feat(t27b): module constants of a struct with str fields - #6324
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A module constant whose struct (or array) type holds a str at a leaf is lowered as a compile-time aggregate (Val::A, one element per field) and written into a frame temporary where memory is needed, as a constant array of strings already was. A module var of such a type stays refused as VarDecl(module, pointer/str/slice). Reference-backed corpus: counted pass 592 -> 597 of 720, mismatch 0. Closes #6323 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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This was referenced Oct 5, 2026
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Closes #6323
Refs #6063
What
ConstDecl(str field)was first in the reference-backed greedy order (tri t27b next): sole blocker on 5 specs the reference passes. Shape:const PIN_CLK: PinAssignment = PinAssignment{ .port_name = "clk", .bank = 35, ... };-- a module constant of a struct withstrfields. t27b kept struct constants as read-only data images, which cannot hold a string's address.Now such a constant (and any array/struct constant with a
strat a leaf) is a compile-time aggregate (Val::A, one element per field: string literal, nested aggregate, read-only image of a str-free aggregate, or constant scalar/enum), written into a frame temporary where memory is needed -- the path constant arrays of strings already took.holds_strnow looks through struct fields;store_constwrites struct fields too;coerce_toaccepts it where a struct is wanted. A modulevarof such a type stays refused asVarDecl(module, pointer/str/slice)(writable data would need relocations).Test:
struct_constants_with_str_fields(fields, defaults, enum and nested struct fields, alias, by-value and by-pointer params, copy-then-mutate, arrays of such structs, runtime index,for, a failing assert with its line). Same source throught27c test-report: 3 pass, 1 fail -- same verdicts.Corpus (
t27b corpus specs --blockers --reference <t27c master e8513e0b5>, 1257 files, reference passes 720)Gain: +5 counted (checked 317 -> 322):
specs/boards/arty_a7.t27,specs/boards/xc7a100t_full.t27,specs/fpga/boards/arty_a7_integration.t27,specs/fpga/boards/qmtech_a100t_integration.t27,specs/port/trios/crates/trios-cli/src/metrics.t27. The sixth reference-passing file,specs/boards/xc7a100t_minimal.t27, is now blocked byVarDecl(module, pointer/str/slice)(modulevar all_pins: [12]PinAssignment) -- not small, left for a later lane.Reference-backed top 5 after: ExprLiteral(char literal) +4, ExprIf +5, StmtExpr +4, StmtFor +4, ExprArrayLiteral +4.
Load average during the runs: 5-60.
docs/reports/t27b_expectations.jsonuntouched (the steward blesses it from the lab).🤖 Generated with Claude Code