8c47268539
Erasing a single comptime-pack element to a protocol value (`xx sources[0]` with a protocol target) tripped the pack-as-value error: buildProtocolErasure treated the index_expr as an lvalue and took its address via lowerExprAsPtr, whose .index_expr arm lowers the bare pack as a value (a pack is comptime-only with no runtime storage). isLvalueExpr now reports a comptime pack index as an rvalue, decided via the same packArgNodeAt predicate the value path uses — so the value and lvalue paths can't diverge on what counts as a pack element — and erasure heap-copies the already-materialized element instead. Resolves issue 0135. Regression tests: examples/0547, 0548.
28 lines
1.0 KiB
Plaintext
28 lines
1.0 KiB
Plaintext
// `xx <pack>[i]` erased to a protocol-typed local.
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//
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// Erasing a single comptime-pack element to a protocol scalar routes through
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// buildProtocolErasure. A pack index is a comptime rvalue (a pack has no
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// runtime storage — `sources[i]` resolves to the call-site arg, which only
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// gets storage when lowered as a value), so the erasure must heap-copy the
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// materialized element rather than take its address.
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//
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// Regression (issue 0135): `xx sources[0]` used to lower the bare pack as a
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// value and error with "pack 'sources' has no runtime value".
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#import "modules/std.sx";
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VL :: protocol(T: Type) { get :: () -> T; }
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IntCell :: struct { v: i64; }
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impl VL(i64) for IntCell { get :: (self: *IntCell) -> i64 => self.v; }
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first :: (..sources: VL) -> i64 {
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x : VL(i64) = xx sources[0]; // erase element 0 to VL(i64)
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return x.get();
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}
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main :: () -> i32 {
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print("{}\n", first(IntCell.{ v = 7 })); // 7
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print("{}\n", first(IntCell.{ v = 42 }, IntCell.{ v = 99 })); // 42 (element 0)
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0
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}
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