[David Geier <geidav.pg@gmail.com>]

Hi hackers,

While working on an extension, I found that simplehash.h is missing 
explicit casts in four places. Without these casts, compiling code 
including simplehash.h yields warnings if the code is compiled with 
-Wc++-compat.

PostgreSQL seems to mostly prefer omitting the explicit casts, however 
there are many places where an explicit cast is actually used. Among 
many others, see e.g.

bool.c:
     state = (BoolAggState *) MemoryContextAlloc(agg_context, 
sizeof(BoolAggState));

domains.c:
    my_extra = (DomainIOData *) MemoryContextAlloc(mcxt, 
sizeof(DomainIOData));

What about, while not being strictly necessary for PostgreSQL itself, 
also adding such casts to simplehash.h so that it can be used in code 
where -Wc++-compat is enabled?

Attached is a small patch that adds the aforementioned casts.
Thanks for your consideration!

--
David Geier
(ServiceNow)

Attachments:

0001-Add-explicit-casts-to-simplehash.h.patch (text/x-patch, 1.8K) download
From d2665b4065227ffa6efd37ee912e4add082869cb Mon Sep 17 00:00:00 2001
From: David Geier <geidav.pg@gmail.com>
Date: Thu, 3 Nov 2022 12:28:08 +0100
Subject: [PATCH] Add explicit casts to simplehash.h

Without these casts compilation yields warnings when compiling the
code with -Wc++-compat.
---
 src/include/lib/simplehash.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/include/lib/simplehash.h b/src/include/lib/simplehash.h
index 329687c1a5..cdfae537a1 100644
--- a/src/include/lib/simplehash.h
+++ b/src/include/lib/simplehash.h
@@ -438,7 +438,7 @@ SH_CREATE(MemoryContext ctx, uint32 nelements, void *private_data)
 #ifdef SH_RAW_ALLOCATOR
 	tb = SH_RAW_ALLOCATOR(sizeof(SH_TYPE));
 #else
-	tb = MemoryContextAllocZero(ctx, sizeof(SH_TYPE));
+	tb = (SH_TYPE *) MemoryContextAllocZero(ctx, sizeof(SH_TYPE));
 	tb->ctx = ctx;
 #endif
 	tb->private_data = private_data;
@@ -448,7 +448,7 @@ SH_CREATE(MemoryContext ctx, uint32 nelements, void *private_data)
 
 	SH_COMPUTE_PARAMETERS(tb, size);
 
-	tb->data = SH_ALLOCATE(tb, sizeof(SH_ELEMENT_TYPE) * tb->size);
+	tb->data = (SH_ELEMENT_TYPE *) SH_ALLOCATE(tb, sizeof(SH_ELEMENT_TYPE) * tb->size);
 
 	return tb;
 }
@@ -493,7 +493,7 @@ SH_GROW(SH_TYPE * tb, uint64 newsize)
 	/* compute parameters for new table */
 	SH_COMPUTE_PARAMETERS(tb, newsize);
 
-	tb->data = SH_ALLOCATE(tb, sizeof(SH_ELEMENT_TYPE) * tb->size);
+	tb->data = (SH_ELEMENT_TYPE *) SH_ALLOCATE(tb, sizeof(SH_ELEMENT_TYPE) * tb->size);
 
 	newdata = tb->data;
 
@@ -1059,7 +1059,7 @@ SH_STAT(SH_TYPE * tb)
 	double		fillfactor;
 	uint32		i;
 
-	uint32	   *collisions = palloc0(tb->size * sizeof(uint32));
+	uint32		*collisions = (uint32 *) palloc0(tb->size * sizeof(uint32));
 	uint32		total_collisions = 0;
 	uint32		max_collisions = 0;
 	double		avg_collisions;
-- 
2.34.1