b9311e7de4
emitSubslice handled a struct (slice/string) base and an array base, but a many-pointer [*]T base is an LLVM pointer kind — it fell through to the else arm that mapped the result to LLVMGetUndef(slice_ty), so a slice of a many-pointer (mp[lo..hi]) had a garbage .len/.ptr and iterating it segfaulted. Add a LLVMPointerTypeKind branch: the base value IS the data pointer, so GEP by lo and len = hi - lo (the caller supplies the bound; no length is read from the unbounded pointer). An open-ended mp[lo..] has no resolvable upper bound (a [*]T carries no length), so lowerSliceExpr now diagnoses it instead of emitting a .length op that yields garbage. A List (whose items is [*]T) is now iterable with for items[0..len] (e); applied in Scheduler.deinit. Regressions: examples/types/0195 (valid slice + List for-each) + examples/diagnostics/1192 (open-ended rejection).
27 lines
1.1 KiB
Plaintext
27 lines
1.1 KiB
Plaintext
// Slicing a many-pointer `mp[lo..hi]` builds a correct `{ ptr = mp + lo,
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// len = hi - lo }` slice — the caller supplies the bounds (a `[*]T` carries no
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// length of its own). This makes a `List` (whose `items` is `[*]T`) iterable
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// with a `for`-each over `items[0..len]`.
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//
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// Regression (issue 0159): a many-pointer base previously fell through the
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// subslice emitter's `else` arm to an undefined slice (`LLVMGetUndef`), so the
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// resulting `.len` was garbage and iterating it segfaulted.
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#import "modules/std.sx";
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main :: () -> i64 {
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a : [4]i64 = .[5, 6, 7, 8];
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// Slice a many-pointer with explicit bounds.
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mp : [*]i64 = xx @a[0];
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s := mp[1..4]; // { &a[1], len 3 }
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print("mp[1..4]: len={} [{} {} {}]\n", s.len, s[0], s[1], s[2]); // 3 [6 7 8]
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// The payoff: iterate a List with a for-each over items[0..len].
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xs : List(i64) = .{};
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xs.append(10); xs.append(20); xs.append(30);
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sum := 0;
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for xs.items[0..xs.len] (e) { sum = sum + e; }
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print("List for-each sum={}\n", sum); // 60
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return 0;
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}
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