Files
sx/library/modules/trace.sx
agra 178449b548 ERR/E3.0 (slice 3c): source snippet + caret in traces
Each trace frame now shows the offending source line with a `^` caret
under the column — in the catch-handler formatter, the failable-main C
reporter, and the comptime path.

The source line is embedded at compile time as a 5th Frame field
(line_text), not read from disk at runtime: the file field is a
basename and a runtime read would add a filesystem dependency that
fails under the test harness and on locked-down targets.

- errors.lineAt(src, offset): shared helper for the whole source line.
- Frame gains line_text (mirrored in emit_llvm getFrameStructType,
  trace.sx Frame, sx_trace.c SxFrame). emitTraceFrame embeds it; the
  interp .trace_resolve extracts it from the source map.
- trace.sx (new spaces helper) and the C reporter render the line +
  a col-aligned caret, guarded on a non-empty line_text.

Snapshots 243/244/247/253 regenerated. Gates: zig build, zig build
test, run_examples.sh -> 291 passed.
2026-06-01 15:43:22 +03:00

95 lines
3.6 KiB
Plaintext

#import "std.sx";
// =====================================================================
// trace.sx — error return-trace formatting (ERR step E3.3).
//
// Reads the thread-local return-trace buffer (ERR E3.1, populated by the
// push/clear wiring in E3.2) and renders it. A `raise` / propagating `try`
// pushes a frame; an absorbing site (`catch` / `or value` / destructure)
// clears the buffer. So at format time the buffer holds exactly the frames
// of failures that escaped to where you're formatting — typically inside a
// `catch` handler (the clear fires when the handler completes, so the body
// still sees the chain) or the (future) failable-`main` wrapper.
//
// Frame resolution (ERR E3.0 slice 3a): in compiled code a frame is a pointer
// to an interned `Frame` the compiler stamped in at the push site, so the
// location resolves in-process with no DWARF and no symbolizer. (The comptime
// path — a packed `(func_id, ir_offset)` resolved via the interpreter's IR
// tables — lands with slice 3b.)
// =====================================================================
libc :: #library "c";
// The compiled return-trace frame. Layout MUST match `getFrameStructType` in
// src/ir/emit_llvm.zig and `SxFrame` in library/vendors/sx_trace_runtime/sx_trace.c.
Frame :: struct {
file: string;
line: s32;
col: s32;
func: string;
line_text: string; // the source line, for the snippet + caret
}
// `n` spaces — used to position the `^` caret under a column.
spaces :: (n: s32) -> string {
s := "";
i : s32 = 0;
while i < n {
s = concat(s, " ");
i = i + 1;
}
s;
}
// The error-trace buffer C API (library/vendors/sx_trace_runtime/sx_trace.c),
// linked in for the JIT and auto-injected for AOT when traces are used.
// `frame_at` returns the raw stored `u64`; `__trace_resolve_frame` turns it
// into a `Frame` — by reinterpreting the stamped `*Frame` in compiled code, or
// by resolving the packed `(func_id, span.start)` in the comptime interpreter.
sx_trace_len :: () -> u32 #foreign;
sx_trace_truncated :: () -> u32 #foreign;
sx_trace_frame_at :: (i: u32) -> u64 #foreign;
write :: (fd: s32, buf: [*]u8, count: usize) -> isize #foreign libc;
// Render the current trace buffer to a string (allocated from
// context.allocator). Empty buffer → "" so callers can cheaply skip output.
to_string :: () -> string {
n := sx_trace_len();
if n == 0 { return ""; }
result := "error return trace (most recent call last):\n";
if sx_trace_truncated() != 0 {
result = concat(result, " ... older frames omitted (buffer full)\n");
}
i : u32 = 0;
while i < n {
f := __trace_resolve_frame(sx_trace_frame_at(i));
result = concat(result, format(" {} at {}:{}:{}\n", f.func, f.file, f.line, f.col));
if f.line_text.len > 0 {
result = concat(result, format(" {}\n", f.line_text));
result = concat(result, concat(" ", concat(spaces(f.col - 1), "^\n")));
}
i = i + 1;
}
result;
}
// Write the current trace to stderr (fd 2). No-op when the buffer is empty.
print_current :: () {
s := to_string();
if s.len > 0 {
write(2, s.ptr, xx s.len);
}
}
// Dump the comptime (`#run`) interpreter call-frame chain (ERR E4.1). At
// comptime the interpreter walks its active sx frames and appends them to the
// build output; in compiled code this folds to nothing (there is no
// interpreter stack — the only caller is a dead `is_comptime()` branch).
// Frame source locations await IR-offset resolution, so only names print today.
print_interpreter_frames :: () {
__interp_print_frames();
}