The DELETE replacement functions check the size argument, but this doesn't actually exist.
Only the DELETE_SIZED replacement functions get a size (and should check it).

On i386 (fedora gnu/linux) this causes the following failures:

memcheck/tests/cxx17_aligned_new         (stderr)
memcheck/tests/leak_cpp_interior         (stderr)
memcheck/tests/mismatches                (stderr)
memcheck/tests/mismatches_xml            (stderr)
memcheck/tests/new_aligned_delete_default (stderr)
memcheck/tests/new_nothrow               (stderr)
memcheck/tests/realloc_size_zero_mismatch (stderr)

All showing "size" being undefined:

+Conditional jump or move depends on uninitialised value(s)
+   at 0x........: ...operator delete[]... (vg_replace_malloc.c:...)

or 

+Mismatched new/delete size value: 4
+   at 0x........: ...operator delete... (vg_replace_malloc.c:...)

Oddly no other architecture seems to show issues. Maybe we just got lucky?

The following patch fixes the issues on i386 (and shows no regressions on x86_64):

diff --git a/coregrind/m_replacemalloc/vg_replace_malloc.c b/coregrind/m_replacemalloc/vg_replace_malloc.c
index e238a52f3..7859f5f32 100644
--- a/coregrind/m_replacemalloc/vg_replace_malloc.c
+++ b/coregrind/m_replacemalloc/vg_replace_malloc.c
@@ -1027,13 +1027,12 @@ extern int * __error(void) __attribute__((weak));
 
 #define DELETE(soname, fnname, vg_replacement, tag) \
  \
-    void VG_REPLACE_FUNCTION_EZU(10050,soname,fnname) (void *p, SizeT size); \
-    void VG_REPLACE_FUNCTION_EZU(10050,soname,fnname) (void *p, SizeT size)  \
+    void VG_REPLACE_FUNCTION_EZU(10050,soname,fnname) (void *p); \
+    void VG_REPLACE_FUNCTION_EZU(10050,soname,fnname) (void *p)  \
  { \
  struct AlignedAllocInfo aligned_alloc_info = { .mem=p, .alloc_kind=AllocKind##tag }; \
       \
       DO_INIT; \
-      TRIGGER_MEMCHECK_ERROR_IF_UNDEFINED((UWord)size); \
       VERIFY_ALIGNMENT(&aligned_alloc_info); \
       MALLOC_TRACE(#fnname "(%p)\n", p ); \
       if (p == NULL)  \