Fix issue with memory allocations in lisp::serialise

Was to do with sv_make.

oats.org

@@ -4,15 +4,6 @@
 #+FILETAGS: :oats:
 
 * Issues :issues:
-** TODO Fix issue with memcpy overlap when string concatenating
-[[file:lisp/lisp.c::// FIXME: Something is going wrong here!]]
-
-Ideas on what's going wrong:
-- String sizes seem off
-- Maybe something is wrong with arena allocator; we use
-  [[file:lib/sv.c::newsv.data = arena_realloc(allocator, sv.data,
-  sv.size, newsv.size);][arena_realloc]] which seems to be the root of
-  the memcpy-overlap
 * Features :features:
 ** WIP Reader :reader:
 We want something a bit generic: able to handle reading from some
@@ -205,3 +196,18 @@ more work than the lowest byte (to look at it we'll need to push that
 byte all the way down).  So we'll be going for a low byte strategy by
 shifting the pointer up by one byte.  This leaves us with the lowest
 byte to play with as we choose.
+** DONE Fix issue with memcpy overlap when string concatenating
+[[file:lisp/lisp.c::// FIXME: Something is going wrong here!]]
+
+Ideas on what's going wrong:
+- String sizes seem off
+- Maybe something is wrong with arena allocator; we use
+  [[file:lib/sv.c::newsv.data = arena_realloc(allocator, sv.data,
+  sv.size, newsv.size);][arena_realloc]] which seems to be the root of
+  the memcpy-overlap
+
+2025-05-30 08:11:24: Was an issue with ~sv_make~; if you pass a data
+pointer, it will try to copy the size you passed as bytes from the
+pointer.  In ~sv_concat~ we pass the overall new size of the string
+we're allocating and pass in the first argument to copy in the initial
+part of the data first.