The --emit-header path previously called parse() which builds the entire
program AST in memory before writing the .elh file. For checkout.el (~491
lines with HTML template trees and deep BinOp string-concat chains), this
exhausted memory before the header could be written.
Fix: replace parse() + emit_header() with scan_fn_sigs_el() +
emit_header_from_sigs(). The new path tokenises the source once, then
walks the flat token list skipping over function bodies entirely — peak
memory is O(tokens) instead of O(whole-program AST).
New functions in parser.el:
- scan_type_el: reads a type annotation and returns its El source string
- scan_params_el: reads (name: Type, ...) and returns El params string
- scan_fn_sigs_el: token-level scan that collects El-style fn signatures
without building any expression AST nodes
New function in compiler.el:
- emit_header_from_sigs: writes .elh from scan_fn_sigs_el output
Self-hosting check: elc compiled with new elc, diff of outputs is
identical (zero difference).
Smoke test: elc --emit-header checkout.el produces correct three-entry
.elh (previously truncated at two entries due to mid-parse OOM).
will.anderson
5f9cad5908