Subject: [PATCH 2/5] Add va_header field to the varattrib_4b union.

From: Antonin Houska <[email-masked]>
Date: Wed, 11 Mar 2026 14:53:19 +0100

Since VARSIZE_ANY() may call VARSIZE_4B(), it's possible that the compiler
(when invoked with -Warray-bounds) complains if the argument of VARSIZE_ANY()
is actually smaller than what VARSIZE_4B() expects. With the new field,
VARSIZE_4B() can check the size w/o dereferencing varattrib_4b pointer.

The problem does not exist in the tree at the moment since the current users
of VARSIZE_ANY() pass a pointer to a dynamically allocated memory, so the
compiler has no idea about the memory available. However, in an upcoming
patch, it makes sense to pass a pointer to a local variable of "varlena"
type. In such a case, the compiler warning might appear because
sizeof(varlena) is lower than sizeof(varattrib_4b).
---
 src/include/varatt.h | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/include/varatt.h b/src/include/varatt.h
index 000bdf33b92..c54d5160c22 100644
--- a/src/include/varatt.h
+++ b/src/include/varatt.h
@@ -137,6 +137,10 @@ typedef union
 								 * compression method; see va_extinfo */
 		char		va_data[FLEXIBLE_ARRAY_MEMBER]; /* Compressed data */
 	}			va_compressed;
+	uint32		va_header;		/* Without this, compiler might raise warning
+								 * (-Warray-bounds) if the argument of
+								 * VARSIZE_ANY() is smaller than
+								 * varattrib_4b */
 } varattrib_4b;
 
 typedef struct
@@ -207,7 +211,7 @@ typedef struct
 
 /* VARSIZE_4B() should only be used on known-aligned data */
 #define VARSIZE_4B(PTR) \
-	(((const varattrib_4b *) (PTR))->va_4byte.va_header & 0x3FFFFFFF)
+	(*((const uint32 *) (PTR)) & 0x3FFFFFFF)
 #define VARSIZE_1B(PTR) \
 	(((const varattrib_1b *) (PTR))->va_header & 0x7F)
 #define VARTAG_1B_E(PTR) \
@@ -240,7 +244,7 @@ typedef struct
 
 /* VARSIZE_4B() should only be used on known-aligned data */
 #define VARSIZE_4B(PTR) \
-	((((const varattrib_4b *) (PTR))->va_4byte.va_header >> 2) & 0x3FFFFFFF)
+	((*((const uint32 *) (PTR)) >> 2) & 0x3FFFFFFF)
 #define VARSIZE_1B(PTR) \
 	((((const varattrib_1b *) (PTR))->va_header >> 1) & 0x7F)
 #define VARTAG_1B_E(PTR) \
-- 
2.47.3

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 filename=v41-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch