Build History for pull/1400

Further fixes for duplicate identifiers As well as during loading, we also have to handle `includes` with potentially duplicate identifiers during `lang_of.ml`. This commit moves the 'synthetic parent' functions into path.ml and uses them both in cmti.ml and lang_of.ml

Fix broken test

Fixup mdx tests

Fixup mdx tests

Update CHANGES.md

Fix issue #930: Crash when substituting for the same name at different arities The fix applies inline TypeSubstitution items during include expansion. When a module type containing a TypeSubstitution (like `type 'a t := unit`) is included elsewhere, the substitution is now applied at that point rather than being preserved as-is. Key changes: - Add `apply_inner_substs` function in tools.ml that processes TypeSubstitution, ModuleSubstitution, and ModuleTypeSubstitution items during include expansion - Add `is_elidable_with_u` optimization to skip recompilation for pure signatures - Add assertion for arity mismatch in type substitution to aid debugging - Add `Subst.pp` for debugging substitution maps This matches OCaml's behavior where destructive substitutions are applied to produce a simplified signature when included. Fixes #930, #1385 Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>