[master] 8bc28ccd3 miniobj: Extract SIZEOF_FLEX_OBJ() macro

[Nils Goroll]

commit 8bc28ccd3417092a1197845e5450214a126a82e4
Author: Dridi Boukelmoune <dridi.boukelmoune at gmail.com>
Date:   Thu Feb 13 08:49:22 2025 +0100

    miniobj: Extract SIZEOF_FLEX_OBJ() macro
    
    committer edit: Updated Flexelint silencing
    
    Picked from #4271

diff --git a/flint.lnt b/flint.lnt
index f8340ea20..4cc5cb348 100644
--- a/flint.lnt
+++ b/flint.lnt
@@ -283,8 +283,8 @@
 
 -emacro(774, REPLACE)
 // Flexelint does not understand offsetof(typeof(*ptr))
--emacro(10, ALLOC_FLEX_OBJ)
--emacro(40, ALLOC_FLEX_OBJ)
+-emacro(10, SIZEOF_FLEX_OBJ)
+-emacro(40, SIZEOF_FLEX_OBJ)
 
 
 // It is ok to default after handling a few select SLT_* tags
diff --git a/include/miniobj.h b/include/miniobj.h
index ecb341f49..df5018d96 100644
--- a/include/miniobj.h
+++ b/include/miniobj.h
@@ -37,10 +37,12 @@
 			(to)->magic = (type_magic);			\
 	} while (0)
 
+#define SIZEOF_FLEX_OBJ(to, fld, len)					\
+	(offsetof(typeof(*to), fld) + sizeof *(to)->fld * len)
+
 #define ALLOC_FLEX_OBJ(to, fld, len, type_magic)			\
 	do {								\
-		(to) = calloc(1, offsetof(typeof(*to), fld) +		\
-		    sizeof *(to)->fld * len);				\
+		(to) = calloc(1, SIZEOF_FLEX_OBJ(to, fld, len));	\
 		if ((to) != NULL)					\
 			(to)->magic = (type_magic);			\
 	} while (0)