[PATCH] fix uneccesary copy of function bodies for BASH_SOURCE

[Koichi Murase]

The function `bind_function_def' (variables.c) stores the function
metadata in the hash map `shell_function_defs' in variables.c.  The
saved information is used by BASH_SOURCE (execute_cmd.c) and the
output of `declare -F func' with `shopt -s extdebug'
(builtin/declare.def) through the interface `find_function_def'
(variables.c).  The function body (i.e., funcdef->command) saved in
the hash map is not used anywhere and does not need to be saved in the
hash map.  In fact, the function body is not saved in the first call
of `bind_function_def' for the function name.

The problem is that the function body is saved for the second and
later calls of `bind_function_def' for the same function name.  When a
function is defined, `bind_function_def' is always called twice in its
parsing phase (`make_function_def' in make_cmd.c) and its defining
phase (`execute_intern_function' in execute_cmd.c).  As a result, the
function body is always saved in the hash map `shell_function_defs'
after the second call.  This doubles the memory used for shell
functions because the function bodies are already intended to be saved
in a separate hash map `shell_functions' (variables.c).

This patch fixes `bind_function_def' so that it skips the function
body also for the second and later calls.  This reduces the memory
uses of Bash for shell functions by almost half.

---
 variables.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/variables.c b/variables.c
index 84b30d93..0e785742 100644
--- a/variables.c
+++ b/variables.c
@@ -3507,7 +3507,11 @@ bind_function_def (const char *name, FUNCTION_DEF 
*value, int flags)
   if (entry && (flags & 1))
     {
       dispose_function_def_contents (entry);
+
+      cmd = value->command;
+      value->command = 0;
       entry = copy_function_def_contents (value, entry);
+      value->command = cmd;
     }
   else if (entry)
     return;
-- 
2.45.0