookup_static_symbols (gdbpy_borrowed_ref<> args,
 
 	    if (symbol != nullptr)
 	      {
-		/* FIXME: Python safety.  symbol_to_symbol_object should throw,
-		   but the other callers aren't ready for this yet.  */
-		gdbpy_ref<> sym_obj = symbol_to_symbol_object (symbol);
-		if (sym_obj == nullptr)
-		  throw gdb_python_exception ();
+		gdbpy_ref<> sym_obj = safe_symbol_to_symbol_object (symbol);
 		gdbpy_list_append (return_list, sym_obj);
 	      }
 	  }
diff --git a/gdb/python/python-internal.h b/gdb/python/python-internal.h
index b57f3b0123d..5515820411b 100644
--- a/gdb/python/python-internal.h
+++ b/gdb/python/python-internal.h
@@ -534,10 +534,10 @@ const char *gdbpy_frame_stop_reason_string (gdbpy_borrowed_ref<> args,
 					    gdbpy_opt_borrowed_ref<> kw);
 gdbpy_ref<> gdbpy_lookup_symbol (gdbpy_borrowed_ref<> args,
 				 gdbpy_opt_borrowed_ref<> kw);
-gdbpy_ref<> gdbpy_lookup_global_symbol (gdbpy_borrowed_ref<> args,
-					gdbpy_opt_borrowed_ref<> kw);
-gdbpy_ref<> gdbpy_lookup_static_symbol (gdbpy_borrowed_ref<> args,
-					gdbpy_opt_borrowed_ref<> kw);
+symbol *gdbpy_lookup_global_symbol (gdbpy_borrowed_ref<> args,
+				    gdbpy_opt_borrowed_ref<> kw);
+symbol *gdbpy_lookup_static_symbol (gdbpy_borrowed_ref<> args,
+				    gdbpy_opt_borrowed_ref<> kw);
 gdbpy_ref<> gdbpy_lookup_static_symbols (gdbpy_borrowed_ref<> args,
 					 gdbpy_opt_borrowed_ref<> kw);
 PyObject *gdbpy_start_recording (PyObject *self, PyObject *args);
@@ -572,6 +572,7 @@ void gdbpy_register_tui_window (gdbpy_borrowed_ref<> args,
 gdbpy_ref<> symtab_and_line_to_sal_object (struct symtab_and_line sal);
 gdbpy_ref<> symtab_to_symtab_object (struct symtab *symtab);
 gdbpy_ref<> symbol_to_symbol_object (struct symbol *sym);
+gdbpy_ref<> safe_symbol_to_symbol_object (struct symbol *sym);
 gdbpy_ref<> block_to_block_object (const struct block *block,
 				   struct objfile *objfile);
 gdbpy_ref<> value_to_value_object (struct value *v);

-- 
2.49.0