# Unsupported-gap reproducers

One minimal source per known V3 gap (2026-10-18).  Each file's header
comment carries its **tag** and the gm2 corpus file(s) it stands for.
These are *not* part of the test suite (they are expected to fail); they
exist so each gap has a runnable, self-contained example.

Verify one with:

```sh
cd compiler && ./build.sh
./M2 ../docs/gaps/gap07_convert.mod     # prints the diagnostic on stdout
```

## Index

| tag | file | diagnostic | corpus exemplars |
| --- | --- | --- | --- |
| `gap01-fwd-type-const-conv` | `gap01_fwd_type_const_conv.mod` | `undeclared identifier` | `subrange4`, `subrange7` |
| `gap02-fwd-type-var` | `gap02_fwd_type_var.mod` | `undeclared identifier` | `subrange11` (procedure-local part) |
| `gap03-fwd-type-heading` | `gap03_fwd_type_heading.mod` | `undeclared identifier` | `shift3`, `shift4` |
| `gap04-fwd-const-bound` | `gap04_fwd_const_bound.mod` | `undeclared identifier` | `setconst3` |
| `gap05-fwd-type-size` | `gap05_fwd_type_size.mod` | `undeclared identifier` | `constsize2` |
| `gap06-fwd-setconst` | `gap06_fwd_setconst.mod` | `undeclared identifier` | `setoverflow` |
| `gap07-convert-builtin` | `gap07_convert.mod` | `undeclared identifier` | `procconv2` |
| `gap08-set-word-cast` | `gap08_val_cast_set_word.mod` | `not supported yet` | `constset`, `constset2`, `constset3`, `packed`, `bitset5`, `packed` |
| `gap09-scalar-to-bytearray` | `gap09_scalar_to_bytearray.mod` | `invalid call` | `aochar`, `arrayofbyte`, `bytearray` |
| `gap10-var-param-type` | `gap10_var_param_type.mod` | `invalid call` | `testparam2`, `testparam3` |
| `gap11-bare-proc-stmt` | `gap11_bare_proc_stmt.mod` | `invalid call` | `tinyproc2`, `tinyproc4` |
| `gap12-variant-empty-arms` | `gap12_variant_empty_arms.mod` | `invalid VarLabel` | `varient2`, `varient3`, `varient8`, `tsize`, `tsize2` |
| `gap13-builtin-proc-name` | `gap13_builtin_proc_name.mod` | `ident expected` | `fileio.def`, `fileio.mod` |
| `gap14-builtin-pragma` | `gap14_builtin_pragma.def` | `ident expected` | `builtin.def`, `builtin.mod` |
| `gap15a-qualified-import` | `gap15a_qualified_import.mod` (+ `gap15_base.def`, `gap15_lib.def`) | `undeclared identifier` | `impf`, `impk`, `impl`, `impq` |
| `gap15b-from-import` | `gap15b_from_import.mod` (+ `gap15_base.def`, `gap15_lib.def`) | `undeclared identifier` | `impi` |
| `gap16-wide-set` | `gap16_wide_set.mod` | `not supported yet` | `settest1` |
| `gap17-set-of-cardinal` | `gap17_set_of_cardinal.mod` | `not supported yet` | `settest3` |

Observed first diagnostics (line:col) at commit time:

```
gap01_fwd_type_const_conv.mod:5:13   undeclared identifier
gap02_fwd_type_var.mod:7:9           undeclared identifier
gap03_fwd_type_heading.mod:5:17      undeclared identifier
gap04_fwd_const_bound.mod:5:19       undeclared identifier
gap05_fwd_type_size.mod:5:17         undeclared identifier
gap06_fwd_setconst.mod:5:12          undeclared identifier
gap07_convert.mod:8:12               undeclared identifier
gap08_val_cast_set_word.mod:7:35     not supported yet
gap09_scalar_to_bytearray.mod:9:13   invalid call
gap10_var_param_type.mod:9:11        invalid call
gap11_bare_proc_stmt.mod:6:7         invalid call
gap12_variant_empty_arms.mod:8:12    invalid VarLabel
gap13_builtin_proc_name.mod:5:11     ident expected
gap14_builtin_pragma.def:5:11        ident expected
gap15a_qualified_import.mod:8:21     undeclared identifier
gap15b_from_import.mod:6:16          undeclared identifier
gap16_wide_set.mod:5:29              not supported yet
gap17_set_of_cardinal.mod:5:19       not supported yet
```

## Not represented by a source

- **Size-sensitive V3 miscompile** — a *latent* codegen bug that only
  manifests at the compiler's own scale (the historical "removing
  `ASTDUMP` breaks the fixpoint"); see `docs/summary_l3_selfhost_fix.md`.
  No small standalone source triggers it.

Companion files (`gap15_base.def`, `gap15_lib.def`) are not gaps
themselves; they model the `impc` → `impb` re-export chain.