[PATCH] widl: Handle C++ aggregate returns in a MSVC compatible way.
Henri Verbeet
hverbeet at codeweavers.com
Thu Jul 20 07:18:33 CDT 2017
This mainly affects 64-bit winelib applications, and potentially mingw-w64
usage of the Wine headers. As explained in commit
fabfa59aea5c5b3201142382038beb3e76cb7567, MSVC returns aggregates through an
implicit parameter immediately after the this/interface pointer. GCC's
"ms_abi" attribute is supposed to match this, but unfortunately current
versions of g++ (confirmed up to at least g++ 6.3) place the implicit return
pointer before the this/interface pointer. See also
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52792.
This commit takes an approach similar to the earlier commit
fabfa59aea5c5b3201142382038beb3e76cb7567: For ABI compatibility the return
pointer is listed as an explicit parameter in the vtbl entry, while an inline
helper is provided for source code compatibility.
Signed-off-by: Henri Verbeet <hverbeet at codeweavers.com>
---
tools/widl/header.c | 44 +++++++++++++++++++++++++++++++++++++++++---
1 file changed, 41 insertions(+), 3 deletions(-)
diff --git a/tools/widl/header.c b/tools/widl/header.c
index e48b488..0481368 100644
--- a/tools/widl/header.c
+++ b/tools/widl/header.c
@@ -1043,14 +1043,52 @@ static void write_cpp_method_def(FILE *header, const type_t *iface)
const var_t *func = stmt->u.var;
if (!is_callas(func->attrs)) {
const char *callconv = get_attrp(func->type->attrs, ATTR_CALLCONV);
+ const var_list_t *args = type_get_function_args(func->type);
+ int aggregate_ret = is_aggregate_return(func);
+ const var_t *arg;
+
if (!callconv) callconv = "STDMETHODCALLTYPE";
indent(header, 0);
fprintf(header, "virtual ");
write_type_decl_left(header, type_function_get_rettype(func->type));
+ if (aggregate_ret)
+ fprintf(header, " *");
fprintf(header, " %s %s(\n", callconv, get_name(func));
- write_args(header, type_get_function_args(func->type), iface->name, 2, TRUE);
- fprintf(header, ") = 0;\n");
- fprintf(header, "\n");
+ if (aggregate_ret) {
+ ++indentation;
+ indent(header, 0);
+ write_type_decl_left(header, type_function_get_rettype(func->type));
+ fprintf(header, " *__ret");
+ if (args)
+ fprintf(header, ",\n");
+ --indentation;
+ }
+ if (!aggregate_ret || args)
+ write_args(header, args, iface->name, 2, TRUE);
+ fprintf(header, ") = 0;\n\n");
+
+ if (aggregate_ret) {
+ indent(header, 0);
+ write_type_decl_left(header, type_function_get_rettype(func->type));
+ fprintf(header, " %s %s(\n", callconv, get_name(func));
+ write_args(header, args, iface->name, 2, TRUE);
+ fprintf(header, ")\n");
+ indent(header, 0);
+ fprintf(header, "{\n");
+ ++indentation;
+ indent(header, 0);
+ write_type_decl_left(header, type_function_get_rettype(func->type));
+ fprintf(header, " __ret;\n");
+ indent(header, 0);
+ fprintf(header, "return *%s(&__ret", get_name(func));
+ if (args)
+ LIST_FOR_EACH_ENTRY(arg, args, const var_t, entry)
+ fprintf(header, ", %s", arg->name);
+ fprintf(header, ");\n");
+ --indentation;
+ indent(header, 0);
+ fprintf(header, "}\n\n");
+ }
}
}
}
--
2.1.4
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