gdb: make debug_target use one-liners

Turn the debug prints in debug_target's method to be one liners.  For
instance, change this:

    gdb_printf (gdb_stdlog, "<- %s->wait (", this->beneath ()->shortname ());
    gdb_puts (target_debug_print_ptid_t (arg0), gdb_stdlog);
    gdb_puts (", ", gdb_stdlog);
    gdb_puts (target_debug_print_target_waitstatus_p (arg1), gdb_stdlog);
    gdb_puts (", ", gdb_stdlog);
    gdb_puts (target_debug_print_target_wait_flags (arg2), gdb_stdlog);
    gdb_puts (") = ", gdb_stdlog);
    target_debug_print_ptid_t (result);
    gdb_puts ("\n", gdb_stdlog);

into this:

    gdb_printf (gdb_stdlog,
               "<- %s->wait (%s, %s, %s) = %s\n",
               this->beneath ()->shortname (),
               target_debug_print_ptid_t (arg0).c_str (),
               target_debug_print_target_waitstatus_p (arg1).c_str (),
               target_debug_print_target_wait_flags (arg2).c_str (),
               target_debug_print_ptid_t (result).c_str ());

This makes it possible for a subsequent patch to turn this gdb_printf
call into a `target_debug_printf` call.

Change-Id: I808202438972fac1bba2f8ccb63e66a4fcef20c9
Approved-By: Tom Tromey <tom@tromey.com>

gdb/make-target-delegates.py

@@ -290,28 +290,34 @@ def write_debugmethod(
     print(", ".join(names), file=f, end="")
     print(");", file=f)
 
-    # Now print the arguments.
+    # Generate the debug printf call.
+    args_fmt = ", ".join(["%s"] * len(argtypes))
+    args = "".join(
+        [
+            (",\n\t      {printer} (arg{i}).c_str ()").format(
+                printer=munge_type(t), i=i
+            )
+            for i, t in enumerate(argtypes)
+        ]
+    )
+
+    if return_type != "void":
+        ret_fmt = " = %s"
+        ret = ",\n\t      {printer} (result).c_str ()".format(
+            printer=munge_type(return_type)
+        )
+    else:
+        ret_fmt = ""
+        ret = ""
+
     print(
-        '  gdb_printf (gdb_stdlog, "<- %s->'
-        + name
-        + ' (", this->beneath ()->shortname ());',
+        (
+            "  gdb_printf (gdb_stdlog,\n"
+            '\t      "<- %s->{name} ({args_fmt}){ret_fmt}\\n",\n'
+            "\t      this->beneath ()->shortname (){args}{ret});"
+        ).format(name=name, args_fmt=args_fmt, args=args, ret_fmt=ret_fmt, ret=ret),
         file=f,
     )
-    for i in range(len(argtypes)):
-        if i > 0:
-            print('  gdb_puts (", ", gdb_stdlog);', file=f)
-        printer = munge_type(argtypes[i])
-        print(
-            "  gdb_puts (" + printer + " (" + names[i] + "), gdb_stdlog);",
-            file=f,
-        )
-    if return_type != "void":
-        print('  gdb_puts (") = ", gdb_stdlog);', file=f)
-        printer = munge_type(return_type)
-        print("  " + printer + " (result);", file=f)
-        print('  gdb_puts ("\\n", gdb_stdlog);', file=f)
-    else:
-        print('  gdb_puts (")\\n", gdb_stdlog);', file=f)
 
     if return_type != "void":
         print("  return result;", file=f)

gdb/target-debug.h

@@ -308,7 +308,7 @@ target_debug_print_target_waitstatus_p (struct target_waitstatus *status)
 
 /* Functions that are used via TARGET_DEBUG_PRINTER.  */
 
-static const char *
+static std::string
 target_debug_print_step (int step)
 { return step ? "step" : "continue"; }
 
@@ -331,7 +331,7 @@ target_debug_print_signals (gdb::array_view<const unsigned char> sigs)
   return s;
 }
 
-static const char *
+static std::string
 target_debug_print_size_t (size_t size)
 {
   return pulongest (size);