Overload-resolution failure dumps compiler internals to stdout

Found 2026-07-19 (noted while filing feature-nilpy-len-of-str; re-filed standalone so it is not lost in a resolved ticket).

$ pascal26 t.npy out
Mismatch in MatchProcCall: name = len, nArgs = 2
  arg[0] = 6
  arg[1] = 1
  Candidate idx 140: paramCount = 1
    param[0] = 6
  Candidate idx 141: paramCount = 1
    param[0] = 23
pascal26:2: error: no overload of len matches these arguments ()

MatchProcCall (compiler/symtab.inc, the if not MatchQuiet block) writes raw internal state — symbol indices and TTypeKind ORDINALS — to stdout ahead of the real diagnostic. It reads as leaked debug output: a user cannot act on param[0] = 23, and it precedes rather than follows the actual error line.

Not wrong, just unpolished — the information is genuinely useful, so the fix is presentation rather than removal:

• render type ordinals as NAMES (str, TPyList) instead of numbers;
• print it AFTER the error line, indented, as "candidates were:";
• gate it behind a verbosity flag, or emit it only when the candidate set is small enough to be readable.

Also note the trailing () on the error text itself ("...these arguments ()"), which looks like an empty format slot.

Low priority: cosmetic, no wrong behaviour. Worth doing before any 1.0-facing polish pass — a leaked-debug-looking dump is the kind of thing that reads as unfinished to a first-time user.

Log

• 2026-07-20 — resolved, commit 36fb2a55.