Commit df1a699e5ba3232f373790b2c9485ddf720c4a70 introduced a
StaticAssertStmt() into a header file, which will fail if a module
written in C++ uses that header file. Currently, that header file is
not widely used, but it's a potential problem if the use of static
assertions expands.
As discussed in
<https://www.postgresql.org/message-id/[email protected]>, a
more general solution would be to add specific C++ support for static
assertions in c.h. Here is a patch for that, extracted from my
previously posted C++ patch set, but also a bit reworked from what was
previously posted.
Also attached is a little C++ test file that one can use to test this
out. (Just compiling it should cause a compiler error without the patch
and a static assertion failure with the patch.)
--
Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
From 93adbf7bfa7afc1c8e25b037fce8227f3a225639 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <[email protected]>
Date: Tue, 30 Aug 2016 12:00:00 -0400
Subject: [PATCH v3] Add support for static assertions in C++
This allows modules written in C++ to use or include header files that
use StaticAssertStmt() etc.
---
src/include/c.h | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/src/include/c.h b/src/include/c.h
index af799dc1df..e238edb7d1 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -749,6 +749,7 @@ typedef NameData *Name;
* 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
#define StaticAssertStmt(condition, errmessage) \
do { _Static_assert(condition, errmessage); } while(0)
@@ -760,6 +761,18 @@ typedef NameData *Name;
#define StaticAssertExpr(condition, errmessage) \
StaticAssertStmt(condition, errmessage)
#endif /* HAVE__STATIC_ASSERT
*/
+#else /* C++ */
+#if defined(__cpp_static_assert) && __cpp_static_assert >= 200410
+#define StaticAssertStmt(condition, errmessage) \
+ static_assert(condition, errmessage)
+#else
+/* not worth providing a workaround */
+#define StaticAssertStmt(condition, errmessage) \
+ ((void) 0)
+#endif
+#define StaticAssertExpr(condition, errmessage) \
+ ({ StaticAssertStmt(condition, errmessage); true; })
+#endif /* C++ */
/*
base-commit: b5c75feca7ffb2667c42b86286e262d6cb709b76
--
2.14.1
extern "C" {
#include "postgres.h"
}
extern "C"
int
somefunction(void)
{
StaticAssertStmt(1 + 1 == 3, "arithmetic!");
return 0;
}
--
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