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Add proper error for attempted use of undef slot #50556

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Merged
merged 2 commits into from
Jul 16, 2023
Merged

Add proper error for attempted use of undef slot #50556

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eb37e92
Add proper error for attempted use of undef slot
Keno Jul 14, 2023
38ae975
Merge branch 'master' into kf/unusederror
Keno Jul 15, 2023
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6 changes: 6 additions & 0 deletions src/codegen.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4921,6 +4921,12 @@ static jl_cgval_t emit_local(jl_codectx_t &ctx, jl_value_t *slotload)
size_t sl = jl_slot_number(slotload) - 1;
jl_varinfo_t &vi = ctx.slots[sl];
jl_sym_t *sym = slot_symbol(ctx, sl);
if (sym == jl_unused_sym) {
// This shouldn't happen in well-formed input, but let's be robust,
// since we otherwise cause undefined behavior here.
emit_error(ctx, "(INTERNAL ERROR): Tried to use `#undef#` argument.");
return jl_cgval_t();
}
return emit_varinfo(ctx, vi, sym);
}

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5 changes: 3 additions & 2 deletions src/julia-syntax.scm
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Expand Up @@ -296,7 +296,7 @@
(if (eq? n '|#self#|) (gensy) n))
arg-names))))
(let ((body (insert-after-meta body ;; don't specialize on generator arguments
`((meta nospecialize ,@arg-names)))))
`((meta nospecialize ,@(map (lambda (idx) `(slot ,(+ idx 1))) (iota (length arg-names))))))))
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IIRC, there was previously a bug (and open issue) that vararg arguments didn't get nospecialize'd for macros. Any idea if this fixed it?

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I don't think so. This is for generated functions.

`(block
(global ,name)
(function (call ,name ,@arg-names) ,body)))))
Expand Down Expand Up @@ -5051,7 +5051,8 @@ f(x) = yt(x)
(define slot-table (symbol-to-idx-map (map car (car (lam:vinfo lam)))))
(define sp-table (symbol-to-idx-map (lam:sp lam)))
(define (renumber-stuff e)
(cond ((symbol? e)
(cond ((eq? e UNUSED) (error "Attempted to use slot marked unused"))
((symbol? e)
(let ((idx (get slot-table e #f)))
(if idx
`(slot ,idx)
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5 changes: 5 additions & 0 deletions test/syntax.jl
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Expand Up @@ -3507,3 +3507,8 @@ let x = 1 => 2
@test_throws ErrorException @eval a => b = 2
@test_throws "function Base.=> must be explicitly imported to be extended" @eval a => b = 2
end

# Test that bad lowering does not segfault (ref #50518)
@test_throws ErrorException("syntax: Attempted to use slot marked unused") @eval function funused50518(::Float64)
$(Symbol("#unused#"))
end