Do not generate code dereferencing type-punned pointers

For variable-length arrays, up to 2048 bytes are transmitted inline.
If the array is larger, the data is transmitted out-of-line, and a
pointer to a vm_allocated region is stored at the beginning of the
array.

Previously, the generated code casted the field.  Use a union instead.

This fixes the gcc warning `dereferencing type-punned pointer will
break strict-aliasing rules [-Wstrict-aliasing]'.

* global.c (OOLPostfix): New variable.
* global.h (OOLPostfix): New declaration.
* server.c (WriteServerCallArg): Avoid cast.
(WriteDestroyArg): Likewise.
(WritePackArgValue): Likewise.
(WritePackArg): Likewise.
* user.c (WriteExtractArgValue): Likewise.
* utils.c (WriteFieldDeclPrim): Generate a union with an additional
pointer field for variable-length arrays.

1 files changed, 1 insertions, 0 deletions

diff --git a/global.h b/global.h
index ca4d865..8dbb6fd 100644
--- a/global.h
+++ b/global.h
@@ -53,6 +53,7 @@ extern const_string_t UserPrefix;
 extern const_string_t ServerDemux;
 extern const_string_t SubrPrefix;
 extern const_string_t RoutinePrefix;
+extern const_string_t OOLPostfix;
 
 extern int yylineno;
 extern string_t yyinname;