[Xen-devel] [PATCH 13/15] libxl: make LIBXL_INIT_GC a statement, not an initialiser

[Ian Jackson <ian.jackson@xxxxxxxxxxxxx>]

Previously LIBXL_INIT_GC was an initialiser, which you were expected
to use like this:
    libxl__gc gc = LIBXL_INIT_GC(ctx);

But we are going to want to put things in the gc which are to be
initialised using other macros.  That means that LIBXL_INIT_GC has to
become a statement too.  So instead, we make it so that it's used like this:
    libxl_gc gc;
    LIBXL_INIT_GC(gc,ctx);

In fact there is only one caller now, GC_INIT, which uses this trick:
    libxl_gc gc[1];
    LIBXL_INIT_GC(gc[0],ctx);

Signed-off-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
---
 tools/libxl/libxl_internal.h |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 1d1dc35..d015c7c 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -145,7 +145,12 @@ typedef struct {
     libxl_ctx *owner;
 } libxl__gc;
 
-#define LIBXL_INIT_GC(ctx) (libxl__gc){ .alloc_maxsize = 0, .alloc_ptrs = 0, 
.owner = ctx }
+#define LIBXL_INIT_GC(gc,ctx) do{               \
+        (gc).alloc_maxsize = 0;                 \
+        (gc).alloc_ptrs = 0;                    \
+        (gc).owner = (ctx);                     \
+    } while(0)
+
 static inline libxl_ctx *libxl__gc_owner(libxl__gc *gc)
 {
     return gc->owner;
@@ -676,7 +681,7 @@ libxl__device_model_version_running(libxl__gc *gc, uint32_t 
domid);
  * as a local variable.
  */
 
-#define GC_INIT(ctx)  libxl__gc gc[1] = { LIBXL_INIT_GC(ctx) }
+#define GC_INIT(ctx)  libxl__gc gc[1]; LIBXL_INIT_GC(gc[0],ctx)
 #define GC_FREE       libxl__free_all(gc)
 #define CTX           libxl__gc_owner(gc)
 
-- 
1.7.2.5


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