On Sat, May 28, 2022 at 12:26:34PM +0900, Michael Paquier wrote:
> On Fri, May 27, 2022 at 10:43:17AM -0700, Nathan Bossart wrote:
>> Makes sense. Here's a new patch set. 0001 is the part intended for
>> back-patching, and 0002 is the rest (i.e., adding pg_attribute_nonnull()).
>> I switched to using __has_attribute to discover whether nonnull was
>
> Okay, I have looked at 0001 this morning and applied it down to 12.
> The change in GetConfigOptionByNum() is not required in 10 and 11, as
> the strings of pg_show\all_settings() have begun to be translated in
> 12~.
Thanks!
>> supported, as that seemed cleaner. I didn't see any need for a new
>> configure check, but maybe I am missing something.
>
> And I've learnt today that we enforce a definition of __has_attribute
> at the top of c.h, and that we already rely on that. So I agree that
> what you are doing in 0002 should be enough. Should we wait until 16~
> opens for business though? I don't see a strong argument to push
> forward with that now that we are in beta mode on HEAD.
Yeah, I see no reason that this should go into v15. I created a new
commitfest entry so that this isn't forgotten:
https://commitfest.postgresql.org/38/3655/
And I've reposted 0002 here so that we get some cfbot coverage in the
meantime.
--
Nathan Bossart
Amazon Web Services: https://aws.amazon.com
>From 88ac1a95e84998ce473d461424b81b91a0a3e3cc Mon Sep 17 00:00:00 2001
From: Nathan Bossart <nathandboss...@gmail.com>
Date: Fri, 27 May 2022 10:10:09 -0700
Subject: [PATCH v5 1/1] Introduce pg_attribute_nonnull() and use it for
DefineCustomXXXVariable().
pg_attribute_nonnull() can be used to generate compiler warnings
when a function is called with the specified arguments set to NULL.
An empty argument list indicates that all pointer arguments must
not be NULL. pg_attribute_nonnull() only works for compilers that
support the nonnull function attribute. If nonnull is not
supported, pg_attribute_nonnull() has no effect.
In addition to introducing pg_attribute_nonnull(), this change uses
it for the DefineCustomXXXVariable() functions to generate warnings
when the "name" and "valueAddr" arguments are set to NULL.
Idea by: Andres Freund
Author: Nathan Bossart
Reviewed by: Michael Paquier, Tom Lane
Discussion: https://postgr.es/m/20220525061739.ur7x535vtzyzkmqo%40alap3.anarazel.de
---
src/include/c.h | 11 +++++++++++
src/include/utils/guc.h | 10 +++++-----
2 files changed, 16 insertions(+), 5 deletions(-)
diff --git a/src/include/c.h b/src/include/c.h
index 4f16e589b3..0c64557c62 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -144,6 +144,17 @@
#define pg_attribute_no_sanitize_alignment()
#endif
+/*
+ * pg_attribute_nonnull means the compiler should warn if the function is called
+ * with the listed arguments set to NULL. If no arguments are listed, the
+ * compiler should warn if any pointer arguments are set to NULL.
+ */
+#if __has_attribute (nonnull)
+#define pg_attribute_nonnull(...) __attribute__((nonnull(__VA_ARGS__)))
+#else
+#define pg_attribute_nonnull(...)
+#endif
+
/*
* Append PG_USED_FOR_ASSERTS_ONLY to definitions of variables that are only
* used in assert-enabled builds, to avoid compiler warnings about unused
diff --git a/src/include/utils/guc.h b/src/include/utils/guc.h
index efcbad7842..be691c5e9c 100644
--- a/src/include/utils/guc.h
+++ b/src/include/utils/guc.h
@@ -303,7 +303,7 @@ extern void DefineCustomBoolVariable(const char *name,
int flags,
GucBoolCheckHook check_hook,
GucBoolAssignHook assign_hook,
- GucShowHook show_hook);
+ GucShowHook show_hook) pg_attribute_nonnull(1, 4);
extern void DefineCustomIntVariable(const char *name,
const char *short_desc,
@@ -316,7 +316,7 @@ extern void DefineCustomIntVariable(const char *name,
int flags,
GucIntCheckHook check_hook,
GucIntAssignHook assign_hook,
- GucShowHook show_hook);
+ GucShowHook show_hook) pg_attribute_nonnull(1, 4);
extern void DefineCustomRealVariable(const char *name,
const char *short_desc,
@@ -329,7 +329,7 @@ extern void DefineCustomRealVariable(const char *name,
int flags,
GucRealCheckHook check_hook,
GucRealAssignHook assign_hook,
- GucShowHook show_hook);
+ GucShowHook show_hook) pg_attribute_nonnull(1, 4);
extern void DefineCustomStringVariable(const char *name,
const char *short_desc,
@@ -340,7 +340,7 @@ extern void DefineCustomStringVariable(const char *name,
int flags,
GucStringCheckHook check_hook,
GucStringAssignHook assign_hook,
- GucShowHook show_hook);
+ GucShowHook show_hook) pg_attribute_nonnull(1, 4);
extern void DefineCustomEnumVariable(const char *name,
const char *short_desc,
@@ -352,7 +352,7 @@ extern void DefineCustomEnumVariable(const char *name,
int flags,
GucEnumCheckHook check_hook,
GucEnumAssignHook assign_hook,
- GucShowHook show_hook);
+ GucShowHook show_hook) pg_attribute_nonnull(1, 4);
extern void MarkGUCPrefixReserved(const char *className);
--
2.25.1
