From f53156f2ee9b76328641b714d4dd847881711951 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ren=C3=A9=20Scharfe?= <l.s.r@web.de>
Date: Sun, 10 Jul 2022 12:05:51 +0200
Subject: [PATCH] cocci: avoid normalization rules for memcpy
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Some of the rules for using COPY_ARRAY instead of memcpy with sizeof are
intended to reduce the number of sizeof variants to deal with.  They can
have unintended side effects if only they match, but not the one for the
COPY_ARRAY conversion at the end.

Avoid these side effects by instead using a self-contained rule for each
combination of array and pointer for source and destination which lists
all sizeof variants inline.

This lets "make contrib/coccinelle/array.cocci.patch" take 15% longer on
my machine, but gives peace of mind that no incomplete transformation
will be generated.

Suggested-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 contrib/coccinelle/array.cocci | 94 +++++++++++++++++-----------------
 1 file changed, 46 insertions(+), 48 deletions(-)

diff --git a/contrib/coccinelle/array.cocci b/contrib/coccinelle/array.cocci
index 9a4f00cb1b..aa75937950 100644
--- a/contrib/coccinelle/array.cocci
+++ b/contrib/coccinelle/array.cocci
@@ -1,60 +1,58 @@
-@@
-expression dst, src, n, E;
-@@
-  memcpy(dst, src, n * sizeof(
-- E[...]
-+ *(E)
-  ))
-
-@@
-type T;
-T *ptr;
-T[] arr;
-expression E, n;
-@@
-(
-  memcpy(ptr, E,
-- n * sizeof(*(ptr))
-+ n * sizeof(T)
-  )
-|
-  memcpy(arr, E,
-- n * sizeof(*(arr))
-+ n * sizeof(T)
-  )
-|
-  memcpy(E, ptr,
-- n * sizeof(*(ptr))
-+ n * sizeof(T)
-  )
-|
-  memcpy(E, arr,
-- n * sizeof(*(arr))
-+ n * sizeof(T)
-  )
-)
-
 @@
 type T;
 T *dst_ptr;
 T *src_ptr;
+expression n;
+@@
+- memcpy(dst_ptr, src_ptr, (n) * \( sizeof(T)
+-                                \| sizeof(*(dst_ptr))
+-                                \| sizeof(*(src_ptr))
+-                                \| sizeof(dst_ptr[...])
+-                                \| sizeof(src_ptr[...])
+-                                \) )
++ COPY_ARRAY(dst_ptr, src_ptr, n)
+
+@@
+type T;
+T *dst_ptr;
+T[] src_arr;
+expression n;
+@@
+- memcpy(dst_ptr, src_arr, (n) * \( sizeof(T)
+-                                \| sizeof(*(dst_ptr))
+-                                \| sizeof(*(src_arr))
+-                                \| sizeof(dst_ptr[...])
+-                                \| sizeof(src_arr[...])
+-                                \) )
++ COPY_ARRAY(dst_ptr, src_arr, n)
+
+@@
+type T;
+T[] dst_arr;
+T *src_ptr;
+expression n;
+@@
+- memcpy(dst_arr, src_ptr, (n) * \( sizeof(T)
+-                                \| sizeof(*(dst_arr))
+-                                \| sizeof(*(src_ptr))
+-                                \| sizeof(dst_arr[...])
+-                                \| sizeof(src_ptr[...])
+-                                \) )
++ COPY_ARRAY(dst_arr, src_ptr, n)
+
+@@
+type T;
 T[] dst_arr;
 T[] src_arr;
 expression n;
 @@
-(
-- memcpy(dst_ptr, src_ptr, (n) * sizeof(T))
-+ COPY_ARRAY(dst_ptr, src_ptr, n)
-|
-- memcpy(dst_ptr, src_arr, (n) * sizeof(T))
-+ COPY_ARRAY(dst_ptr, src_arr, n)
-|
-- memcpy(dst_arr, src_ptr, (n) * sizeof(T))
-+ COPY_ARRAY(dst_arr, src_ptr, n)
-|
-- memcpy(dst_arr, src_arr, (n) * sizeof(T))
+- memcpy(dst_arr, src_arr, (n) * \( sizeof(T)
+-                                \| sizeof(*(dst_arr))
+-                                \| sizeof(*(src_arr))
+-                                \| sizeof(dst_arr[...])
+-                                \| sizeof(src_arr[...])
+-                                \) )
 + COPY_ARRAY(dst_arr, src_arr, n)
-)
 
 @@
 type T;