37bea63302
Scalar K vs array K in two modules: minimal repro panics (unresolved-type LLVM tripwire), the std-tail topology silently clobbers (0786 family reads hash.sx's SHA table as its own K). Blocks the PLAN-STDLIB full-tail follow-up; co-blockers (eager global emission, 0601 comptime-meta, error-int shifts) noted in the issue.
105 lines
4.6 KiB
Markdown
105 lines
4.6 KiB
Markdown
# 0115 — same-name consts of different shapes collide across modules (panic / silent clobber)
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**Symptom.** When two modules in one program declare a same-named module
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const with DIFFERENT shapes (scalar `K : s64 : 4` vs array
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`K : [4]s64 : .[...]`), resolution conflates them instead of selecting
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per-author:
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- **Observed (minimal repro below)**: compiler PANIC — `unresolved type
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reached LLVM emission` (`src/backend/llvm/types.zig:175`, the
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`.unresolved` sentinel tripwire).
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- **Observed (full std-tail topology)**: SILENT WRONG VALUES — a module's
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own scalar `K` reads as the other module's array global (prints the
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array's address or the whole array). Seen corpus-wide when
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`hash :: #import "modules/std/hash.sx"` (hash.sx declares the SHA-256
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`K : [64]s64` table) is added to the std.sx namespace tail: examples
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0786/0787/0788/0789/0791/0793/0794 (same-name-const family), 0162, 0168
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all read hash's `K` instead of their own.
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- **Expected**: own-wins / per-author const selection (the documented F2
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semantics — readme "Own-wins holds at every one of those sites") applies
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regardless of the consts' shapes; no cross-shape leakage, no panic.
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This blocks the PLAN-STDLIB "full tail" follow-up: fs/process/socket/
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json/cli/hash/test cannot join the std.sx namespace tail until same-name
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consts are robust across every module pulled into every program.
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## Reproduction (panic variant — minimal, standalone)
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```sx
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// h.sx
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K : [4]s64 : .[11, 22, 33, 44];
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use_k :: () -> s64 { K[2] }
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```
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```sx
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// main.sx
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#import "modules/std.sx";
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h :: #import "h.sx";
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K : s64 : 4;
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main :: () { print("K={} h.use_k={}\n", K, h.use_k()); }
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```
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Run `main.sx` → panic `unresolved type reached LLVM emission`.
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Expected: prints `K=4 h.use_k=33`.
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## Reproduction (silent-clobber variant — full topology)
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Add the full tail to `library/modules/std.sx` after the existing
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`mem/xml/log` lines:
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```sx
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fs :: #import "modules/std/fs.sx";
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process :: #import "modules/std/process.sx";
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socket :: #import "modules/std/socket.sx";
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json :: #import "modules/std/json.sx";
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cli :: #import "modules/std/cli.sx";
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hash :: #import "modules/std/hash.sx";
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test :: #import "modules/std/test.sx";
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```
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Run `bash tests/run_examples.sh` → ~50 failures. The const-family
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failures (0786 prints `a=4318334368 b=4318334368`, 0162 prints the whole
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64-entry array for `K=...`) are this bug. (A flat-importing main + a
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namespaced array-K module WITHOUT the tail topology resolves correctly —
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the silent variant needs the tail's shape, where hash.sx itself
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flat-imports std.sx. The panic variant above is the minimal entry point.)
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## Co-blockers observed in the same experiment (note, possibly separate issues)
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1. **Eager emission bloat**: with the tail in place, every program emits
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hash's 64-entry `@K` table plus `@OS/@ARCH/@POINTER_SIZE` globals even
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when unused (visible in every pinned `.ir` snapshot). Tail modules'
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globals should emit lazily (only when referenced).
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2. **0601-comptime-meta** prints nothing (comptime meta machinery breaks
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with the tail in place — root cause unknown, possibly same-name
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generic/comptime fn last-wins: `isPlainFreeFn` excludes generic /
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comptime authors from own-wins rerouting).
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3. **1055/1056 errors-enum-value**: user-visible error ints shift when
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tail modules' error sets join the global error-tag registry (numbering
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coupling, arguably inherent; snapshot fragility at minimum).
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## Investigation prompt
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Same-name module consts are selected own-wins via `selectModuleConst`
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(F2, src/ir/lower/expr.zig ~1641) over `module_const_map` — but ARRAY
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consts lower as GLOBALS (`@K = internal global [4 x s64]`), registered in
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a different, still last-wins registry (find it: grep the lowering for
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where a top-level array const becomes a module global — likely
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`lowerGlobalDecl` / the global-var map in src/ir/lower/decl.zig). The
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panic happens because the scalar `K`'s type resolution reads the OTHER
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author's array shape (or vice versa) and poisons to `.unresolved`.
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The fix likely needs:
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1. Source-aware selection for the globals registry, mirroring
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`selectModuleConst` (own-wins, ≥2 flat-visible authors → loud
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ambiguity) — including the MIXED scalar/array case where the two
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authors live in different registries today.
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2. The 0786-family examples already pin scalar/scalar own-wins; add a
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scalar-vs-array pin (the minimal repro above) once fixed.
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Verification: run the panic repro (expect `K=4 h.use_k=33`), then add the
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full tail to std.sx and run `bash tests/run_examples.sh` — the const
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family (0786/0787/0788/0789/0791/0793/0794, 0162, 0168) must pass; the
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remaining tail failures decompose into co-blockers 1-3 above (file
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separately if they persist).
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