Joseph Ferano
9e0ae3a4ce
Running a macro means compiling it and loading it into the compiler, and the step that reads as small in NEXT.md is not: OCaml has no dlopen for ELF, and lib/dune had no foreign_stubs. So the boundary is built first and the expander not at all. lib/dynload_stubs.c is the whole of it — dlopen, dlsym, a four-argument call into a macro thunk, and a peek/poke family, because OCaml cannot address the raw memory a Form image has to be laid out in. Nothing aggregate crosses to C. The unions lane verified a union's memory layout against clang, which is a different claim from LLVM's convention for an aggregate passed or returned by value in hand-written IR, so Emit.macro_thunk wraps every macro in void(ptr,i64,ptr,ptr): the slice is built and the result stored on the LLVM side, and the compiler's side is four pointers. Build.macro_module links the runtime in rather than declaring it external, so the module has no undefined symbols and the compiler's own link needs no -rdynamic. That is the difference from Build.shared, whose host is a running Flan program. defunion Form and the list-building surface quasiquote will desugar into are in the prelude. Form mirrors Form.value and not Form.t: no loc field, so the compiler stamps the call site's location onto everything a macro returns. The compiler builds. dune test was not run, and Form's layout is asserted nowhere — NEXT.md's new handoff section says what the three numbers are, what the next two commits should be, and the four decisions this made that the design did not settle.
