[PATCH 3/3] gdb: handle default argument in make-target-delegates.py

[Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>]

The regular expression to dissect argument types in
make-target-delegates.py does not recognize default argument values.
For example, in target.h, we have

   virtual void rcmd (const char *command, struct ui_file *output)
     TARGET_DEFAULT_FUNC (default_rcmd);
   virtual const char *pid_to_exec_file (int pid)
     TARGET_DEFAULT_RETURN (NULL);

Suppose we change these to the following where we define default
values for the arguments.  The example for the default argument
of "pid" is deliberately chosen to contain a space character.

   virtual void rcmd (const char *command=0, struct ui_file *output = nullptr)
     TARGET_DEFAULT_FUNC (default_rcmd);
   virtual const char *pid_to_exec_file (int pid=sizeof n)
     TARGET_DEFAULT_RETURN (NULL);

After generating the target-delegates.c file via make-target-delegates.py
we obtain invalid code:

   void rcmd (const char *command=0 arg0, struct ui_file *output = nullptr arg1) override;
   const char *pid_to_exec_file (int pid=sizeof n arg0) override;
   ...
   void
   debug_target::rcmd (const char *command=0 arg0, struct ui_file *output = nullptr arg1)
   {
     ...
     target_debug_print_const_char_pcommand=0 (arg0);
     ...
     target_debug_print_struct_ui_file_poutput_=_nullptr (arg1);
   }
   ...
   const char *
   debug_target::pid_to_exec_file (int pid=sizeof n arg0)
   {
     ...
     target_debug_print_int_pid=sizeof_n (arg0);
     ...
   }

When the fix in this patch is applied, the default argument values
are correctly detected and we obtain the same generated result for
target-delegates.c, which is

   void rcmd (const char *arg0, struct ui_file *arg1) override;
   const char *pid_to_exec_file (int arg0) override;
   ...
   void
   debug_target::rcmd (const char *arg0, struct ui_file *arg1)
   {
     ...
     target_debug_print_const_char_p (arg0);
     ...
     target_debug_print_struct_ui_file_p (arg1);
   }
   ...
   const char *
   debug_target::pid_to_exec_file (int arg0)
   {
     ...
     target_debug_print_int (arg0);
     ...
   }

Currently, target.h does not contain any arguments with default
values.  The goal of this patch is to address potential future and
downstream cases; we (Intel) have cases with default argument values.
---
 gdb/make-target-delegates.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/gdb/make-target-delegates.py b/gdb/make-target-delegates.py
index fd5f436a43d..2758f900c9b 100755
--- a/gdb/make-target-delegates.py
+++ b/gdb/make-target-delegates.py
@@ -76,6 +76,8 @@ METHOD = re.compile(
 # Space-separated symbols.
 CP_SYMBOLS = CP_SYMBOL + r"(\s+" + CP_SYMBOL + r")*"
 
+DEFAULT_ARG_VALUE = r"(\s*\=\s*[^\s].*)?"
+
 # Regular expression used to dissect argument types.
 ARGTYPES = re.compile(
     "^("
@@ -86,6 +88,7 @@ ARGTYPES = re.compile(
     + CP_SYMBOLS
     + r"(\s|\*|&)+)"
     + SYMBOL
+    + DEFAULT_ARG_VALUE
     + ")$"
 )
 
-- 
2.34.1

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