jolt/host/chez/cli.ss
Dmitri Sotnikov 8180c85393
Source locations: reader positions, error locations, native stack traces (#218)
* Reader records source line/column on list forms

The reader stamps 1-based :line/:column metadata on every list form (plus
:file when load-jolt-file is reading a file), and jolt.host/form-position
reads it back so the analyzer's :pos scaffold finally gets real data. A
left-to-right cursor counts newlines over the delta between successive forms,
so it stays O(n). Vector/map/set literals are untouched (their metadata is a
runtime value the analyzer would have to wrap in with-meta); empty () can't
carry meta. ^meta now merges onto the position keys instead of clobbering them.

Re-mint is byte-identical (the backend doesn't emit :pos), so this is a pure
scaffold for the error-location work that follows.

* Report source location on uncaught errors

Each top-level form records its source position (thread-local) before it
compiles+evals, and cli.ss jolt-report-uncaught appends 'at file:line:col'
when an error propagates out. Covers joltc -e, joltc run <file>, and
load-string — every interpreted path. Top-level granularity, one set per
form; deeper frames come from the Phase 2 frame walk.

Runtime .ss only, no re-mint.

* Clojure stack traces via source registry + native frame walk

A direct-link build emits (jolt-register-source! short-name ns name file line)
once per fn def — at definition time, so zero per-call cost. On an uncaught
error the reporter walks Chez's native continuation frames (jolt-throw captures
the live continuation via call/cc; host conditions carry their own
&continuation), maps each frame's procedure name through the registry, and
prints a Clojure backtrace 'ns/name (file:line)'. Wired into both the cli and a
built binary's launcher.

Frames are keyed by the short munged fn name Chez actually reports (emit-fn's
letrec self-binding), not jv$ns$name; a cross-namespace collision degrades to
the bare frame name rather than a wrong attribution. The analyzer carries the
original form's position through defn macroexpansion onto the def node.

Calling a non-fn now throws a catchable ClassCastException (via jolt-throw)
naming the operator, instead of a raw Chez error.

Caveats (documented in source-registry.ss): names map only in direct-link/AOT
closed-world builds — the open-world -e/repl/run path falls back to the
top-level location; and pervasive TCO erases tail-call frames, so a mapped
trace shows only the non-tail spine. JOLT_DEBUG_FRAMES dumps raw frame names.

Re-mint (analyzer + backend); prelude byte-identical (direct-link off during
mint). Corpus rows certified, build-smoke asserts the trace.

* Propagate source position through macroexpansion

hc-expand-1 now carries the macro call form's :line/:column onto the top of a
list expansion that has none of its own (merged under any meta the macro set),
so errors and stack traces in macro-generated code point at the call site —
Clojure parity. The analyze recursion re-expands inner macros, so each level's
top form picks it up, matching the reference compiler. (meta (macroexpand-1
'(when x y))) now reports the call-site line.

A direct-link fn defined through a user macro (build-app's defguarded) registers
with a real line, so build-smoke's trace assertion covers macro-defined fns.

Runtime .ss (host-contract.ss) — no re-mint; selfhost holds.

Phase 3's optional items are deferred: :line-in-ex-data has no clean consumer
(it would pollute ex-data, break = and printing, and positions already surface
via the trace + top-level location), and Chez source-object emission is a large
backend change the jv$-name registry already sidesteps.

* Review fixes: registration key, thread-locals, debug flag timing

- Register a fn under the name Chez actually reports for its frame, not the def
  name: a named fn literal whose name differs from the def (def foo (fn bar …))
  is framed as 'bar', and an anonymous fn def (def foo (fn …)) as jv$ns$foo.
  Both previously registered under the def name and so never appeared in traces.
- rdr-source-file / rdr-pos-cursor are thread parameters, so concurrent compiles
  (futures, core.async) don't clobber each other's file/line attribution.
- Read JOLT_DEBUG_FRAMES at call time: a built binary evaluates top-level forms
  at heap-build time, where a load-time getenv is always unset.

Re-mint (backend + reader); prelude byte-identical, selfhost holds.

---------

Co-authored-by: Yogthos <yogthos@gmail.com>
2026-06-26 02:14:34 +00:00

66 lines
3.3 KiB
Scheme

;; cli.ss — the jolt runtime.
;;
;; Loads the checked-in seed (host/chez/seed/{prelude,image}.ss — the bootstrap
;; compiler) and the spine, then either evaluates a -e expression or dispatches a
;; CLI command (run/-M/repl/path/task) through jolt.main. The loader
;; (loader.ss) turns `require` into real file loading off the source roots, so a
;; multi-file project with deps.edn dependencies runs end to end.
;;
;; Run from the repo root (bin/joltc cd's there); the project dir is JOLT_PWD.
(import (chezscheme))
(define cli-args (cdr (command-line))) ; drop the script name
(load "host/chez/rt.ss")
(set-chez-ns! "clojure.core")
(load "host/chez/seed/prelude.ss")
(load "host/chez/post-prelude.ss")
(set-chez-ns! "user")
(load "host/chez/host-contract.ss")
(load "host/chez/seed/image.ss")
(load "host/chez/compile-eval.ss")
(load "host/chez/png.ss") ; jolt.png — a baked namespace before the snapshot
(load "host/chez/loader.ss")
;; jolt.ffi host primitives (memory / library loading) load AFTER the loader's
;; baked-ns snapshot, so a library's (require '[jolt.ffi]) still loads jolt.ffi's
;; Clojure side (the foreign-fn / defcfn macros, stdlib/jolt/ffi.clj).
(load "host/chez/java/ffi.ss") ; jolt.ffi (FFI: a library binds native code)
;; jolt.main + jolt.deps live under jolt-core; keep them (and stdlib) on the
;; roots so the CLI's own namespaces — and any jolt.* an app pulls in — resolve.
;; A project's resolved deps roots are prepended to these by jolt.main.
(set-source-roots! (list "jolt-core" "stdlib"))
;; Render an uncaught jolt throw (any value, not just a Chez condition) to stderr
;; and exit non-zero, instead of Chez's opaque "non-condition value" dump. The
;; message/ex-data/cause + a mapped Clojure backtrace come from the shared
;; renderer (source-registry.ss); the cli adds the top-level source location.
(define (jolt-report-uncaught v)
(let ((port (current-error-port)))
(jolt-render-throwable v port)
;; The top-level form that was evaluating when this propagated (file:line:col).
(let ((loc (jolt-current-source-string)))
(when loc (display " at " port) (display loc port) (newline port)))
(let ((bt (jolt-backtrace-string v)))
(when bt (display " trace:\n" port) (display bt port)))
(exit 1)))
(guard (v (#t (jolt-report-uncaught v)))
(cond
;; -e EXPR — evaluate one expression and print it (blank for nil). Wrapped in
;; (do …) so a multi-form string evaluates every form and returns the last.
((and (= (length cli-args) 2) (string=? (car cli-args) "-e"))
(let ((result (jolt-final-str
(jolt-compile-eval (string-append "(do " (cadr cli-args) ")") "user"))))
(unless (string=? result "")
(display result) (newline))))
;; otherwise dispatch the argv through jolt.main/-main
(else
;; `build` AOT-compiles an app to a standalone binary — load the build
;; driver (the cross-compiler emitter) on demand so a normal run never pays
;; for it. It defines jolt.host/build-binary, which jolt.main's build cmd calls.
(when (and (pair? cli-args) (string=? (car cli-args) "build"))
(load "host/chez/build.ss"))
(load-namespace "jolt.main")
(let ((mainv (var-deref "jolt.main" "-main")))
(apply jolt-invoke mainv cli-args)))))