GPR#142: add a CAMLdrop macro for undoing CAMLparam*/CAMLlocal*

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@15814 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02

2 files changed, 9 insertions, 4 deletions

diff --git a/Changes b/Changes
index bbb215732..0077b3de2 100644
--- a/Changes
+++ b/Changes
@@ -83,6 +83,7 @@ Features wishes:
 - PR#6691: install .cmt[i] files for stdlib and compiler-libs
   (David Sheets, request by Gabriel Radanne)
 - PR#6742: remove duplicate virtual_flag information from Tstr_class
+- GPR#142: add a CAMLdrop macro for undoing CAMLparam*/CAMLlocal*
 
 OCaml 4.02.2:
 -------------
diff --git a/byterun/caml/memory.h b/byterun/caml/memory.h
index 2aa9c74eb..98a30cc1b 100644
--- a/byterun/caml/memory.h
+++ b/byterun/caml/memory.h
@@ -154,7 +154,9 @@ CAMLextern struct caml__roots_block *caml_local_roots;  /* defined in roots.c */
    Your function may raise an exception or return a [value] with the
    [CAMLreturn] macro.  Its argument is simply the [value] returned by
    your function.  Do NOT directly return a [value] with the [return]
-   keyword.  If your function returns void, use [CAMLreturn0].
+   keyword.  If your function returns void, use [CAMLreturn0]. If you
+   un-register the local roots (i.e. undo the effects of the [CAMLparam*]
+   and [CAMLlocal] macros) without returning immediately, use [CAMLdrop].
 
    All the identifiers beginning with "caml__" are reserved by OCaml.
    Do not use them for anything (local or global variables, struct or
@@ -294,15 +296,17 @@ CAMLextern struct caml__roots_block *caml_local_roots;  /* defined in roots.c */
   CAMLxparamN (x, (size))
 
 
+#define CAMLdrop caml_local_roots = caml__frame
+  
 #define CAMLreturn0 do{ \
-  caml_local_roots = caml__frame; \
+  CAMLdrop; \
   return; \
 }while (0)
 
 #define CAMLreturnT(type, result) do{ \
   type caml__temp_result = (result); \
-  caml_local_roots = caml__frame; \
-  return (caml__temp_result); \
+  CAMLdrop; \
+  return caml__temp_result; \
 }while(0)
 
 #define CAMLreturn(result) CAMLreturnT(value, result)