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fix(lower): fn-value site lazily lowers winner only on resolver .none [0102d F1]

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The bare-fn-as-value site (func_ref / fn-ptr / closure coercion) eagerly
lazily-lowered the name-keyed first-wins WINNER before the resolveBareCallee
block could reroute a genuine flat same-name collision to its per-source
author. Taking a SHADOW author's fn value therefore lowered (and could
mis-diagnose) the unused winner's body. Move lazyLowerFunction INSIDE blk_fv
onto the `.none` fallback only, mirroring the closure(fn) and free-function
UFCS sites: on `.func` use the resolved author's FuncId and never touch the
winner; on `.none` fall through to lazy-lower + resolveFuncByName the winner.

Regression: examples/0735-modules-flat-same-name-fn-value-winner — the
first-wins winner's body is independently broken and never used; a shadow
taken as a function value binds the shadow and runs (exit 0) while the winner
is not lowered. Fails-before (unresolved symbol in the winner), passes-after.
This commit is contained in:
agra
2026-06-06 16:41:01 +03:00
parent bd24996d8b
commit 96e3d2d5ae
8 changed files with 46 additions and 6 deletions
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17
examples/0735-modules-flat-same-name-fn-value-winner.sx Normal file
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@@ -0,0 +1,17 @@
// fix-0102d site 2 / attempt-2 (issue 0102): the first-wins winner's body is
// independently BROKEN (references an undefined symbol) and is never used. A
// shadow author from a later flat import takes its OWN `pick` as a function
// VALUE (`g : () -> s64 = pick`). The value must bind the shadow (own-author
// wins) and the broken winner must NOT be lowered — a rerouted fn value never
// uses the winner. Before the fix the fn-value site eagerly lazily-lowered the
// name-keyed winner BEFORE the resolver rerouted, surfacing the winner's
// `unresolved 'missing_from_a'` for a function the value never touches.
// Regression: per-source function-value conversion must not pre-lower the winner.
#import "modules/std.sx";
#import "0735-modules-flat-same-name-fn-value-winner/a.sx";
#import "0735-modules-flat-same-name-fn-value-winner/b.sx";
main :: () -> s32 {
print("from_b_value = {}\n", from_b_value());
0
}

4
examples/0735-modules-flat-same-name-fn-value-winner/a.sx Normal file
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@@ -0,0 +1,4 @@
// a.sx authors `pick` (imported first → the first-wins name-keyed winner) but
// its body references an undefined symbol, so lowering a.pick AT ALL is an
// error. Nothing uses a.pick — taking b.pick as a value must not pre-lower it.
pick :: () -> s64 { return missing_from_a(); }

7
examples/0735-modules-flat-same-name-fn-value-winner/b.sx Normal file
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@@ -0,0 +1,7 @@
// b.sx authors its OWN `pick` (returns 2) and takes it as a function VALUE. The
// value binds b.pick (own-author wins), never the broken winner from a.sx.
pick :: () -> s64 { return 2; }
from_b_value :: () -> s64 {
g : () -> s64 = pick;
return g();
}

1
examples/expected/0735-modules-flat-same-name-fn-value-winner.exit Normal file
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@@ -0,0 +1 @@
0

1
examples/expected/0735-modules-flat-same-name-fn-value-winner.stderr Normal file
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@@ -0,0 +1 @@

1
examples/expected/0735-modules-flat-same-name-fn-value-winner.stdout Normal file
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@@ -0,0 +1 @@
from_b_value = 2

11
issues/0102-flat-import-same-signature-collision.md
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@@ -60,7 +60,9 @@ collision:
args fill from the RESOLVED author's defaults, not the winner's.
2. **Function-value conversion** (`closure(fn)` and the bare-fn-as-value
`func_ref` / fn-ptr / closure-coercion path): captures the resolved
author's FuncId.
author's FuncId. The winner's body is lazily lowered ONLY on the `.none`
fallback — a rerouted value never uses the winner, so taking a shadow as a
value must not pre-lower (and possibly mis-diagnose) the winner's body.
3. **Free-function UFCS** (`recv.fn()` → `fn(recv, …)`): dispatches the
resolved author for the receiver's source.
4. **Comptime `#run`** of a bare call: `lowerMainAndComptime` now sets
@@ -71,7 +73,7 @@ collision:
## Regression tests
`examples/0722`–`0734` (each a focused multi-file flat-collision scene that
`examples/0722`–`0735` (each a focused multi-file flat-collision scene that
fails on pre-fix code and passes after):
- `0722-modules-flat-same-name-own` — own-author wins on the call path.
@@ -93,3 +95,8 @@ fails on pre-fix code and passes after):
callee.
- `0734-modules-flat-same-name-ufcs-ambiguous` — `≥2` flat authors, UFCS call
→ loud diagnostic (pre-fix: silently bound the winner).
- `0735-modules-flat-same-name-fn-value-winner` — the first-wins winner's body
is independently broken and never used; a shadow taken as a function value
binds the shadow and runs while the winner is NOT lowered (pre-fix: the
fn-value site eagerly lowered the winner before the resolver rerouted,
surfacing the winner's error for a function the value never touches).

10
src/ir/lower.zig
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@@ -3250,14 +3250,13 @@ pub const Lowering = struct {
const str = self.builder.constString(sid);
break :blk self.builder.boxAny(str, .string);
}
if (!self.lowered_functions.contains(eff_fn_name)) {
self.lazyLowerFunction(eff_fn_name);
}
// fix-0102d site 2: taking a bare same-name fn as a VALUE
// (func_ref, fn-ptr / closure coercion) must capture the
// RESOLVED author's FuncId for a genuine flat collision, not
// the first-wins winner's. Plain bare name only; `.ambiguous`
// → loud diagnostic; `.none` → existing first-wins path.
// → loud diagnostic; `.none` → existing first-wins path. The
// winner is lazily lowered ONLY on `.none` — a rerouted value
// never uses the winner, so its body must not be lowered.
const value_fid: ?FuncId = blk_fv: {
if (std.mem.eql(u8, eff_fn_name, id.name) and
self.program_index.ufcs_alias_map.get(id.name) == null and
@@ -3275,6 +3274,9 @@ pub const Lowering = struct {
}
}
}
if (!self.lowered_functions.contains(eff_fn_name)) {
self.lazyLowerFunction(eff_fn_name);
}
break :blk_fv self.resolveFuncByName(eff_fn_name);
};
if (value_fid) |fid| {