Refactor compile-time assertion checks in c.h
This commit refactors and simplifies the definitions of StaticAssertStmt,
StaticAssertExpr and StaticAssertDecl.  By unifying the C and C++
fallback implementations, this reduces the number of different
implementations from four to three.
Author: Michael Paquier
Discussion:
@@ -836,43 +836,37 @@ extern void ExceptionalCondition(const char *conditionName,
* The macro StaticAssertDecl() is suitable for use at file scope (outside of
* any function).
*
+ * On recent C++ compilers, we can use standard static_assert().
+ *
* Otherwise we fall back on a kluge that assumes the compiler will complain
* about a negative width for a struct bit-field. This will not include a
* helpful error message, but it beats not getting an error at all.
*/
-#ifndef __cplusplus
-#ifdef HAVE__STATIC_ASSERT
+#if !defined(__cplusplus) && defined(HAVE__STATIC_ASSERT)
+/* Default C implementation */
#define StaticAssertStmt(condition, errmessage) \
do { _Static_assert(condition, errmessage); } while(0)
#define StaticAssertExpr(condition, errmessage) \
((void) ({ StaticAssertStmt(condition, errmessage); true; }))
#define StaticAssertDecl(condition, errmessage) \
_Static_assert(condition, errmessage)
-#else /* !HAVE__STATIC_ASSERT */
-#define StaticAssertStmt(condition, errmessage) \
- ((void) sizeof(struct { int static_assert_failure : (condition) ? 1 : -1; }))
-#define StaticAssertExpr(condition, errmessage) \
- StaticAssertStmt(condition, errmessage)
-#define StaticAssertDecl(condition, errmessage) \
- extern void static_assert_func(int static_assert_failure[(condition) ? 1 : -1])
-#endif /* HAVE__STATIC_ASSERT */
-#else /* C++ */
-#if defined(__cpp_static_assert) && __cpp_static_assert >= 200410
+#elif defined(__cplusplus) && __cpp_static_assert >= 200410
+/* Default C++ implementation */
#define StaticAssertStmt(condition, errmessage) \
static_assert(condition, errmessage)
#define StaticAssertExpr(condition, errmessage) \
({ static_assert(condition, errmessage); })
#define StaticAssertDecl(condition, errmessage) \
static_assert(condition, errmessage)
-#else /* !__cpp_static_assert */
+#else
+/* Fallback implementation for C and C++ */
#define StaticAssertStmt(condition, errmessage) \
- do { struct static_assert_struct { int static_assert_failure : (condition) ? 1 : -1; }; } while(0)
+ ((void) sizeof(struct { int static_assert_failure : (condition) ? 1 : -1; }))
#define StaticAssertExpr(condition, errmessage) \
- ((void) ({ StaticAssertStmt(condition, errmessage); }))
+ StaticAssertStmt(condition, errmessage)
#define StaticAssertDecl(condition, errmessage) \
extern void static_assert_func(int static_assert_failure[(condition) ? 1 : -1])
-#endif /* __cpp_static_assert */
-#endif /* C++ */
+#endif
/*
